J and M Machine
Senior Member
Head gasket.! You have to retorque a few times and don't forget the copper spray on both sides of gasket.
engine runs rough
- Thread starter freak
- Start date
freak
Senior Member
How do I properly do a leak down test? Also I don't have a tester but is it worth getting for this case?
Last edited:
Mitch//pa
BANNED
freak here is a previous thread for leak down testing info
http://fordbarn.com/forum/showthread.php?t=126838&highlight=leak+test
http://fordbarn.com/forum/showthread.php?t=126838&highlight=leak+test
No just pull the head and fix it
While your at it inspect the valves and service if needed. If you don't know what you doing on the valves get someone to help you . If they have a good centered seat on them then you are probably ok. I would check the head for cracks and plane . Get it surfaced and replace head gasket and your back in business
Larry Shepard
While your at it inspect the valves and service if needed. If you don't know what you doing on the valves get someone to help you . If they have a good centered seat on them then you are probably ok. I would check the head for cracks and plane . Get it surfaced and replace head gasket and your back in business
Larry Shepard
tbirdtbird
BANNED
leak down is nice but not mandatory. Compr test told diagnosis clearly. Blown between 3&4. Common. There ain't much gasket there!
Pull head. Have it surfaced to be sure (did car overheat anytime that you had it? You would not know if before you bought it.) Cheap insurance.
Get the Felpro copper (Felpro PN is 7013) NOT the silicone gasket which is junk.
Use a copper spray-on liberally, Permatex makes a good one, as well as others. There is K-W copper in a dauber can, forget it, you will never get the head off again.
Use proper torque sequence (it is in the Bratton catalogue maybe others)
Torque in steps, ie all to 20 lbs, then all to 40 lbs, then all to 55 lbs. Some use a final torque of 50 on the two nuts on the water neck to prevent cracking; your call.
Run engine for 10 min. Shut off. Re-torque right now while hot. Under no circumstances should you back the nuts off a half-turn doing this I do not know how this fool-hardy suggestion ever came to be. I do this for a living and I would get beat up by my clients if I messed up their head seal.
Run car on road for 20 min. Re-torque hot again.
Wait a day, allow full cool down, drive car for 30 min, then re-torque hot one more time. At this point you will take up very little on the nuts. We have always tried a 4th hot re-torque but are never able to take up any more.
Do not drive like a maniac while doing any of this.
This has been standard shop practice in this country since at least 1950 when I started working on cars. i have never seen a professional do it any other way. I have several racing buddies who do it this way. I have never had a failure. Should you elect to deviate from this method your results may vary!
I have never had a client's A in the shop that did not need a re-torque, never, because they were improperly torqued in the first place.
This is actually an easy fix, and inexpensive.
Good luck
Post questions if you have any
There will be naysayers to all that I have written. Procede at your own risk. Try to imagine how many head gaskets I have installed since 1950 on every variety car.
Pull head. Have it surfaced to be sure (did car overheat anytime that you had it? You would not know if before you bought it.) Cheap insurance.
Get the Felpro copper (Felpro PN is 7013) NOT the silicone gasket which is junk.
Use a copper spray-on liberally, Permatex makes a good one, as well as others. There is K-W copper in a dauber can, forget it, you will never get the head off again.
Use proper torque sequence (it is in the Bratton catalogue maybe others)
Torque in steps, ie all to 20 lbs, then all to 40 lbs, then all to 55 lbs. Some use a final torque of 50 on the two nuts on the water neck to prevent cracking; your call.
Run engine for 10 min. Shut off. Re-torque right now while hot. Under no circumstances should you back the nuts off a half-turn doing this I do not know how this fool-hardy suggestion ever came to be. I do this for a living and I would get beat up by my clients if I messed up their head seal.
Run car on road for 20 min. Re-torque hot again.
Wait a day, allow full cool down, drive car for 30 min, then re-torque hot one more time. At this point you will take up very little on the nuts. We have always tried a 4th hot re-torque but are never able to take up any more.
Do not drive like a maniac while doing any of this.
This has been standard shop practice in this country since at least 1950 when I started working on cars. i have never seen a professional do it any other way. I have several racing buddies who do it this way. I have never had a failure. Should you elect to deviate from this method your results may vary!
I have never had a client's A in the shop that did not need a re-torque, never, because they were improperly torqued in the first place.
This is actually an easy fix, and inexpensive.
Good luck
Post questions if you have any
There will be naysayers to all that I have written. Procede at your own risk. Try to imagine how many head gaskets I have installed since 1950 on every variety car.
Last edited:
Growley bear
Well-known member
I don't know where the idea of backing the head nut off a half turn or so before a retoruqe was started either. I decided to try it on my A; I marked the nuts with a sharpie and first checked them without backing off, no movement. Next I backed them off and retightened ant they all save one stopped at the mark. That one barely split the mark in half, surely not enough to worry about. I have the silicone gasket with standard head and retorqued 4 times before I got it to seat. I check the head nut torque on a regular basis.
Chet
Chet
Tom Wesenberg
Well-known member
I agree that most likely you have the head gasket blown between 3 and 4.
