: Overhaeting Or Not or Maybe PLEASE HELP



momsdeville
07-28-08, 11:21 PM
OK, Yes I have read the overheating post but i think I'm a bit different.

2002 DTS
135000KM (70 Miles?)
Waterpump done
Thermostat Done
Coolant flushed

Temp JUMPS and yes it JUMPS from 220 to 235 to 250 and JUMPS back down and up and repeats. :banghead::banghead::banghead:

Now i have the message of ENGINE HOT - AC OFF

Stupid question #1 When it starts to over heat and you turn on the heat should it not blow HOT air? :ill:

It changes form hot to cold on it's own.

Also when we stopped and popped the hood, the engine bay did not seem any hotter than normal....

We are just about to check the purge line...

PLEASE ANY SUGGESTIONS would be helpful ......

CadillacSTS42005
07-28-08, 11:40 PM
if it jumps as you say then i would suspect the engine temp sensor

momsdeville
07-29-08, 12:13 AM
Ok, we checked the purge line and it flows just fine and not temp is back to normal ????

momsdeville
07-29-08, 12:14 AM
if it jumps as you say then i would suspect the engine temp sensor

And how do we know if that is the case?

and where pray tell is that???

CadillacSTS42005
07-29-08, 12:29 AM
mounted in the coolant lines somewhere id have to check
but there no way the coolant goes from 220 to 250 and back down to 220 instantaneously
the thing that determines the engine temp and would send out the alert if overheating would be the engine temp sensor

momsdeville
07-29-08, 01:06 AM
mounted in the coolant lines somewhere id have to check
but there no way the coolant goes from 220 to 250 and back down to 220 instantaneously
the thing that determines the engine temp and would send out the alert if overheating would be the engine temp sensor

It sure didn't make sense to us either and like i said it did not seam any hotter under the hood than normal. No tic tic sounds or anything fishy.

I've never seen a temp guage "jump" before and i hope never to see it again...:annoyed:

it's going back to the mechanic tomorrow. he'll check that as well as the thermostat (this will be #4) and rad cap as well.

Ranger
07-29-08, 01:08 AM
Stupid question #1 When it starts to over heat and you turn on the heat should it not blow HOT air?
Not if there is air in the system.


It changes form hot to cold on it's own.
Leads me to believe that there is air in the system.


And how do we know if that is the case?

and where pray tell is that???
A FSM would have the procedure to test it. If memory serves me correctly, I think it is on the rear of the right bank head (near the master cylinder). You might want to have the coolant tested for the presence of exhaust gases.

zonie77
07-29-08, 03:14 AM
Does it blow coolant out the overflow?

Submariner409
07-29-08, 07:54 AM
The engine coolant temperature sensor is just to the right and below the throttlebody, in the coolant crossover. Have your mechanic check the electrical connection first: it's a plug & play item......

I believe the surge tank cap pressure spec is 18 psi.

If you want an idea of what the sensor looks like, go to www.rockauto.com (http://www.rockauto.com) and surf to your car, cooling system. Look for coolant temp sensor/switch and click on the pictures.

momsdeville
07-29-08, 01:21 PM
Does it blow coolant out the overflow?

IF it does, then it evaporates right away as there are no puddles / spots under the car. I have been checking at every place I stop.

tateos
07-29-08, 01:22 PM
The ECT is on the right cylinder head - not the crossover.

momsdeville
07-29-08, 01:41 PM
[QUOTE=Ranger;1591217]Not if there is air in the system.


Leads me to believe that there is air in the system.


OK, i'll bite on this one. Reading through the posts, my understanding was that "IF" the system is functioning correctly, the "surge line" burps the air out on it's own.

We did check the surge line and it has very good flow. ( it was disconnected from the overflow tank end)

QUESTION : can the nib that comes out of the overflow tank that the surge line coneccts to be plugged? Is it a straight though or is there a little valve in there? We did not want to "push" anything through for fear of puncturing something.

One other item to note.... We had the thermostat replaced about 3 months ago and then again about 1 month ago (it was defective) we also had the upper red hose replaced at the same time. So new rad hose....when the car is off that rad hose is very very hard (not really squeezable). we compared to another vehicle that was running and just shut off and you could "squeeze" that hose.

