The cylinder compression readings you provided indicated a serious issue with the 2 low reading cylinders. This issue should be investigated because there is the possibility this is causing your hard starting. To determine if it is requires a visual inspection of the cylinders, pistons and rings. It is best to follow thru on all findings during your troubleshooting as you find them and not leave several findings on the side till later.
There are at least a dozen possible causes for your hard starting. Troubleshooting will expose suspects but unless you investigate each of those suspects as you find them it is like leaving your back door open.
For example you determined you did not have a fat blue spark. You bought a new coil and replaced a wire & condenser. The engine was still hard to start but once warmed up it ran fine. This tells me that the spark alone is not the source of the hard starting. Even though you still seem to have a weak spark from your description.
This type of troubleshooting results in multiple part rebuilds and replacements without ever knowing for sure which combination actually solved the problem. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Thank you for your patience. I was hopeful it was an ignition problem. I've had CJs with low compression, but they always started. My previous experience with old Jeep engines is they run when technically worn out. This is the first Jeep I could not get started without a fight.
Is the next step to have an engine expert open up the F-134 to inspect/measure cylinder wear?
A local engine shop suggested a "top end soak" with ACDelco 10-3015 Top Engine Cleaner and Decarbonizer. Will be my last chance to free up stuck rings (if that is the problem) and possibly improve compression.
Just afraid I may never get it started again.
Joined: Oct 02, 2014 Posts: 1909 Location: South Carolina, Dorchester County
Posted: Thu Mar 04, 2021 6:44 pm Post subject:
I think that Wes was pretty clear about it.....it's time to take it apart. No amount of ACDelco 10-3015 Top Engine Cleaner and Decarbonizer is going to fix broken or worn rings.
Unless I missed it, I noticed you haven't taken the compression and leak down tests again since you soaked them with PB Blaster and ATF. If you run those tests one more time and get the same results, do you think using the ACDelco product will fix anything? Not.
If the test results show some improvement, maybe consider using the ACDelco Decarbonizer? But when the tests show the same problem, Wes will say "I told you so!" and it's time to take it apart.
The question is: do you feel lucky? _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
Joined: Oct 02, 2014 Posts: 1909 Location: South Carolina, Dorchester County
Posted: Thu Mar 04, 2021 9:03 pm Post subject:
Yup, one day my Go-Devil took me past my skill level in the blink of an eye. Not a good feeling, but I'm learning, and was fortunate to find a great machine shop in the neighborhood. There's light at the end of the tunnel for me. I never figured that tear-down and rebuilding a flathead motor would ever be on my bucket list .
I hope you find a great old school machine shop that knows these old motors. Keep us posted once in awhile! Good luck! _________________ Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51
“The only good sports car that America ever made was the Jeep."
--- Enzo Ferrari
I've had CJs with low compression, but they always started.
I am more concerned with the imbalance of cylinder performance. As a rule any old mogas engine will run ok with 80 to 90 compressions balance on all cylinders. Those with a large margin between cylinders tend to knock or run rough and beat themselves to death.
Find a good shop that has a good background in Willys F-134's. I suggested a few test questions you can use when interviewing shop managers. I believe I suggested a while back that you join the local MV club. The MMVC based in Waukesha. Any of their members can get you pointed towards a quality shop with Willys background.
WI - MIDWEST MILITARY VEHICLE ASSOCIATION http://www.mmva.us/
Ken Spencer- President City: Waukesha MVPA#: 37264 414-839-9966 kent@wi.rr.com
Daryl Lehman- Newsletter Editor City: Cascade MVPA#: 18771 920-528-8640 daryl_lehman@hotmail.com
CLUB MEETING INFORMATION
Quarterly, contact for details. members get news flyers via eamil.
The Red Bull MVCA is another good club in Minneapolis. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: May 30, 2014 Posts: 3447 Location: Texas Hill Country
Posted: Fri Mar 05, 2021 8:31 am Post subject:
Before I pulled the motor I’d sure try everything available before that.
You said,” 6. The PO has this timed at #4 cylinder, with #4 spark plug at 5:00 o'clock position on distributor (where #1 should be) so oil pump not clocked correctly. However, I don't believe this is my starting problem and can be changed at some point. ”
I’d reclock the oil pump and distributor, retime per factory. It can’t hurt, and beats pulling the motor.
Before I pulled the motor I’d sure try everything available before that.
4x4M38: I would agree if both you and jeepdaddyRC were both thoroughly versed in what needs to be done and have access to adequate tooling.
JeepdaddyRC has already told us he is too short on tools and skills to even remove the head.
JeepdaddyRC: You still do not have to pull the engine to proceed. You can tow or trailer the jeep to a qualified shop which Madison WI has dozens of or as I mentioned above secure local help from the local MV Club. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
I'm certainly willing and able to pull the head. I've removed CJ heads before (258 6 cyl). My challenge is no ability to bore or repair damaged cylinder walls.
Wouldn't you know it? I've talked to all the machine shops recommended by local MV club - thanks for contacts Wes. Unfortunately all the machine shops are short staffed (due to covid) and swamped with spring agriculture/farm work. It will be months before they can take it.
So I tried starting it again today. It cranks and cranks with no kick at all, nothing. After several attempts with no kick, I sprayed carb cleaner in carb throat with choke open and throttle open. It finally kicked over. After a few attempts with the carb cleaner, it started.
Let it warm up for 10 min. Engine ran fine, no smoke. Then shut it down. Unable to restart. No kick at all. Nothing. Did not re-try the carb cleaner because engine was hot.
Pulled spark plugs and confirmed spark at all plugs (my spark at plugs is a bright white).
Then I removed the YS-950S carb top to confirm there was fuel in the bowl. Fuel was present in carb bowl.
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