In 1970 I bought a 1950 Studebaker Commander with an engine miss. First thing I did was check compression and got 100-100-100-100-40-40, so I guessed it must be the head gasket. I was surprised to find the last 2 exhaust valves were burned. I like to keep everything well matched, so I replace all 6 exhaust valves for a total cost of $7.60. I guess those were the good old days.
You can bring #3 to TDC firing, then use a rubber tipped blowgun to inject air into that cylinder and see where you hear it coming out. It will come out the carb, tail pipe, oil fill pipe, or #4 if the head gasket is blown between 3 and 4.
In 1970 I bought a 1950 Studebaker Commander with an engine miss. First thing I did was check compression and got 100-100-100-100-40-40, so I guessed it must be the head gasket. I was surprised to find the last 2 exhaust valves were burned. I like to keep everything well matched, so I replace all 6 exhaust valves for a total cost of $7.60. I guess those were the good old days.
You can bring #3 to TDC firing, then use a rubber tipped blowgun to inject air into that cylinder and see where you hear it coming out. It will come out the carb, tail pipe, oil fill pipe, or #4 if the head gasket is blown between 3 and 4.
Purdy Swoft
Well-known member
If it has 30 pounds compression on cylinders three and four, the gasket isn't burned in two between the cylinders. If the gasket was burned in two between number three and four, you would have no compression on either cylinder.
freak
Senior Member
So what is your theory?
Mitch//pa
BANNED
purdy i rarely disagree with your valuable input
but i dont agree that compression is always 0 when a head gasket leakage occurs between two cylinders..
Last edited:
tbirdtbird
BANNED
on the outside chance it is a valve issue the head has to come off anyway.
Purdy Swoft
Well-known member
Not necessarily. If the valves stems are gummed up from using ethanol gas, valve action will be slow enough to cause weak compression without complete loss of compression. If the head gasket is burned in two between cylinders 3 and 4, number 4 cylinder will be down when number 3 is on compression stroke. I just can't see it holding any compression if the gasket is burned in two between the two cylinders. Maybe in the early stages of burn through, it may briefly hold a small amount of compression but not for long. I just feel that other things should be tried before jumping into removing the head. Running Marvel mystery oil through a temporary vacume line while the engine runs will free up slow sticky valve action. Just trying to help. Its a forum, we can disagree, no harm meant.
Growley bear
Well-known member
I think that Tom already pointed this out. An adapter can be fabricated to introduce a metered amount of air into one cylinder or the other. All spark plugs removed and with say # 4 on top dead center apply 30psi (don't just apply 110 psi as the engine might try to turn) to that cylinder and see where the sound of leaking is coming from. Out of #3 spark plug hole blown head gasket between the cylinders. If leaking air is found at tailpipe or carburetor then a valve is leaking. If it was my engine I would pull the head as what ever is wrong at 3&4 is probably not far from wrong at 2&3. Best to repair this at home or in the shop than have a problem out on the road.
Chet
Chet
Purdy Swoft
Well-known member
I agree, Toms test is good as usual. Sticky valves can give similiar symptoms . In the spirit of trying to help the guy ,I would do some easy tests before I removed the head . I have experience with bad gaskets, burned valves and sticky valves . A simple test with a temporary vacume line and some Marvel oil will be easy and inexpensiuve . This simple test will give quick results if the problem is actually sticky valves. If the guy jumps into head removal and gasket replacement, the chances are better than average that some of the old head studs will wring off in the process, no matter how careful a person tries to be. Sometimes you get lucky and no studs break. Most want to replace the old studs while they are at it, this is generally where the problems begin. Broken head studs are not good for the average guy at home. Many times the engine will have to be removed and then find a machine shop that will even take the job of removing the broken studs. I don't know what the real problem is. I just recommend exploring all avenues before doing something as major as removal and replacement of the head. The last engine that I had with partial loss of compression on the back two cylinders had two broken piston skirts and some of the rings had dropped into the oil pan. The engine was weak but would still run , it had a low speed miss but would still hit on all cylinders when RPMs increased. Removing the head in some cases may not show the real problem. Still just my thoughts.
Tom Wesenberg
Well-known member
Well, an intake leak won't cause low compression, so we can rule that out for the loss of power on 3 and 4. I would still do the simple checks first though. Try putting air pressure into #3 and see if it escapes. If it does, then the head will need to be removed. If it doesn't, then it might be a sticky valve that is slow to close and I'd try sea foam in the gas and oil, or spray some penetrant on the valves directly.
If that doesn't help then start soaking the head studs with penetrating oil and get ready to remove the head.
If that doesn't help then start soaking the head studs with penetrating oil and get ready to remove the head.
Purdy Swoft
Well-known member
Thanks for the heads up. Good luck.
tbirdtbird
BANNED
Purdy, to back up, I mostly agree with you about MMO, and that sticky valves don't nec. mean the head has to come off for those, I was a bit ahead of myself there.
