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77K views 78 replies 36 participants last post by  normalicy 
#1 ·
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.
 

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#29 ·
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....
 
#30 ·
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...

Thanks





 
#33 ·
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
http://autorepair.about.com/cs/coolingsystem/l/aa052601c.htm

They mention corrosion issues that suggest a full coolant flush if you see oxide buildup on components.
 
#35 ·
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!
 
#37 ·
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.
 
#39 ·
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.
 
#40 ·
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: ...
 
#42 ·
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.

Thanks



 
#43 ·
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....
 
#44 ·
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:

http://www.cadillacforums.com/forums/cadillac-catera-cimarron-forum/95970-cruise-control-photos.html

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!!!
 
#45 ·
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?
 
#48 ·
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.
 
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