Mercruiser diesels rebuild

[Cavalierbond]

Hi .. what would be the learned opinion on rebuilding the engines
I’ve purchased a 98 boat with a pair of 4.2l with 600 hours
I’ve got to take one of them out to repair the transom plate , should I take this chance to over haul the engine ?
I know the 600 are depended on use and maintenance but whisky it’s out ??
Thanks

 

[gordmac]

I tend to go with the if it isn't broken don't fix it philosophy. If it starts ok, good oil pressure and performs fine best left alone although you could do a compression check.

 

[spannerman]

600 hrs is nothing for one of these engines, as stated if it runs well then leave well alone. They are not as simple to rebuild as a lot of other engines, it has 6 separate cylinder heads and these have head gaskets of different thicknesses. Also the crankshaft doesn’t sit directly in the block but in circular frames which split to remove the crank, not difficult but not straightforward either. Having said that as a Mercruiser mechanic I have only had a couple in pieces in the past 24 yrs! Whereas I rebuild 4-5 V8 petrols every year.

 

[omega2]

Just check the sump is not rusty!

 

[Cavalierbond]

Thanks for the advice ...

 

[Reality61]

The exhaust Risers ate the week point on all the early Mercruisers.

 

[Cavalierbond]

Even the diesels ??

 

[spannerman]

Yes, it usually corrodes around the water pipe at the rear and isn’t noticed until its too far gone.