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97 DeVille Concours
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Discussion Starter #1
ok,

We all know that head gaskets are a common problem in the Northstar.... for the benefit of all, can we get clarification on symptoms of this, causes, and preventions? I tried searching for this topic, but could not find any with all three.

I think we can all benefit from this

:bouncy:
 

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94 ETC,97 STS
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3,531 Posts
The cause is usually lack of cooling system maintainence.

The symptom is loss of coolant and secondary symptoms caused by that.

I don't think it is especially common. It is a topic of discussion because cramming a V8 in FWD configuration causes a large amount of labor to replace said gaskets.:stirpot:
 

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White Diamond '03 DHS (with DTS floor shift)
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Prevention (as much as possible) is changing the coolant at recommended intervals.
 

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1997 Eldorado, 2003 Audi RS6
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Symptoms are loss of coolant with no white smoke, sudden overheating immediately after high throttle operation, totally unstable temperatures (swings of 30+ degrees in less than a minute), also you will see excessive pressurization of the cooling system and the loss of fairly large quantities of coolant through the spill line on the pressure tank when the system is not overfilled.
 

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2006 STS V8 AWD, '95 Ford Ranger
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The old Northstar guru told us that the root cause of headgasket failures was a lack of cooling system maintenance caused the metal center of the headgasket sandwich to corrode and disappear thus relieving the squeeze on the gasket so it could squirt out from combustion pressure. The head gasket itself is layers of gasket material with a metal center layer.
 

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1997 Eldorado, 2003 Audi RS6
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Never seen a hear gasket failure cause smoke. Have seen severe steam from blown crossover gasket resulting from cooling system overpressure from head gasket failure.

Another one to watch... All the pro-dexcool guys are about to jump on me for this one, but whatever. If you have any leak, even a very small one, dexcool tends to produce chalky buildup where the leak is. You will see a little on the outside, and it makes it very easy to see where the leak is in many cases. What you don't see is the mountain of the stuff on the inside of whatever part is leaking. I had a water pump housing gasket leak, and found a huge amount of the crap in the water pump housing, actually getting chopped up by the impeller. It doesn't dissolve into the coolant either once the leak is gone. I flushed it using different chemicals, as well as just running water through it with a hose for a few hours and never got it all out.

What I think caused my head gasket failure is the purge line (small metal line running under the beauty cover from the water pump housing to the tank) getting plugged with this crap, because it did get plugged, caused the car to overheat a couple of times, and then everything went to hell. The high pressures, dumping coolant, all of it. I didn't know about problems with the line getting plugged at all until after the fact. The blockage was this white chalky crap material.

I will not use GM's coolant or recommend it to anyone, simply because of attributes like that that are a problem. Other organic acid coolants don't seem to have this problem, so if you want to go the dex-cool route, buy Prestone's red Dex-cool certified stuff.

I turned this whole thing into a high level college chemistry thing a couple years back, which showed this and other things as well, not only about GM's coolant.
 

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The Northstar Tuner
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Never seen a hear gasket failure cause smoke. Have seen severe steam from blown crossover gasket resulting from cooling system overpressure from head gasket failure.

Another one to watch... All the pro-dexcool guys are about to jump on me for this one, but whatever. If you have any leak, even a very small one, dexcool tends to produce chalky buildup where the leak is. You will see a little on the outside, and it makes it very easy to see where the leak is in many cases. What you don't see is the mountain of the stuff on the inside of whatever part is leaking. I had a water pump housing gasket leak, and found a huge amount of the crap in the water pump housing, actually getting chopped up by the impeller. It doesn't dissolve into the coolant either once the leak is gone. I flushed it using different chemicals, as well as just running water through it with a hose for a few hours and never got it all out.

What I think caused my head gasket failure is the purge line (small metal line running under the beauty cover from the water pump housing to the tank) getting plugged with this crap, because it did get plugged, caused the car to overheat a couple of times, and then everything went to hell. The high pressures, dumping coolant, all of it. I didn't know about problems with the line getting plugged at all until after the fact. The blockage was this white chalky crap material.

