Main bearings or not?
 

Hi

Someone told me that I shouldn't have any need to replace the main bearings in my 96 850 with 215K. I'm taking the engine down to do rod bearings and rings. Any ideas? I hate to go this far and not do the mains but it would save me spliting the block.

Also, what material are the cylinders? cast iron? aluminum? Nikasil? I want to get a flex hone but don't know if I should get the Aluminum oxide for nikasil or the silicon carbide.

Thanks

I believe the cylinders are aluminum.

As for the main bearings, if you are going to pull the engine to do everything else, might as well do the main bearings while you have it out.

I was told to always do bearings. But there is this rope stuff you can get to test if your bearings are worn to the point that they should be replaced, I'll try to find what it's called.

It's called a Plasti-gauge(any parts store will give them to you). Used to check the bearing oil clearance. Not typically used to check old bearings. A visual inspection of the bearing halves usually tells all you need to know about the condition. You will be able to see discolorations, plating that has worn through etc. As for the journals, an easy test is run a penny across the journal or a finger nail and if your nail catches or any copper comes off the penny, the crank should be inspected further by a machine shop for out-of-round and possibly be turned or polished.

For the OP. the cylinders are not lined with Nikasil or Alusil. Just make sure to use the correct grit hone for the cylinders where chrome rings will be used.

PS. For someone to make a general statement that the main bearings should not need replacing due to only taking into consideration the mileage, is a bit ludicrous. You should always, at least, do a visual inspection of the rods and mains of any engine, especially when you will have the engine torn down as far as you will.

rope stuff...........eh?? I'll be the plastigauge 'people" would get a laugh.

r.

Thanks All,

Gilbert... are you going to rebuild that engine? I remember you telling me I should find a used one...what's up with that? Anyway.. my engine is being plucked this weekend so we should compare notes if that's your path.

Schigara... I really appreciate your perspective in your recent thread on rebuilding after timing belt damage, it helped inspire me to rebuild my engine. Even though I am doing it as preventative measure.

Turns out the cylinders are cast iron... according to Haynes.

That were my original plans, but it was cheaper and easier get a used motor. The one I got for my wagon only has 104k miles on it and is really clean.

Oh... Yeah makes sense.. 104K is just broken in.

Exactly. But I'm doing quite a bit to the motor while it's out of the car so I can still get my hands dirty.

You will have to split the motor in half to check the main bearings. Well take the intermediate section from the main block section to see the bearings.

If you want to go that far you can. It will also be a good learning experience.

The main reason I wanted to rebuild a motor. I don't care if it necessarily needs it or not, I want to see what it looks like inside.

It is pretty unique have fun!!!!
I did on my first one!!