Engine Problem

kevinbly · 10-17-2005, 08:20 AM

I have a problem that I was hoping one of the experts could help with.

1987 951, 120k miles

Here is what happened:
- While driving, noticed a small sound, which I thought was a small exhaust leak (sputtering, faster with rpm change)
- sound got a bit louder just before squealing from engine, and loud knock developed. Car still runs, but poorly
- shut down engine ASAP, and towed home
- I checked the obvious stuff, as the squealing noise sounded like a belt
- All rotating components were fine and spun by hand and smoothly - alternator, water pump, a/c compressor, turbo, p/s pump, etc all were fine
- The lower balance shaft was slightly harder to turn, but nothing drastic
- CAM was fine
- I thought maybe the loud banging sound could have been a valve, but when I removed the head, all looks fine
- Crankshaft seems to turn fine, with all pistons moving up and down smoothly
- I only thing I found was that one of the ports on the intake boot was blown off

Could the large hole in the intake boot by itself possibly cause these symptoms?

Anyone experience symptoms like these?

Kevin

ae1969 · 10-17-2005, 08:53 AM

Did you check the oil ? ANy large chunks present.....

kevinbly · 10-17-2005, 09:03 AM

I actually drained the oil, and did not find any "large" chucks, but the magnetic drain plug had some VERY fine shavings on it. When I wiped it all off with a paper towel, there was nothing large enough to be seen until it was gathered together again with a magnet.

nize · nize's Garage

wow this is crazy, i have never heard of anything like it on the 951 before.

valve or shatterred plug sounds likely, but if you've removed the head i'm sure you would have noticed.

also, the engine is aluminum so a magnet won't catch everything.

i'd suggest try running it by rennlist.

WaA420 · 10-18-2005, 07:03 PM

One of my '86 951's did the same thing and it turned out to be the lower balance shaft bearings were all messed up. You said that it was a little harder to turn and the noise was kinda like knocking. I think you should take off the lower balance shaft cover and have a look, you may be surprised.

kevinbly · 10-19-2005, 07:59 AM

I will check it out. Thanks for your help!

Cory9584 · 10-19-2005, 12:45 PM

are you sure it wasnt a drivetrain noise?

F1Rocks · 10-19-2005, 05:24 PM

I just had the same thing with my 951. I changed to the spare engine and have the "new" spare torn down to the crank.

Exact same noises/symptoms
Everything in the cam tower looks great.
Cylinders are clean/Pistons look nice
All the rod bearings look new...why did I tear this down again
ONLY thing similiar is the lower balance shaft is also hard to turn on mine.

I'll have the crank out and the lower balance shaft off by Friday night. Maybe I'll see something of interest for you.

F1Rocks · 10-20-2005, 08:04 AM

Balance shafts look cleaner than a spanked baby's butt.

Bearing surfaces looked like new.

Gotta be something in the valve train for me.

ae1969 · 10-20-2005, 12:11 PM

Quote:

Originally posted by kevinbly
- I only thing I found was that one of the ports on the intake boot was blown off..............

Do you have a pic of this........ You may find what blew off........was actually sucked in.

ae1969 · 10-20-2005, 12:13 PM

Quote:

Originally posted by nize
.......also, the engine is aluminum so a magnet won't catch everything.....

The rod/main bearing chunks we were hoping to eliminate by looking at the magnet.....

The metalic paste that forms is normal.

kevinbly · 10-31-2005, 10:13 AM

Well, I finally got the lower balance shaft cover off last night, and the bearings look fine.

Could the problem/noises/symptoms possibly be caused by a failed clutch / throw-out bearing?

Dougster · 11-02-2005, 04:14 PM

Quote:

Originally posted by ae1969
Do you have a pic of this........ You may find what blew off........was actually sucked in.

I second this...

kevinbly · 11-03-2005, 09:22 AM

In my original message, I stated that the head was removed and all looked fine. This has really got me baffled.

If it was a lower engine problem (crank/rod bearings), would I still be able to turn the crankshaft pulley relatively easily and have all of the pistons move smoothly up and down?

Any suggestions ?

kevinbly · 11-28-2005, 11:09 AM

Well, I finally broke down and dropped the oil pan. It was the notorious #2 rod bearing failure. It scored both the rod and the crank pretty good.

So, what is now required to get this engine back up and running? I would like to do as much of this myself as I can. Would it be more cost effective to buy a new crankshaft? Or have this one rebuilt? Would I need to replace the scored rod?

Anyone have experience with this?

Thanks in advance for your help.