3.9 rebuild

[doctorvaltar]

I originally posted this on the modified section, but I thought I might see if you rangie boys had any more thoughts!!

My head gasket went a few weeks back and I've taken the engine apart now. Took the block to an engine specialist to pressure test and it passed ok.

I knew I was going to need the bores honed but the specialist has advised me to have a 20 thou rebore becuase two of the bores are "borderline". Originally the idea was to rebuild this engine on a budget as it only gets to do about 1500 to 2000 miles a year. If I have a rebore and new pistons it adds £500 to the budget.

But, and this is my main concern, in anyones experience does overboring a 3.9 cause problems. Having had the block pressure tested I know there's no cracks behind the liners, but if I take a bit more material off the inside will it bring about problems? My engine man says not, but RPI said it would be rubbish, and offered me £1700's worth of new block. For this sort of limited mileage, not a chance!!

The Des Hammell book mentions all the problems with the 3.9 having un-equal water jacket cast problems, but I know mine is ok at the moment with the standard size.

What shall I do, buy new rings and existing pistons and hope its ok, or spend the extra on an overbore and hope its ok??

[Range Rover Blues]

Hmm, toughy :-k  Think I've read the same book and I can understand your dilema.

Ordinarily a20thou overbore is nowt, commonplace even.  TBH if it goes along the middle of the liner I can't see any issue, the problem lies in theblock splitting, RPI will of course offer you a new block, though I've heard things about them............

Anyhoo, if it will go back together as is, for the mileage you do  :-k possibly so, otherwise the overbore and new pistons would give you a minty lump for years to come.

My advice though, get another engine that runs and save yourself some money ;)  alternatively canibalise it for the block.

[meathumper]

If you buy a new engine ill buy the old block.

[doctorvaltar]

I may be selling the block, crank and pistons now, what's it worth? Has been pressure and passed ok.

[meathumper]

Hi, does it include timing cover, oil/water pum, sump? or is it just block and inerds? What milage is it?

[doctorvaltar]

Not too sure about mileage, in my hybrid, came out of a range rover my friend owned that had well over a 100k on the clock.

It will include block, con rods, crank and pistons. So basically just a short block in bits