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Head gasket question

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Michael Oritt

Michael Oritt

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I have a DW "Fast Road" AL head on my car along with the DW metal competition head gasket and high-strength head studs, nuts and washers. The head and gasket have been on the car for at least ten years and frankly I do not remember that I have ever retorqued it--or felt I had the need to. However I just noticed that with the engine warm there is a slight bubbling of air and seeping of oil right above the #2 spark plug, about where the small square tab on the head gasket projects out from under the head. DW claims that the metal head gasket is "reusable up to three times" so a retightening of the nuts should certainly be "within limits".

My question is what procedure I should follow:

1. Should I do this with the engine hot or cold?
2. Should I drain down the water level or simply remove radiator cap?
3. Should I loosen, then retighten the nuts?
4. Is there any reason that the original head nut tightening sequence would not apply?

Thanks in advance for any input.
 
When one builds an engine the studs are torqued cold and the retorqued after running....or not. I would never loosen and retorque unless I was going to pull the head, perform all the head off checks and clean an reinstall the gasket with sealant/adhesive, or nothing, based on the research you do and what your religion is. You obviously attend the church of Dennis Welch so I'm sure, rightfully so, you do what they do. If it were me, I would do a torque check in the specified sequence. If something moves, go to the specified torque and observe for any change. If nothing moves when you get to the proper torque value I'd probably ask Randy Forbes what he thinks or one of the folks who runs the alloy head. I am not sure why you ask about draining the coolant or removing the cap. I seen no reason to do that.

I have a copper gasket with a thin coating of some stuff that seemed a good idea at the time. I also treated my cooling system with Irontite as the block and head were hot tanked and cleaned so that would tend to seal the cooling circuit. I never retorqued the studs. I figured why mess with something that was working well. I think it's been 7 years. Your mileage may vary but that's my story.
 
Michael Oritt said:
My question is what procedure I should follow:

1. Should I do this with the engine hot or cold?
2. Should I drain down the water level or simply remove radiator cap?
3. Should I loosen, then retighten the nuts?
4. Is there any reason that the original head nut tightening sequence would not apply?

Thanks in advance for any input.
Click to expand...

It has always been my understanding that you should lower the water level if you are loosening the head bolts to ensure that no coolant moves over into the cylinders or the oil passages. I would lower the water level even if I wasn't actually loosening the head bolts because its just an extra precaution. I would do the torgueing cold because that is the way you usually do an engine and I would also follow the original torque pattern. Although I have to admit that if I had one area
that appeared troublesome I probably would try tightening that one or two bolts. But on the 6 cylinder engines you have to take the rocker arms off to get to some of the bolts and in doing that I would torque them all because of the trouble to have to do it all over again. If I was retorqueing I would not loosen them first. As a matter of note, I have built a few engines and I have never retorqued the head bolts although I have thought about it a few times. How many OEM head bolts get retorqued?
 
Mike:

You could try retorgue to the original spec when warm, however, i woud do it warm only in the area of the leak first and see if it stops.?
 
Your point #3. Yes, I was taught to always back off the nut first (1/4 turn or so) to break loose any 'bonding' of stud/nut threads so you can get a true 'torque to turn' rather that 'torque to break loose' and then tighten to proper torque using the original torque sequencing. Do this with engine cold. I would not worry about coolant because you are only loosening one at a time and all the rest are still tight.
Dave
 
IIRC, aluminum has a greater coefficient of expansion than steel, so I would re-torque cold. To re-torque, do it in the original sequence, loosen each nut slightly, then re-torque. One sets the torque while the nut is moving.
 
Michael-
We also have the DW steel gasket but not an alloy head (VSCCA does not allow it, but plenty of people are running them). They can be used as stated 3 times. We have never coated them with any type of sealant, nor have we re torqued it, (at least not that I remember). The best advice is to drain the water, and then add some Moroso Ceramic seal (use distilled water) and then follow the directions on the bottle. All 100/4's tend to leak above the # plate on the block, more of a weep then a "leak." This sealer works fantastic and we have never had a leak or failure.
 
red57 said:
Your point #3. Yes, I was taught to always back off the nut first (1/4 turn or so) to break loose any 'bonding' of stud/nut threads so you can get a true 'torque to turn' rather that 'torque to break loose' and then tighten to proper torque using the original torque sequencing. Do this with engine cold. I would not worry about coolant because you are only loosening one at a time and all the rest are still tight.
Dave
Click to expand...
That is the way I’ve always been told to retorque y.inder heads from engine builders and machinists.
 
Retorque aluminum heads when cold. Hot torque will distort heads. I have been building cars with aluminum heads for over 50 yrs and all my books say cold. I have never lost a head to wrong torque. Just like changing plugs in aluminum head, cold. When you retorque head and leak resumes, new gasket with a known copper sealer and torque to full torque in 25lb segments ( 25-50-spec final). Redo at 1000 mile interval, then yearly.
 
The thing to remember is that the AH 100/4 head stud spacing is what causes the leaking. You can have a brand new head, and a 'decked" block, and it will still leak. DW will tell you NOT to coat their gasket with anything. I know all of this goes against traditional engine building/assembly. BUT the 100/4 block is not like most 4 cyc engines. Again, contact them, its their head, and their gasket.
 
Thanks to all for the input.

Jeremy Welch first commented that leaking of coolant and/or oil from under the head at this position is a common issue. His concern with retorquing the head was that doing it in the conventional manner of undoing the nuts and then retightening them might result in pulling a stud and damaging the block given that I have the high-strength studs, nuts and washers and the age of the block casting, etc. His suggestion was to simply check each nut and retighten to 75, if need be, this on a cold engine. I drove the car this morning and am now waiting for the engine to cool...
 
Just to retorque you do not undo nuts. Just torque to 75. Only undo nuts if removing head for a gasket replacement. Let us know how things turn out. I had a gentleman that had his Jag engine rebuilt and the shop knew nothing of Jags or British engines of old. He drove it for 500 miles and oil came out everywhere along head gasket. Did not know about retorque of head after intial warmup and 500 miles. I redid engine and did all the retorques and all is well, until I found he hasn't changed oil in 2 yrs. I'm not happy about that.
 
Following up on my last post I went through the head nuts in the prescribed order, simply checking them for tightness at 75 ft/lbs. None of the nuts moved before the torque wrench clicked so I must assume that my engine has simply added one more drip to its particular pattern of oil leaks. Much as whale-watchers identify individual animals by markings on their tail flukes perhaps we can set up a Healey drip-pattern database.
 
:encouragement:
 
Do you think the drip patterns would be genetic and you might be able trace your car's heritage based on the pattern? You might be able to determine if some MG or Triumph genes have somehow been added to what you thought was a purebred Healey.......
 
At Rendezvous 2013 we had to put paper diapers under the cars for the show. We gave an award for the best Rorschach pattern.
 
I have taken down my last comment and I apologize if I offended anyone.
 
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