(please be kind, I have done so many searches and reading i'm getting crosseyed)

Submariner409
07-29-08, 07:43 PM
tateos.....2000+ has a very different coolant crossover which deleted the coolant lines to the TB. Temp sensor is in the "right" lower leg, just under the throttle body, in the recirculation flow path before the thermostat. That's why the post-2000 engines heat so quickly. (1997 and 2000 p/n's are the same........2134396.)

momsdeville.....If the car has been running and is hot, that hose should be hard. The system carries 18 psi. There is no valve in the surge tank end of the purge line. You can safely stick a bamboo skewer or similar in the nib to make sure it's clear. If the hose, disconnected, was spitting water, that part is OK.

Ranger
07-29-08, 10:05 PM
I suppose the nipple on the surge tank could be plugged, but I'd rather doubt it. Like Sub said, stick something in there to be sure. After rereading you symptoms I can't help but wonder if it may not be a bad sensor with the sudden jumping as you describe. Even if there where air in the system, I think it would rise a little slower than that.

momsdeville
07-30-08, 01:29 PM
momsdeville.....If the car has been running and is hot, that hose should be hard. The system carries 18 psi. There is no valve in the surge tank end of the purge line. You can safely stick a bamboo skewer or similar in the nib to make sure it's clear. If the hose, disconnected, was spitting water, that part is OK.[/QUOTE]

Ok, stupid question # 2

Is it a straight through or does it curve inside the tank? IE the part you can't see?

momsdeville
07-30-08, 01:38 PM
UPDATE

So i picked up the car today from the mechanic.

He changed the following:

Engine Collant Temp Sensor
Rad cap - it was iffy that it was holding proper pressure

So far this morning (knock on wood) it's been fine. he checked all the codes and had it hooked up when he started it. He said even though the guage jumps a bit between dead center and 1/4 inch above, the temp DOES NOT "jump".

His opinion was that the sensor was pooched. Advice was to keep an eye on it, if it starts to climb above one notch above center then pull over and chech to see if it is overheating (coolant pissing out)

If all is well then the next possible issue is the guage it's self.

If it comes down to that then Autometer here we come :p:p

THANK YOU TO EVERYONE......

I'll post updates ... hopefully good news !

tateos
07-30-08, 02:48 PM
tateos.....2000+ has a very different coolant crossover which deleted the coolant lines to the TB. Temp sensor is in the "right" lower leg, just under the throttle body, in the recirculation flow path before the thermostat. That's why the post-2000 engines heat so quickly. (1997 and 2000 p/n's are the same........2134396.)

momsdeville.....If the car has been running and is hot, that hose should be hard. The system carries 18 psi. There is no valve in the surge tank end of the purge line. You can safely stick a bamboo skewer or similar in the nib to make sure it's clear. If the hose, disconnected, was spitting water, that part is OK.

OK - thanks sub - sorry I implied you were wrong. RM

Submariner409
07-30-08, 06:22 PM
tateos.......never thought you implied I was wrong.....picked up on your '97 and remembered that her '01 was a bit different.

If we could all keep 13 years of 4.6 Northstars separated change-by-change it would be a miracle ! (Look at the running STS-Eldo motor mount thread.....)

Ranger
07-30-08, 07:20 PM
Sounds like you have it fixed mom. If the gauge never jumps more than you say it does now. I'd just live with it. Best of luck and keep us posted.

tateos
07-30-08, 07:47 PM
tateos.......never thought you implied I was wrong.....picked up on your '97 and remembered that her '01 was a bit different.

If we could all keep 13 years of 4.6 Northstars separated change-by-change it would be a miracle ! (Look at the running STS-Eldo motor mount thread.....)

Well - you have a good attitude, sub. I noticed the difference in years, but I never dreamed the ECT would be in a difference location. I mean, either location is OK, but I wonder why they moved it? I suppose it is a little more accessible, right? I thought about changing the ECT when I did my HG job, but it was working fine and not leaking, so I decided to leave it alone.

Ur7x
07-30-08, 09:45 PM
IF it does, then it evaporates right away as there are no puddles / spots under the car. I have been checking at every place I stop.

That is VERY common when the water pump cover leaks... which is not uncommon on the 2000-2004 Northstars... The coolant drips onto the hot tranny and disappears... So if the Mechanic is replacing the thermostat (again?!) have them replace the water pump cover and gasket too.

