: Catera coolant leak

01-01-06, 10:58 AM
I heard someone talking about coolant leaking from a Catera at the rear of the engine but the water valve had already been replaced. I thought it didn't belong where I saw it so I thought I'd talk about it here.

On the top of the engine, in what would usually be a "valley" they installed a metal plate. This plate has sealer around the edges and bolts to the engine block but in it is mounted the oil cooler. Below the plate is coolant flowing through the engine to remove heat from the engine oil. Why they mounted this thing under the intake I'll never know, but needless to say if you have a pretty good coolant leak from this area it's likely this plate leaking.

You have to remove the upper and lower intakes and move some pipes, remove some banjo bolts and take off the coolant crossover in the back.
I have only done it a couple times so I'll post the images I think might help but this job is not for the timid. It could take you an entire day and if you mess up, you'll have to do it all over again, I'd advise finding someone who can work on this with some degree of skill.

Here are some images.

01-01-06, 11:45 PM

Good to know info - and thankyou for the tips.


By the way, looks like ours will be going in Wednesday :bomb:

01-02-06, 06:46 AM
Glad to be able to help.
They use an RTV type sealer around the base of the plate, it has a tendency to leak after temperature cycling with that pressure on it from the cooling system. I am not sure what the total charge is but I know it's a bit pricey.

01-02-06, 04:51 PM
Could it be the coolant cross flow valve for the heater core thats on the back of the engine also because mine waqs cracked and leaking also and i first thought it was that oil cooler to

01-02-06, 06:15 PM
The water valve is a definite player in that area.
The person that I was talking to said that they had already replaced the water valve but still had a leak from the same area.
Sorry I didn't clarify that in my original post.

Make sure to check the water valve back there before tearing into this one.
Thanks for reminding me.

01-02-06, 07:17 PM
I just replaced the HCV in my '01 yesterday .... and I'm happy to say that took care of the leak. Surprisingly, I went to the dealer today and had them run my VIN to get a record of all the warranty work that's been done to date (I'm not the original owner), and foound that this valve was replaced once before at ~20K miles. Apparently, this is almost a maintenance item! Good thing it's only $50 and can be changed in your garage!

01-10-06, 02:35 PM
Are there any step by step instructions on how to get to the oil cooler? Removing the upper and lower intakes, ect.?

I beleive mine needs to be replaced. I removed the two intake tubes from the front of the engine today and saw what looked like burnt crusted coolant all down below the intakes. I've had a sercious coolant leak from the back of my engine so it's a pretty safe bet that this is the problem. So anyway are there any step by step instructions on replacing this shitty cooler?

01-10-06, 02:46 PM
Nevermind I found the document that JefferyG posted.

http://autos.groups.yahoo.com/group/CateraOwners/files/Cadillac%20Catera%20TSB%20%26%20Service%20Files/%20Replace%20Oil%20Cooler/ Heres the link. Easier access because this thread is always at the top.

01-21-06, 03:42 PM
Nevermind I found the document that JefferyG posted.

http://autos.groups.yahoo.com/group/CateraOwners/files/Cadillac%20Catera%20TSB%20%26%20Service%20Files/%20Replace%20Oil%20Cooler/ Heres the link. Easier access because this thread is always at the top.

Now thats instructions on how to fit an "Oil Cooler" what you have in fact on the Catera/Opel/Vauxhall and why its located in the V of the Cylinder Block is in fact NOT an Oil Cooler but to give its correct tital a HEAT EXCHANGER.

Every dam forum calls it an Oil Cooler, which it is and isn't Oil coolers dont have coolant flowing on one side and oil on the other they are also located at the front of a car/motorcycle not in one of the hotest locations outside an engine, hope thast clears this up.


01-21-06, 11:30 PM
Why is this unit referred to as an "Oil Cooler" in the official GM service manuals if in fact it is not?

01-22-06, 09:33 AM
Maybe the term is not scientifically correct, but the principal is that heat is taken out of the oil and transferred to the coolant.
Seems to me that it makes the oil cooler than it was when it went in.

Most oil coolers on other cars are located in the radiator side tanks, but it's still the same principal.

