Engine stripped, strange marks on bearings - Not Vauxhall

[Lee H]

Hi all,

Not a Vauxhall but figured it was worth asking as there are knowledgable people on here and an engine is an engine after all. Its a Toyota engine I have stripped to fit forged pistons.

Stripped it over weekend and was a little disappointed to find a score down one of the bores. Can feel it with my nail but not sure if it warrents a rebore or not. Picture below.
Also the bores are a funny colour in places, not sure if this is normal.

http://i192.photobucket.com/albums/z163/Lee_H25/ff3885ee.jpg

http://i192.photobucket.com/albums/z163/Lee_H25/dd4bd5f3.jpg

http://i192.photobucket.com/albums/z163/Lee_H25/c4cef18d.jpg

Then moved on to looking at the crank and big ends. Crank looks ok but the big ends have some really funny marks on the upper bearing of each rod.

http://i192.photobucket.com/albums/z163/Lee_H25/dc09ab1e.jpg

http://i192.photobucket.com/albums/z163/Lee_H25/7025c88b.jpg

http://i192.photobucket.com/albums/z163/Lee_H25/2dff6870.jpg

http://i192.photobucket.com/albums/z163/Lee_H25/d9b161ac.jpg

Anyone have any ideas what would have caused this? Don't want to repace them for the same to happen again. Funnily enough number 4 was in the best shape and this is the furthest from the oil pump so if it was an oil issue i'd expect the opposite.

[MK999]

Mark on the bearing is wear, they have a softer upper surface which it's worn through. I'd get the crank measured up and checked over, is there any scoring on it? I wouldn't be surprised if it was undersized or oval though.

If you can feel that mark with your nail and you're going to the expense of forged etc I'd go up a size and rebore. Besides that bores look pretty acceptable but again worth measuring if you're fitting forged etc.

[Royston]

The conrod looks fairly normal to me, the marking is from the load applied on the power stroke, is it your Turbo MR2?.

What are the bearings like?

Need to get everything measured, bore wise it also wants checking for wear, the scores probably warrant an rebore/hone

[Benn]

I was told bore wise, if you can feel it with your nail get it honed.

[Andy]

There is a guide to bearing wear somewhere in haynes manual,oil starvation,infrequent changes,running dry etc all cause marks like that.This needs looking into to prevent it happening again.
The bore might hone out,have a try,if it dont-+.5 oversize is probably required.
The marks on the bores look like thrust marks,perfectly normal,but check again for any excessive wear

[Andy]

Even better,heres one for you in more detail.......http://www.bobistheoilguy.com/bearingwear/bearingwearanalysis.htm

[Lee H]

Mark on the bearing is wear, they have a softer upper surface which it's worn through. I'd get the crank measured up and checked over, is there any scoring on it? I wouldn't be surprised if it was undersized or oval though.

If you can feel that mark with your nail and you're going to the expense of forged etc I'd go up a size and rebore. Besides that bores look pretty acceptable but again worth measuring if you're fitting forged etc.

There is no scoring on the crank at all but will get it measured and checked. My concern with going up a size in piston is these engines are renowned for cracking the cylinder wall at high boost as the cylinder wall is so thin so really wanted to avoid the risk of this by sticking with 86mm pistons.


The conrod looks fairly normal to me, the marking is from the load applied on the power stroke, is it your Turbo MR2?.

What are the bearings like?

Need to get everything measured, bore wise it also wants checking for wear, the scores probably warrant an rebore/hone

It is for the MR2, building a bigger power engine to replace the one thats in so I don't have to take it off the road. The picture of the conrod still has the bearings fitted.


I was told bore wise, if you can feel it with your nail get it honed.

I would be honing it anyway as otherwise the new rings won't bed in, just reluctant to fit bigger pistons.


There is a guide to bearing wear somewhere in haynes manual,oil starvation,infrequent changes,running dry etc all cause marks like that.This needs looking into to prevent it happening again.
The bore might hone out,have a try,if it dont-+.5 oversize is probably required.
The marks on the bores look like thrust marks,perfectly normal,but check again for any excessive wear

Hoping worst case I might have to go to 86.25mm pistons due to the reasons stated above. Last thing I want is a cracked block and have to do it all again. Will get the crank out at weekend and get it checked.

Cheers for the link, look most like the bottom left ones on the link.

"Offside" wear is usually an indication of misaligned crankshaft or bore. This may not apply to "Offside" connecting rods.