Having said that, the guy had his problem occur while he was driving the car. I am not sure that is when the valves would stick. I myself have seen blown gaskets with low readings like he got between to adjacent cyls. It doesn't have to be a major blowout; in the early stages it could be more like a 'leak'.
He wants to know why the gasket blew, and my answer is that it was never properly torqued in the first place; or that someone drove the car like hell and over-revved the motor/overheated the motor. There is so little gasket material in between those cyls to begin with I am surprised they don't blow more often.
If the car had been overheated at anytime that could have warped the head easily; these issues don't always show up right away. If i ever have any head off for any reason, it gets machined regardless. All this deal about checking with a straight edge and all is a bunch of BS. They can be warped at any angle and a straightedge is like using a crescent wrench to measure thousandths of an inch like somebody said they did on here not that long ago.
Maybe the copper spray was not used. Who knows. In any event, all the more reason to do a fresh install by professional mechanics standards, and not by myth, guessing, random Barn comments from folks who have never done even one, and Ouija board.
You and I and the other responsible posters here want the best job for this guy. Which is why we are here.
I hope this renewed discussion of possible stuck valves will highlight once againthe need to use MMO in the gas tank, and some in the crankcase as well. Thanks to the senator from Iowa, we all have to live with a gasoline fuel that is highly polluted and does really bad things to our cars, not that he cares; they just want the govt subsidy. Pure gasoline is not available to all of us. It is easier to get in some areas, like I think Tom W has access to it because he mentions 'good' gas every so often. And I can't figure out why it is only available in certain places.
I encourage the OP to carefully study the advice he has been given, proceed slowly and thoughtfully, gather the correct tools (he will need a way to get a torque wrench on #8 stud, me I use a crow's foot wrench which throws my reading off only a tiny bit), etc. I think the suppliers have a special offset 11/16 socket or extension to get around this problem. Bratton's PN 6082. And do not be afraid to ask questions as you go. Spray a good 3 coats of copper spray on both sides of the gasket, for heat transfer if nothing else.
Be sure your cooling system is not borderline. Run something to help you keep an eye on the temp, a thermoquail, an actual temp gauge, an infrared temp gun, etc , something anything to give some idea of what is going on.
You might consider a fresh set of head studs; the old ones are stretched. Use Permatex PTFE (Teflon) sealant (comes in a tube) (PN 80631) around the threads in the block since many of them go into the water jacket.
good luck. a blown head gasket is actually one of the cheapest and easiest repairs on an A, and will give good service if done right
keep us posted on your progress. This is actually a very educational thread for more novice A owners, and closure from the OP will help with that
Having said that, the guy had his problem occur while he was driving the car. I am not sure that is when the valves would stick. I myself have seen blown gaskets with low readings like he got between to adjacent cyls. It doesn't have to be a major blowout; in the early stages it could be more like a 'leak'.
He wants to know why the gasket blew, and my answer is that it was never properly torqued in the first place; or that someone drove the car like hell and over-revved the motor/overheated the motor. There is so little gasket material in between those cyls to begin with I am surprised they don't blow more often.
If the car had been overheated at anytime that could have warped the head easily; these issues don't always show up right away. If i ever have any head off for any reason, it gets machined regardless. All this deal about checking with a straight edge and all is a bunch of BS. They can be warped at any angle and a straightedge is like using a crescent wrench to measure thousandths of an inch like somebody said they did on here not that long ago.
Maybe the copper spray was not used. Who knows. In any event, all the more reason to do a fresh install by professional mechanics standards, and not by myth, guessing, random Barn comments from folks who have never done even one, and Ouija board.
You and I and the other responsible posters here want the best job for this guy. Which is why we are here.
I hope this renewed discussion of possible stuck valves will highlight once againthe need to use MMO in the gas tank, and some in the crankcase as well. Thanks to the senator from Iowa, we all have to live with a gasoline fuel that is highly polluted and does really bad things to our cars, not that he cares; they just want the govt subsidy. Pure gasoline is not available to all of us. It is easier to get in some areas, like I think Tom W has access to it because he mentions 'good' gas every so often. And I can't figure out why it is only available in certain places.
I encourage the OP to carefully study the advice he has been given, proceed slowly and thoughtfully, gather the correct tools (he will need a way to get a torque wrench on #8 stud, me I use a crow's foot wrench which throws my reading off only a tiny bit), etc. I think the suppliers have a special offset 11/16 socket or extension to get around this problem. Bratton's PN 6082. And do not be afraid to ask questions as you go. Spray a good 3 coats of copper spray on both sides of the gasket, for heat transfer if nothing else.
Be sure your cooling system is not borderline. Run something to help you keep an eye on the temp, a thermoquail, an actual temp gauge, an infrared temp gun, etc , something anything to give some idea of what is going on.
You might consider a fresh set of head studs; the old ones are stretched. Use Permatex PTFE (Teflon) sealant (comes in a tube) (PN 80631) around the threads in the block since many of them go into the water jacket.
good luck. a blown head gasket is actually one of the cheapest and easiest repairs on an A, and will give good service if done right
keep us posted on your progress. This is actually a very educational thread for more novice A owners, and closure from the OP will help with that
Last edited: