M38A1 Rebuild

[mydadsjeep]

We have come to the conclusion that Compression is our issue with my jeep. The Smoking and loss of power and a compression test is very low. so my new question to the forum is two fold.
After sitting for 38 years the rings are more than likely shot and need replaced. I have been told that you can buy a Engine Restore at Autozone that may fix the rings and compression issues. I tend to think that wouldn't work cause of the age of the engine and sitting for so long.
I have found a two places that could do a engine rebuild. One I would have to pull the motor and wait 12-18 months for it to be done for $1800. The other place I can take it there and they can pull the motor $75 hour. And work on it as they have time from other projects and only need to pull and replace it after machine shop is done rebuilding it. That cost is $2000-$2500..
The engine has had everything rebuild and replaced as needed and this is last thing before I think of what to do on the body if anything. So I am leaning to just having the jeep taken over and letting the second option work..
Looking for ideas and comments. And help, thanks in advance....
Dan

[wesk]

I am living in a much less populated area then you are and I have the choice of at least 7 or 8 local automotive machine businesses that are willing to rebuild an engine for me. They prefer I drop the engine off and expect about 2 months max wait.

I would canvass a few more Penns. shops first.

[4x4M38]

Yes and you pulling it yourself is not that difficult.

You could save time and money, even if you had to rent an engine hoist for a day.

[mydadsjeep]

Was told that I may only need a head job on the engine from a guy that said he has done these. If compression is low on one or all what's the difference?

[wesk]

The single question you just asked only addresses a single test of the engine's condition. To answer it alone will not help you gauge the condition of your engine. All low speaks to the possibility of age, worn rings, leaking valves, leaky head gasket and so on. One low and the rest all close together and over 100 PSI indicates any of the above listed problems on that one cylinder.

There is not a single "Tells All" test in this process of determining the condition of any internal combustion engines. The industry standard is to get as much information as possible from a battery of tests before you tear it down. Then get a final analysis using the clues that are uncovered during the teardown inspection.

What does this battery of tests include?

1 - Initial runup to prewarm engine to it's normal operating temp range.

2 - Connect a vacuum gauge to the intake manifold and a fuel pressure gauge Tee"d into the pump to carb tube in a way that allows you to run the engine.

3 - If you have a tachometer that can be used with your 24 volt system connect it.

4 - If you have a timing light that can be connected to your 24V system connect it. Make sure your timing marks are clean and readable.

5 - If you have a digital VOM use it to check operating voltages on startup and while running.

6 - Do your homework reading on how to use each of these instruments and run their related tests. Keep a note pad handy.

7 - Run these tests and RECORD ALL RESULTS!

IE: a - Idle RPM
b - Idle Vacuum
c - Ignition timing at idle.
d - Fuel pressure at idle.
e - Rapidly advance throttle from idle to about 1500 RPM recording the
lowest and highest vacuum readings attained. Do it again observing
the timing light results for maximum distributor governor advance.
f - With a steady 1500 RPM record vacuum and fuel pressure readings.
g - Record coolant temp.
h - Shut the engine down.
i - Remove spark plugs and perform compression checks while engine is
still warm. Record each.
j - Perform leakdown test. Record any evidence of air leakage at intake
(Carb throat), exhaust tailpipe, oil sump (thru dipstick tube), at
adjacent cylinder spark plug openings or bubbles in coolant observed
while radiator cap is removed. Record results for each cylinder.

Now by weighing this ton of engine operating condition evidence a very sound analysis of your engine's condition can be made.