As much fun as it is to argue semantics, comments like that can serve to confuse more people than it helps.
Walk into a parts store and ask for a "heat exchanger" and see what you get.
I think they call it that for the sake of convenience.

Mike in Ohio
01-22-06, 04:40 PM
Iím about to break into oil cooler next weekend on a Ď98. I have a couple of questions:

Do you recommend draining the oil and coolant before doing the procedure? Itís time for an oil change anyways so I figured Iíd do that but didnít want to drain the coolant unless I needed to. I imagine the best bet is to drain the coolant, do the procedure, flush, then refill if this is necessary to begin with.
The GM shop manual mentions you have to remove one of the catalytic converter in order to remove the feed/return lines by the oil filter Ė would you recommend that? Also mentions removing part of the exhaust heat shield - same question on that as well.
Any clue what pressure to test the cooler at for leaks? Was going to try and hydro test it myself.
I see several items mentioning washers/gaskets at the banjo bolts at the oil cooler itself - are there similar ones at the connection point by the oil filter that need to be replaced?

Thanks for any advice you have.

01-22-06, 07:52 PM
Draining the oil isn't required, but you have to remove the cooler and the filter so it won't hurt.
Draining the coolant is more important, I'd go ahead or it's going to get everywhere.
You don't have to remove the catalyst, but you do have to reach behind the motor and loosen the bracket for the oil lines in order to reposition them, I think the fittings on the block screw in with flare nut fittings, they could be banjo bolts, I have to confess I have only done this job twice.
I try to stay away from Cateras because I don't know them as well as I do other cars.
Cooling system pressure tests should be about whatever rating is on the cap, if that's what you mean. Most caps are rated for 15 psi or 16 psi.
I don't know of any way to test the cooler itself for holding oil, I have never seen one leak oil though.

Good luck and be patient. Don't rush yourself and don't get frustrated.

02-02-06, 02:51 PM
Just finished this job amoung many others on my 97 catera. I started her for the first time in two months today. I need to re-fill the cooling system and then Im going to drive it around for awhile to see whats what. After that I'm plaining on changing the oil.

Good luck to anyone going to do this job. It sure is a lot of work.

03-30-06, 11:08 AM
hi there,
the purpose of the heat exchanger is to heat up the engine oil faster by supporting the heating process with hot coolant.
that way the oil get hot a lot faster than in a regular engine.
that is a great idea cuz the faster the oil becomes hot the less the engine wears out.
sideeffect is that the oil doesnt become a lot hotter than the desired oiltemp.
cuz the coolant keeps it at a certain level.
hope my english wasnt too bad.

04-02-06, 11:03 PM
hi there,
the purpose of the heat exchanger is to heat up the engine oil faster by supporting the heating process with hot coolant.
that way the oil get hot a lot faster than in a regular engine.
that is a great idea cuz the faster the oil becomes hot the less the engine wears out.
sideeffect is that the oil doesnt become a lot hotter than the desired oiltemp.
cuz the coolant keeps it at a certain level.
hope my english wasnt too bad.


From an engineering perspective, we live in a world of tradeoffs. Years ago rapid oil warmup doubtless enhanced oil lubricity and engine lubrication. This was good. It is what we got in the tradeoff for a heat exchanger which can, at times, become problematic.

That was then and this is now.

Today we live in a world of highly engineered, sophisticated, multigrade oils. These exhibit excellent lubricity over a far wider temperature range than oils of old.

Also, many regions of the USA do not experience seriously cold weather regardless the season.

My personal view::stirpot:

Today use of a heat exchanger carries more downside potential than upside benefit.

I agree with the course taken by other posters here who deep sixed their heat exchanger in favor of an aftermarket oil cooler.

Also for USA Catera owners living in warm or hot regions of our country:

An aftermarket oil cooler, as contrasted with use of the heat exchanger, moves oil heat directly to air. This has the effect of increasing your cooling system capacity. It is akin to fitting a stouter radiator. And it is smart. Here is why:

The Catera can be intolerant of overheating. It has aluminum heads resting atop a cast iron block. These metals have significantly differing coefficients of expansion which can cause trouble out at the edge of the envelope. Especially for owners operating in warmer climates, it is wise to add to your cooling system capacity cushion.