I will not use GM's coolant or recommend it to anyone, simply because of attributes like that that are a problem. Other organic acid coolants don't seem to have this problem, so if you want to go the dex-cool route, buy Prestone's red Dex-cool certified stuff.

I turned this whole thing into a high level college chemistry thing a couple years back, which showed this and other things as well, not only about GM's coolant.
We see a lot of cars chugging white smoke from the tail pipes.
.
All customer pay cars get Prestone Dex-cool.
 

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I just flushed and filled my Northstar and used O'Reily's non-silicate, extended life antifreeze blended 60/40 with distilled. Should I be draining it and using DexCool or something else - or am I ok as is? Please advise, as I don't want to screw up a good motor.
 

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The Northstar Tuner
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I just flushed and filled my Northstar and used O'Reily's non-silicate, extended life antifreeze blended 60/40 with distilled. Should I be draining it and using DexCool or something else - or am I ok as is? Please advise, as I don't want to screw up a good motor.
From all the information that I have read. I understand that the difference between Dex cool and the old coolant is that they removed the silicate.
Yes they took out the sand so the water pumps last longer
 

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White Diamond '03 DHS (with DTS floor shift)
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I just flushed and filled my Northstar and used O'Reily's non-silicate, extended life antifreeze blended 60/40 with distilled. Should I be draining it and using DexCool or something else - or am I ok as is? Please advise, as I don't want to screw up a good motor.
Your fine. Leave what you have in there.
 

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1997 ETC (GAVE TO STEPSON 2011), 2000 DTS (RIP)
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My Experience On Two Separate Northstar Engines Has Been Sudden, Severe Overheating Caused By The Coolant Being Blown Out Of The Surge Tank Due To Combustion Gases Introduced Into The Cooling System
 

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1997 Eldorado, 2003 Audi RS6
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My Experience On Two Separate Northstar Engines Has Been Sudden, Severe Overheating Caused By The Coolant Being Blown Out Of The Surge Tank Due To Combustion Gases Introduced Into The Cooling System
Do not capitalize every word. It makes it hard to read. :thepan:
 

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I was told by a Caddy tech that all the new Dexcool products are just ethylene glycol anyway as opposed to the old stuff. They just keep the name due to legal issues.

True or false?
 

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White Diamond '03 DHS (with DTS floor shift)
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I believe both green and Dex are ethylene glycol (and always have been). Dex is silicate free though.
 

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97 ETC x2, 04 GXP, 04 STS x2, 97 ESC, 99 Deville, 05 SRX
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I believe something completely different is causing the HG problems with the Northstar engines. It's not the headgasket at all. I've pulled a few apart. Why is it that when I pulled the head bolts, the threads were moist and corroded? I've read before in these forums (and I believe it as well) that the head bolts lose their grip in the block and the head floats a bit under WOT and high RPM conditions. I think that because the aluminum block castings can be a bit porous, the coolant eventually seeps through to the head bolt threads, and with the wrong type of antifreeze (or old stuff), the threads corrode to the point where they lose their hold. This explains why these problems only occur later in engine life- never when brand new. And of course, once the head floats, the head gasket will obviously go next because of that. Some people (careless people) will top up their cooling systems with regular tap water, and run with more water than coolant. This would increase the chances of the HG problem, where as using the right coolant and keeping up with maintenance could postpone or eliminate the chances of the head gasket problem altogether. I know it sounds strange- coolant seeping through the block- but why else would the threads have been wet on the bolts, and why else would it look like the threads were corroded?

The best thing you can possibly do for a Northstar is spring for the high-dollar coolant (I use prestone long-life Dexcool aproved)- and run a 70/30 mix using De-Ionized water and change/flush it every now and then. These are great engines when they don't have the overheating problems- I've got four caddy's and an Olds Aurora (4.0 DOHC N* equivelent) and nothing runs like these. They're worth the extra cost for the right stuff.
 
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