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seville sts 1998
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Discussion Starter #1
Hello my name is herman i am from holland i drive a seville sts 1998.
I am a big usa car fan, i had an el camino, a 69chevelle and a 1991 caprice.
Now i drive a seville sts 1998 a red one whith black interieur.
It is the nicest car i ever hade and plenty of power.
My english is not that good i am sorry for that.
I had some cooling problems.
I drove it one the higway 2 months ago and it starts to overheat, whent back too my house.
Coolant was coming out of the surge tank cap because it was too hot.
When it was cool i filled it and started the car i had a big cooling leak.
Looks like the waterpump was leaking, replaced it started the car still a big leak.
Than we put the car on jackstands, looks like the leak cames from the watercrossover.
We removed it was a pain in the ass, all new gaskets voor the crossover.
Started the car again still a leak.
Then after a nother inspection the freeze plug behind the water pomp was bad.
So we took it apart again.
Now the coolingsystem has no leaks any more.
But now when the engine is cold there is still pressure on the surge tank when engine is cold, ther is a brand new cap on it.
My idee is that ther is coming combustion gas in the cooling system.
But the car drives good now coolant los, temp meter is perfect 12 o clock even after a one hour drive 130km/pu.
If there was coming cumbustion gas in the coolingsystem then the pressurecap whould spill out coolant and thats not hapening.
Or is the presser normal?
I hope that some one has een anwser.

Greets herman.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Welcome Aboard !!!

Please go to the Engines; Northstar forum and study the several sticky threads concerning overheating, head gaskets, cooling systems, fan operation and gauge operation. Lots of study, but every question is answered there, as well as in Discussions, Tech Tips.

Begin your next diagnosis with a purge line check - if that line is clogged the cooling system can airlock and overheat frequently. IF your engine has a coolant-heated throttlebody that is the first suspicion - and the throttlebody heating circuit may be bypassed with ne effect on the engine - none.

Some pressure in the cooling system would be normal after a few hours of engine: OFF. If you are not currently using/losing coolant and the temperature stays about 188F - 206F under most conditions then I would not suspect a head gasket failure due to head bolts pulling from failed cylinder block bolt hole threads.

Are you familiar with how and when the cooling fans operate ?
 

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seville sts 1998
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Discussion Starter #3
Purge line is clear, if i take the purge line of the tank blow some air in it bubbles in the surge tank.
And mine is going trough the throttle body.
If the cars stands still for 24 hours there is still pressure.
I have not check the purge line when engin is running too see if theres a coolant flow.
 

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White Diamond '03 DHS (with DTS floor shift)
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My english is not that good i am sorry for that.
Your English is better than some U.S. born and educated people who post here.

I have not check the purge line when engin is running too see if theres a coolant flow.
You must have coolant flow at idle. Check it at a cold start so as not to burn yourself. The amount is irrelevant as long as you have flow.
If that turns out good, it might be time for a block test is you suspect exhaust gases in the cooling system.
 

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seville sts 1998
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Discussion Starter #5
I did the block test, whit the blue stuff,it went dark green not yellow.
I did a snif at the excaust pipe and it was bright yellow in no time.
The strange thing is that i have no prolems, only the pressure.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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I did the block test, whit the blue stuff,it went dark green not yellow.
I did a snif at the excaust pipe and it was bright yellow in no time.
The strange thing is that i have no prolems, only the pressure.
=============================
unfortunately - you have ALL the symptoms of failed head gaskets -

If the cars stands still for 24 hours there is still pressure.
normally - pressure only builds as a result of coolant expanding as it gets hot -
and the pressure goes away when the coolant cools down -

the ONLY way the cooling system remains pressurized - when cold -
is from exhaust gas pressure introduced into the cooling system -

and you failed the BLOCK TEST -
I did the block test, whit the blue stuff,it went dark green not yellow.
ANY color change is a positive result -
 

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seville sts 1998
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Discussion Starter #7
I was affraid of that.
The problems is we dont have companeys like northstar performance in holland.
So i must do it my self, and order a insert kit from northstar performance.
There is a seville sts for sale in holland that has bin in a car crash the whole left side is damaged its a 2004 model whit 75000 miles on it.
Are those engines better?
Or should i take that engine out and timesirt it en put it in my car?
Its al so strange that the pressure is not getting higher than the 15psi on the cap of the surge tank or its a verry small leak.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,273 Posts
I was affraid of that.
The problems is we dont have companeys like northstar performance in holland.
So i must do it my self, and order a insert kit from northstar performance.
There is a seville sts for sale in holland that has bin in a car crash the whole left side is damaged its a 2004 model whit 75000 miles on it.
Are those engines better?
Or should i take that engine out and timesirt it en put it in my car?
Its al so strange that the pressure is not getting higher than the 15psi on the cap of the surge tank or its a verry small leak.
==============================
Are those engines better?
YES - but it wouldn't be able to be used in your 1998 car -
simply not compatible -

there were many changes made to the motor in 2000 -
flat tappets were replaced with roller lifters -
and longer head bolts were used -

the longer head bolts helped - but still didn't cure
the failed head gasket problem -

in mid-year 2004 - they changed the thread pitch of the head bolts to a coarse thread -
that seems to have solved the problem -