A badly overheated Catera all too often becomes a dead Cat.

JMHO, of course.

04-03-06, 11:55 AM
i can see that. and i agree to your oppinion.
i simply forgot that its warmer in the US. as where here we can really use the heat exchanger.

06-10-06, 04:45 PM
I have recently run into the a problem where my Radiator Fan, is running all the time until it kills my battier. The been disconnecting my battier unitl I can take it into a shop. of coarse its a 2001 with a coolent light that came on a couple of month after I purchased the car. I love the Catera it just seems to have so many problems with the electrical system and being too hot. Any way, My alwasy on fan, is killing my battier, I think it must be a sensor or something. anyone have any Ideas.


08-21-06, 02:16 PM
I have a pretty bad coolant leak at the bottom of the engine. I think its leaking oil in the same area. I had it almos over heat once because i had no coolant. coolant keeps disapearing errr. Where is the water valve located?

08-21-06, 06:52 PM
Here is a picture. It wasnt leaking as strong but u can see a little.. looks like the leak is coming from that hose and then sprying up and back while driving. what is that hose for?


08-21-06, 07:27 PM
more pics.
It actualy looks like its coming from higher up now.. any help would be greatly apreciated.

the second one shows how bad the leak is (pic taken about 20 min after runing the engine and shutting off. I havent spoted oil yet. its mostly water and coolant by the looks.

08-23-06, 11:14 AM
Heater cross flow valve seems to be where the leak is coming from. Anyone know the part number?

09-01-06, 12:25 AM
mine started leaking, AGAIN, a couple weeks ago. Last summer it was heater control valve. This time it's the head gaskets. Local shop wants $1200 just for labor! Found a GM mechanic that will do it for $700 incl. parts. Waddaya think?

09-10-06, 06:42 AM
mine started leaking, AGAIN, a couple weeks ago. Last summer it was heater control valve. This time it's the head gaskets. Local shop wants $1200 just for labor! Found a GM mechanic that will do it for $700 incl. parts. Waddaya think?

These problems are routine Cat problems. You gotta tell us how many MILES are on your car!!

It's a lot of money. If you have high miles it might be time to sell her, take that money and the seven hundred, and go buy a newer Cat; a 2000 or 2001 if you can find one.

If your Cat is a low mileage cream puff, spend the seven hundred for sure.

10-09-06, 08:33 PM
Heater cross flow valve seems to be where the leak is coming from. Anyone know the part number?

It's officially called the "Heater Control Valve" & GM Part# 90566947

I just changed mine from what I've heard the hard way (removed the upper intake). I heard that you can take out the wiper blades & remove the cowl cover per this http://www.cadillacforums.com/forums/169213-post1.html

01-02-07, 01:15 PM

I am new to the forum and I am looking for some info/advice. I have a 98 Cat with 75K miles. I have a coolant leak, and I am in the processes of diagnosing the leak. I did take it to the dealer and they said it was the head gasket $$$.

I removed cowl and wiper motor HCV does not appear to be leaking. Next I would like to confirm it is not the Oil Cooler (heat exchanger), prior to dismantling the intake.

The leak appears to be coming from the drivers side near the exhaust manifold. It is difficult to spot the actual origin. I have used a mirror to inspect from the bottom. Anyway to easily tell if the source is the head gasket or oil cooler?

Thanks in advance...


01-02-07, 05:27 PM
From what I know, the coolent only leaks into the oil when it's the cooler. In my opinion, it's not too hard to reseal just in case (probably should, because it's notorious). Have you tried leaving the cowl & wiper motor off & just driving around for 10 minutes & then checking to see if the leak is more visible?

01-02-07, 05:39 PM
That's exactly what I did prior to taking the photo. I did find a thread that mentioned air bubbles in the overflow tank is a sign of damaged head gasket (air entering system). Unfortunately I do see small air bubbles entering the overflow tank.

