During the last session of the last day of my DE at Shenandoah Circuit last weekend, I developed engine problems. Specifically, my engine, which had previously run at about 150-180 oil temp, 5 bar oil pressure, and 180-190 water temp started running hotter (maybe 225-240 temp oil and water) with lower oil pressure (never below 2 bar even in the corners), started smoking (I believe from the tailpipe) and developed a knock.

I don't want to throw good money after bad.

So here are my questions:

First, does anybody around the DC metro area have a 2.5L 8v for sale?

Second, what are the relatively inexpensive tests/steps I should take to determine whether it is worth it to try to dig into my exising motor, which still runs.

Thanks in advance.

TD

 

If you have knock you have spun rod bearing. 95% sure on this.

This means at BEST... you need to pull the bottom end and replace the bearings.

At worst if you keep running the engine it can explode and completely destroy the block. The head will probably survive.

I have had two rod bearing faiures on my 944.
First one I did not catch and it blew while on track. The results were not pretty, but the head was saved. Not much else on the motor however.

The second on I caught it relativly early. #2 bearing spun, but that was it. I pulled the crank out however and found it was damaged. Not really bad and it could be repaired. However the repair was going to be expensive since I would need exotic triple undersize bearings.

Instead I got a used crank for about $80-$100.

I have heard of some folks being able to fix the crank. If you can do it and stay to one undersize you are ok as these are common and not that expensive. Other wise you need to find a used crank.

In any event you will be doing a motor rebuilt. When doing that I have heard good results from cross drilling rods 2 & 3 only. Of the motors I have used over the years (3 of them). Both motors with stock cranks spun bearings. The one did not I have used the most and for some strange reason had been cross drilled (all 4) before I ever got it.

On my replacement crank I had my crank shop drill 2 & 3. I have built this motor, but have yet to put it in my car.

 

Yep, sounds like rod bearings to me as well. Most likely you have caught it pretty early, unless you mean oil pressure didn't go under 2 bar with the engine at high revs. It really shouldn't go below 4 bar in that situation.

The increased oil temps, and smoking seem related, but smoking is not indicative of a rod bearing failure, unless metal shards got nicely distributed through the motor. What color is the smoke, blue? That one is a big of a melon-scratcher.

 

Hey Joe,

As always, thanks. I have been assuming I spun a rod bearing as well. What I am really worried about is the smoke from the tailpipe. Wouldn't that be caused by ring/cylinder wall damage rather than a spun rod bearing? What else could cause the smoke?

TD

P.S. Wanna fedex me your spare motor?

 

I have a 2.5L engine for sale, you have a PM.

 

Sure... just send me your 996. Fair trade!

 

As far as I can tell, it was light to medium grey (on the lighter side). Maybe I will post a video clip of it. I didn't see/smell it, but it got sucked into the cockpit during corners and the video cam picked it up. It makes me sick watching it, sorta like rubbernecking at your own car wreck . . .

 

hahahahahahah ummmmm No.

 

TD have you pulled the plugs & drained the oil yet? Also operating under the theory of head gasket leak + coolant oil mixing/thinning = dead bearing.

 

Ken,

No I haven't, not yet. Interesting theory. I take it that I might have caught it early enough that I wouldn't see a "milkshake" by looking at the overflow tank or checking the oil with the dipstick (I did both, and everything looked fine).

TD

 

Rod bearing halfs have a hole machined in the center, its an oil port that normally guides oil into the piston rod, which lubs the wrist pin and cylinder walls/rings. Spin a rod bearing and u loose oil lubrication to that cylinder=lots of heat=losts of smoke. In the mid 1970's I spun a GM rod bearing, and the crank was damaged. The machine shop I hired had the tooling to reweld the damaged crank journal and machine it back to its original size. Good Luck

 

944 rod bearings are solid. No hole at all.

944 Main have holes in them to feel passages in the crank the feed the rods.

I believe the wrist pins are splash lubricated.

 

You can actually spin the bearing on this car without damaging the crank, not often but can happen.

 

Well correct me and explain...how does oil flow thru the engine. Don't tell me its splashed lubed, even my 6.5 hp lawn mower has an oil pump, I just can't buy splash lubing !
Its been awhile since I rebuilt an engine, crank main bearings had hole and maybe rod bearings had a slot, I forget, so how does oil move inside the engine ?

 

Here you go