1959 Cj5 F134 Engine Knock

Howdy!

I recently purchased my 1959 CJ5 (below), but am running into some motor issues. Unfortunately I don't have the time to completely diagnose and rebuild, so I'm looking for some suggestions on sending the motor out to get rebuilt/repaired.
A little history on what happen...Cruising down the road (with a big a** grin of course) everything seemed to be running fine, oil pressure was between 40-60, and she started loosing power. Got to the top of a small hill (1-2% grade) and the motor cut out. Got to the side of the road, checked a few things and she fired right back up (but only on choke). Thought maybe it was bad fuel so I started going again hoping it would clear up...well that didn't happen. Started knocking, so I pulled over right away and shut er' down so I could tow it back. Oil pressure and temp still normal, will start with a little choke love, but still has a knock. The guy I purchased from had done the following:
Piston Rings
Timing Gear
Replaced all gaskets/seals
new points and condesor
New plugs
Carb kit
New water pump

Anyone have anything similar, or have any recommendations? I'm going to dig into this more tonight when I get home and hopefully find this is an easy fix, otherwise I'll be needing suggestions on who and where to send the motor out to get rebuilt.

New to this thread (sorry if this topic has already been posted) as well as new to the Jeep community. Have wanted an old Willy's since my grandpa showed me the picture of him driving one in WWII!

 

I had a 59 fhead that rarely but sometimes made a horrible knocking noise that to me mine sounded like the rockers possibly not getting enough oil but I never diagnosed it and soon replaced the motor. I would go months without hearing it, then hear it for about 3 minutes and then not hear it again for months.

If it were the rockers I wonder if you could hear the knocking, quickly pop off the top rocker cover, spray it with wd40 real good, put the cover back on and fire it up and see if it's gone

 

Since it happened with power loss on a hill it may be as simple as detonation from the timing being too far advanced.

Is the knock under load, upon deceleration, low pitch/high pitch? At high speed, or low speed? When stationary? A Rap, or a Rumble?

How fast were you cruising? F-heads over-rev very quickly to someone used to modern cars, 50mph is fast.


Try a stethoscope,or a dowel to your ear, touching the engine, see if you can localize the sound - at the top end, bottom end, front, rear, or whatever.

Oil pressure being "still normal" suggests maybe it's not a total disaster. Unless PO filled it with 90-weight to cover up a bad engine…

 

Thanks for the quick responses!
Fired er' up when I got home from work and guess what...no tick!...well for about 30 seconds. Now the tick is intermittent, which is definitely making me lean towards distributor/timing issue.

The knock is at all speeds, high pitch and I would call it a rap....I was rolling down the road around 45mph (guessing by the line of cars I had behind me).

I will check the timing, but I'm curious if switching to an electric ignition is worth considering?

Thanks

 

Great looking Jeep by the way.

 

I think I am seeing sticky valves much more often these days, maybe since various additives have been removed from oil and fuel.

That might mesh with the noise developing as it warms up.

"I'm curious if switching to an electric ignition is worth considering?"
That is a whole debate in itself, but don't start changing stuff at random, and adding new variables, until you diagnose the initial problem.

 

Try to fix one thing at a time. Hold off on any ignition changes until you figure out what is going on. Fuel filter is always a cheap good start since you lost power. Double check the points, and for any play in the distributor. Since you just bought it, might be a good idea to change the oil with some 15-40w to rule out any PO shenanigans.

 

Thanks for all the advice! I took a step back and made sure to focus on one thing at a time last night.
I checked the distributor cap and confirmed it is not lose, everything seems to be functioning as it should.

Grabbing a compression tester from my buddy on my way home tonight as well as some fresh oil.

Is it recommended to throw seafoam in these little motors to help with releasing a sticky valve? As far as fuel goes...I do have access to 91 octane clear leaded fuel, would this be recommended over 87 unleaded?

Thanks

 

Cranking Compression should be about 90-110 lbs.....................Have you adjusted or checked your valve lash.......those should be solid tappets and if loose will get you the ticking noise in the valve train and if too loose will also effect the power. I would check that before you run a compression test.

You first mentioned that the PO replaced rings? Did he also replace Pistons? The knock as it warms up could be a piston or skirt that is loose in the cylinder.............

 

Tarry, just wondering where you got those cranking compression figures. Everything I have read puts the F-134 at 120-130 psig. Not trying to start a battle. I just wonder if what I have was wrong. After I got done with my engine and did a little run-in time on it, i was getting around 128 psig per cylinder. I did not shave the head, but maybe a PO did at one time. That is why I am asking.

Thanks...

 

Just me, but I'm happy to see anything over 100, on older f-heads.

 

Just from my notes...........Average................depends wet or dry hot or cold and how many revolutions you turn it over , also make sure your throttle blade is wide open.........I have read the same thing 120-130 lbs but at 6.9:1 static compression ratio .............I agree with Pete , anything over 100 -110 would be fine.

 

Good news..I've narrowed it down to what the issue is, bad news...it's a crank bearing. Throwing it on the lift tonight to pull the pan and inspect further...see if it is repairable without pulling the motor or not.
Thanks for all the tips and direction...I was really hoping it was going to be a simple loose distributor.

 

That is sad. A main bearing normally won't knock so it appears the PO was aware of the rod bearing problem when he did the re-ring.. Just saying....

 

Main or rod?

Sometimes if the journal is still relatively okay, an undersize bearing shell can be fitted to get you by.

It's not totally crazy. In the olden days, I even have had rod journals re-conditioned without tearing down the engine. There was a hand tool to do it with the oil pan off.

The recent top-end rebuild may well have increased stress on the bottom end. It was traditionally always advised to do both together. A high speed run would be enough to expose the loose bearings. BTDT.