3.2 main bearings like new, can I assume the same for the rod bearings

[marlinaness]

I just opened a 3.2 and it appears to have been rebuilt recently. The main bearings looked like new. Can I assume the same for the rod bearings? Or do I just need to check them? Anybody have experience with great main bearings and trashed rod bearings?
thanks again
Marlin

[brp914]

I'm not Steve, Henry, or some of these guys, but I've built a number of these things over the years. If anything, I would say the opposite is true. I just took down a 90k mile 964 and the mains looked great, but the rods had obvious wear plus one had absorbed some debris. Id give them a look-see to be sure, especially now that you got it all apart.

[chris_seven]

The old saying is the assumptions are the Mother and Father of all F**k Ups - excuse the language.

It must be wise to check and also make sure the rods are still round with regard to the big end caps.

[911nut]

Rod bearings spin at 2x the speed of main bearings and are getting beat up at every firing event. You should always replace them.

[Eagledriver]

I'm normally a big fan of top end overhauls. In this case you have already split the case. The rod bolts are a weak link on 3.2 engines anyway. I'd buy ARP rod bolts and at least check the bearings.

-Andy

[JV911SYDNEY]

never assume!

engine is apart anyway so check them out

[irobertson]

If you have it 90% apart, why would you not do the last 10% and have the crank checked and measured? Then get the rods serviced, new small end bushings & the big ends checked and machined to round again if required. (They oval over time) As Eagledriver mentioned, go with ARP bolts while you are at it.

[RedCoupe]

I agree with all the comments. Even if the rod bearings look okay, it's important to check the clearances to make sure they're within spec. Excessive rod bearing clearances have a lot to do with low oil pressure, and when the clearances are too big excess oil is thrown into the cylinders causing oil burning. It's SOP to have the rods checked and/or resized at overhaul time and the bolts replaced with new high quality ones. You won't be sorry.

[marlinaness]

I heard and I will comply. Sending the rods out for the rebuild. Most likely Ollies unless somebody has other good recommendations. I took some pictures showing the wear. Main bearings were from 1986 and showed no wear, so I had not planned on doing anything with the crank. All the rods were the same grams except one was +1 gram and one was +2 grams so I guess balancing is in order as well.

What do I need to have done to the crankshaft?
thanks again

Marlin

[safe]

Originally Posted by 911nut

Rod bearings spin at 2x the speed of main bearings.

What do you mean?
I was going to contest your statement since they don't. But they do travel at a larger circumference so in a sense the actual speed between the rod bearing and crank is greater, not by 2x more likely 4x (without doing the math).

Otherwise I agree that the rod bearing takes a bigger beating.