tod84944

If the rod bearings are bad, should you be loosing oil pressure or have really low oil pressure? Would a 87 with 4 to 5 bar pressure on start up and still holding a 3 bar after running 10-15 minutes have a failed bearing or one going.
If you have had bearing failure, did you replace the bearings after checking the clearance, and no damgae to the crank, and how is it holding up?

nine-44

Hmm, I kinda lost your line there. I'll shoot anyway... I did rod and main bearings on my 86 at 310K afterI had lost oil pressure. The psi was pretty much like yours, maybe 2.5 bar at idle after warm up. I;m guessing the oiling system lost prime and couldn't pick it back up. I started the car after work and showed no oil pressure, revved it, nothing. It made NO noises, lifters or knocking. Figuring that it was a shot sending unit, I made the 21 mile ride home with no oil pressure, I know because when I got off the highway(aprx16 miles) she was making a ton of valvetrane noise, I limped the remainder on side roads. I tore everything in the oiling system apart to find no culprit. I pulled the oil pan to see if the pick up tube broke or dropped off, all fine??? I pulled the original bearings out in actually good condition, even after 21 miles of no oil pressure! The crank looked beautiful, so I threw rod and main bearings in and she's been great since. I run Shell Rotella 15W40 oil and still have the 4-5 bar cold and aprx. 3 bar hot with the new bearings. I've been into a few 944 engines with various milages now. I'd say that 150K miles on a car that gets moderately driven, it would be a good time to do the preventative rod and main bearing swap. If it gets run hard or tracked, probably want to do them by 100K and maybe do them every season or two if it's a dedicated track car. Just my personal opinon and what I read here. Hope to help, Andy

hoffman912

knock knock

whose there

rod

rod who

rod bearing.. knock knock.. time for a rebuild..

nine-44

Hey, who cares if it blows when you have a fully regasketed 88 motor in excellent condition begging to get swapped in. 310K miles plus 21 with no oil pressure and the bottom end(bearings included) looked just as good as my 87K mile 951 motor that spent most of it's life with synthetic oil and was meticulously maintained. I was amazed when I got in there! BTW, I don't baby it either,not even with that milage. She sees red on a regular basis and gets the occasional AutoX. Damn I love this car, can't wait to see 500K!

joseph mitro

my experience:

126K miles at time of failure, several prior autocrosses without problem. oil cooler seal failure at about 123K. finally repaired after 800-1000 miles. oil pressure 4+ on startup, 2.5 or so when hot. maybe dipping to 2 with autocrossing. i was worried about my oil pressure compared to a 951 that was autocrossing and had about 4 bar oil pressure when hot. this was a warm day, too.

the day i spun the bearing i was driving hard on the back roads, redlining the engine hard. oil pressure suddenly dropped to zero and i started hearing the knocking.

still being rebuilt at this point. crankshaft rod journals had to be ground by .25mm. see my website in the signature for pics.

Dave951M

Tod- based on your description, I'd doubt you have a bearing going bad. My 951 has 5bar at start and when warm, holds at 3bar, going up as revs increase. If you don't get a pressure increase as the revs go up, then maybe there's a problem, assuming the sending unit is good.

Dave in Chicago

Both times my '88 had rod bearings going, oil pressure was just fine. The warning sign was tell-tale collection of thin metal shavings forming a little x-mas tree shape on the drain plug magnet. Some flaking in the pan also appeared.

Clearance checked both times and remained in spec for crank and rod itself. The second time, #2 actually spun! Believe it or not, still all in spec (not by a lot), NO drop in pressure, and NO knock. This time, I had the pan and pick-up modified per recommendation of local P-car race shop (should've done that the first time).

Andy's guidelines above for PM on the rod bearings seems spot on from my experience.

tod84944

The engine I'm asking about is a 87. A friend purchased the car on e-bay non-running (really clean actually). Got the car running. At idle, I have her pretty quite with a steady idle. I will get a slight ticking from the top( lifter bucket I suspect), and the idle will drop, when it goes away, idle comes back. But...... when I give it just a slight throttle, hard rattle comes around. I suspected rod bearings, but the oil pressure on start up is at 5 bar and only goes down to 3 bar after it idles for a while. I"m not concerned about dropping to 3 bar, my 84 and 86 both do that.

M758

I had a rod bearing failure and have replaced rod bearings.

My failure was a little different. It happend on the race track at some 65-85 mph. I felt a stumble then bang and my engine blew-up.

I had not noticed, but review of incar video showed that I was losing oil pressure under hard braking and getting it back under accell. This happened for a couple laps and I did not notice it.

The bottom end of that motor was toast. I rebuilt another and crank was fine. In this case I believe I broke the oil-pickup tube and motor sucked air and the #2 failed. All other bearings were great so I don't think it was a wear issue.

I have also seen a few failures were there is rather loud low knocking sound. Usally material is removed from the crank and it needs to be turned. Some times the crank is too far scored and you are screwed.