Will A HeadGasket Solve This Problem?

[model 10]

Originally Posted by AnchorageGuy

But how would he know that? Chuck

Maybe one of the easiest checks that you can do yourself. A straight edge and a feeler gauge.
Problem with some engines is that no skimming is allowed , Perkins 107-108, 4.99 for example.

[bwells79]

Make sure you get the manufacturer's instructions for torquing the head bolts. Have a friend with a 1946 Chris Craft and he had a mechanic pull the head for service and the next thing he new there was a crack on the block near one of the head bolts. He thinks the guy did not follow the correct procedure and over torqued one of the bolts.

[a64pilot]

Originally Posted by AnchorageGuy

But how would he know that? Chuck

A good straight edge will tell you if your head is warped or not, once it's removed of course.
Myself I don't have a head machined unless it needs it, sort of like boring out a cylinder, you can only do it once or twice sometimes.
But if it does go to the shop, get the valves done and probably new guides and seals of course. In other words if it goes to the shop, go whole hog and have the head re-built.

[charliehows]

Originally Posted by boden36

What I would suggest is you find the appropriate head bolt sequence, and starting with number 1 , back it off about 30 degrees and then re- torque to specifications. Go around each in turn.
You may find that on re-tightening each one that they will go just a little further, but if you don't loosen them a little first they will not budge at all.

Regards,
Richard.

been giving this a bit of thought. The manual does recommend re-torquing the head bolts as routine maintenance, which is why i looked at it when i was setting the tappets. One question; 'appropriate head bolt sequence' - as is common practice with almost all engines, the tightening sequence is from centre to extremity, the loosening sequence is the opposite. So which is the 'appropriate' sequence? I'm assuming centre out. I doubt whether re-torquing the head bolts is going to help once a leak has already occurred but, as my approach to this engine is conservation rather than restoration, I think I'll give it a shot before i pull the head.

[four winds]

Give me a minute and I can post a pic from the manual on that sequence.

Edit.... re-read and seems you have the manual.

It's always middle to ends on install. But I've never read a manual recommendation on removal.

My habit has always been from ends to middle to remove but I start by just barely cracking them loose first.

For re-torquing the usual middle to ends sequence seems best to me.

[model 10]

Originally Posted by charliehows

been giving this a bit of thought. The manual does recommend re-torquing the head bolts as routine maintenance, which is why i looked at it when i was setting the tappets. One question; 'appropriate head bolt sequence' - as is common practice with almost all engines, the tightening sequence is from centre to extremity, the loosening sequence is the opposite. So which is the 'appropriate' sequence? I'm assuming centre out. I doubt whether re-torquing the head bolts is going to help once a leak has already occurred but, as my approach to this engine is conservation rather than restoration, I think I'll give it a shot before i pull the head.

It should be clear that you could only do one bolt at a time. Any disturbance with a sealing surface would be the end. There is no new crush in a head gasket. If it were solid copper you would be good but it's not. It's not reasonable to expect that you can re- squish a small portion of the head gasket when you are dealing with a big old cast iron lump like a cylinder head. If there was a part of the gasket or head that was not tightened the first time this idea of might work.

[Terra Nova]

A service manual is a good starting point, rather than guessing.

[charliehows]

Originally Posted by Guy

It should be clear that you could only do one bolt at a time. Any disturbance with a sealing surface would be the end. There is no new crush in a head gasket. If it were solid copper you would be good but it's not. It's not reasonable to expect that you can re- squish a small portion of the head gasket when you are dealing with a big old cast iron lump like a cylinder head. If there was a part of the gasket or head that was not tightened the first time this idea of might work.

yep, one at a time, loosen 30*, then tighten to torque, on the tightening sequence is my thought. What do you think of this idea of loosening with a 30* turn before tightening? It makes some sense to me because metals under pressure over time tend to 'cold-weld', which could hide the real torque pressure. Essentially what is suggested is to 'crack' them first.
form the point of view of the leaking - I give it maybe up to 5% chance of any effect, but there's nothing to lose trying it first.

[model 10]

Originally Posted by charliehows

yep, one at a time, loosen 30*, then tighten to torque, on the tightening sequence is my thought. What do you think of this idea of loosening with a 30* turn before tightening? It makes some sense to me because metals under pressure over time tend to 'cold-weld', which could hide the real torque pressure. Essentially what is suggested is to 'crack' them first.
form the point of view of the leaking - I give it maybe up to 5% chance of any effect, but there's nothing to lose trying it first.

I don't think it would matter if you took the bolt all the way out. Once you back it off any amount it's done. It's only the stretch part of tightening the bolt and the crush of the gasket that matters and you would be releasing that tension right away. Consider lubing the threads so you get a more even torque. It's not always recommended but what you're doing is not either.

[DeepFrz]

I don't think it would matter if you took the bolt all the way out. Once you back it off any amount it's done. It's only the stretch part of tightening the bolt and the crush of the gasket that matters and you would be releasing that tension right away. Consider lubing the threads so you get a more even torque. It's not always recommended but what you're doing is not either.

Of course the manual recommends re-torquing the head bolts and even suggests loosening 30 deg. before torquing. Oiling the threads is not recommended.

[model 10]

Originally Posted by DeepFrz

Of course the manual recommends re-torquing the head bolts and even suggests loosening 30 deg. before torquing. Oiling the threads is not recommended.

I guess I would like you to prove that. Re-torquing an 30 yr. old engine cylinder head is not any any service manual I have ever seen.
As for oiling the threads, it depends on who you talk to. One maker will say yes and another no, for the same bolt. It's very easy to over torque a bolt with lube on the threads.

[charliehows]

Originally Posted by Guy

I guess I would like you to prove that. Re-torquing an 30 yr. old engine cylinder head is not any any service manual I have ever seen.
As for oiling the threads, it depends on who you talk to. One maker will say yes and another no, for the same bolt. It's very easy to over torque a bolt with lube on the threads.

Yeah, my manual says re-torque the head nuts every 250 hrs, its in the routine maintenance schedule. I couldnt find the bit about 30deg loosening but he's right about the first bit so i'm going with the 3 other posters who mention this, as well as my own instinct. The only mention of oiling the threads in the manual is that it is recommended when undoing the nuts to remove the head. Think I'll save it til then.

Dont get the wrong end of the stick, though, i value your input and thank you for taking the trouble. I pretty much agree with you about replacing the head gasket, but I've got 7 days to twiddle me thumbs 'til they get one in stock for me so I'll have a play with her in the meantime. I suspect the reason i've got this problem in the first place is because the recommended re-torquing schedule hasnt ever been followed.

[model 10]

I get it. But 30 something years is probably not the same as every 250 hours. You may have passed the point of any reward.
The worst case would be you overheat because you broke the seal, right?

[boden36]

Work from the number one on your tensioning diagram. If possible try to
find the correct sequence rather than making one up. That way you will know
that the best possible job has been done. You should also check the valve
clearances afterwards. If they have tightened up a little then you know the
head has settled.

Regards,
Richard

[charliehows]

thorough chaps that wrote my manual, they give a very unmistakeable diagram with the tightening sequence as well as a further unequivocal diagram showing the loosening sequence (opposite of the tightening sequence, if one takes the trouble to examine it carefully). Given that there are a grand total of six (6) nuts to deal with, one feels confident of the procedure.
Sorry, can't help meself...