northstar overheating

[Ralf]

Hello EricTheCarGuy forum,

I am back again with a question.
My 1999 Cadillac seville is overheating, since the headgasket is a common problem on the 4,6 Northstar i fear the worst.
I few weeks ago i noticed that the cooling water temp when up i little bit and then quickly goes down.
As of yesterday the temperature is not going down anymore.

The problem only occurs on the highway, when driving in the city the temperature is dead center.
When the car overheats it starts leaking coolant from the expansion tank cap.
The expansion tank is very dirty, there is some mayonaise looking gunk in there.
The dipstick and oil cap look normal.
There is no white smoke out the exhaust.

I have also been told that my car smells when i accelerate hard and some dark smoke.
This smoke is not visible from the rear view mirror though.

Does this look like a headgasket porblem or should i be looking elsewhere?

Thanks in advance,

Ralf,

Topic

[college man]

Based on the junk in you overflow, You may want to change your coolant.
sounds like your radiator/cooling system is dirty. which will cause radiator
inefficiency.

[Its me]

It could be a water pump going bad. The water pump on these is run off the #2 bank camshaft to the front right of the engine.

However, there is also a very great chance that you do have the dreaded blown head gasket and the only fix is to re stud the or re tap the head bolts. I prefer the stud method.

There are cottage businesses dedicated to just repairing this northstar and charge a single fee. Usually it is 2000 to 2500 dollars

I met the Cadillac doctor in youngstown… his place was nothing but caddies lined up to work on..

[Rob]

ya I agree with you guy’s…. you need to check it out more… sounds like it might be a thermistat to me… persally if it would be me I would take the water pump out and check it and/or replace it… also would replace the thermistat too…. would check the system liuke heater core and see if it will allow water to pass through it… and the ratator and flush the whole system nice and good allowing it to pass all dirt… if you want to check the chance of it to be a head gasket … do a compression and leak down test… would give you an idea…. but I would start with a good flush and replace some parts… mayonaise in the oil means that you probly have a bad head gasket but mayonaise looking like thing in the coolent is probly some very old coolent and is very dirty or something might be bad in the cooling system cuasing corrotion… like a failing ratator or heator core… you will have to check out them when you do a flush and see how they are and go from there…

PS to get a water pump out if you have bolts on the pully is to use a rubber wrench to help you… I have known ppl that say you have to take out the whole engine to do a water pump because you cant get the bolts … I have never seen any you cant get out with some work arounds

[Andrew Harris]

First things first is the coolant full? do you have any coolant leaks. GM dexcool is know to go bad and gums up. looks like a rusty paste. Start simple move to complex

[Ralf]

Thank you all for your input.

I have had the car serviced at the Cadillac dealership 3 weeks ago wich was a very expensive service.
Appartenly the did not notice my coolant was very dirty.

I also remember there has been an intermittent squeaking noise witch has gotten worse lately.
Maybe this noise is coming from a failing water pump.

I will go back to the dealership and see what they have to say.
otherwise i will start by flushing the system and go from there.

thanks again,

ralf

[Ralf]

Thank you all for your input.

I have had the car serviced at the Cadillac dealership 3 weeks ago wich was a very expensive service.
Appartenly the did not notice my coolant was very dirty.

I also remember there has been an intermittent squeaking noise witch has gotten worse lately.
Maybe this noise is coming from a failing water pump.

I will go back to the dealership and see what they have to say.
otherwise i will start by flushing the system and go from there.

thanks again,

[Ralf]

I am back with some more information.
I decided not to bother going to the dealer ship as this will probably cost me a lot of money again.

I’ve been doing some more test driving and the engines does not overheat when i keep the rpm’s above 3k rpm.
The cooling fan does kick in when the temp rises.

Could this symptom be a clear give away of what is not working?

[Bryan]

Armed, Rob, College Man, and Toyota Karl already told you how to proceed… you need to change the coolant, first and foremost.

Anything else is mere speculation and is not indicative of any problem that may or may not be present.

Change the coolant first, and then take it from there.

-Hinoki

[Its me]

As far as sqealing. The water pump is run off a small belt off the front bank camshaft. If the sound is there, you may indeed have an issue with the water pump.

[Author]

Replies