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main bearing/rod bearing replacment

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shadow001dsm

10+ Year Contributor
183
0
Mar 26, 2009
las vegas, Nevada
Hey Tuners, i have been looking all over the site for a couple of hours now and i cant seem to find a good write up on main bearing and rod bearing installation procedures.

My 6 bolt walked on me, so i purchaced the new bearing all the way around and would like to know all the specifics on the install proccess so i do not walk it again and or spin bearings.

All help is greatly appreicated, i have the crank out and the motors is in the car still, im planing a on doing a write up on how i successfully removed the crank while the engine was in the car all i need is to know the torque sequence and all that fun stuff.

The crank walk was cought very early so nothing was damaged at all. i have lucas assembly lube for the install.
 
it walked, i know its rare but it really did do the unspeakable.
 
I did my 7 bolt with motor in car and soon it walked again. Wasnt too bad. Good luck and usually there is a culprit to thrust bearing failure whether itd be age, clutch, main alignment etc. I would check EVERYTHING
 
If it walked then you've got metal through the whole engine. I feel like a broken record posting this again but the block and head need to be stripped and cleaned to get rid of all of the metal particles. If you don't, chances are that you will experience another failure due to oil contamination. You also need to look at the crank and repair the thrust surface, if damaged. Also, you will need to replace your oil cooler and oil filter housing.

It is odd for a 6 bolt to "walk". Typically with the DSM's it's clutch related as I'm sure you already know. Being that this is an odd case, I would look at other reasons. Believe it or not this same problem exists outside the DSM community. In almost all cases that I've seen personally, the problem was caused by the owner using the wrong oil. People will build a high performance street or race engine and will often continue to use the same oil as recommended by the owners manual. This is a big no-no as most OEM oil recommendations are based on how the engine left the factory. When you increase the HP, RPM's and turn up the boost, the thin oils don't hold up to the stress and heat. The thrust surface is not fed by a pressurized oil galley. It is fed by "splash" and a very little amount of oil that may escape the main bearing surface. This minimal supply means that the oil that does reach the thrust surface must be capable of lubricating under the increased loads and stress. The oil you choose must be able to maintain its film strength and viscosity under high temperatures and pressures. For this reason, we use Brad Penn almost exclusively in our engines. Especially in turbocharged applications.

I'm not saying this is your problem but it's a possibility and I've never seen it mentioned here.
 
20w 50 sounds great for summer, 5w30 in winter. Which is what happens to be what mitsu recommends depending on the climate. So in your rebuilt motors you don't recommend 5w30 for winter?

What weight oil would you recommend for a stock 7 bolt making somewhere between 450 and 500hp?

That's in your owners manual, since your car is stock. It is climate dependent.
 
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20w 50 sounds great for summer, 5w30 in winter. Which is what happens to be what mitsu recommends depending on the climate. So in your rebuilt motors you don't recommend 5w30 for winter?

"This is a big no-no as most OEM oil recommendations are based on how the engine left the factory. When you increase the HP, RPM's and turn up the boost, the thin oils don't hold up to the stress and heat"
 
Right, but since your car is stock you still have to stick with the correct viscosity for your climate. A high performance synthetic will help, like eneos, elf or mobil 1.
 
Right, but since your car is stock you still have to stick with the correct viscosity for your climate. A high performance synthetic will help, like eneos, elf or mobil 1.

Even though I'm running more than double the stock hp? Wouldn't I need a thicker oil to handle the increased heat and stress?
 
In the winter most of our engines run 15w40. I would never run less than 10w30. The concession is that you must be sure to allow the engine time to warm up before driving because the thicker oils don't flow well at lower temps.

Once you start modifying your engine, throw the owners manual out the window.
 
Well the motor did in fact walk, as rare as it is disturbing to me, it did mildly start to shift, i reaplaced all the bearings yesterday and broke it in like you should. changed the oil after the 20min idle and then again after i put some miles on it. i am using castrol 10w 30 at the moment and the car has no mods other than the big 16g and a fuel pressure regulater , with a wally 255, i have turned the boost up, matter of fact i have not even put the boost controller on its all stock besides that. the motor runs great and sounds as healthy as every. but oddly enough im have transmition problems now. I think its the inner or outer race bearing, i just replaced the tob this morning and it didnt help it. I now have a bunch of pinging sounds from the transmition. its casuing harsh virbartions when the clutch is engaged and makes rattling noises but makes hardly any noise when the clutch is disengaged.
 
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