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14.1 @ 100mph N/A
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Discussion Starter · #1 ·
I changed my rod bearings on my 135k mile N/A. They were all worn bad enough to need replacing. I Plasti-Gauged the cleaances, and I got .0018 inches. The tolerances are .0008-.002, so I was just barely within spec. Any time a bearing is copper colored instead of silver, it's time to replace them... all my lower rod bearings were worn to copper. The uppers were scraped up and worn, but not worn to copper yet.

I replaced all of them and Plasti-Gauged again... .0008 on all journals!

The crank has a few microscopic scratches on it, so the worn bearings were already starting to do damage. I took a penny and rubbed it on the crankshaft journals where the bearings were, and copper came off the penny... that's the old ******* test to see if a crank needs to be polished. So my crank does need polishing, but I'm gonna leave it as-is until I pull the motor and rebuild it.

One other thing I noticed is: all the cylinders still have cross-hatching from the factory honing... and this is on a 135k mile motor! There were a few tiny scrapes going up-and-down in the cylinder walls, so a refinishing and re-ring would be ideal, but I still have good compression so I'm gonna leave it alone for now.

Everything went smoothly, and the car runs fine. :bigthumb:

Pics:

Notice how all the lower bearings are copper, and all the uppers are still silver:



Check out the scrapes:



Notice how the #6 upper bearing(the 5th one over) shows damage from oil starvation... I've heard this is the most common bearing to "spin".



If anyone has any questions, let me know. I HIGHLY recommend that everyone with over 100k miles do this to their own car. The bearings are only $75 from a dealer, and even cheaper from Auto Zone.
 

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Captain Slow
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Hey Drew, how long did it take ya to do it? I've been looking into it for a winter project. Also did you have to pull your engine? I've got access to a lift, but if I've gotta pull the engine, I'm gonna pass.
 

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Somebody posted some stuff from the porsche 944 crank. basically the oiling holes are setup on both sides and the crank was lightned to reduce stress ont he ebarings.

It sounds like a good idea. Anything that reduces the load on the motor should be a good thing.

I relaced all my beargins with clevites a while back.
 

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Booooossstt
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Did you do this stuff with the motor still in the car and just yank the oil pan and the piston rod bolts? BTW just look at this.... You removed these for the hell of it or whatever but everyone is having spun bearing issues but look at the danged things! This should be a recall considering that there is OBVIOUSLY something wrong with this damned motor! Thanks for the info!
sean
 

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14.1 @ 100mph N/A
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Discussion Starter · #6 ·
3KGTCRUISER said:
Hey Drew, how long did it take ya to do it?

It took me about 3 hours, but I'd say it could take as much as 5 hours for a "beginner" or on a car with seized bolts.

did you have to pull your engine?

No. I did it with the engine still in the car.
Internexus said:
Did you do this stuff with the motor still in the car and just yank the oil pan and the piston rod bolts?

I dropped the exhaust, driver's side crossmember, starter, two block-to-tranny brackets, and the oil pan, then did one rod at a time. I Plasti-Gauged all the rods just out of curiousity, but it's really only necessary to do one.

BTW just look at this.... You removed these for the hell of it or whatever but everyone is having spun bearing issues but look at the danged things! This should be a recall considering that there is OBVIOUSLY something wrong with this damned motor!
These are normal for an engine with 135k miles and a hard life. It's also normal for the bearings furthest from the oil pump to be more worn. I think the main problem with spun bearings on these cars is owners who think that modern import cars are exempt from standard maintenance, which includes bearings and oil pumps at high miles.

If everyone changed their rod bearings and oil pump at the 120k tune-up. The world would be right.
 

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Tire Pumper Extraordinair
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I'm having the oil pump changed in the spirng (car is in storage) along with my 60k (65k on the car right now). Wondering If I should do the bearings too. Mind you, I don't drive the car hard and it does only have 65k on it. Probably should wait to 120k eh Drew?

Can changing the bearings make things worse? That is, what's the chances of a dealership screwing things up and not putting everything back together. Errr, hmmm...Dodge we're talking here, nevermind I'll wait to 120k...:(

Ted
 

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Official 3SI Mouth
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I'm very suprised. In the spring, my 118k turbo engine showed no scraching on the bearings, and like Drew, I did the old penny bit (I'm suprised to see that pop up :) ), and the crank took no copper.

What milage did your girlfriend pick that Stealth up at, Drew? And did she get any sort of maintenence history with it?

Naturally, I'm in complete agreement with the oil pump and bearing swap over 100k. Why it was never listed as a service item is beyond my comprehension. Then again, even regular commuter vehicles come without such a warning- I suppose every manufacturer is looking to be the next Toyota, with their 10k oil change intervals. :rolleyes:
 

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tbadiuk said:
Probably should wait to 120k eh Drew?
Mine spun bearings at 114k, bent crank, damaged rods, the whole nine yards. I would stick with drew, anyone at 100k should do this.
 