Has anyone tried using "stop leak or miracle cure products", or would I be doomed to replace the gasket?

It is difficult to see exactly the leaks origin (tight space).


Marks DTM Calib
01-03-07, 02:53 AM
The headgaskets dont fail and cause water leaks on these power plants.

In the very rare occasison they do fail (normaly following infrequent coolant changes causing rotting of the head gasket composite material) it results in water in the cylidners and NOT being elaked from the block.

As said before....the favourites are:

1) Heater bypass valve
2) Thermostat to block seal
3) Oil cooler plate to block seal
4) Coolant brdge seals

and in very rare cases

5) Coolant pipe to rear of block seal

Numbers 2-5 will result in water around the bellhousing as they are in or around the valley area of the block....

01-04-07, 06:12 PM
Looks like we have a winner behind door number 2 (Thermostat). I am enjoying a CAT that doesn't leak and a well deserved ice cold beer.

The job is not that bad, could probably do again in about 1/2 to 1/3 the time. The integrated thermostat/housing on the CAT is located on the top forward part of the block, just in front of the oil cooler, under the plenum and injectors (I remember these being in plain view and two separate parts, housing and thermostat, things have come a long way since my 69 Chevy):yup:. The most difficult part I found was removing the aluminum tube that passes thru the head and connects the thermostat/housing to the upper radiator hose.

The removal/installation of the hidden bolt that secures the aluminum tube to the block was the most challenging part of the job (no space, and working blind). I used a star socket and a thin breaker bar to free the bolt, then used a small 10mm box wrench to extract once it was freed. This bolt secures the dipstick, aluminum tube bracket and another metal/plastic bracket to the block. I would hate to strip either the bolt or the threads, as I could not imagine having to repair it.

I found in twisting the tube (as mentioned in other posts) counter-clockwise, the bracket wedges against the block and frees it from the thermostat housing. The thermostat housing and aluminum tube are held together by two "O" rings seated on the tube.

Also mentioned in other post, I did get the thermostat and "O" rings from the dealer. The thermostat/housing is slightly different then the original thermostat/housing. I was able to remove the old one without removing the lower portion of the injectors (spacer), but needed to remove it to install the new one. Also, the two bolts that secure the thermostat needed to be about 1/2" longer. I applied a small amount of anti-freeze to the seal on the thermostat and two "O" rings prior to installation, rather then oil.

I have attached some photos of the new and old thermostat housing and connector tube. Notice the gasket on the old thermostat is non-existent, as well as the thickness of the bolt holes between new and old. The other photos are of the aluminum tube/bracket.

I would like to thank you for your help...



01-04-07, 06:48 PM
I thought the 98's ran DEXCOOL or compatible... Why is your fluid green?

01-04-07, 06:51 PM
It's actually my dads car, this is the first time I have worked on it.

Do I need to flush/replace the anit-freeze????


01-04-07, 09:55 PM
DEXCOOL is the orange stuff. I was surprised to see green antifreeze in your pictures, but maybe only the 99+ engines are dexcool. Anyone know if the older engines, or current for that matter, are happy with the green stuff? Supposedly

I know prestone sells an antifreeze that is supposed to work with either color fluid, but I thought that was yellow in color. Maybe there is a green one as well.

Interesting articles http://www.imcool.com/articles/antifreeze-coolant/dexcool-macs2001.htm

They mention corrosion issues that suggest a full coolant flush if you see oxide buildup on components.

01-04-07, 09:57 PM
Interesting response from Chad in the other Catera forums:


So, maybe running green is okay if you are sure the coolant was flushed completely.

Marks DTM Calib
01-05-07, 02:58 AM
Over in the Uk many of us have now converted across to the long life red stuff......including units as old as 95.......nothing realy changed on the cooling setup throguhout the manufacturing life of this power plant and hence the red is fine. (it was factory fit in the UK as of 2001)

Just make sure its a 50:50 mix and changed every 2 years!

01-09-07, 02:06 PM
Well, it appears the leak is still present after the thermostat has been replaced:hmm: . I would like to investigate option 5) Coolant pipe to rear of block seal.

