Thread: 1993 D1 3.9L V8 - buggered sparkplug hole

I cleaned up both heads, the plenum and manifold today. What a vile job. Both heads need a decent skim to fix the exhaust gas erosion shown on one pot each.

Is there a limit to what can be taken off?

Getting the cactus spark plug out was entertaining. It was achieved with a combination of Mrs MacMan turning anticlockwise with a plug spanner as I tapped away with a hammer and punch from below. T'was truly stuffed but should be very easy to repair with a timesert.

Is there a limit to what can be taken off?

i suppose , though it depends if you are putting thin tin gaskets on or thicker composite's

i just had mine skimmed, nothing taken so to speak, though i wish i had had it pressure tested while i had it off.

also if id had the money i would have had the valve's, guides and seats checked and fixed if needed. apparently gas teds to 'coke' these up im told

Hmmm.

Some new info this morning. I have been told by two sources this morning that if the liners have moved even slightly then the block is fit for the recyclers or top hat liners only, else it's going to be a wasted effort. Also one source said that if they've moved then the engine has been cooked and the heads will also be soft so they're also junk.

One source was a head reconditioner who said he can do the top hats but he has suggested that it's not worth it when a complete changeover motor can be had for not much more.

yeah its totally something to consider with buses this old. it doesnt take much to put the cost over the threshold of being worth doing, and you need to decide that early rather than start small and find out theres more and more or that it still is no good...

Another update.

After having various people in the position to sell me an engine tell me that almost certainly everything was due to overheating and fit for the bin, I had the heads tested for hardness today. They are absolutely fine at 110 and 115 BHN, so indicate that the engine has never been cooked, and that supports my theory that the liners should be OK. I'm still going to pull the block out and may still have the top hats done since I'm there. I'll check crank and piston ring grooves and then decide how much further to go.

I've had a quote of $1400 to do the top hat liners.

Originally Posted by MacMan

Another update.

After having various people in the position to sell me an engine tell me that almost certainly everything was due to overheating and fit for the bin, I had the heads tested for hardness today. They are absolutely fine at 110 and 115 BHN, so indicate that the engine has never been cooked, and that supports my theory that the liners should be OK. I'm still going to pull the block out and may still have the top hats done since I'm there. I'll check crank and piston ring grooves and then decide how much further to go.

I've had a quote of $1400 to do the top hat liners.

liners can slip and leak at as little as 70 deg c...

to check this sit the block on a couple of blocks of wood on your BBQ with a 44 gallon drum cut and shaped to cover it... put the BBQ on low, heat till your temp gauges says 70 and then hold it between 70 and 80 degrees for about half an hour... with a good set of gloves on see if you can wiggle the liners.

If you're not stripping the block

grab a jewelers loupe and inspect the leading edge of the liners, the head gasket and the head. IF there is any signs of hammering on the leading edge of the liner, the gasket fire rings show signs of uneven "pinching" or there are buffing marks on the head where the fire rings sit I have some bad news for you.

i was thinking about this, and recon if you were faced with buying a new motor id just re-coil the spark threads and put another head gasket on it and see how much longer it can last you

you can pin the liners by pulling the sump drilling into the edge of the liner and support, tapping it and screwing in then peening in a grub screw.