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Tire Pumper Extraordinair
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From what I've gathered on here the 91-93.5 (93.5+ changed) cranks are weaker causing a lot of spun bearing stories. My gut feel right now is that on 1st gen's it the crank + crappy oil pump causing it at >100k and on 2nd gen's it's mainly a failed oil pump. I think the bearings themselves should be good to 300k if you run at stock power levels(*), change oil regularly, and change the oil pump every 60k. Mind you if you change the pump you can inspect the bearings at the same time.

(*) Not so much that more power = bad, but more power usually = knocking engine while tuning which mashes bearings which is bad.

Ted



dreadie said:


Mine spun bearings at 114k, bent crank, damaged rods, the whole nine yards. I would stick with drew, anyone at 100k should do this.
 

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The Reality Of Tomorrow
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We were just talking about this in the "Spun Bearing" thread and I recommended changing the bearings @ around 100k or at most your 120k service.

Like you said Drew, they are cheap (must cheaper than a rebuild) and relatively easy to swap out (much easier than a rebuild as well).

-m
 

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I had spun bearings on my old 91TT, with only 59k miles on it (just barely made the warranty period, by like 135 miles.) Power levels were stock too. The post about the Porsche 944's was about taking our cranks and having them crossdrilled, ie, the one hole that is drilled in them to lubricate the bearings is matched by another hole drilled perpendicular so that more oil can flow to lubricate them. I think it's a great idea, if my current Stealth spins one, I will be rebuilding it with a forged crank and having this done to it.
 

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14.1 @ 100mph N/A
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Discussion Starter · #14 ·
Re: bearing wear...

TurboTurd said:
This couldn't POSSIBLY be from running an underdrive-pulley without a harmonic balancer, could it?...
Once more: My engine has 135k miles on it and has been driven hard. This is normal wear.
 

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14.1 @ 100mph N/A
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5,289 Posts
Discussion Starter · #15 ·
tbadiuk said:
I'm having the oil pump changed in the spirng (car is in storage) along with my 60k (65k on the car right now). Wondering If I should do the bearings too. Mind you, I don't drive the car hard and it does only have 65k on it. Probably should wait to 120k eh Drew?

Can changing the bearings make things worse? That is, what's the chances of a dealership screwing things up and not putting everything back together. Errr, hmmm...Dodge we're talking here, nevermind I'll wait to 120k...:(

Ted
I'd change the 60k and 120k services to 50k and 100k, and do the oil pump and rod bearings then. I would recommend that you do it yourself or have a competent 3si member do it so you know it was done right.
 

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14.1 @ 100mph N/A
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Discussion Starter · #16 ·
Kenneth Ellis said:
I'm very suprised. In the spring, my 118k turbo engine showed no scraching on the bearings, and like Drew, I did the old penny bit (I'm suprised to see that pop up :) ), and the crank took no copper.

What milage did your girlfriend pick that Stealth up at, Drew? And did she get any sort of maintenence history with it?
This car has been driven hard. It has seen 9k+rpm a few times. I wasn't surprised at all by the wear I found.

When WE bought the car it had 89k miles on it and had full dealership maintenance records, but it had synthetic oil in it and they had only been changing it every 7500 miles(what the manual recommended)... so the lifters were crudded up and it sounded like a diesel.
 

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14.1 @ 100mph N/A
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Discussion Starter · #17 ·
tbadiuk said:
I think the bearings themselves should be good to 300k if you run at stock power levels(*), change oil regularly, and change the oil pump every 60k. Mind you if you change the pump you can inspect the bearings at the same time.
It takes a couple hours to change the bearings, so why not do it? There's NO WAY these bearings are gonna last 300k miles. Even with a new oil pump at every oil change the bearings would wear... that's what they're there for. We're talking about an easy job that costs <$100, so it makes no sense to NOT do it.
 

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Hitokiri Battousai
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WickedDrew:

How have you got to see 9k rpm's? Have you modded the ECU?

It looks like it's tiem to start saving some cash (timing belt+accessory belts+tools to put these in+bearings+beer for guys to help me everything done in a day= I'm one poor bitch).
 

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Official 3SI Mouth
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"This car has been driven hard. It has seen 9k+rpm a few times. I wasn't surprised at all by the wear I found."

Simply driving hard doesn't generate bearing scores. If so, an engine that was consistently shifted through redline (mine- red is just a suggestion, and fuel cut is a manufacturer's warning to slow down ;) ) would have developed the same manner of wear. I think it says a lot more about what that engine went through up until the point it came into your posession.

Bearings have the capacity to endure a lot when you think about it- you can go through some seriously horrid oil change cycles, then get your head screwed on straight, and not really have much effect take place afterwards, depending on how bad you let the engine go.

I'd sum it up more as your girlfriend's car got very lucky- it got picked up by someone with half a clue, with some care, and the willingness to do the servicing it needs. I doubt that car would have made it this long with that sort of treatment it received originally.

As for tbadiuk, 300K mile bearings- what the hell are you smoking? I want some of that shit. Bearings are the same as a clutch- they're a renewable resource, a frictional surface, and should be looked upon as expendable. Are $85 dollars in Clevites down at Autozone too much insurance for a $3500 small block?

I guess so.
 
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