Head removal help

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ducter

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This is an AMC 360 in an 80 SJ Cherokee, I posted earlier about getting it running. It's sat since 91 and after doing a compression test I found a few cylinders that have 30 lbs or less so I want to pull the heads and take them to a machine shop to be fixed.

While I have replaced a motor in an xj, transmissions, intakes etc I have never messed with heads, a bit apprehensive on pulling them and would like any advice you guys can offer. Perhaps I am thinking it's a bigger deal then it is, none the less it's got me concerned. Just looking for any advice or suggestions that may help.

Thanks
 
Nothin to it really, but what's the condition of the bottom end? It has the same mileage I bet. I'd be yankin it out and doin it all.
 
Here is a head bolt tightening sequence for ya. Was trying to find my sheet for torque specs....
 

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Dartn440 said:
Here is a head bolt tightening sequence for ya. Was trying to find my sheet for torque specs....
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Uh, he's talking about an AMERICAN MOTORS 360 I believe

vintage.mitchell1.com/PClubData/chassis/ent79/V2D797127.pdf
 

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RustyRatRod said:
Nothin to it really, but what's the condition of the bottom end? It has the same mileage I bet. I'd be yankin it out and doin it all.
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It has about 90k miles on it, assuming all stock and never been opened up. I should pull it and rebuilt it, just can't afford it right now and hope it can run a year or so till I can. It's a vehicle I plan on keeping, restoring it as I can.

67Dart273 said:
Uh, he's talking about an AMERICAN MOTORS 360 I believe

vintage.mitchell1.com/PClubData/chassis/ent79/V2D797127.pdf
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Yeah, it's an AMC. I realize this is a Mopar forum but honestly the wealth of information I have read on these boards and the overall decency of the people here I just prefer asking for help from you guys.
 
I would pull it regardless. If you can afford to get the heads done, you CAN afford to pull it and make it easier and also catch and oil leaks such as the pan and rear main seal. Those items are cheap and pulling the whole thing will make your job much easier. JMO.
 
OP, how do you know the heads are the cause of the low compression? Did you put some air in the low chambers with the valves closed and listen for leakage pas the valves, or... ???
 
nm9stheham said:
OP, how do you know the heads are the cause of the low compression? Did you put some air in the low chambers with the valves closed and listen for leakage pas the valves, or... ???
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When trying to start it it will not run, it backfires back thru the carburetor. I replaced the carb with a new one and same results. Figured timing or stuck valve/s, checked compression and 1-3-5-7 were all right around 120 dry, #2 was 30 and increased only slightly with oil in the cylinder. From what I have gathered and read it's most likely a valve issue, broke, bent, stuck.
 
Ok, at least you got some supporting evidence. A broken ring might not seal up well with the addition of oil, though. I'd put some pressurized air in the bad cylinder(s) and listen for where it leaks (via intake or exhaust or crankcase) before pulling the heads; it will be a very good diagnostic step to make sure of where the problem is.

The timing could be messed up for the backfires; timing chain is suspect......I'd change it too as it is not all that hard and can be done in-car. Chain/sprocket wear retards the cam timing and shows up as sluggish throttle response. Keep your pushrods and rockers in the same order, just as a good practice. Keep the head gaskets and examine for leakage spots. Look at the ridge in the cylinder bores as an indication of wear.
 
nm9stheham said:
Ok, at least you got some supporting evidence. A broken ring might not seal up well with the addition of oil, though. I'd put some pressurized air in the bad cylinder(s) and listen for where it leaks (via intake or exhaust or crankcase) before pulling the heads; it will be a very good diagnostic step to make sure of where the problem is.

The timing could be messed up for the backfires; timing chain is suspect......I'd change it too as it is not all that hard and can be done in-car. Chain/sprocket wear retards the cam timing and shows up as sluggish throttle response. Keep your pushrods and rockers in the same order, just as a good practice. Keep the head gaskets and examine for leakage spots. Look at the ridge in the cylinder bores as an indication of wear.
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Okay. I called around to the auto stores and no one even rents or carries a leak down tester. If I rig up my compression tester, while I wouldn't be able to measure leak down percentage I should be able to still tell where/if it's leaking correct? What should I set my compressor to, 60 psi or so? Also, I have all the plugs out currently, have read where some say only take out the plug from the cylinder you are working on and others say pull them all... one way better compared to the other?

