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This is a 1979 Leyland Sherpa 230 1.7 L Petrol "O-series" engine.

I'm suspecting a blown head gasket and if this is confirmed I'll be removing the aluminium head and getting it resurfaced at the engineers.

I've read and it makes sense that the aluminium head is more vulnerable to warping than cast iron due to its material properties. The head I can manage to sort out but having the cast iron block resurfaced as well poses some logistical problems - never mind the added expense. I can remove the head and take it on the bus if need be but to check the cast iron block I would need a mobile engineer or park up by the engineers and sort the whole thing out from there. Either way this is impractical.

I understand that it would be a risk and all mine but what in your experience is the likelihood of the cast iron block needing resurfacing as well?

I did replace the blown head gasket recently myself not too long ago and was satisfied that the surfaces were within 2/3 thousands of an inch (using a 2 ft long steel rule and feeler gauges) - but, well obviously it didn't work out.

To give you a little history the engine had been suffering with overheating for some months (occasionally creeping up into the red a little before I would have to pull over and wait), so I replaced head gasket with care.

This time round the degree of overheating has been more manageable but I suspect that a little amount of combustion gas is escaping from cylinder No. 1, enough to put an air lock in the cooling system.

So, I don't think the problem is severe but it does need sorting as I am comically dependent on this van. I understand that there is probably no exact right or wrong answer to this question and so your general opinion or accounts of your own experience would be appreciated.

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Used to work on these and 99% you will be fine just doing the head.

Do check the block - decent straight edge and feeler gauges...

Make sure it is clean when you put it back together and follow the instructions precisely to torque it back down. Can’t temember if it tells you to use new bolts, but if it does - then do, as that may be part of the cause of your problem... Some “cheap jobs” re-use the old bolts and they have stretched...

  • Thanks @solar mike . That's given me some confidence. Need a straight edge to check my straight edge. I would like to use a new set of head bolts but don't seem to be able to find any. I'm wandering if over torqueing the bolts a little might be worth a try unless that's a strict no no. – Michael Sherpa Feb 22 '18 at 14:07
  • I don't do this sort of work but I've heard to def get new bolts. Barring finding some, get some studs? – seizethecarp Feb 22 '18 at 15:44
  • Hi @seizethecarp. I've heard you can use studs but then you would have to know threads etc. etc.. – Michael Sherpa Feb 22 '18 at 16:31
  • @MichaelSherpa additionally, use a straight edge to check the head, it may not need resurfacing and there are specs to how much material can be removed for resurfacing before a head is re-used. That information is usually in the Service Manual. Definitely get new head bolts, they are torque to yield by design. Meaning they have already stretched once and now have to be overtorqued to get the same effect (which is very undesirable). – finleyarcher Feb 23 '18 at 22:03
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I watched a YouTube video once about a guy who had a recurring head gasket problem. The solution was to re-torque the bolts after first use. I'm no expert, so don't criticize me too much if I'm wrong here -- it's just a suggestion.

  • Thanks @carguy That's relevant! This raises the question if it might be worth while over torqueing them a little. They were torqued correctly before and after but my torque wrench was calibrated crudely against a spring measure and measuring tape. Hmmm... that's got me thinking ? – Michael Sherpa Feb 22 '18 at 14:01
  • Nothing wrong with spring measure and tape... Force * Distance... as always it's application... – Solar Mike Feb 22 '18 at 14:03
  • @carguy I've just done some more research on google and a serious article says generally to torque down again after running engine 1st time. But then it goes on to say unless you have an aluminium head in which case you wait to the engine is cool before re torqueing. My manual doesn't mention this. I wander how much difference it makes. – Michael Sherpa Feb 22 '18 at 16:28
  • Wait for it to cool - aluminium is a "soft" metal... – Solar Mike Feb 22 '18 at 16:32

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