3.9 RV8 - Salvageable or not?

[mickeyw]

I recently got hold of another serpentine 3.9 to stick in my Ninety. Its current engine is rather unwell, and I thought that a quick one-out, one-in solution would minimise time out of action.

The engine I had lined up had good credentials, only it turned out to be full of brown water in the inlet ports and cylinders.

The sheer quantity of water does not suggest a leak problem, but I have no idea quite how it got in there. Clearly it had been there some time though.

Having removed the inlet manifold and then one of the heads I was gobsmacked to see extensive corrosion in the bores and to the valve area.

The engine had been well oiled prior to decommissioning, so as well as water in the bores there was a good deal of oil, not that this had helped much.

Not being one to give up on something too easily I decided to clean things up a little and find out how bad things really were. I rubbed some green Scotchbrite in the bores, then some Emery cloth with WD40 to remove the corrosion. I have only removed one head so far, but this was the worst bore on that side. As you can see there's a fair amount of pitting top the cylinder wall.

There is virtually no bore wear, indicating that the engine would have been in good shape, had the rust not been present. I have yet to make any attempt to determine the depth of the pitting.

Then I thought I'd have a look at the heads. Removing the valves revealed this:

Now the orange sludge makes it all look a lot worse than it is. Having wiped away the sludge I bead blasted the heads of the valves. This did reveal some pitting on the faces, but I have lapped away worse damage in the past. No pictures of the cleaned valves at this stage.

I have not tried to turn the engine over yet, as it's pretty obvious that such attempts will only damage the pistons more than they may or may not already be. My thoughts were to remove the crank and pistons before doing much else.

So the big question - is it worth trying to salvage this lump? What do people think?

I know the block could be re-bored, but this would then means new pistons and gawd knows what else, leading to silly spiralling costs.

I had a vague thought that (depth dependant) it may be possible to hone out the damage and reuse the existing pistons. How much oversize can a bore be before the rings refuse to seal? I know blocks are usually re-bored at 0.010" increments, but could a thou' be removed and still be OK? Or am I being silly here?

There are some good bits on this engine, the rockers are in excellent condition, the pads show very little wear. The lifters are still flat on the bottom, so maybe the cam is good too. I can't really see this yet as I haven't turned the engine.

Now I have started, I feel I shall end up dismantling and inspecting further before making any decision.

Does anyone have any useful comments? No remarks about diseasel engines please .

[CwazyWabbit]

As a thought to how the water got in, as rust is evident around the valves it seems quite likely it came in through the inlet/exhaust ports. I don't suppose the outside of the engine looks particularly clean does it? Could it be the results of over enthusiastic washing efforts post removal?

[mickeyw]

Errr no Barry. The engine wasn't particularly clean, which was why I jetwashed it immediately prior to checking it over.

I very much doubt that quite so much water could have got in by jet washing, although it was my first thought. When I saw the extent of corrosion though I knew the water ingress wasn't recent.

[CwazyWabbit]

Oh well, regardless of how the water got in the damage is done. That pitting looks pretty bad to me with the 3 pits in the top left corner looking particularly deep, I wouldn't think they will hone out.

I'd also be wondering if the water has damaged the crank bearing surfaces as well.

[Bowie69]

Rebore time.... but don't waste your money, get it top hatted instead, £5-600 in a few places now, coming down a lot.

[Hybrid_From_Hell]

Prob got it through valley gasket

I would clean it up put back together and do a compression test, you MIGHT get away with it, depends where

the pitting is in relation to the rings etc and bore meeting (or not)

Nige

[mickeyw]

Nige, I'm puzzled. How might water get into the bores of a standing engine via the valley gasket?

The pitting is a fair way down the bore, within the area contacted by the rings I would have thought.

Anyway, time for an update, as I've had the other head off tonight.

Initial reaction was ooh, this side isn't as bad for rust......

No.1

No.3 was at the top, No.7 nothing to worry about, and No.5 was pretty rusty, but not as bad as the other bank.

Then I noticed no 5 liner is 4.5mm below the surface Oh C**p!

Now I can see that a slipped liner could let water in, but I can't imagine it's possible for it to back fill to the inlet, and then into other cylinders. The engine would have been far from happy if that much water was leaking!

I guess this really is the end of the road for a cheap and quick clean up and sling it back together for this engine.

Bowie69 - I'd love to know where you can get top hats done for £5-600. Turners are well over a grand, which is well beyond budget.

[Bowie69]

Nige, I know has the number very handy, drop a PM, I could find it, but would take me a while in my so-called filing system...

[Team Idris]

The rotten moo ! Thats well unlucky

I was going to make a diesel comment. Because I wouldn't use that without a rebore if it were diesel, but on a petrol, I'd give it a go.

Choices are rain water or mouse wee?