---------------

should i take that engine out and timesirt it en put it in my car?
fixing your existing engine is really your only option -

Its al so strange that the pressure is not getting higher
than the 15psi on the cap of the surge tank

not strange at all -
the serge tank cap is designed to maintain 15psi -
pressure above 15 is simply released -

or its a verry small leak.
you are in the "early" stage of head gasket failure -
so yes - the leak is very small - but will constantly get larger -

keep in mind that at the moment if ignition -
the cylinder pressure will be in the thousands of psi -

at this time -
the PURGE LINE is able to keep up
with eliminating the exhaust gasses from the cooling system -

and the 15psi pressure cap is not overwhelmed -
and can maintain the correct pressure -

that will change as the leak gets larger -

when the PURGE LINE can't eliminate all the exhaust gasses -
you will overheat the engine -
mainly because the water pump can't pump air -
 

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seville sts 1998
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Discussion Starter #9
My seville has now driven180.000km.
There are seville sts in holland whith 300.000km on the clock and no problems.
With the newer sts there are no problems with the headgasket, never hurd of it.

But i find the seville sts a much nicer car.
Im gone think about it what too do, repair it or bring it too the screapyard.

----------

Thanx for the input every one.
 

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seville sts 1998
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Discussion Starter #10
Is it possible too pul the engine from the top?
I pul engines out of cars before but the northstar isnt that easy i think.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,273 Posts
Is it possible too pul the engine from the top?
I pul engines out of cars before but the northstar isnt that easy i think.
=========================
Is it possible too pul the engine from the top?
yes
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The pressure cap has both a pressure release setting and a vacuum release setting - vacuum release is designed to prevent cooling hoses from collapsing under a bit of vacuum. So, all things assumed perfect, the surge tank (part of this sealed cooling system) should be at or very near atmospheric pressure with the engine at ambient temperature. The proper airspace in the surge tank is designed to supply enough volume to act as the air "spring" against which expanding coolant acts to raise the boiling point of the mixture (boil points of different ratios vary slightly) and the pressure also assures less blade cavitation of the water pump. Too much coolant in the system, the coolant expands, pressure rises - but at some point the airspace is gone - the expanding coolant has pushed the necessary air out of the tank and further expansion results in coolant blowoff. Normally, given an overfilled system, a week or so of normal driving will eventually blow off enough coolant that the airspace in the tank returns to close to normal and the system once again reaches equilibrium.

A bad vacuum release causes hose collapse on cooldown; operating properly it returns the system to atmospheric pressure upon cooldown to ambient temperatures.

Normal coolant level in these Northstar systems is surge tank half full, cold. "Cold" being ambient temperature.

Hot, warm, in between, there should be some pressure on the system. Ambient temperature, very little or no pressure.
 

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seville sts 1998
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Discussion Starter #16
I have a strange thing now.
I had pressure on the surge tank after the car was standing still for 30hours,i explaind that in my first post,the upper and lower radiater hoses where hard al so.
Now i checkt the car yesterday and today,and the pressure is gone hoses are not hard anymore even after a long drive?
I dont get it,i have no leaks no los of coolant.
Is it possible that a big air bubble cost the problem.
If it was the head gasket the problem should stay.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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After a 10 - 20 minute drive, regardless of ambient temperatures, the coolant hoses should get pretty hard: 10 - 16 psi is quite a bit. If the surge tank pressure cap is in good order the system pressure will (should) never exceed the pressure cap relief pressure rating.
 

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seville sts 1998
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Discussion Starter #18 (Edited)
I now that.
But the hoses were even hard after 20 hours ore more.
An lots off pressure on the surge tank.
The pressure is now gone when engine cold thats good.
When the car is warm pressure is good al so.
The hoses are hard after a long drive like it should be its a pressure system too make the boling point higher.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,273 Posts
I now that.
But the hoses were even hard after 20 hours ore more.
An lots off pressure on the surge tank.
The pressure is now gone when engine cold thats good.
When the car is warm pressure is good al so.
The hoses are hard after a long drive like it should be its a pressure system too make the boling point higher.
===========================
head gaskets don't heal themselves -

you failed the BLOCK TEST - post #5 -
 

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seville sts 1998
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Discussion Starter #20
i know but little bit strange that the problem is gone now.But if the head gasket was bad the pressure most still be there.
 
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