Thread: 3.9 Rebuild Options

This is opportune

Me too - I also have a 3.9 lying around with a possible slipped liner - I would also like the same information as Kieth.

Thanks

Garry

My 3.9 went through this exercise a couple of years back - there is a thread on here about it. Mine was rebuilt with a torque cam and higher compression pistons. The engine which came out was in a pretty bad state - we didn't realise how bad until we had already had the heads reconditioned, so were already too far into the rebuild to through it out and start again.

First step is probably to strip it and get everything checked for hardness etc, mine was reheat treated twice to get it to the correct hardness

Prices for alternate engines have come down greatly in price and may be a cheaper option than rebuilding the 3.9

One course of action if the 3.9 has slipped a liner and needs a complete rebuild: take off the heads, sump, front cover and efi and swap in a top hat linered 4.6 block with crank, rods, pistons assembled. Cheapest around is Sean at Roverparts in Ballarat at $4.5k. TRS do them for $5k and Bruce Davis for $5.3k without a changeover.

Traco

Thanks- I take it the 3.9 efi will run the 4.6 and from what you say all I need is a 4.6 block, pistons and crank to be able to convert.

Would there be any heating/cooling issues with the larger motor usign the standard radiator?
Keith

A 3.9 radiator should be ok but get it cleaned out to ensure it's in good order.

All the bits will bolt back up. Have you got the later 19 bolt heads. If so it dhould have 29cc chambers, just fit with composite head gaskets. If not, use tin gaskets.

Roverparts use a rising rate fuel pressure regulator to get the fuelling for the bigger engine + $330; TRS use an adjustable regulator +$260; Bruce Davis fits a chip to the ECU +$600.

Sorry that should read 20 bolts heads; thinking about 19mm reach spark plugs!

Try 10 bolts (or 20 for two heads)!

Thanks Traco
Engine is out of a 96 Disco - so should be the latter model head.
Could be just head gaskets - how will I tell if the liner has gone? vs just a head gasket
Keen to pull it down just for the fun of it anyway and show my younger sone how an engine works.
Keith