Grim Reaper Posted March 22, 2014 Share Posted March 22, 2014 Latest head gasket torquing requirements are 20Nm + 180* + 180* or 20Nm + 180* + 135* depending on manufacturers recommendations I understand this to be initial torque then two runs through the correct tightening sequence turning each bolt through the required angle.. Have read on an elise forum of someone doing it 20Nm + 90* + 90* + 90* + 45*. This sounds like 4 runs through the sequence. While I can see that this might reduce the amount of difference in areas of compression of the gasket between having bolts at differing torque (I know what I mean but can't think of a way to put it any better) is there really any benefit to doing it in smaller increments? Would some lubricant like ARP ultra torque lube assist in smoothing the inevitable cracking when starting to turn the bolts each time or not? Link to comment Share on other sites More sharing options...
oilyhands Posted March 22, 2014 Share Posted March 22, 2014 Oil the threads and oil under the heads. The technique I use is as follows.. Torque each bolt to 25nm to snug them, do this is the right order. Slacken each bolt, then re tighten to 20nm, the snugging is complete Turn each bolt in order by 180 degrees Turn each bolt in order by a further 180 degrees. No further tightening is required. Oily Link to comment Share on other sites More sharing options...
elan_fan Posted March 22, 2014 Share Posted March 22, 2014 I like the idea of "snugging" the bolts. certainly when I did mine recently I went around about 4 times with the initial torque setting and each time I could tighten a bit more. On the fourth time round I got the obvious solid click of a torqued up bolt and went round again, then did the stretching 180+90+45 I was using the N series gasket Link to comment Share on other sites More sharing options...
Slipper man Posted March 24, 2014 Share Posted March 24, 2014 Thank God for BlatChat! I have just put my car together after replacing the HG. Reading this, I realise I didn't do the second 180 deg! Could have been very annoying at Cadwell... Link to comment Share on other sites More sharing options...
ECR Posted March 25, 2014 Share Posted March 25, 2014 Link to comment Share on other sites More sharing options...
Slipper man Posted March 25, 2014 Share Posted March 25, 2014 Thinking about it, I am not certain that I didn't. Trouble is, I am not sure I did!! Only solution I guess is to slacken them all off and tighten them correctly... Link to comment Share on other sites More sharing options...
revilla Posted March 25, 2014 Share Posted March 25, 2014 I'm not sure that's actually a good solution. As I understand it the bolts are stretch-bolts, designed to yield, i.e. stretch permanently and irreversibly. However I do believe that the Rover system is unusual in that the actual torqueing of the bolts is designed to take them to just below the yield point and as the allow engine expands the first time it gets hot, this takes the bolts into yield. If you have actually torqued them fully and then run the engine up to temperature, they will already have stretched. Repeating the torqueing procedure will stretch them further, possibly resulting in them snapping under load. I think you will actually need to measure the bolts individually to ensure they are still within spec. I think what I would do would be to slacken the bolts in the recommended sequence but as each bolt becomes loose, lightly snug torque it back to prevent anything from moving. You could then take the bolts out one by one and check them for length, returning them back to snug torque after measuring (replacing any that have gone out of spec). From there you could repeat the tightening procedure. Maybe Oily could advise on whether this would be the correct procedure to follow? Link to comment Share on other sites More sharing options...
ECR Posted March 25, 2014 Share Posted March 25, 2014 In the meantime, go and kick the dog, you'll feel a lot better 😬 Link to comment Share on other sites More sharing options...
oilyhands Posted March 25, 2014 Share Posted March 25, 2014 Reusing the bolts will not give too much of a problem. If you are not sure about tightening, then Mark one of the end bolts radially and then see how far you have to turn it in order for it to come loose, if it is less than 1.25 turns before it goes slack then it has not been correctly tightened, if it is more than 1.25 turns then it will be OK, just re tighten that bolt and leave the others. If it is less then undo one at a time and then retighten. Oily Link to comment Share on other sites More sharing options...
Slipper man Posted March 26, 2014 Share Posted March 26, 2014 Thanks Dave - that is very helpful. I was wondering how many turns it should take to undo them if they have been correctly torqued up. Roger - another year older but clearly not another year wiser. I wouldn't like to be in your shoes when Lynn hears what you propose doing to her dog!! Link to comment Share on other sites More sharing options...
Slipper man Posted March 26, 2014 Share Posted March 26, 2014 It took 0.75 turns to undo the cylinder head bolts.... Link to comment Share on other sites More sharing options...
oilyhands Posted March 26, 2014 Share Posted March 26, 2014 Redo them one at a time working inwards using a spiral pattern. Oily Link to comment Share on other sites More sharing options...
Slipper man Posted March 26, 2014 Share Posted March 26, 2014 Thanks. That's what I did. I thought long and hard about the order of redoing them and fortunately did what you advise. Lets hope the HG stays intact this time! Link to comment Share on other sites More sharing options...
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