4th gear & under load, feels like the 2F's binding (1 Viewer)

[GA Architect]

For the past few weeks, my '77 FJ40 has started to feel like it is binding when under load in 4th gear. The first time I noticed it, I was in 4th gear going up a hill, but not at a severe grade. I could feel a slight vibration/loss or power/binding-up and then a subdued pop from under the hood. I was able to coast to a subdivision and pull over. I left my rig running, got out and smelled a little burnt rubber, but the engine was idling just fine. So I got back in and drove on to work with no issues. Checked here on MUD, and seems the pop & burnt rubber was from when my fan belt slipped. So no worries, I tightened the belts when I got home. But it has done it (vibration/binding/fan belt pop) again a few times, all while going up other longer grades, so I figured it was the thin belt that was running my aftermarket A/C compressor.

Last night I installed a wider NAPA 25-22508 and bypassed the A/C compressor. This morning, while driving to work and going up the same hill, my rig seemed to have the same slight vibration and felt like the engine was bind-up under load, but no "subdued pop" this time. I down shifted to 3rd and it still felt like it was binding, but made it up the hill and on to work....After searching here, not sure what to check.

I don't think it is in the drivetrain, but not sure. My rig does have a 2-1/2" OME lift with 33" tires along with mini-truck power steering box with saginaw pump installed last Spring. Drive shaft is tight, no up/down or side to side movement, and it is in phase. Oh, has the original 2F engine in it as well.

In 4th gear on a level grade, no issues....In 4th gear going uphill on a longer grade, issues.

Any suggestions/information would be greatly appreciated. (Note, my rig is desmogged)

 

[pb4ugo]

Maybe look for a vacum leak & check your timing. Are you sure the pop wasn't a small backfire thru the carb?

 

[shelfboy1]

timing ,fuel pressure ,bad coil,bad fuel ,just a start good luck

 

[GA Architect]

Maybe look for a vacum leak & check your timing. Are you sure the pop wasn't a small backfire thru the carb?

Interesting you mentioned about backfire thru the carb as the "pop" I heard. Thought that was it the first time it happened, and maybe it was, but the burnt rubber smell seemed to point towards the fan belt. I'll check for vacuum leaks. I did have the exhaust & intake mani's decked back in May........(Seems as though, after rereading and thinking thru this, I would guess a vacuum leak while being under stress, would cause the turbulence in the engine. Possibly?)

On Wednesday, drove it to work and when I got home, I noticed the oil cap askew. Wasn't the first time that happened. And when it happened a month or so ago, I just figured I didn't put the cap on right. I checked the PVC, it seems good. So there is pressure getting into my valve cover.....I know that is not good.

FWIW - I have an '86 being tore down for rebuild as of Tuesday morning. All thanks to a MUD member from Utah.....Just haven't posted it up on my build thread yet. I'm waiting to get the '86 2F engine block diagnosis and approval back from the machine shop.

 

[GA Architect]

timing ,fuel pressure ,bad coil,bad fuel ,just a start good luck

Timing - I'll check that.
Fuel pressure - checked the carb and it had fuel after the "pop" sound.
Bad Coil - I'll check that.
Bad fuel - Several fill ups in between the pops, and at different stations, so don't think that is it...but could be?

 

[Fast Eddy]

the burnt rubber smell seemed to point towards the fan belt.

Seems like it could be two different problems.

 

[GA Architect]

Seems like it could be two different problems.

Maybe one caused the other?

 

[White Stripe]

I would check your timing first. Even then, its possible somehow your advance is not working correctly and screwing up the timing under load. Maybe try driving it with the advance unplugged.

 

[GA Architect]

I would check your timing first. Even then, its possible somehow your advance is not working correctly and screwing up the timing under load. Maybe try driving it with the advance unplugged.

One thing I haven't messed with...the dizzy. I'll put my light on it to see what its got, plug the EGR cut valve and give it a drive.

 

[TheHardWay]

Oh, forgot to mention, my 40 is desmogged.

Nah, you mentioned it in the original post

 

[White Stripe]

Dont forget to plug the advance hose if you unplug it so you don't have a vacuum leak.

 

[GA Architect]

Dont forget to plug the advance hose if you unplug it so you don't have a vacuum leak.

Yes, I'll cap the EGR cut port at the carb and the port on the dizzy.

Sprayed carb cleaner around the manifolds and carb, no change in RPM's.

Ok, now for something I haven't done yet, timing. I have a light with a dial on back, I'll read and figure out exactly how that works.

 

[78fj40mg]

Your problem sounds like fuel starvation under heavy load, I would definitely replace the fuel filter and check the fuel pump.

 

[GA Architect]

Your problem sounds like fuel starvation under heavy load, I would definitely replace the fuel filter and check the fuel pump.

I thought the same thing, but pulled over and saw the sight glass half full. Installed an OEM fuel filter back with the new fuel tank installation back in July. But won't rule it out the "starvation under heavy load" scenario.

 

[Bones]

not to hi jack, but i am curious about the oil cap askewed. i have noticed mine doing the same thing when i drive it under load. i don't have any of the other issues you are having though. i cant seem to figure out why i am having increase pressure in my valve cover. PVC is new and functioning as far as i can tell.

i am desmogged and running a weber carb with HEI.

 

[78fj40mg]

The site glass maybe perfect at idle but low under load.

 

[GA Architect]

not to hi jack, but i am curious about the oil cap askewed. i have noticed mine doing the same thing when i drive it under load. i don't have any of the other issues you are having though. i cant seem to figure out why i am having increase pressure in my valve cover. PVC is new and functioning as far as i can tell.

i am desmogged and running a weber carb with HEI.

Oil cap skewed - Being that the valve cover is vented to the air cleaner with a 1/2" line, I would think that there to be a minor vacuum at the oil cap. At the least, if there was any pressure inside the valve cover, it would be released/vented to the 1/2" line to the carb?.....

I read a funny about where Mark A. had a client that kept having her oil cap blow off. After the third one he installed, he put a chain on it.

 

[GA Architect]

The site glass maybe perfect at idle but low under load.

Thanks....carb was rebuilt just a few months ago, and that original Aisan was done by a professional.

If it happens again. I'll quickly shut the rig off, safely coast to a stop and check the site glass.

 

[Solace in Solitude]

GA ...as Jim told me... "When it occurs, turn the key off, throw it in neutral and coast to a safe place to park. That sequence will leave the sight glass exactly as it was when the problem occurs".

As usual, he was correct.

If you haven't followed that sequence, the sight glass level could change just because you came to a stop with the engine still running, e.g. No longer under load.

HTH

 

[GA Architect]

No vacuum leaks at idle.
Coil checks out.

Tomorrow, I'll venture out and learn about timing.

Side note. Checked the spark plugs....2 thru 5 look just like the manual says they should, a grayish tan color. However, 1 and 6, not so good. Those are brown on one side and black on the other. Also, those plugs aren't totally wet, but the threads aren't dry either....I'll throw a new set on tomorrow and see how it runs.