GM has redesigned both to solve this issue.

momsdeville
07-31-08, 01:27 PM
That is VERY common when the water pump cover leaks... which is not uncommon on the 2000-2004 Northstars... The coolant drips onto the hot tranny and disappears... So if the Mechanic is replacing the thermostat (again?!) have them replace the water pump cover and gasket too.

GM has redesigned both to solve this issue.

Nope..Only on Thermostat #3....

However, we may be going to an aftermarket temp guage:(:(

On the way to work this morning doing 100 k/hr outside temp 21 celcius in a matter of 30 / 45 seconds guage went from dead center to next line and back again.:alchi:

unless anyone has another suggestion??????

Submariner409
07-31-08, 01:55 PM
momsdeville..............With all the tinkering and draining and changing and worrying it's entirely possible that there is/are air pockets in the coolant piping. Drive the car for a week or so, don't get hooked on staring at temperatures, and let the cooling system purge itself and settle into a routine. Three thermostats cannot, by any stretch, have been faulty. Let things return to "normal" (whatever that is.....).

momsdeville
07-31-08, 02:24 PM
momsdeville..............With all the tinkering and draining and changing and worrying it's entirely possible that there is/are air pockets in the coolant piping. Drive the car for a week or so, don't get hooked on staring at temperatures, and let the cooling system purge itself and settle into a routine. Three thermostats cannot, by any stretch, have been faulty. Let things return to "normal" (whatever that is.....).

Thanks, Sub

I just really really like this car and am determined to make sure it's taken care of properly...IE not letting small issues escalte into big issues.

Also, this is my main mode of transport and it's never fun to have a small child with you and need to get towed:crying2: (it's happend before with another car)

We are also planning a trip to the states and that can get very expensive should something go astray..

Thanks, again and i'll do that and post back any new info;);)

tateos
07-31-08, 03:27 PM
Sub is correct - sudden changes in temperature are either artifacts (perhaps caused by a bad ECT sensor) or could be caused by air in the system.

momsdeville
08-05-08, 01:20 PM
:bomb::banghead: Ok the "happy" vehicle "overheated" AGAIN.

Hubby was driving it yesterday and temp shot up to 250 + and the "engine hot A/C off" message came on again. He was driving up hill under load at a normal speed. He stopped the car and when it cooled down, coolant level was low. We topped it up and well, we'll keep an eye on it.

Could this have been a massive air bubble? There was NO coolant leaking from the overflow and no coolant smell.

One thing I just thought of. I don't think the little "temp" light has ever come on exept in "safe mode". You know the light that lights up when you start the car and then goes out.

Could this mean anything?

This morning it went from dead center to next line and back down again.

STUPID QUESTION::drool:

Theoretically, how many "air bubbles" could this thing have? It has been a week since the rad cap and coolant temp sensor change.

Should we consider the aftermarket temp guage? will that effect the computer in any way?

Is there a specific guage to buy? IE mechanical / electrical? Is install a pain?

Thanks again for listening to my rambling and up/down issues....everyone has been very helpful...

Ranger
08-05-08, 06:39 PM
If you have coolant flow from the purge line, there are no bubbles unless it is creating them from a bad head gasket. I forgot, have you had the coolant tested for the presence of exhaust gases? Are you sure that the thermostat is working?

If you use an after market gauge the PCM will still relay on the OEM gauge for info. If you replace it, it will probably go to an override mode and run rich.

momsdeville
08-05-08, 07:17 PM
[QUOTE=Ranger;1597674]If you have coolant flow from the purge line, there are no bubbles unless it is creating them from a bad head gasket.

I forgot, have you had the coolant tested for the presence of exhaust gases? Mechanic said HG was all good and he did not suspect there were any issues. Is there a way to test at home?


Are you sure that the thermostat is working? 3 thermostasts later??? i would hope that we didn't get 2 defective ones in a row:thepan:



If you use an after market gauge the PCM will still relay on the OEM gauge for info. If you replace it, it will probably go to an override mode and run rich.

The way you say that i would guess that is BAD?

jeffrsmith
08-05-08, 08:36 PM
You can go to Napa and buy their Engine Block Leak Tester - costs around $50.00. Very simple test and will tell you instantly if you have HG issues.

