Any value in a Blown Head Gasket 4.2?

[brogenville]

As the title says, my cerb now has a blown head gasket. Some how the coolant pipe that joins into the water pump managed to get dislodged, which in a very short space of time emptied to engine of coolant. Despite managing to stop as soon as i noticed anything going wrong, after a quick fix of the pipe and a refill of coolant, upon restarting the engine I've got pints of water spraying out of the near side exhaust.

I'm pretty gutted (not least because I'm selling the car right now due to travel plans, and I had just agreed a price on it with a chap last week), but st happens I guess.

Anyway, I gather its an engine out job to get the heads off, and like any cerb lover, Im now trying to think of ways to use this as an excuse to upgrade, specifically with a view to dropping a nice race prepped 4.5 in the car. So, firstly, does anyone out there want to hazard a guess at what a 23k mile late 4.2 engine with a blown gasket might be worth, as I would probably need to sell it against the cost of the new engine to justify it to myself?\

The alternative is just to fix the engine, so can anyone who's gone through the same process tell me how much a top end rebuild might cost (with me doing the engine removal/replacement)?

[RUSSELLM]

I think TVR Power charge approx £3500 for a top end rebuild with a two year warranty.

[longbow]

If you've got A LOT of water coming out, then it may be worse than just the gaskets i.e. the head might have warped. Just something to consider.

[Mr Freefall]

brogenville said:

As the title says, my cerb now has a blown head gasket. Some how the coolant pipe that joins into the water pump managed to get dislodged, which in a very short space of time emptied to engine of coolant. Despite managing to stop as soon as i noticed anything going wrong, after a quick fix of the pipe and a refill of coolant, upon restarting the engine I've got pints of water spraying out of the near side exhaust.

I'm pretty gutted (not least because I'm selling the car right now due to travel plans, and I had just agreed a price on it with a chap last week), but st happens I guess.

Anyway, I gather its an engine out job to get the heads off, and like any cerb lover, Im now trying to think of ways to use this as an excuse to upgrade, specifically with a view to dropping a nice race prepped 4.5 in the car. So, firstly, does anyone out there want to hazard a guess at what a 23k mile late 4.2 engine with a blown gasket might be worth, as I would probably need to sell it against the cost of the new engine to justify it to myself?\

The alternative is just to fix the engine, so can anyone who's gone through the same process tell me how much a top end rebuild might cost (with me doing the engine removal/replacement)?

Head gasket replacement of one side should be in the region of £1300 inc labour, but, more than likely once the head is off, you will end up having more work done, and as Longbow has quoted, £3.5 k would be about right.

Mr F

[g20v6]

If needs be and you're considering replacing the engine I've got a 4.2 engine sat on my workshop floor, it's done 44K, early 98, I was looking for around £2250 with all the ancillaries but no engine management system. Good luck sorting it out, I like the sound of the upgrade option.

[eLSerbera]

The car is for sale?

Just curious is it on the Pheads Classifieds... couldn't see it.

I might be interested as I am looking for a car for my future LS to go into.

[brogenville]

The car is for sale, but rather than take a gigantic hit and sell the car as is, I'd probably be mor inclined to fix it up, and with that done and th money spent, I think I might just hold ontothe car for a while.

In regards to the head having warped, that did indeed occur to me. I take it there shouldnt be too much bother in getting them skimmed?

[Mr Freefall]

brogenville said:

The car is for sale, but rather than take a gigantic hit and sell the car as is, I'd probably be mor inclined to fix it up, and with that done and th money spent, I think I might just hold ontothe car for a while.

In regards to the head having warped, that did indeed occur to me. I take it there shouldnt be too much bother in getting them skimmed?

Depends how bad they are, The RR conversion on the 4.5 head allows 1mm to be skimmed from the head to raise the compression. You would have to balance the cc's of each pot on the head after this really.

If not, yep, you will need to source a new head, and tbh, they have to be replaced in pairs.

Good luck

Mr F

[brogenville]

Mr Freefall said:

You would have to balance the cc's of each pot on the head after this really.

Just for my interest, how would this be done?

If i was to have say 1mm skimmed, would a remap be called for?

[Mr Freefall]

brogenville said:

Mr Freefall said:

You would have to balance the cc's of each pot on the head after this really.


Just for my interest, how would this be done?

If i was to have say 1mm skimmed, would a remap be called for?

Just for my interest, how would this be done?

Put a flat piece of plastic that covers the whole head, and drill a little whole in the plastic on each pot, then get some fluid with constat vicosity and fill each pot up, measuring the amount of fluid that goes in each. The the pot that take the biggest mount of fluid it what you would have to machine each head to to make sure they are balanced.


If i was to have say 1mm skimmed, would a remap be called for???
Depends on the above. if you still have the same amount of CC in each pot on the head as a std 4.2 head after the skim and the cc balancing, then theoritically no your compression would not have changed, so no remap.

Mr F

Edited by Mr Freefall on Wednesday 18th June 14:33

[brogenville]

But either way, if the CR changes, a remap would be in order? Presumably if a remap was necessary, its not going to be too harmful for the engine running it temporarily without the remap?

[Mr Freefall]

brogenville said:

But either way, if the CR changes, a remap would be in order? Presumably if a remap was necessary, its not going to be too harmful for the engine running it temporarily without the remap?

Depends on the CR. Pre-detonation will put holes in your pistons...

Mr F