: thermal meltdown of n* engine ?



loooiearmstrong
12-05-03, 11:23 PM
i have a '94 seville with the northstar engine . i recently got it and it showed no signs of trouble for a while. first indication i had of trouble was a low coolant level msg from the dash info area. i checked under hood found a small amount of coolant by the left side of the radiator. it turned out there was a threaded port attached to the radiator that was leaking,being the smart guy i am i figured tightening it would stop the coolant from leaking.ha! it became too bad to drive anywhere so i had it towed to shop.they replaced the radiator.next time i got coolant level msg was about 2 months later, now realise that i generally do not drive this car so it sits for extended periods of time.this time i open hood to add some coolant and found a puddle on the ground by the front right side, it was the hose leaking close to the radiator. i replaced it and refilled the coolant but did not drive it that day, a few days later i got in and drove it about 15 highway miles and after 10 it said check coolant level by 15th mile it was saying engine hot and i pulled over for it to cool. i added some coolant and drove it to a shop where i was told sometimes these closed cooling systems need to be babied into getting full. the system took a while to fill and i was on my way it seems the temp was about 219 for the most part. a few days later i was going to use the car for a trip and was doing my errands when it said check oil level. within a few minutes it said check coolant level i was about 4 miles from home when it began and went straight home just before i got home the msg read engine hot .the next morning i went out and looked in the radiator and sure enough it was low on coolant so i topped it off.then remembering the oil warning i checked the oil and found the level to be at the top end of the dip stick like about a foot above the mark and the oil was looking like creamy coffee . so my coolant has gotten into the crankcase. i got a guy from a shop to look at ,it he tells me the steel cylinder inserts in the aluminum block are sealed with some sort of o-rings and they will never seal again due to block warpage and the coolant will just run thru into the crankcase again .does anyone have an idea what the actual problem is with this engine and if so, is it repairable or is that economically feasible to consider?

Aurora By Olds
12-06-03, 12:08 AM
Your problem sounds like one or both of the headgaskets leaking. It is a common problem with the northstars, especially the older ones, due to the green coolant as well as improper cooling system maintainenece.
There is a way to fix this problem, however it is rather costly, unless you do it yourself. It is not an easy job either, by all means.
The head gaskets will need to be replaced, and usually at least one of the head bolts will be stripped due to the aluminum on aluminum design, allowing the pressure of the leaking coolant to seperate the head from the block. Also, your heads may be warped which can be fixed in some instances, however, there is not much tolerance on head warpage for the N*.
My suggestion: Get some estimates on the the problem and compare the costs with swapping the engine with a decent one from a salvage yard.

DaveSmed
12-06-03, 12:29 AM
This one is pretty easy to figure out. Either do a leak-down or compression test on it. In this case, hope for either test to fail, because this indicates headgaskets. If it passes, then it is probably the O-rings.

loooiearmstrong
12-06-03, 11:17 AM
thanks for your replies, davesmed is it possible to have both problems by now which is what the guy suggests to be the scenario?i.e. headgasket a useless fix due to o-rings? any way beside trial and error to eliminate the o-rings? has anyone else gone thru this and what did things turn out like?i hate to sound stupid but i am already out a good deal of money for this car. thanks for anwers, this is a great forum i was very relieved to find it on the web!!!

elwesso
12-06-03, 11:33 AM
What you gotta do is replace the headgaskets (remove engine required) and use a timsert kit to fix it up.... What happens is the head bolts pull for many reasons (IE not torqued down right from the factory to name one) and it causes the gasket to fail......

This is 99% chance gonna be the headgasket... Hopefully it hasnt overheated and warped the heads...... If it is, your gonna be looking at a new engine.....

Usually it costs about 2000 to replace the headgaskets and timesert it..... 8000 for a new engine...

Dave- What O-ring are you referring to??

DaveSmed
12-06-03, 03:00 PM
The O-ring is the one that seals the iron cylinder sleeves to the aluminum engine block. The cylinder sleeves are NOT replaceable. It is possible to have both problems, and it can get a little tricky trying to distinguish between the two. The only way to really tell for sure that it is the O-rings is to pull the oil pan and pressure test the cooling system. But before that, try the leakdown or compression test. If it passes, then you know it's the O-rings. If it doesn't pass, then the only way to be sure it is JUST the headgaskets is the oil pan method.

elwesso
12-06-03, 03:02 PM
Learn something new every day.... :worship:

Ive never heard anything about those before.... I just thought they were fused in there somehow....

zonie77
12-06-03, 10:55 PM
There are no Orings on the heads. I think what the mechanic was referring to was the metal ring of the head gasket.
The N* doesn't seem to have a cylinder or head cracking problem. The threads/headbolt problem is the biggest problem with these engines.(Not saying it can't happen, just not common.)
Look at the N* headgasket thread. I just posted a pic of the head gasket and you can see the metal rings around the cylinder holes.

kcnewell
12-07-03, 05:04 PM
What happens is the head bolts pull for many reasons (IE not torqued down right from the factory to name one) and it causes the gasket to fail......


Answer....Yes and ...no!


Hopefully it hasnt overheated and warped the heads...... If it is, your gonna be looking at a new engine.....

Answer.....Total nonsense!



Usually it costs about 2000 to replace the headgaskets and timesert it..... 8000 for a new engine...

Answer.....Better check your prices!



Dave- What O-ring are you referring to??

Answer.....LOL!

epanightmare
12-11-03, 11:08 PM
The O-ring is the one that seals the iron cylinder sleeves to the aluminum engine block. The cylinder sleeves are NOT replaceable. It is possible to have both problems, and it can get a little tricky trying to distinguish between the two. The only way to really tell for sure that it is the O-rings is to pull the oil pan and pressure test the cooling system. But before that, try the leakdown or compression test. If it passes, then you know it's the O-rings. If it doesn't pass, then the only way to be sure it is JUST the headgaskets is the oil pan method.
correct me if I'm wrong but I thought that the northstar motors used a cast in iron sleeve with no O-rings but the 4.1, 4.5, and 4.9 OHV motors used a pressed in steel sleeve with an O-ring on the bottom end of the sleeve were it joins the block..:rolleyes:

zonie77
12-12-03, 12:11 AM
epanightmare, you are correct. The liner is cast in or pressed in. It is one with the block.

elwesso
12-12-03, 04:45 PM
epanightmare, you are correct. The liner is cast in or pressed in. It is one with the block.
Thats what I thought.... I never have ever heard anything about these "o-rings"

DaveSmed
12-12-03, 08:01 PM
Wow. I musta had 4.9 on the brain that day. Ah well.

lex97sls
08-13-10, 04:39 PM
Sooo the 4.6 wouldnot have the o-ring issue, correct?

STSS
08-13-10, 04:45 PM
Wow, you drug up a 7 year old thread to ask a question that was already answered earlier in the thread?