My Willys 3A and 3B Community

3A, 3B, DJ Technical Knowledge Base => "Original"-- Technical Questions, Answers, Observations => Topic started by: garage gnome on February 27, 2015, 02:58:43 PM

Title: Teds compression test results
Post by: garage gnome on February 27, 2015, 02:58:43 PM

Well I'm a little worried about Ted. I did a compression test on him. Dry they were 75, 75, 65, 60psi. Then I did them wet. 140, 150, 125, 125 psi. What do you guys think? Time for a rebuild? I know the FSM call for the cylinders to be between 120 and 90 psi.

Title: Re: Teds compression test results
Post by: athawk11 on February 27, 2015, 04:41:24 PM

I'm no engine expert.  I've only done a partial rebuild on one L-134.

How is your oil pressure.  If decent, and because they are inexpensive, I might be inclined to slip in a new set of rings and see if this is enough to get the dry compression up.

Tim

Title: Re: Teds compression test results
Post by: garage gnome on February 27, 2015, 06:43:54 PM

Reason I tested it was because he was running like garbage last weekend. It probably didn't help that the intake was full of gas from the screwed up carb. All the oil could have been washed off from the gas.

I did a complete tune up, rebuilt the carb, new plugs, wires, cap and rotor. The new plugs are hotter too. He seems to run fine now. I'll do another test in a bit.

Title: Re: Teds compression test results
Post by: corpsman on February 27, 2015, 06:51:08 PM

this probably isn't the case, but the further away the splits in the upper and lower rings are from 180 degrees apart, the better the chance to get some blow by, therefore reducing power.  just a thought.

Title: Re: Teds compression test results
Post by: garage gnome on February 27, 2015, 07:21:08 PM

The engine has never been apart. They could have spun in the grooves.

Title: Re: Teds compression test results
Post by: athawk11 on February 27, 2015, 07:41:26 PM

I wanted to try a hotter plug in Whitey.  What did you use?

Tim

Title: Re: Teds compression test results
Post by: garage gnome on February 27, 2015, 08:04:05 PM

I was running Autolite 306s. I was away for work all week, so I ordered plugs from Walcks along with all the other parts. Those are Autolite 295s. They do make a big difference!

Title: Re: Teds compression test results
Post by: athawk11 on March 01, 2015, 12:23:02 AM

Thanks Nate.  That's the plug I'm currently running.  Just wondered if there was something that was a touch hotter than the 295.

Tim

Title: Re: Teds compression test results
Post by: stony on March 05, 2015, 05:19:40 PM

2X difference between wet and dry?  yeah the gas could have washed the walls and was REALLY DRY.  I guess I would redo the tests, and if you get the same results, time to pull the head and n take a look.  Would not be surprised if you had some broken rings.

Title: Re: Teds compression test results
Post by: CJPilot on March 08, 2015, 10:43:13 AM

Nate, you might be able to get a look around the cylinders with a USB dental camera.  The aircraft folks are using them to inspect aircraft engines.  I haven't used one but they are cheap.  Look on ebay.

Steve