300 TDi HEAD INFO PLEASE

[BeJay]

right, Disco started overheating at 55-60 mph, (system was overpressurising) I've pulled the head and although the head gasket wasn't obviously knackered, there were rust witness marks in the bores (2 & 3 just a few spots as it had stood a week before I got round to taking the head off), so obviously water was seeping into bores 2 & 3 from the water gallery that's in the centre (hence the overpressurising when running) now I don't want to just put a new head gasket on and then find I've got to do it all over again, so the question is how much 'bow' is acceptable across the head e.g. I've got 0.003"-0.004" between 2 and 3 in the centre using a straight edge and feelers (I haven't got a D.T.I.) and if this is unacceptable (or unadvisable) how much can safely be skimmed off the head before there's a danger that the valves start getting  overfriendly with the pistons  :lol:
                                            cheers, Jack.   

[Range Rover Blues]

According to the LR manual you can't skim a 300 TDi head, you need a new head.  If it's overprssured then it probably is warped.

Dozens of us have skimmed them with no ill effects, though the newer heads are cast differently to help cooling.

Anyhoo, I think ours lost about half a mm with no ill effects, a good engine shop will be able to advise.  If anywhere near to you there is a really good one on Roman ridge in Sheffield and they charged me

[BeJay]

 
thanks RRB  :thumbup:, Landrover probably like to sell as many new 300TDi heads as possible so that would explain the no skimming  :lol: I think I'll go with your experience of skimming with no ill effects first, I reckon a 0.010" (0.25mm) skim should sort it so hopefully I'll get away with that OK if you had 0.020" taken off yours without any problems.
                                                    cheers, Jack.

[lurch_917]

hi one reason landrover say no skimming is due to the amount of piston protrusion you have several thicknes head gaskets 1 hole going to 0 holes cant remember wich way round it goes but its to do with thickness

[Saffy]

There is an acceptable level of wrap and that figure is stated in the manual that is often forgotten about and people skim needlessly. Also the manual states how to calculate which thickness gasket is required (there is a thicker save ur ass gasket available too which is not mentioned in manual) . Your old gasket will have a tab on the side with a number of indicator holes in (or blank) which is the thickness indicator.

[BeJay]

 
thanks for the replies guys,   :thumbup:

Lurch, I know about the piston protrusion but thanks for the heads up anyway, mine is 0.65mm max which is right in the middle of the 2 hole gasket range, so I was going to use a 3 hole gasket (the thickest) on rebuild to help compensate for the skim anyway.

Saffy, do you know what the limit is on the acceptable warp? I can't find any mention of it in my Haynes manual, as above I've checked the piston protrusion and was going to use a 3 hole anyway, but I didn't know about the extra thickness save your arse gasket  :lol:, so thanks for that just in case I have to get more skimmed off the head than I expect.
                                                                  cheers, Jack. 

[Saffy]

thanks for the replies guys,   :thumbup:


Saffy, do you know what the limit is on the acceptable warp? 

Yes, sorry didn't detail as I was still in bed when I posted. The max is stated as 0.08mm, see the attached image I have posted for more information...

[ChrisW70]

The gaskets start at one hole for thinnest increasing in thickness up to the three hole and no holes for thickest.

[BeJay]

 
thanks for that Saffy, I've got 0.004" (0.1mm) on mine using straight edge and feelers (not as accurate as a D.T.I.) so I'll get it skimmed and tell them to just remove as little as poss (hopefully under 0.010") piston protrusion on mine is max 0.65mm and 3 hole gasket covers up to 0.8mm so as long as I can get away with less than 0.010" (0.25mm) skim I reckon I'll get away with the 3 hole gasket, I'll risk the extra 0.003"/0.004" if it's any more I'll chase up a 'save my arse' gasket :lol:
                                                                             cheers, Jack.
 
 

[BeJay]

The gaskets start at one hole for thinnest increasing in thickness up to the three hole and no holes for thickest.

Chris, is 0 holes the thickest gasket? there's no mention of a 0 hole gasket in the haynes, if it is then I'll get one of them for rebuild, or is the 0 hole the same as the 'save your arse' one Saffy mentioned.
                                                                     cheers, Jack.

p.s. just noticed your avatar, I've got a T shirt with that exact picture and comment on it  :lol: :lol:     

[Saffy]

Chris, is 0 holes the thickest gasket? there's no mention of a 0 hole gasket in the haynes, if it is then I'll get one of them for rebuild, or is the 0 hole the same as the 'save your arse' one Saffy mentioned.
                                                                     cheers, Jack.

That's the one, it's not mentioned in haynes.

[burgerman]

 As quoted above, A good engine shop will advise correctly, Every cylinder head has a minimum thickness, So heads can be skimmed and the valve heights should be checked and adjusted ( by cutting the seats and refacing the valves) also tip the top of the valves so you dont loose valve clearence adjustment, If all this is in spec and done correctly you should be able to use the same thickness of gasket as you removed ( presuming it was correct? )  I worked in a engine shop for 14 years and done work for most manafacturers whose heads "cant be skimmed"

[BeJay]

 
cheers Burgerman, thanks for the info, I'll see what the engine shop says.

[Range Rover Blues]

Skimming has no effect whatsoever on piston projection.

Don't fit a thicker gasket than you need, it is important.

Head warping accross the diagonal is acceptable, a concave head is not and this is oftne what happens with an overheat.

LR did not design the head to be skimmed unlike the 200 TDi but it's an acceptable risk.  If you go too mad you need to worry about the valves but 0.010, just make sure you set the tappets.

You need to skim it 'till it's flat BTW, I'm sure they won't take off more than is needed.

[BeJay]

 
thanks RRB, I realise skimming the head has no effect on piston protrusion, but it will obviously 'drop' the valves by an amount equal to the skimming which is why I was going for the thicker gasket, as I have no idea how much clearance there is theoretically between a fully open valve and a TDC piston, the head is concave by about 0.004" using straight edge and feelers, so allowing for another couple of thou because obviously this isn't the most accurate method, I'm hoping 0.010" will clean it up, you reckon I'll still be OK with the same gasket as original then? (vave clearances being set properly)
                                                                              cheer's Jack.

[Range Rover Blues]

Yeap I went back to the same.  I did have some data but it's not at hand, the valves don't get anywhere near that close though.  If you are worried then cut the valve seats to match the head skim.

I've measured both ours and annoyingly only one piston dictates the gasket thickness, the other 3 could tolerate a thinnner gasket.  On my sister's it;s one side of one piston that takes i into a 3 hole gasket.


BTW for those who don't know, 1 hole is the thinnest, 2 hole the next, 3 hole the thickes t used in production and no holes the thickest service gasket readily available, the thickest of the lot typically needed on blocks that had been refaced.

Don't have the thicknesses to hand either but 0.2mm between sizes rings a bell :-k