alex8882

alex8882

Well-Known Member
Ok so after spending a week welding my disco back togther again(there were quite a few botches uncovered), I then turned to the head gasket. Once the head was off it has the ports cleaned up and smoothed,the face was cleaned up, valve guide cleaned, valves relapped and had to have a valve seat recut. Put the engine back togther new gasket, and head bolts, adjusted the tappet screws to book settings 0.20mm. refilled all liquids and fired it up. Ran like a dream for 1 mins, then started to vent exhaust gases through the inlet. Next guess was a sticking valve, so found cleared the problem it reset the tappets and fired it up again, this time all four cylinders would work as they should, but every min or so it would start venting through the inlet again, then clear. This morning it runs like a bag of nails. Took the head back off only to find small cracks around three of the four glow plugs. Used a 3 notch h/g as the one i took off was a 3, head was checked for warps, and level and was fine. Followed the the head bolts tigthening steps to the letter. Never had this before i had the head work done.
 
We think alittle bit of swarf stuck down the valve stem after the new valve seat was cut althou it was blown out a few times. I guess not good enough thou. Also found that no.2 piston had a mark on top of it like the exhaust valve had just tapped it yet that was the only one tappet ajustments were all at 0.20mm thou. The mind ponders lol
 
how much was skimmed off head though was head skimmed before ,worth measuring valve depth after skimming
 
no head wasn't skimmed matey. Had an old school engirneer take alook at it he clean the face up but didn't skim it as the head was true. Really the head should have been skimmed i guess. was running fine before all this but ran like a bag of nails afterward. Don't know if the cracks in the head were there before hand as there was alot of carbon present on the face. Can't remember if they were there after we cleaned it up either lol. What we did notce after the first run was that no.7 valve was sat lower than the rest. What had been said was that the block may have been decked but not the pistons, however the guy wasn't 100% sure on that, and like i said it ran fine before hand. also before the h/g change there was oil running out of the inlet ports, and lots of black smoke(over fueling) after the h/g change the smoking had almost gone, but there was still oild running out of the inlet ports. I have fitted new stem seals. We also found that the bores had been washing, and also that they looked like they had never been beded in and were glazed. We did also glaze bust them.
 
you cant skim tdi pistons as are coated,cracks would have been there before ,are all threads on tappets fairly equal above lock nut ,lot of sideways play in valve guides
 
yeah the treads seem fairly level to be honest, none that stand out and make you think that there is something wrong. As for the valve guides there isn't alot of sideways play no. However on no.7 if alittle side load was but on it it would go so far then stick, but it wouldn't always do it. Also when running smooth you would here a ping then it would run rough, then another ping and run smooth. it would run smooth for say 10mins, then run rough for a min or 2 then run fine again it was very intermitent. but today we struggled to get to run on 3 properly let alone 4
 
never thought of that doh. I'll take alook at that tomorrow its worth a shot. still need a new head but hey, better to know lol
 
Ok so replacement cylinder head going on today, along with headgasket number 2. after measuring the old head compared to the new head, there was a huge amount of difference. The replacement head hasn't been skimmed at all, where as i my old head unkniwn to me had so the differece between the two was 1.55mm. Hopefully now have a right good clean she should be running again this afternoon.
Cheers to james for your help this far. Checked the brass sliders, had two that were alittle sticky, but have now been free'd off.
 
quick update. new head fitted and all refitted. Started first turn, and runs great. Big thanks to james for his help. One thing i did find, was that after i had completed the first stage on the head bolts at 40nm there was more than one or two that had become loose, so just re did stage 1 again and all was fine. Had read about it on another thread and i think it was james that had said it. Can't stress enough recheck stage one. Anyways all is good. Bring on the next brake down
 
good to see that I'm not the only one that has a load of problems with these old discos!...do you think that due to the amount of material removed from the head, effected the valve stand down? that caused your problem?

Glad you got it sorted in the end.
 
yep i would say it was pal. had a 1.6mm head gasket on, adjusted the tappet screws to 0.20mm as per the book, and had one of the valves kiss the piston, only lightly but enough. the new head i bought was 1.16mm thicker than the head i took off
 
well after i run out tonight, it drove like a new engine, had lots of power, and temp stayed at 1/2. popped the bonnet, water sprayed everywhere, engine was very hot, and on hell of alot of pressure, in the coolant. also has bubble coming out of the injector ports,and glow plug ports. Guess it wasn't fixed after all
 
all the hoses are fine, and the rad is also good. It was the pressure valve in the coolant cap that sprayed out. I guess it could have sprayed onto the head. Istarted to build alot of pressure after 30secs of running from cold
 
no matey second hand one. Han't been skimmed or atleast i don't think it had still had a landrover stamp on the face. fell for the "oh its a good one mate no problems with it" and to top it off he wants no part of it now, as i got it off him £20 cheaper than what he was asking
 
lr stamp on face ?if been hot before head can often move again ,presuming car has good circulation and cooling system works well
 
yes pal there was a little lr logo on the machined surface it was only about 5-6mm long. The car hasn't overheated before, however the h/g was leaking oil, plus the valve stem seals needed doing. The old head had alot skimmed off it, and when i refitted it using the the same notch h/g it ran like poo, even had a piston and valve kiss. I am going to check the head bolts this morning, and put another 30 degrees turn on the m12. Nothing to loose as i'm looking at another engine anyways.
 
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