Thanks
 
ducter said:
Also, I have all the plugs out currently, have read where some say only take out the plug from the cylinder you are working on and others say pull them all... one way better compared to the other?

Thanks
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For a compression test? Pull them all, ideally engine warm, pull all of the plugs, block open the carb, disconnect coil wire, battery charger on the battery.

3 to 5 revolutions per cylinder recording the highest reading. Followed by a wet test.
 
Bad Sport said:
For a compression test? Pull them all, ideally engine warm, pull all of the plugs, block open the carb, disconnect coil wire, battery charger on the battery.

3 to 5 revolutions per cylinder recording the highest reading. Followed by a wet test.
Click to expand...

I already did the compression test, now being advised on a leak down test.

Thanks
 
ducter said:
I already did the compression test, now being advised on a leak down test.

Thanks
Click to expand...


How did you do the compression test? Did you do wet and dry for the same cylinder?

What did the compression test tell?

Is it in the cylinder piston and walls or the valves? (compare the results of a wet and dry test in the same cylinder).
 
krazykuda said:
How did you do the compression test? Did you do wet and dry for the same cylinder?

What did the compression test tell?

Is it in the cylinder piston and walls or the valves? (compare the results of a wet and dry test in the same cylinder).
Click to expand...

Sorry, it's posted in another post. Had 120's dry on 1-3-5-7 and when I went to the other side #2 was 30 dry and 45 wet. I didn't continue testing after that point.

Here's the original thread giving a bit more info.
 
The only thing a leak down will tell you now that you've done compression, is "some idea" of where the problem is. That is you can HEAR air leaking out the exhaust or carburetor, it's a bad valve, etc etc.

With that low reading, there is no question. It's time to get out the wrenches and pull the head.


I would spend a marathon at Google. There surely is info you can download on working with these. I already posted the "stuff" I found above, it took me about 30 seconds on Google.

Believe it or not, of all the junk I've worked on, and it's been a few, I've never been into an AMC V8. "Back when" we were tearing around 4x4, the "Jeepers" really had very little problems with those engines.
 
If you have a sticking valve, try to remove the rocker arms and tap on the valve with a hammer to see if it can break free, but not hard enough to bend one....

To see which valves may be leaking, just pull the heads with the spark plugs installed, flip them over and fill the combustion chamber with water and see which valves are leaking...
 
krazykuda said:
If you have a sticking valve, try to remove the rocker arms and tap on the valve with a hammer to see if it can break free, but not hard enough to bend one....
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I just tried what you recommended, had a piece of wood and a rubber mallet. Tapped lightly a few times and heard a light thud sound, put everything back together and now have 0 compression on that cylinder. Not real sure what I did but don't think it was good.
 
It not a leak-down test that is being suggested; just put some air pressure in the cylinder in question when it is at TDC on the compression stroke (valves closed) and listen to where the air leaks out: intake, exhaust, or oil filler/PCV. It's another bit of info for diagnosis that can only be done while the engine is still together.
 
I am going to start pulling the heads off tomorrow. Going to be a pia with the manifold's and tight clearance, also, realizing times like this a lifted vehicle kinda sucks. Standing on a bucket, while worked wasn't the best way lol.
 
ducter said:
I just tried what you recommended, had a piece of wood and a rubber mallet. Tapped lightly a few times and heard a light thud sound, put everything back together and now have 0 compression on that cylinder. Not real sure what I did but don't think it was good.
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It could be something simple like a piece of carbon stuck on the seat not letting the valve close fully.

Or could be that it needs to have a valve job.

Pull the head and take pictures of the head and block and gaskets (both sides) before cleaning them up. sometimes witness marks on those surfaces can help identify any problems there. Don't ruin the evidence before recording it in case you need to look back at it later...

Try flipping the head upside down and filling the combustion chambers with water. Any that leak are not sealing properly and need work.
 
ducter said:
I am going to start pulling the heads off tomorrow. Going to be a pia with the manifold's and tight clearance, also, realizing times like this a lifted vehicle kinda sucks. Standing on a bucket, while worked wasn't the best way lol.
Click to expand...

That's what makes a man out of ya... :violent1:

Learning how to take all those skinned knuckles... :pale:

Get a propane torch and heat up any stuck exhaust bolts. Then try to tighten first to crack them loose, then back them off after you get them to break free, I find that I break less bolts that way.
 
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