Nicholbry

Hello fellow Rennlisters:
I am 1/2 way into the motor mount exchange/oil pan gasket replacement/etc. and I was considering doing the Rod Bearing replacement WIAIT. I realize there are some very specific torque requirements for the different nuts. What I was wondering, has anyone completed the Rod Bearing replacement and documented it with images? I'm new to this DIY stuff and learning as I go so any detail that you guys might think trivial would be appreciated by this rookie.

I have a '90 S4 experiencing low oil pressure, occasionally, so I thought I might check out the rod bearings (paying paticular attention to #2 & #6 of course). A fellow Rennlister previously recommended I not get into this with my lack of experience as he was concerned for me. However, I'm just thinking about it at this point. If I were to get a good tutorial on it from one of you guys I might be brave enough to tackle the job. After all, I don't expect to be going back into the bottom of the motor any time soon.

Thanks.

docmirror

I do not have an instruction or pics, but only advice. Get help. If you are taking rod end journals apart, it's very easy to score, or nick the crank journal. Even though it's quite hard, even a small nick can cause real problems. It's unlikely that rod end bearings will be the source of your low oil pressure alone. However, looking at the state of the bearings might give you an idea of the general condition of the rest of the bearings.

You could also put a bearing shell on wrong, or reverse an end cap and that could be catastrophic. If you are a DIY guy with limited experience, pay someone to assist you at this time. Money well spent.

AO

Nicholas-

It's really pretty easy. The one thing you have to remember is that the nuts need to be replaced. Pretty much all you have to do once you have the oil pan off, is unscrew the nuts, separate the connecting rod, push the piston up to gain clearance and slip the bearings out (sometimes they fall out.) Pre-coat the new bearings with motor oil and re-assemble. I forget the tq value but I think it was 47 ftlbs, but you should double check to be sure. One time is to put some rubber hose on the stud of the connecting ros to make sure you don't scratch the crank. I used this method with great success.

Good luck.

AO

The bearing shells are keyed, so I would think it's near impossible to put them in wrong. BTW, when I did mine, it was my first time doing anything like this, and it seemed very straight forward!

Big Dave

Yep, they're keyed to slip into place. Make sure you lubricate each one when installing. New rod nuts are a must.

Good luck.

marton

Which oil do you use?

Marton

marton

Which oil do you use?

Marton

docmirror

I've seen and repaired the results of amateur lower end engine work before. I know the caps and rods are notched, I know it looks easy. Making a mistake here is so costly as to warrant getting skilled help for the neophyte. If he doesn't want to, it's not costing me anything. But it may cost him something.

There are several threads each month where a seemingly simple job turns into the sinking of the Edmund Fitzgerald. I stand by my opinion.

Mrmerlin

you might want to check and replace the pressure relief springs in the oil filter /pressure sensor housing, these are ususally the most likely over looked parts for Lo oil pressure, but if you have the pan off you really need to check the 2/6 rods if they are good you can leave the rest alone unless you going to replace all of the rod bearings, instead of using oil to lube the new rod bearings it would be better to use assembly lube, press the new rod bearings into the rods and caps then add the lube to the bearing surface and crank journal, if your really into it you could also get some plasti gauge and check your clearances use the old nuts to check the clearances the plasti gauge is used dry dont turn the crank with this in there and take it apart to clean out the plasi gauge . you should use the green plasti gauge

Nicholbry

Thanks guys for sharing your experience.

Doc: I wish I could call on someone, but unfortunately I live in a very rural area and I don't know of anyone locally that I would want to touch my car. The nearest mechanic that I would consider is about 1 hr. away and he has a very active business to run servicing Merc./BMW/Porsche 911 & 944. This is the reason for my inquiry. Indeed, in the end I may shy away from the rod bearings, but I didn't want to button things back up without doing all that I could. Although inexperienced, I am very careful - sometimes overly careful so I trust myself to details; however, I like to have all the information before proceeding. If I can't get what I think is sufficient, then I will move on. I appreciate your concern for me.

MrMerlin: I assume you are referring to that piece that screws into the block above the oil pressure sensor next to the oil filter location??? I had considered taking that thing apart for cleaning or replacing the spring inside if that is what you are referring to. Thanks for the heads up on that.

Maron: I used the factory recommended viscosity from my manual but used the full synthetic variety by Mobil 1. Any recommendations for my refill?

Andrew: I appreciate your reply and knowing that you have had success.

Big Dave: Thank you for your pic. Not having gotten so far as to remove my pan yet, it was reassuring to be able to see what is in there. Those nuts that need replacing; once they are removed how does that assembly come apart to reveal the rod bearing? Is that two crescent shaped pieces bound together by a top/bottom bolt & nut to form a circle which encapsulates the rod bearings? Any basic, elementary description would likely suffice. I just don't want to go unscrewing nuts without knowing how that assembly is supposed to come apart to get at the rod bearings. Thanks again for the pic.

Tony

RyanPerrella

ha ha nice pic tony

GUMBALL

Nicholbry:

It sounds like you have not done something like this before. If that is the case, I must concur with "docmirror".....something like this seems simple, BUT the costs of a tiny error can be extreme.

It is not a bad idea to look at the 2/6 rod bearings when you have the motor out and accessable, but unless you know what you are looking at, and looking for, it is a waste of time.

Just a thought....you are in the heart of stock car country......is there a "race shop" anywhere near you..? To a good engine builder, an engine is an engine, is an engine, if you can provide specs and clearences for him......

Big Dave

Here ya go...

Aatos

I did rod bearing swap when I did MM's/OPG and I had never opened an oilpan in my life before that. Amazingly, the car still seems to work .