The sump on my 1.4 8V Punto has rusted and gone porous and I am planning on replacing it very soon. Whilst the sump is off I am wondering if it is worth considering replacing the Big End bearing shells. The car has done nearly 90,000 miles and although it runs well the engine is making more noise when pulling from low speed than I think it should.

Back "in the day" (1970's cars) it was common practice to replace bearing shells where crankshaft journals were bright and unscored, but the white metal on the shells was begining to wear thin, this being done before the need for expensive crank regrinds.

So, what do we think of this?

I wouldn't bother ... not if there's no problem, not at that millage, not with modern oils and regular servicing.

+ if the engine is similar to other fire engines, the main caps are part of a girdle... will be pretty difficult to replace with the engine in the car, not sure if you'll have enough space to take the rod caps off.

aurick86 said:

, the main caps are part of a girdle... will be pretty difficult to replace with the engine in the car,

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Thanks for your quick response. I wasn't planning on replacing the Mains bearings though, just the con rod big end shells.

The car has been well maintained with a complete service record following the recommended service interval of 18,000 miles, although I do think that is a long way to go between oil changes. If I am in there anyway, replacing the sump, I may just take one big end cap off to see what the shell looks like.

ddclutch said:

Thanks for your quick response. I wasn't planning on replacing the Mains bearings though, just the con rod big end shells.

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I only said that so you realize you might not have enough space to do it comfortably.

Let's be honest, if you're going to take a rod bearing off you are going to replace it.. then all of them.

aurick86 said:

I only said that so you realize you might not have enough space to do it comfortably.

Let's be honest, if you're going to take a rod bearing off you are going to replace it.. then all of them.

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Sorry, you mentioned mains, so I was just saying I didn't intend to replace them, just the big ends. But I accept thatyou are suggesting that access for those may be difficult.
On a triumph engine, notorious for running big ends, I used to check them every 20,000 miles, removing one cap to inspect. For some reason on those engines #4 always wore fastest so that was the one to look at but sometimes it was Ok and I would leave the others alone until the next time.


What I don't know is if on a "modern" engine like the 1.4 8V Punto, the clearances are such that renewing shells without regrinding the crank is practical or worthwhile.