Head gasket

snoosky

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Ive had my 79 for about a year and a half with some minor oil leaks from the head gasket. Suddenly it will only fire on one cylinder. After pulling the plugs, its oil fouled bad. So ill be replacing the head gasket. I should mention this was a strong runner with very little issues and 150/155 compression. My questions to the more experienced:
Can the engine be stripped down to the head gasket with it still in the frame?
If so, what can be left intact to get to the gasket?
What else would be recommended if diving in this far?
Thanks ahead :)
 
of course theoretically, the head will come off with the motor in the frame if you tilt it just right, but it's such a crazy act to do it, that's it's easier to pull it. saw it done once on here.

what's the compression now? did you check after adding a bit of oil to see if it goes up, saying if it doesn't it's the gasket or burned valve and it it does, it's rings? prepare for it to be more than a gasket. With that kind of compression previously, I wouldn't disturb the pistons and jugs if after i took the head off I saw the problem was a valve or gasket. Did you try just re-tightening the head?
 
No it can’t be stripped down while on the frame because the long bolts inside the engine won’t allow the clearance. Some people have had luck with a retorque of the head bolts for leaks of the gasket. I agree with Gary check your compression because the cylinder may be getting oil blowing by the piston. If it was just the gasket the oil would probably be more on the outside of the plug and not the tip. If the compression is still good though are you sure it’s oil fouled and not fuel?
 
Gave her a squirt in each cylinder and its slightly better 160/160. I think the previous numbers weren’t bad tho?? Plugs aren’t covered in oil, just a little shiny looking. Def not fuel. Head was retorqued last year, maybe 300 miles ago. I dont remember making big turns when doing so.
Is there a chance the bolts were seized from age and a replacement with the new copper washers could save me a tear down?? Maybe someones been down this road.
 
Have you read the retorque thread? The nuts are ALWAYS seized, you have to back them off one at a time, retighten torque repeat. I don't replace the rubber washers and it works for me, but many others do and that works for them. Torque values are with oil or anti seize on the threads.
 
with compression that good, i suspect your ignition system. it would have trouble sparking through oil, which would cause more oil..which would... Don't know your year well, but if you have two coils, switch them and see which side runs now. switch the plugs too. if there's a change, switch the plugs back and leave the coils, to break it down to coil or plug. If you have one coil, just switch the wires
 
In general the leaking head gasket is more about external leaks than oil into a cylinder. :shrug:
I agree; your first compression readings were good numbers, both gross and balance.
Stiff or cracked intake valve seals tend to reveal themselves as smoke on start up and deceleration. Drip down while sitting, and vacuum in the intake?
An "in place valve seal replacement" is not terribly difficult, but does require some "special tool" fabrication and fiddly work with the valve retainers.
The one time I did it, I felt it reduced smoke and consumption (halved?) but was not a "total cure" for that motor. It's still in use for a new owner.
 
not sure if switching the wires if you have a single coil would do much, but at least if it somehow did, you'd know the coil or wires was a problem

I seem to remember 2M saying something one time about checking for a bad coil by temporarily making the plug gap real small? Or something similar. Would be nice to know what it was again. At any rate, with compression like that in both cylinders, it has to be ignition or fuel. Definitely not any significant compression leaking going on, whether it's gasket, valves, or rings.
 
Ok. Did the whole head retorque per the thread mentioned earlier. Put in clean plugs and it fired up on both right away but soon fizzled into one side firing. Pulled the plugs and still saw fouling on both plugs. :umm:
Swapped plug wires. No change
Swapped coils. No change. Although i did read resistance and my R (problem side was at 5.15 ohm) So I think some fresh coils and wires are def in order. These were all stock.
Ill see what shakes out from there..
 
for the record, if coils read bad they're bad, but they can read good and still be bad. there can be high voltage only low resistance paths that don't show up with a multimeter. to test the windings on a high voltage motor, for example, use a "megger" that is basically an ohmmeter that uses high voltage for its tests
 
Update: Got some new coils, plugs and wires. Started up good. Sounded normal and finally puttered out on the R side. I brushed and cleaned the plugs real goid then put them in and tried the choke OFF this time when starting. Went straight to one side. Now when i flip the choke up and rev, it started firing on both sides. Looking like a carb issue now.
 
Turns out it was the ignition all along.Tried The tuneup but it just left me with this feeling about the firing on the R side. To someone who’s never done the points before, it was confusing. The instruction from 650central.com was the easiest for me to make sense of. I got it dialed and blasted around to make sure it all stayed. And it did! Now about to tear it apart for the head gasket. At least now i know it was dialed beforehand. Thanks everyone!
 
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