Compression Test Results.

Did a compression test on my 1961 CJ-5 w/134 engine. Test results are: 103, 98, 108, & 105, a variance of 10%. The odometer reads 19,600. If the odometer is correct, would you say there's 19K or 119K on this engine?

 

119K would be a huge mileage for an F-head, but who knows? 60 years is a lot, too, even on a low-mile engine. But I wouldn't trust the odo, either way.

That compression is on the low side for sure but I've seen similar on my F-heads with under 50K.

Weigh all the other factors too... oil pressure, general wear and tear on pedal pivots, seats, steering parts, so on and such.

Bottom line.... is it driveable?

 

After a complete brake job, bell crank shaft for the pedals, new radiator, thermostat, hoses, alternator, rear drive shaft, front diff pinion seal, carb rebuild, new tires, and a few miscellaneous sundry items, yes it is. Now that the weather is nice, I'm driving it just about everyday.

 

I'ld run 'er

 

Just for reference a f-134 is doing good if it can pull any sort of slope above 55mph.
They are not fast but are good for most offroad trails.

I swapped mine out when it burnt more oil than gasoline.

 

Yep, a little low on compression but if it isn't fouling the plugs and leaving a blue fog that the neighbors get upset about, run it.

 

I love the little four bangers in Jeeps, they just seem right. Most of the Jeeps I have owned have been flat fenders with the L-134 but the 67 CJ5 I got last Summer has the F-134 and it does all I need it to do.

Mine had sat in a barn since 1979 and when I first got it running it smoked a lot, and compression was not great. After generous application of Marvel Mystery Oil it now runs like a new one.

For the first couple of months after I got it running every week I would pump a few ounces of it into each cylinder and let it sit a few days, and I put a whole bottle into the crankcase when I changed the oil.

I haven't checked compression again, but it has plenty of power for my use which is mostly running around on my little farm, and occasional runs into town. Pretty steep hill from the house down to where my barn is and it will scratch gravel and growl as it comes up that slope.

The main purpose of this Jeep will be for trout fishing trips in an area with very narrow tar and gravel or dirt roads with a few streams to cross. The area I fish most is only 50 miles away, and I will probably trailer the Jeep for most of these trips, but I can take a route that mostly avoids major highways, with only one stretch of about 15 miles on a highway where the speed limit is 55 mph. I am finishing up a refresh of a Warn OD to go into this Jeep which will make it better for that stretch, should I decide to drive the Jeep up there.

As is, without the OD it seems to handle 45 MPH comfortably enough.

 

x2. I set a personal limit of 50mph for myself in the '56.

If it was meant to go fast it wouldn't be shaped like a brick.

 

Ummm... what if it runs perfectly, but I DO leave a blue fog? (I got some comments when I joined the NH Jeep trail ride, from the jeepers behind me... )

 

50 mph is my personal limit also. Plugs look good & no blue fog, so she's not burning oil, but a leaker she is. Not sure if it's the pan gasket or rear main. I plan on dropping the pan & cleaning it out, then reinstalling it w/a new gasket & seeing if that helps my Exxon Valdez garage floor.

 

Gaskets won't be too bad in place, rear main would be a good reason to pull and refresh all the seals. With the pan off you can see the cylinder bore and get a better feeling about the rest of it.

Just know you are on top of a slippery slope that can down the vehicle for quite some time waiting on a machine shop to be available.

 

At this point I would only do what I could w/the engine in place. Our summers are fleeting here in Cheese Head Land, so anything major would wait until the snow flies.

 

Oh boy howdy. Even if things look reasonably acceptable, mission creep will set in.
Gee that main looks a bit worn, should replace them.
Might as well do the rods while I'm in here.
Well, got the crank loose, might pop the head and hone the cylinders
Gotta toss a set of rings on now that the pistons are out.
Might as well do the valves while the head is off.
Well hell, lets toss an oil pump on there.

And the snowball gets bigger and bigger.

 

My Dad always said 'If it ain't broke, don't fix it," especially in regard to vintage vehicles.

 

You just can't please everyone. You try to keep the mosquitoes off them and get no thanks.

 

The very point that I made at the time...