What is the best way to gain access to this part of the engine (any tips/hints)?

Thanks in advance

Marks DTM Calib
01-10-07, 03:45 AM
Pop the plenum off and remove the inlet system so you can see the valley. At the the rear of the valley you will see a large stainless steel pipe that travels around the 1-3-5 cylidner head to the rear where it attaches with two torx headed bolts (T12 I think), access to them is easier if you remove the heater bypass valve and associated pipes (two faston connectors to the bulk head, one clamp to the coolant bridge and one to the stainless coolant pipe plus a single vaccum connection).

There is an additional fixing screw on the 1-3-5 head into the lifting bracket and then two coolant pipes to remove, one to the header tank and the main return pipe from the rad. It should now move enough to get to the O-ring and allow it to be replaced. Do clean the block surface with some fine carboundrum paper (emery) before re-fitting.

Whilst its stripped inspect the vallet for signs of leaks paying attention to the stat to block seal, oil cooler plate and coolant bridge seals.

01-10-07, 07:18 AM
I appreciate the clear/detailed instructions. I will do this shortly (today/tommorrow), as I plan to replace the oil cooler in the process.


Marks DTM Calib
01-10-07, 08:22 AM
If doing the cooler......disconnect the oil pipes at the block end first....dont bend them as it can result in oil leaks and they are a swine to refit once bent!

Also make sure the block etc is fully clean before applying the grey sealent, I also us this sealent on the thermostat to block interface to.

01-12-07, 08:34 PM
I was a little late in reading your post:eek: ...

Oil cooler replaced, looks like my coolant leak is solved. Will need to drive for a while. I did not seal the thermostat with the RTV, gasket should hold for the remaining expected life.

I did bend the oil line slightly near the front of the block a bit to get the oil cover off. During installation, I started block/oil line nuts then tightened cooler/oil line nuts, then went back and tightened block/oil line nuts.

I did notice smoke on the drivers side exhaust manifold (burning oil). I have my fingers crossed as there was some spillage when topping off the oil, time will tell. Your warning on the bend has me a bit concerned. (Is the leak resulting from bending due to a kinked/cracked line, or poor seal at the block/oil line nut???)

I replaced the Heater Control Valve even though it was not leaking (precaution).

Flushed radiator, and purged until water ran clear, replaced standard green anti-freeze with DEX-COOL.

Added a container Techron Fuel Injector cleaner and a filled-up of High Test...

Also checked the records and the timing belt tensioner recall was taken care of in 2002 at ~40K.

Anything else that will need attention on a 98 CAT with ~75K miles, or should I start a new thread...

Thanks Again:thumbsup: ...

01-13-07, 07:59 AM
Just a quick follow-up.

Could someone tell me the book hours for oil cooler replacement, thermostat replacement and heater control valve replacement?

Also, has anyone replaced, or thought of replacing the hard oil cooler lines with flexible lines?


01-14-07, 10:10 AM
Burning Oil odor went away after a few days. It must have been residual oil that spilled when filling.

There was one hose that did not appear to be connected, and if I re-call it was not connected prior to dis-assembly. Also the end does not seem to be distorted as is typical when fitting a hose to a barbed connector and tightened with a clamp.

Is this a drain hose, or does it need to be attached (vacuum hose)?

See photos.




Marks DTM Calib
01-15-07, 02:45 AM
Thats the auto box breather hose and does not need connecting to anything.....

Very clean engine bay by the way....

Any chance you could take a pic of where the aux electric coolant pump bracket attaches to the cruise control unit under the coolant expansion tank.....its rare to see this in the Uk and a common question when upgrading base model Omegas to cruise....

01-15-07, 02:58 PM
Yes, it is clean:bigroll:, my dad got the car back and noticed some white grease on the engine compartment, and had to immediately wipe it off. I use the grease in my socket wrenches to capture difficult to reach bolts. I told him the grease helps to preserve the engine:) .

Instead of posting the photos of the cruise control here in the Coolant thread, I started a new thread:


Let me know if you need anything else, as I do not think I would have had any fun trying to solve the coolant leak without your insight.

