Thread: 3.9 rebuild or just fix

I think you should be doing some more diagnosis before condemning the engine.
Camshafts wear out & at 400000km it's going to be on at least it's 2nd one by now. If not, it'd be well overdue & could well be the cause of your noise & poor running.

Thanks I'm not condemning it at all. For all I know the engine as it was originally a 3.5 is only 200k old but I have no receipts to know for sure. If I was to rebuild or fix that would be one thing I would be looking at. The engine it's self has power or should I say my hearing helps it move well for a 3.9 and I like them but if I was going to rebuild or modify I would be weighing it up as compared to a newish unit swap in either rover or ls2

It could be an easy fix, but should you find out it's curtains for the engine, I wouldn't bother with a rebuid on it - I'd bung a Chev in it. That's what I plan to do on my RRC if the current motor dies (which won't be for a long time with the amount I drive it) but that's the plan...

Yep I'm doing the heads anyway but If I suspect more it's making way for a low k rover or a ls swap

Originally Posted by disco dan

Thanks I'm not condemning it at all. For all I know the engine as it was originally a 3.5 is only 200k old but I have no receipts to know for sure. If I was to rebuild or fix that would be one thing I would be looking at. The engine it's self has power or should I say my hearing helps it move well for a 3.9 and I like them but if I was going to rebuild or modify I would be weighing it up as compared to a newish unit swap in either rover or ls2

The first thing is to work out what is causing the noise. If it does it when cold, it could be the tappets or cam. If it only does it when warm, it could be slipped liners.
If you are happy with the power, then there is probably no need to go to a different type. You may want to update to a 4.0 block. It is the exactly same capacity as the 3.9, it just has 4 bolt main bearings and a bigger crank.
The problem is that you cannot really rebore 3.9, 4.0, or 4.6's. But the bores tend not to wear a lot and you will usually get away with just a hone and new rings. Along with new bearings, etc, of course.

If you have slipped liners, or the bores are worn too bad, it costs around the $2,000 mark to have new top hat liners fitted.

Ok thanks. It's started as a tick noise which I located near manifold at cylinder 8. It went away when warm but now only the last day it's making like a rattle like a loose bolt would when under load. If I rev it there isn't anything only when taking off. Not when coming down gears. I can get a full rebuild kit from uk. It doesn't lack power just sounds bad like you don't want it to detonate.

Where can you get a 4.0 block from?

lots of places,, and theres a reason for that

There's no point throwing a "full rebuild kit" at a 3.9 without replacing the cylinder liners with top hat ones, something that only a good machine shop can do. You might as well get a 4.6 short motor and do that up ready for a transplant. In any case, your death rattle could be as simple as a blown head gasket, something to replace over a weekend to keep it together until the replacement engine is ready.