z driver 88t

After a spirited drive with some friends on Saturday I looked down at the temp gauge to see the needle on the red. Seems that I may have a small pin hole radiator leak I did not know about and the low-coolant level light did not come on.

Anyway - after reading some threads I expect at the very least I have some damaged main bearings, and/or rod bearings. and possibly a damaged head gasket, maybe warped heads.

My initial thoughts are to pick up a used long block from 928INTL and swap it out sometime in December. But before I do that, I wanted to trouble shoot the condition of the existing engine. I'm not trying to repair this on the cheap - but I don't have the time these days to rebuild the engine myself, and don't really have the funds to pay for a full professional rebuild. Something in between would be doable.

My plan today is to try to start the engine. If the engine actually starts then I will pressure test it. If the pressures come back ok, then I will presume the heads are ok and no blown head gasket and the most likely potential damage would be to the bottom end. If that is the case, it MIGHT make more sense to just get new main bearings and rod bearings and replace those.

The guys driving with me saw a little white smoke out the back so I'm inclined to think there is a head gasket issue, which will most likely mean some cylinder head work, which at that point it may be more economical just to get a used long block.

Just looking to the Rennlist crew for some input to my proposed strategy. Does this seem like a reasonable approach? Anything I'm overlooking to guys that have faced this before? Thanks.

Lizard928

Pull all spark plugs and rotate engine by hand.
See if any of the cylinders were hydro locked.

davek9

^^^ yes ^^^ and if it does rotate by hand w/o and issue, then do a compression test.
remember to mark the plugs as they are removed.

docmirror

Look for one or two plugs that are much cleaner than the others. Those will be the water leaks.

Then do a cold leak check of the coolant and see if it holds.

Randy V

What make you think a single overheat condition has caused catastrophic engine damage?

soontobered84

White smoke is not ever a good sign

dr bob

^^^^^ This. And echo DaveK9's recommendation on looking for steam-cleaned sparkplugs.

It takes a lot to seize the engine completely. The pistons and the block are both aluminum, so they expand at about the same rate. When oil overheats to the point where it no longer protects the bearings, the bearing shells becobe friction-welded to the crankshaft and spin in the connecting rod. There's a LOT of noise that goes with that, and it typically ends with a broken or bent rod.

Some tools to consider are a small USB borescope camera that lets you look in the cylinder for damage. A leakdown test can be done without cranking the engine, but you will need to be able to roll the crankshaft to get to all the cylinders. If rings are stuck and/or pistons and cylinder walls damaged due to poor lubrication. A cooling system pressure test will help you decide if there are internal leaks besides the hole in the radiator.

If you do find damage, you'll want to get the engine out and into a stand for inspection teardown. Much easier than trying to westle pieces out with the engine still in the car, and safer for the rest of the car.

The Deputy

[Edit...my..."This^^^^"...was meant to be under RandyV's post...a couple guys snuck in between us]

This^^^^

I'm confused, now if I were a woman this would not be out of the ordinary, but did the engine actually "seize" or did you just have a hard time getting it too "turn/crank over" once you had turned it off and tried to restart? You mention it seizing in the topic title, but don't say anything about it again in the post? It is not uncommon for an engine too turn over slow once it has been overheated.

Aluminum blocks and heads can take quite a bit of heat. Yes, it would make a big difference when considering the amount of time you were driving it with the gauge in the red...but it doesn't necessarily mean all of the issues you've listed would come true.

Seeing a bit of white smoke could be from the leaking radiator.

If the engine didn't actually seize and before jumping to any conclusions...I'd refill the system, look for water/anti-freeze leaking out, if I didn't see any, start it and watch/smell the tailpipe (for signs or smell of anti-freeze). You could pull the plugs first, if you were worried about hydro-locking the cylinders and then turn it over and look for any remnants of fluid coming out of the sparkplug holes. But, if you turn it over and it makes a couple revolutions...I'd suspect you don't have any fluid in the cylinders. However, take whatever precautions make you feel comfortable.

Now, if it did seize up and actually stop running on account of the overheating issue...you may be looking at some lengthy/expensive repairs.

Good luck,

Brian.

upstownal

this^^^^...did you shut the engine down or did it die on its own?..the white smoke is just indicative of the coolant getting into the cylinder(s), not necessarily the end of your engine.

yardpro

i agree that there may be no issue at all.

i have a range rover ... they are notorious for being damaged by an overheat....
had a radiator fail on the wife and she drove all the way home... you could fry an egg on the motor.. no water at all in the radiator....
immediate damage.
i am sure it shortened the engines life, but 20K later at 178K it still runs fine.

also had an 03 jaguar xj8 overheat on us
Front top rad. hose blew off... went into limp mode and wife still drove home saying that she thought it was running funny......

both of these survived... and both are delicate motors

FredR

Whereas you may have done some damage to the motor far better to check and prove such damage actually is present rather than assume such. Had the motor seized you would have known about it in no uncertain terms I suspect.

First thing to do is find the source of the coolant loss- fix it and then test the motor. A leakdown test is very informative especially when coupled with a compression test and no need to remove anything other than spark plugs. If the motor cranks with no signs of distress then you can probably run it up and see how it works.

Rgds

Fred

dr bob

Forgot to add that if the engine was seriously hot, give the oil a sniff test before swapping in new fresh oil. And plan to open the oil filter and inspect the pleats in the filter media for debris. Seizure invariably generates stray metal bits from friction, and you would see them in the oil you remove. If the engine we running for even a short while after metal-to-metal contact, the results will be prominent in the filter media.

I think it was Stan who suggested elsewhere that you drain the oil through a white T-shirt. Look for reflective bits filtered by the T-shirt.

Imo000

When and engine overheats, rarely are the bearings that fail. If anything happened here at all it would be either a warped head with a blown gasket or some scored cylinders.

How much do you know about engines in general?

mark kibort

did it seize? the engine died and then the starter couldnt rotate the engine? if so, the pistons have dug into the cylinder walls more than likely.
you get a new short block and take the heads to a machine shop to make sure they are flat and put it together.
S4 or early car?

z driver 88t

OK guys, an update. Yes the engine did seize initially. I.E. it could not be turned by hand and the starter would not turn it over. Today I was able to turn the engine over so assuming I was going to need to order an engine anyway - figured I'd try to start it.

It did start and coolant / water was pouring out the exhaust. Leads me to believe what really happened was a massively blown headgasket and hydrolocked engine.

I know a reasonable amount about engines, but really don't want to spend the downtime checking the cylinder walls and block. Since this is mostly my daily driver I'm mostly inclined to swap in a used engine. I can then take my time if I want to inspect this engine thoroughly and possibly rebuild it over time.

So, final question - get a full engine / long block or just a short block and machine the old heads? I'm inclined to get a complete engine, the cost difference is pretty negligible. But if someone with some 928 engine building experience could chime in on the likelihood that the old heads could be machined and new valve stem seals installed and call it good, that would be appreciated.