Thread: Bad main bearing?

So here's the story: Two weeks ago on a Saturday a friend and I tune up the car. New plugs, PCV valve and air filter. We take it for a spin and it idles really high. On top of that I get an intermittent squeak that matches the RPM. I take it into the shop and they found a loose hose that I couldn't see, but said the squeak is the main bearing. The engine doesn't knock, and only has 136k on it. It does have a bad upper intake gasket, and that *might* have been the issue with the main bearing starting to die, but this all happened really suddenly - right after the tune-up. Prior to taking it in I noticed the power steering pulley wobbled a tiny bit and thought the bearings are shot on that. I'm really sortof frazzled as I know a main bearing is a $2000 job, so I can't think straight to come up with options.

Oh, you can hear the squeak as the engine is shut off -- it slows and stops with the engine stopping.

Thoughts? Can I do my own intake gasket replacements in my garage with standard tools? Taking the belt of is there something I should be feeling for when trying to turn the main pulley? (grinding, looseness, etc)

I don't think you're going to feel anything. Just listen closely for any of the squeeking you're hearing now. Take the belt off and start it up for a second to see if it really is coming from the internals. If the squeek is gone without the belt on then that's good news.

Ah, smart. I didn't think of taking the belt off. I'll get back to you once I've got it home and tested.

Sorry for the double post, but I thought I'd report what the shop said. First they pointed out the leaky intake gaskets (which I knew about) and priced $1300 for that, then they said they wanted $1400 for the bottom end, which *might* be salvagable if I get the top end fixed fast enough. I know the top end is bad, you can easily notice the pools on the intake, and taking the oil filler cap off at idle kills the engine. But I'm still not convinced that the main bearing is leaking. I mean, if one of the mains went bad I'd hear it all the time, right? Instead I only hear squeaking at below 1500 RPM, which gets louder and higher pitch the lower the RPM. Sure sounds like an accessory drive to me, but I haven't got the belt off yet to test it as I just got home.


So now that leads me to a new question -- doing the top end ... upper/lower intake gaskets, valve cover gaskets, and anything else I'd need to replace when doing those. Is that a fix I can do myself? I haven't torn down an engine in 15 years, and then it was mid 70's V-8's in automotive class, but if it really comes down to a remove/clean/apply gaskets/bolt up/torque to specs I can do that. My concerns come with things like pressurized systems and any special tools I'd need.

LIM is an easy one.

As for the bottom end, if its actually gone, it'd be cheaper for you to get either a new short block or long block and drop it in than pay them to repair your old one.

It'd also be a better idea considering the stock block is pretty stout.

So I've been reading up, and it looks like a lot of car engines should die (or at least run bad) when you remove the oil filler cap, because you're creating an enormous vacuum leak. I thought that was the case typically speaking -- do the 3800s fall in that category too?

yes

Took it to a trusted mechanic this morning. He said the squeaking noise I heard wasn't the bearings, and wasn't any of the pulleys. He said that the crankcase wasn't breathing properly, and what I heard was actually air escaping. That's why it only happened at idle. He said when I got to do the LIM and UIM I should thoroughly clean the plenum and throttle body. He said the motor is fine aside from the upper end issues. Good to know, as I can fix that myself.

It's not some dirty acronym or meshup of words if that's what you're thinking. See below.

Teancum - Wikipedia, the free encyclopedia

I just wanted to report that the LIM replacement went off without a hitch. DeBob's tutorial worked perfectly, and everyone was right. It's not hard, it just takes forever. I've still got the squeaking going on that sounds like a belt squeak, but like the more trusted mechanic said it's probably because the crankcase can't breathe. When putting the MAF sensor back on I broke one of the two clips in the piece between it and the PCV valve, so I'm wondering if it not getting a good seal is causing the issue. Does anyone know what that piece is called? I should probably replace it.