FBIII

Can a block that has spun main bearings be repaired? Are main bearings available for a block that has been align bored? Thanks

Vilhuer

Nope. There is only bearings available for smaller crank neck but not with larger outside diameter. Only possible fix is to add aluminium back to block and align bore it back to stock size. Very difficult task to do.

FBIII

Thank you very much! I had thought there was a bearing issue. There is a short block on ebay for cheap with this issue. Seller thinks its repairable.

fst951

We can do it, but it is expensive.

Thanks,

Garrity

John Veninger

Spun mains?!
First time I'm hearing this one.

FBIII

Garrity, when you say expensive, what are we talking?

PorKen

Sounds like a big job! (Or a nice coffee table base.)

"This motor was starved for oil and has been locked up. It is rebuildable, has two seized rods, and three spun mains."

Jfrahm

Probably means spun rod bearings, even so I would not bother with it.

Vilhuer

Spun mains are not totally unheard of but probably much rarer than conrod bearings.

fst951

Hi there.

The mains are tought to fix, but certainly possible. The weld with very little problems once cleaned and using the correct filler rod.

I could weld and machine the central main for about $600. It is expensive, but it is also TERRIBLY time consuming. We can also repair water pumps that have driven into the block

Thanks,

Garrity

Fastest928

... I have seen two repairs by welding. On one, they did a great job on weld and the line bore, but the shop was unable to machine the thrust surfaces perfectly, and the bearing spun again. It appears the thrust surface to bearing tols are very critical and help hold the bearing in place during temperature cycling and expansion.

The second was number two bearing, and so far, no problem....it has been at least 10 years.

Good luck

slate blue

Marc what would your opinion be of this way to fix it? If you had a second cradle as I do could you use this and only weld the block and or could you use a product called Bellzona which is a liquid metal putty? Personally I don't like that idea but it was suggested by somebody to repair an engine we have here with thrust bearing failure. You would of course still line bore the block with its different cradle.

Thanks Greg

John Veninger

Why not just purchase a good used block? At this point they are cheaper than the repair cost.

This may be an issue in the future when the blocks are harder to find and more $$.

Vilhuer

On average case different block is cheaper and much easier solution. But in few years all of the sudden early '78, late '94-95 GTS and some other desirable models like CS, SE and low mileage GT will be clearly more valuable with original drivetrain than non-original similar one. This make even expensive block fix worth the trouble if it's doable.

John Veninger

Maybe, but I would rather have a good block instead of a "repaired" block.
We'll see if the 928 ever gets to "I need matching numbers" status.