Thanks Again!!!

03-15-07, 06:45 PM
after reading this im gonna put in my problems.

yesterday my coolant light popped on. i topped off with DEX and was on my way. this morning on lunch break my light came back on. figured i would top it off after work. while my car was sitting outside i noticed that something was leaking from under the car, BAD.

i brought the car into the bay and found i was leaking coolant on the back of the engine. i looked between the trans and the passenger side exhaust and saw a mass of coolant on what looked to be a T hose?

is the heater control valve around there?

03-16-07, 02:02 AM
^^^ sounds like the heater control valve

03-16-07, 06:51 AM
looks like my next 3 days off will be working on the cat.

03-16-07, 07:26 AM
The heater control valve is much easier to replace.
You can remove the two halves of the cowl and get sufficent room to access it without having to disassemble the engine at all.
The oil cooler takes removal of all 3 pieces of the intake.
It could be either, but it is hard to tell unless you get in there and look really well.

03-16-07, 06:38 PM
ok, where did ya'll get you HCVs? dealership wants about $90 for one.

03-18-07, 07:52 PM
ok, i got the cowl off and access door.
what does the HCV look like and where would it be located when looking in the door?

03-19-07, 05:34 AM
The HCV is on the rear of the engine, passenger's side.
It has a bunch of heater hoses going into it, you can't miss it.

03-19-07, 09:33 AM
i think i found it.

black, has 2 hoses going in one side, one out the other and a vacuum line off the top.

as soon as i grabbed it i felt coolant all over the bottom of it, so im hoping its the problem.

going to the dealer today to get a new one.

03-19-07, 09:54 AM
Sounds like you are on top of it!
The hose clamps can be a pain.
Good luck.

03-19-07, 11:39 AM
the hose clamps were the screw type, so it was easy.
ordered the part this morning and also got me a crapload of tools from sears.

05-07-07, 11:24 AM
anyone know where I can get a cheap ext. oil cooler for mine?

01 catera, been down going on 3 weeks, I've broke 3 of the oil banjo bolts
trying to keep it from leaking, I did repair the coolant leak(oil cooler plate)
I've hacked the lines, just need a cheap oil cooler.

The one's around here are $60 up to like $200+


06-27-07, 08:46 AM
My 2000 Cat is leaking from this area, but when I tore it down to reseal the coolant plate I found a different problem. My leak is at the coolant banjo bolts that feed the heat exchanger. The rubber/metal washer/gaskets on the banjo bolts were blown. I couldn't find any similar ones that would fit so I used copper washers. Still leaking. Does anyone know where I can find these seals?

Thanks for all the help everyone here has been! I'm pretty good mechanically, but without diagnostic help from this site I would have parted with my Cat long ago.

06-28-07, 01:21 PM
Nevermind, found the part # 12992647. Dealership wants $7.04 ea. GMPARTSDIRECT.com $4.17 ea.

06-29-07, 11:34 PM
I had my heater control valve changed about 2 years ago. The the car started leaking cooland slowly sometime last year again. One shop told me it was the head gaskets- probably both. I doubted. The strange thing is that it only leaks when the thermostat seems to open. I was told by a friend of mine that if it was the head gaskets the problem would have progressed, but it hasn't. I know I will need valve cover gaskets soon. Can it be the heater control valve again?

07-19-07, 03:52 PM
what r the torque specs for the coolant bridge bolts ?

07-27-07, 08:46 AM
I have bypassed the bypass, i was tired of replacing that part.

3 in 2 years at $90 each sucked.

here is what i did.

I used a 3/4 to 3/4 hose connector to connect the hose from the coolant bridge( the single hose on right) to the heater core feed line (the lower hose on left, also the one the runs up front under the coolant reservoir) then I used a 3/4 hose to 1/2 npt connector in the top hose on left.

I used teflon tape and a 1/2 flare cap to seal that one tight.

Took about 30mins I've ran it for awhile and not one leak so far, and i have heat when i want it.

Cost me $9 for the parts.

