Engine knocking noise...need help identifying

[j911brick]

Its a bearing, but who knows which one: Rod, main or IMS. Doesn't matter because you need a new/rebuilt motor no matter how you look at it.

[cstreit]

Sorry Max but that's definitely a rod bearing...

Now comes the hard decision, repair or replace. If you repair it's a tough road to clean everything out well enough to get all the bearing bits out of the oil galleys, etc... Scrap or ultrasonically clean oil coolers, flush lines etc... I had to redo my race engine last year because despite fastidious cleaning there was still some debris...

[whiz05403]

That sucks Max, very sorry. Keep us posted.

[maxhofer]

Well my hopes of a failed tensioner or broken valve spring have been shattered...!!!

My first thought is to open the engine to see how much damage was done. According to that, see if a rebuild is feasable or to get a new/rebuilt engine will be best, both moneywise and timewise.

I'n not afraid of getting into a rebuild, but Chris's thoughts about the fastidious cleaning of the debris worries me a bit.

What are the most common causes a rod bearing failure?, other than the obvious of running the engine without oil!

Is it mainly fatigue?

Thanks to everyone for your help so far. Guess I'll keep needing it, this would be my first engine tear down. And in the meanwhile I guess I'll be driving my 944!!!

[cstreit]

Rod Bearing failure?

Low oil pressure and/or overrevving are the usual causes. Tired engines with worn out bearings start losing pressure and wearing faster, vicious circle.

[maxhofer]

Originally Posted by cstreit

Rod Bearing failure?

Low oil pressure and/or overrevving are the usual causes. Tired engines with worn out bearings start losing pressure and wearing faster, vicious circle.

Thanks Chris, I guess my failure was a combination of overreving with a tired bearing.

The problem came up after some hard driving. Motor is about 90.000 miles now. I've had it since 60.000 miles and have no clue of what could have been done by previous owner/s.

[j911brick]

Originally Posted by maxhofer

Thanks Chris, I guess my failure was a combination of overreving with a tired bearing.

The problem came up after some hard driving. Motor is about 90.000 miles now. I've had it since 60.000 miles and have no clue of what could have been done by previous owner/s.

I can't say for sure, but I think I recall the 3.2 having an issue with failing rod bolts at one time. They use a smaller bolt than the 2.0-3.0 engines.

Don't worry about the cleaning issues. All problems can be solved. I have rebuilt several motors that were as bad as yours. In fact I'm doing a turbo motor right now that had a bearing failure. No matter what, you will have to clean the oil lines, cooler, and tank; and that is the hard part. So builders replace all those parts, but that's expensive.

[ZOA NOM]

FWIW, I replaced the P&C and rod for the #6 which failed during heavy acceleration following a tight turn which starved the engine of oil. Had the crank welded and resized to factory specs, and I've been racing that motor for three seasons since, without issue. You will likely find that one rod bearing has failed, but you will obviously want to replace them all and refresh the motor. It is actually a very fun project that will give you tons of confidence. Look to the engine rebuilding forum here for assistance.


edit: like cstreit said, it's definitely a rod bearing. That's what causes the deep knocking sound. I remember it well.

[Flat6pac]

Like I ve said, Putting the cam restrictors in, especially on a Carrera, I would rather loose the cam than the crank and all it can entail. I have seen too many 3.2 wiped on the 2 or 5 throw and it wasnt caused by rod bolts, but oil starvation...
Bruce

[Targalid]

Bruce, can you explain what you just said for the rest of us unwashed ignorant types? Cam restrictors? How does this affect oil starvation? What are cam restrictors?
Al

[brads911sc]

I feel your pain.

Youll love it even more after your done. trust me... Hang in there. Its actually fun and wont take too long. Good luck.

[maxhofer]

Originally Posted by brads911sc

I feel your pain.

Youll love it even more after your done. trust me... Hang in there. Its actually fun and wont take too long. Good luck.

After recovering from the first moments of depression when i found all that metal in the oil I'm getting ready to disassemble the engine.

I have been getting info from the engine rebuilding forum and ordered Wayne's engine rebuild book.

I'm really looking forward to the learning process involved. And more important, enjoying a fresh rebuilt engine!!!

[Targalid]

Found a discussion on oiling and cam restrictors: Cam Tower Oil Line Restrictors Redux

[ZOA NOM]

Originally Posted by Targalid

Bruce, can you explain what you just said for the rest of us unwashed ignorant types? Cam restrictors? How does this affect oil starvation? What are cam restrictors?
Al

What he said is he would rather install the cam line restrictors that restrict oil flow to the cam housings in order to retain higher pressure in the case, thereby protecting the crankshaft and rods more effectively. There is sufficient remaining flow for the cams, so the restrictors are worthwhile. They are simply fittings that are installed at the rear of the motor on the cam housings where the oil lines enter. The factory fitting has a larger hole in it.

[hcoles]

It should be mentioned that there is not 100% agreement that changing to the restricted fittings is advisable. I had stock, rebuilt engine with restrictors, now back to stock fittings. I remember some past threads containing more on this. I think the Wayne book recommends the restricted fittings. With the stock fittings the oil pressure is noticeably lower as seen on the dash. I noticed some issues with what appears to be rocker pad wear (after posting and getting many good comments, not sure what I saw is 100% lube related) and changed back thinking it would help.

[Targalid]

Thanks for the explanation. I see Pelican sells a kit for both sides with replacement oil lines and washers for $32.