Help with engine refurb

I am stripping down my spare 2.5 nas diesel engine. Could someone with some engineering knowledge help me. The pistons are AE A350422 +0.508. My question is are these original and the standard size. Similarly the shells are ERC 8641 and then 6618. There is only a slight score of copper colour on them and the pistons have only a slight scoring mark on one side. I am hoping to just use new rings and shells and rebuild.
Billy

Looks like pistons are + 50 thou, ie it's had a rebore, shells unless they have other markings are standard, look at the crankshaft journals for wear/ scoring rather than shells

freelance said:

Looks like pistons are + 50 thou, ie it's had a rebore, shells unless they have other markings are standard, look at the crankshaft journals for wear/ scoring rather than shells

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they dont do +50 thou pistons its metric for +20

gipsybilly said:

I am stripping down my spare 2.5 nas diesel engine. Could someone with some engineering knowledge help me. The pistons are AE A350422 +0.508. My question is are these original and the standard size. Similarly the shells are ERC 8641 and then 6618. There is only a slight score of copper colour on them and the pistons have only a slight scoring mark on one side. I am hoping to just use new rings and shells and rebuild.
Billy

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ensure you gap every ring in the bore its going to be fitted in, hone bores well or rings will just polish your cross hatch off you need a slow speed drill

Many thanks for this, once I can get the pulley off I will check the crank main bearings and decide what to do. I will no doubt have a question or two. If I order new pistons I presume I order the +20?

Billy

gipsybilly said:

Many thanks for this, once I can get the pulley off I will check the crank main bearings and decide what to do. I will no doubt have a question or two. If I order new pistons I presume I order the +20?

Billy

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yes but you cant guarantee they are the exact right size for your bores, you normally buy pistons and get bores bored to that size, pistons are measured at bottom of skirt degrees to gudgeon pin,thats the only place you need to measure on a piston

How many miles has your spare engine done? Are you replacing the oil pump whilst you are in there?

Col

gipsybilly said:

I am stripping down my spare 2.5 nas diesel engine. Could someone with some engineering knowledge help me. The pistons are AE A350422 +0.508. My question is are these original and the standard size. Similarly the shells are ERC 8641 and then 6618. There is only a slight score of copper colour on them and the pistons have only a slight scoring mark on one side. I am hoping to just use new rings and shells and rebuild.
Billy

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A slight score of copper usually means worn out - measure the crank journals. As for scuffing on pistons - the pistons shouldn't touch anything other than the piston rings. To my ears this doesn't sound like an engine that could / should be put back together with original parts.

I might have gotten the wrong impression but if you've gone so far as to taking it to bits the only way to be sure it is OK is to measure measure measure and compare compare compare with the specifications in the workshop manual.

The engine i run at present is getting hard to start and smoking so I am hoping to put the spare in and run it over the winter and refurb the one of known provenance. The spare engine was just bought for spares. I was told it was a runner and didn't smoke (never heard that one before), but it was only £50 so well worth it for spares. Anyway I want to spend the minimum on it and do a proper job on the one that has run well for the last 7 years. Really happy to be offered advice and grateful for the advice already received. I like these engines and find it really good in the SWB.

Billy

oh ok then,

If you are planning to just run it for a few months whilst your other engine gets refurbed, I would just stick it in without Doing anything to it. Fingers crossed.

Col

Thanks for the advice, I am aware I might be swapping a poor starter for a lot worse. A little bit of me thought put the engine straight in but I have broken it now. Just waiting for some hub pullers for the seized front pulley wheel. Its good experience for when I fix the other one properly as its years since I broke an engine, so quite enjoying it. I will post once it is rebuilt with the results. My plan is to do as Kommer 2013 suggests plus the timing belt and tensioner and yes fingers crossed.

Billy