07-30-07, 02:38 AM
the washers for the banjo bolts can be reused if you aneal them by heating them up a bit and then reinstalling them. this rearranges the molecules and makes the washer soft again..ive done this hundreds of times without leaks.

09-23-07, 06:43 PM
I removed the HCV today. It seems ok, but my Cat started pouring coolant yesterday. Is it still possible that it's the HCV's fault? Where could it be leaking from? I need to get this car back on the road. Also, is it OK to just get a T-connector to connect the hoses, instead of using the alve again? Or could it be some other reason for it?

10-10-07, 09:56 AM
The 3 lines are for 2 paths, It took me awhile to find how it worked and flowed.
the valve is vacume controled to let it flow from the right(feed line) to one of the 2 other lines.
top left (into heater) or bottom left (into bypass feed)

Only way i can explaine it, top left goes into heater then out to radiator, the bottom left goes into the flow after the heater but going to the same place. SO if a vacume is applied you have hot water in the heater core, no vacume no heat as the flow is bypassing the heater core.
I was without heat for a year or so because the vacume line from inside the car to the HCV didn't work, I T-'ed off a line from the intake and ran to the HCV so i could have heat. and after replacing the HCv 3 times in 2 years, i got sick of paying $90 a pop for it.

01-12-08, 08:48 AM
There is also a cross over manifold between the two cylinder heads that has two sensors in it. It could be leaking fronm the threads of the sensors or the o-rings between the manifold and cylinder heads.

02-09-08, 08:44 AM
I took my Cat to dealer for what I thought was going to be a HCV replacement. Small leak, could smell coolant. They call me after 2 hrs, seems that some "bridge" is leaking and is going to cost $800 to fix. But thankfully I can afford it.
I found $25K hidden in the trunk. :thumbsup:

02-17-08, 10:16 PM
$800 for the coolant cross over ??

Where do they get these prices ????

04-12-08, 08:41 PM
When checking into a leak that is located on the driver side on the Catera there is usually a few things to look for.
Is the leak dripping from the manifold? If it is, then it will probably end up being the Head Gasket.
But before assuming the worst check out the obvious first.
Look for a leak in the HCV, Coolant Return Pipe, Oil Cooler Cover, Water Crossover or even the thermostat.
I just completed a complete head job on my Catera and it was the head gasket that caused the mystery leak coming from the Driver Manifold.
One thing that should be noted, The factory engine coolant is the red type and that type is highly corrosive. When changing over the head gasket or doing a complete Flush then change to the Green coolant. I can show the damage on my head gaskets that where eaten away because of the coolant. The head was not damaged but you could clearly see where the coolant ate into the gasket and eventually worked its way out into a leak.
I will post some picture if you would like just email me
Thanks Keith

04-12-08, 09:05 PM
I'd have to pull out the owner's manual, but I think the red type is the only type that should be used in our cars. I don't know the reason why, but I would assume the engineers know why.

Cadi Cat
04-14-08, 05:50 PM
I have 142k miles and counting, and I've never had a problem with leaks in the heads or anywhere else besides my water pump. But I don't think that's because of the "corrosive" factory coolant. It specificly says use dexcool only!

04-18-08, 01:54 PM
So, My poor baby went into the dealership today with a nasty coolant leak.
I brought it into a few other places, but none of them wanted to work on the car because they didn't have the proper tools. So I guess I'm stuck bringing it to the dealership.

1998 Catera with 145,000km.

Prior to this, I've had no major problems, but have only had the car for about 2 years.

I did a run on the vin # and I found that it was diagnosed with a minor coolant leak just before I got the car. In the report I received, it mentioned the leak coming from one of the heads or the oil cooler.

I'm the lucky one who got stuck with it when the coolant leak got really bad. :thepan:

I do notice that its leaking from the back of the engine though.
So I'm kind of hoping its the HCV.

Can anyone suggest a reasonable price that it should cost to get this repaired.
I will post the quote I get from the dealership as soon as it is available.


04-18-08, 04:35 PM
Just got the update from the dealership, $200 parts and labor to replace the HCV.

But I am now leaking oil into the spark plugs and have to get the Valve cover gasket replaced. And they quoted me $770 parts and labor for that.