Good luck

Ranger
08-05-08, 08:52 PM
If you use an after market gauge the PCM will still relay on the OEM gauge for info. If you replace it, it will probably go to an override mode and run rich.


The way you say that i would guess that is BAD?
Yeah, that would not be good. I believe if the PCM does not get a signal from the ECT sensor, it will substitute a figure that is basically a cold engine (worst case) so that it will run. Running it in that condition would waste fuel and foul the plugs.


Are you sure that the thermostat is working? 3 thermostasts later??? i would hope that we didn't get 2 defective ones in a row
Are they all the same brand and did you buy them from the same place? If so, are they a quality name brand stat like Stant?

I'm grasping at straws here. This one is a :banghead:

momsdeville
08-05-08, 10:10 PM
OK , POSSIBLE NEW SYMPTOM TO ADD TO THE MIX....

We have been thinking about this mess a lot and have had a EUREKA moment!!!

This all started when our A/C started getting low ie not blowing as cold as it should.
A/C is now a dud...no cold air at all.

Could THIS influence things at all????


YUP REALLY GRABBING AT STRAWS NOW!

Ranger
08-05-08, 10:32 PM
No. A/C and engine cooling are two totally separate systems. Sorry to burst your eureka moment. Time to start grasping again.

momsdeville
08-05-08, 10:41 PM
No. A/C and engine cooling are two totally separate systems. Sorry to burst your eureka moment. Time to start grasping again.

awe shucks Ranger, you're no fun:rolleyes:

Ok , grasping is fine....

As far as the stat goes, yes it was a "good" brand and yes we trust the mechanic.... Good friend and a fellow Caddy owner

we gone and got him stumped too....

so anyone...NO, really, anyone suggestions???

CadillacSTS42005
08-05-08, 11:01 PM
get the NAPA test and test the coolant
that will confirm it

Ranger
08-05-08, 11:03 PM
Do the coolant test to to rule the HG out. A cylinder pressure test is better , but by now there would be gases in the coolant if it is bad. 2000+ engines are not really as likely as pre 2000's, but you need to positively rule it out. You have some symptoms I don't like.

momsdeville
08-06-08, 12:21 AM
OK will do. I'm heading to the states tomorrow for some shopping anyway.
Is it strictly a "Napa" thing, or any big parts store?

Also what is the correct name?

I'll let you know the results when i get back this Friday / Saturday.

Ranger
08-06-08, 07:10 PM
Napa carries it but it is not a "Napa thing". Ask for a cooling system test kit to test for the presence of exhaust gases, or stop by any radiator shop. They should be able to test it for you.

momsdeville
08-09-08, 01:08 AM
LIFE SUCKS THE BIG ONE

:helpless::cursin::helpless:

IT'S BEEN CONFIRMED.......IT'S THE DREADED HEADGASKETS.......:helpless:

Exhaust gas reading is the same at the tail pipe as the coolant.

I'm REALLY REALLY BUMMED.

nobody will go within 20 feet of the car ...they won't even poke it with a stick.

Dealer Only repair.. $$$$$ Freind of a friend paid $7000....
Biggest problem is that sure you'll get a quote for $3000 but when it's apart who knows what they'll find..cracked heads...block...:doh::doh:


I dunno, might be time to say bye bye caddy

misfit6794
08-09-08, 09:41 AM
The northstars were redesigned in 2000 to supposedly cure the headgasket problem, pretty rare for an 01 to fail. I paid 3500 for the headgaskets to be replaced in mine, 7000 seems rediculous. Try looking around for an independent shop that has done a northstar before.

Ranger
08-09-08, 12:03 PM
Mom,
Sorry to hear of your misfortune, but I was kind of afraid of that. $7000 is for a new engine. Forget that. The heads and block are fine. Almost never heard of a cracked one. If you have it repaired it should be around $3000, but insist on all 20 head bolt holes being Timeserted. Even if they tell you that the threads are good in 18 or 19 of them. The other option is to get another 2000+ engine from a junk yard and have it installed. Since the 2000+ engines are much less likely to have a head gasket failure (you where just very unlucky) that might be a cheaper option for you. Look into it and keep us posted.