?Engine Rattle

[IDave]

Driving home last night and today on a prolonged trip, I have noticed an intermittant rattle that seems to be coming from the engine (F) on my FJ40. It starts suddenly as I am driving along, and if I back off the accellerator and reapply the gas, it is gone. It just lasts a few seconds, and it has so far just seemed to happen while I am driving, except briefly last night before I parked the rig.

I keep thinking it might be a loose valve. It isn't what I would call a knock, and I don't think it is pinging, either, because I have heard that (and I retarded the dizzy a little, since I was at lower than home elevations, just to see if it would go away, but it didn't).

Before I dig in myself, does anyone have an "a-hah" for me on this?

 

[Romer]

Don't know if this will help you Dave, but on my GMC I have had a similar thing. It doesn't impact performance, can't hear it at idle, only happens after you first start driving. I am convinced its in my exhaust system somewhere.

Could it be in the exhaust manifold where that (I forget what it is called) flap shifts based on the engine being warm?

Probably not much help, but since nobody else replied . . . . . .

Ken

 

[IDave]

You mean the heatriser flap? Ok, Ken, I'll check that. I guess it could be loose. Thanks.

 

[Romer]

yeah thats it! Yesterday I could have told you. It's a bitch that you know you know the name of something and you just can't pull it out of your brain. It's a pain to get old.

Good luck Dave

 

[ken_79-fj40]

I had something similiar to this on my 2f. It would come and go with throttle application, I wasn't sure what it was. I was 60 miles from home and continued driving, it got more constant right before I got home. Turned out my harmonic balancer was about to fall off. I tightened it up and it's still a little wobbly, but I haven't had any problems since.

 

[IDave]

Were you able to grab it and wiggle it without removing the fan belt?

 

[65swb45]

Were you able to grab it and wiggle it without removing the fan belt?

On yours Dave, if the fan moves, you've got problems. I had a customer with this one come in on a 74. Definitely a knock tho. You would only hear it when you shut the truck off.

I have heard intermittent noises like you describe that turned out to be hairline cracks in the inner fender skirt[next to the frame brace] and the splash shields around the engine.

Mark

 

[Landpimp]

buddy told me one, dude had a Vette and was chasing down a rattle...............turns out someone left a screw driver in the intake!

 

[ken_79-fj40]

Were you able to grab it and wiggle it without removing the fan belt?

No, I had to remove the belt to really see how loose it was. I still don't see how it ever came loose.

 

[IDave]

Well, I retorqued the head bolts (which was overdue from my head rebuild) and retorqued the rocker arm stand bolts, and reset the valve lashes (which in fact had changed a bit). I replaced and tightened the manifold/downpipe bolts, one of which was totally missing. I checked the water pump and harmonic balancer, which did not wobble.

But the thing that seemed to make the rattle go away was replacing the 4 quarts of oil that were apparently missing (don't know where they went! no puddles). Maybe a new leak at the front end (front seal or oil pan gasket).

Then, I heard the rattle on acceleration (barely, not loud like it was) until the engine warmed up this morning. So, I still don't know.