11-16-09, 01:23 PM
I wonder how this turned out...

01-21-10, 06:30 PM
OK newbie here. I have coolant coming from what appars to be a drain tube above the transmission. No water in the cabin of the vehicle. Any help would be great! 2000 Cat with 102k miles

Lewis Rolen
03-22-11, 06:07 PM
I have water pouring out as quick as I can pour it in, I did replace the oil cooler and all was fine for a week or two, I've been under the car and put my hand behind both sides, can't see where it's leaking!

04-10-11, 07:02 PM
On the top of the engine, in what would usually be a "valley" they installed a metal plate. This plate has sealer around the edges and bolts to the engine block but in it is mounted the oil cooler. Below the plate is coolant flowing through the engine to remove heat from the engine oil. Why they mounted this thing under the intake I'll never know, but needless to say if you have a pretty good coolant leak from this area it's likely this plate leaking.

:yup: exactly what was wrong with ours!! lol, but we thought freeze plugs were the culprit, so took the entire engine out!

does anyone happen to have the part # for this gasket? none of the retail parts stores seem to have it, or we didn't give them the correct name for it...whichever...:annoyed:

08-05-11, 02:48 PM
ok i'm at work so i don't have luxury of reading ALL of the posts, although i have read first 3 pages.. if i'm lucky enough to get seen, i need help or pointed in the right direction.
i have a 1997 Catera w/ 94k miles. the cooling has been giving me a problem that stop leak isn't helping anymore, so i swapped out the radiator that had a clear crack in it.
i was unfortunate and uneducated enough to not know that you should bleed the radiator system before excitedly driving my car home when POP! hot coolant rushes into my passenger side.
and rapidly outside of my car..

what i need, is the easiest directions to access the back of the engine area, and under my passenger dash, since i have to do this myself.. i need to check if its a hose or the core itself, easy fix i hope... if it werent bad enougth that i snapped connection off a $450 "smog reducer" while trying to remove a heater hose.. this is the most fragile, most expensive car i have ever worked on, i think they designed it to make DIY's fear it, so that we take it directly to the dealer.. they break the damn thing so they dont have to work on it either... but i do love this car, shame about all the problems it has.
i have no money to spare at a dealership, everything ive broke on this car has avg'd $400 dollars thank god these things are popping up regularly in the cash and carry junkyard. paid $27 ($350) bucks to get a coil pack, and $7 ($450) for the damn smog reducer.. sorry i think im having a meltdown..

k man
05-30-13, 07:13 AM
i realize this thread is old, but i am hoping someone can offer insight to fixing the oil cooler/heat exchanger problem that plagues this car. I am going to give this a try myself, I have worked on cars before, and what i don't have in knowledge i make up for in determination.

1. when disconnecting the fuel lines from the rail, is disconnecting the negative battery cable enough, or is there some other relief valve i must find and deal with?
2. how likely is the repair to hold? would i be better off attempting the aftermarket cooler option linked to this repair?
3. is it necessary to replace the intake/plenum gaskets when reassembling things back together? there is no mention of this as being necessary in the step by step pdf document explaining the job.

thanks- I really hope someone can help-

05-30-13, 04:57 PM
You don't need to replace the O-rings on the plenum. I haven't yet and I've had them off twice. The best detailed pictures I've found at the Omega Owners Forum. The Europeans have been working on these for years, as they still sell a version of it today. Just be sure to note where the advice comes from. I made the mistake of forgetting the driver side of an English car is opposite our own. As for the oil cooler, why compound their bad design by re-installing it? An aftermarket remote mounted unit has to be a smarter alternative. I always use Mobil 1, so the temp factor is mollified. I'm just concerned as to how you would close the coolant openings after the change. Has anyone done this? My car has 76k on it, and although my cooler is sound, I have to anticipate the repair if it fails.

06-01-13, 07:19 AM
I ended up cutting the lines near the oil filter and just looping them with some hydraulic hose. I did this probably 5 years ago. Make sure you get the hose done right, or you'll dump all your oil in seconds if it fails. My engine temps have always been reasonable.