Engine Might Be Blown in My '94 STS

masterzelda · #1 (**permalink**) 10-10-09, 04:00 PM

I just got my 1994 Sevile STS back in running order. After taking her out for a spin; the engin started making a funny rattling, and knocking sound. When I turned the car off; it made a loud screaching sound like nails on a chalkboard. I am almost certain that the head gaskets are blown since they are the original ones; and this car has over 172K miles on it. I think that might explain the rattling sound.

That is not the biggest concern I have. What concerns me is the other noises it is making. It sounds like the engine is also knocking; and it is running really rough; almost as if the pistons are rubbing against the bare metal on the block. That could also explain the loud screacking sound I get when I turn the engine off. I also discovered that it is getting very poor oil pressure as well; so it may just be time to lay that engine to rest!

SPreston2001 · #2 (**permalink**) 10-10-09, 04:22 PM

Well my baby is at the dealership right now after suffering from similar symptoms. I started getting this horrible rattling clanking sound from my engine and after they tore it down, they discovered that a spark plug had broken and pieces of it had fell down into the cylinder. The good thing about this whole situation is that im killing two birds with one stone since they have to timesert the block when they put everything back together so I should be headgasket worry free lol. Not to scare you but rattling and knocking sounds arent something you wanna hear coming from a Northstar. Also blown headgaskets will not cause any noises. Chances are there is some internal engine damage $$$.

Krashed989 · #3 (**permalink**) 10-10-09, 08:37 PM

Quote:

Originally Posted by masterzelda

... I also discovered that it is getting very poor oil pressure as well...

That's probably the cause for most of your noises. If the hydrolic lifters don't get enough oil pressure, they will make noise. Plus the friction bearings need good oil pressure. Fix the oil pressure issue first.

The screeching/scraping you describe sounds more like a bad serpentine belt or something.

To determine whether the headgaskets are bad, get the coolant tested for exhaust gas byproducts.

Quote:

Originally Posted by SPreston2001

...The good thing about this whole situation is that im killing two birds with one stone since they have to timesert the block when they put everything back together so I should be headgasket worry free lol...

Timeserts have a pretty high failure rate, which is why many dealerships refuse to install timeserts anymore. Instead they choose to only install factory rebuilt engines.

If I were you I'd see if I could get them to stud the block instead.
http://www.cadillacforums.com/forums...t-inserts.html (Northstar Repair without inserts)
http://www.northstarperformance.com/

SPreston2001 · #4 (**permalink**) 10-11-09, 10:54 AM

Hey thanks ill make sure I mention that to the dealership. They didnt they didnt actually say they were using timeserts, but I assumed they were. He actually told me he would have to use a kit to reinstall the heads and I told him I was aware of the process.

jeffrsmith · #5 (**permalink**) 10-11-09, 11:25 AM

I think that you will find that if the dealership is doing the work they will use timeserts. Timeserting is the official GM repair procedure for HG repairs and even then they typically only do the holes that absolutely need them.

N*Caddy · #6 (**permalink**) 10-11-09, 12:10 PM

The N* engine owners are scared with the head gasket as we use to be scared when we were kids with the Bogeyman. Anything that seems to be wrong with the engine has to be the HG. Krashed stands correct; the low oil pressure might be the cause of the knock you hear. Doubtable the squeak sound, the engine will size in seconds with such a sound, most likely the accessories belt does that. Definitely DO NOT drive the car is suspected of low oil pressure. 1 minute of running the engine with low oil pressure makes more damages than 200K miles of regular drive.

submariner409 · #7 (**permalink**) 10-11-09, 12:15 PM

................actually, the Timesert failure rate is relatively low. A dealer would probably want to use a GM crate engine because of less labor time and more profit: A good tech could do an engine swap in a day and a half, while an overhaul ties up the bay for 3 - 4 days.

Krashed989 · #8 (**permalink**) 10-11-09, 01:49 PM

Quote:

Originally Posted by submariner409

................actually, the Timesert failure rate is relatively low....

If that's the case then what's the point in making the norms insert kit, or the stud kit? Obviously, the people who made them first had to see a problem and then turned that problem into something marketable.

This thread alone gives you an uneasy feeling about timeserts.
http://www.cadillacforums.com/forums...ilure-fix.html (Root Cause of Head gasket Failure and a Fix?)

submariner409 · #9 (**permalink**) 10-11-09, 03:07 PM

...........same reason there are different brands and qualities of practically anything manufactured on earth: you do your homework and you make your choice.

You stated that the Timesert failure rate is "pretty high". What is the Timesert failure rate in % of engines overhauled by GM dealers? Where can we get that statistic?

Perhaps someone could contact the company at www.timesert.com and ask for their aluminum block repair failure rate.