Head gasket choice with skimmed heas

Hi All
I have taken off the head on my 1998 TD5 Auto Discovery 2, and i have a three hole gasket.
I am thinking of buying a reconditioned head which would be skimmed to ensure that i have a good head to bolt on.
My question is do i use a three hole gasket even with a slimmed head?
Thanks

speak to ratty about td5 heads he is the eggspurt

Ok will do, thanks

Its a bit more complicated than this but basically It depends if the valves are reground or not. If you only skim the head and refit valves then the valves will sit to low so pistons will hit. If you have the head skimmed and valves reground then you still use the 3 hole gasket.

moynesyt5 said:

Hi All
I have taken off the head on my 1998 TD5 Auto Discovery 2, and i have a three hole gasket.
I am thinking of buying a reconditioned head which would be skimmed to ensure that i have a good head to bolt on.
My question is do i use a three hole gasket even with a slimmed head?
Thanks

Click to expand...

to be sure ,you measure max piston height above block and valve depth, if its a recon head thats skimmed they should have cut the seats so valves sit deeper to match amount skimmed off head face but you need to ask or check

Thanks for the replys guys, that now makes sense. I will probably go sith a recon head that has been skimmed and valve re cut.

I thought it was more to do with the pistons and block, The 3 hole is the thickest so go with that again you'll be fine, I had my head skimmed and then fitted the head to a different block with a 3 hole gasket and all was fine.

The bit I don't under stand is the valves, are you cutting the valve stems down or changing the hydraulic buckets, as I cant see how you can seat the valve into the head further and they still be shut without changing these.

steve's P38 RR said:

I thought it was more to do with the pistons and block, The 3 hole is the thickest so go with that again you'll be fine, I had my head skimmed and then fitted the head to a different block with a 3 hole gasket and all was fine.

The bit I don't under stand is the valves, are you cutting the valve stems down or changing the hydraulic buckets, as I cant see how you can seat the valve into the head further and they still be shut without changing these.

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its both, and saying 3 hole is thickest it will be fine is just trusting luck

steve's P38 RR said:

I thought it was more to do with the pistons and block, The 3 hole is the thickest so go with that again you'll be fine, I had my head skimmed and then fitted the head to a different block with a 3 hole gasket and all was fine.

The bit I don't under stand is the valves, are you cutting the valve stems down or changing the hydraulic buckets, as I cant see how you can seat the valve into the head further and they still be shut without changing these.

Click to expand...

If you were working with a brand new head which has had no work done the thickness of gasket is worked out by measuring piston protrusion from the block. Also the 3 hole gasket may not be the thickest. On the 200tfi you can get a no hole gasket which is the thickest.

As for the valves when skimming and regrinding is concerned we're talking measurements in fractions of millimetres. So to do the job properly you have the head skimmed and valves reground so they do not sit proud of the head. Then you fit back to the engine with the same thickness of gasket. It is often possible to skim the head and refit the valves and fit a thicker gasket to compensate for clearance.

You would never need to shorten the valves or change the hydraulic lifter as the valve is only sitting a fraction of a millimetre further into the head and the adjustment is made via the rocker shaft.

Mark

I'm still concerned that RAVE is adamant that head skimming and valve re-cutting is NOT PERMITTED. I understand that the head is case hardened and that this is the reason, but since we are talking fractions of a mm, and people are clearly going ahead and skimming, I have to question why RAVE is so clear on this?
I'd be keen to know how well reconditioned heads perform and life expectancy, etc. is RAVE being over cautious and perhaps guilty of gold-plating things?

Hi guys

An up date. I bought a recon head, new radiator, intercooler, thermostat, water pump, etc. to put on the discovery.

Fitted everything this weekend, and all seemed fine. The engine started after a few cranks, and ran great for about 5 minutes on tick over. Then it started to slow down and cut out.

It will not start now and just turns over. Any ideas? The only thing i am unsure of, i followed the Haynes manual a set the injector tappets as per their manual. Screw down the screw until you feel it 'bottom out" and then turn back the screw one whole turn. I did have to turn the screw quite a few turns to feel it bottom out.

Would this be an issue?

The other thing i did whilst it was running was to increase the rear air suspension ride height as the air bags do lose a bit of air every so often. Not sure if this would cause an problem. I have the rear chocked up with timber blocks to stop it sitting on the deck.

Any ideas would be great.

Thanks

Dave

RAVE state heads should not be skimmed as when new the aluminium heads were impregnated to seal any porosity. If they are not re impregnated after a skim the head gasket lasts a lot less miles.
There is a company in Manchester who can impregnate castings for the public. I found this out from this months car mechanics.
Vacuum Impregnation Experts - Impregnation Services Limited

steventoon said:

RAVE state heads should not be skimmed as when new the aluminium heads were impregnated to seal any porosity. If they are not re impregnated after a skim the head gasket lasts a lot less miles.
There is a company in Manchester who can impregnate castings for the public. I found this out from this months car mechanics.
Vacuum Impregnation Experts - Impregnation Services Limited

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thats hardly an issue with most lr heads ,the fact a head has got hot enough to warp and possibly relaxed is the greater issue

Pull the rocker cover and check tappet adjustments again incase your push rods weren't seated. It's very unlikely but worth a check. Also might be worth cracking the injector pipes to check your getting fuel.

Mark151151 said:

Its a bit more complicated than this but basically It depends if the valves are reground or not. If you only skim the head and refit valves then the valves will sit to low so pistons will hit. If you have the head skimmed and valves reground then you still use the 3 hole gasket.

Click to expand...

My understanding is It's actually even more complicated yet, because if it's been skimmed and the same thickness gasket is used the timing will be off due to the distance between the chain sprockets being less.

Bennehboy said:

My understanding is It's actually even more complicated yet, because if it's been skimmed and the same thickness gasket is used the timing will be off due to the distance between the chain sprockets being less.

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not true ,as cam gear is just adjusted to take care of it

Thanks for the replies. If it was timing and injectors, surely it wont run at all or run badly?
It runs great for about a minute, and then it seems to run out of fuel. It then takes a lot of cranking to get it to start again, and then runs out of fuel again.

The fuel pump always seems to have squishing noises, and doesnt change tone or noise however long i keep it running with the ignition key on position 2

moynesyt5 said:

Thanks for the replies. If it was timing and injectors, surely it wont run at all or run badly?
It runs great for about a minute, and then it seems to run out of fuel. It then takes a lot of cranking to get it to start again, and then runs out of fuel again.

The fuel pump always seems to have squishing noises, and doesnt change tone or noise however long i keep it running with the ignition key on position 2

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sounds like a faulty pump or air in fuel system, try purging it a few times before starting,

jamesmartin said:

not true ,as cam gear is just adjusted to take care of it

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So as long as the rockers are adjusted all is fine, cool.

Ok I will try purging the fuel pump tonight. I have tried the ignition on, pump accelerator pedal five times for the MIL to come on, but mind doesn't to that. No MIL light.

So I will leave the pump running for 2-3 minutes and turn off for a minute, then re-do this about 10 times to see if that clears the air.