Gentleman,
After combing the archives with the search feature.....I'm stumped.

I recently rebuilt (800 miles ago) the top end of my 84 22R (carb), I installed a dual row timing chain in the process.

In the last 200 miles or so, I've developed a ticking sound coming from the front of the truck when the engine is under load (accelerating) from around 2000-3000 rpm. The sound goes away at 3000+ rpm and does'nt tick at idle.

It sounds like a valve ticking, so I adjusted the valves (for the third time since rebuild) again. The problem is I can't reproduce the sound in my driveway. The engine must be under load, i.e., accelerating from a lower speed relative to the gear the truck happens to be in with the engine at operating temp.

I've poked around the engine with my mechanics stethoscope (the best $10.00 I've spent recently) in the driveway. The valves don't make any unusual noise, same from the block, the oil pump area, water pump area, exaust manifold, etc...can't find any loose heat shields or the like. The dual row timing chain isn't rubbing on the valve cover or the base of the distributer shaft, I looked down the timing chain case, no wear on the guides that I can see with a flashlight.

I can hear the ticking sound with the stethoscope where the downpipe meets the exhaust pipe (although I believe this is just the residual sound coming from somewhere else)

I'm not finding any exhaust leaks and I pulled off the catalytic converter. Nothing loose in there, but I can't see too much daylight coming through it.

The fuel pump is sounding noisy(ticking) and the idler pulley sounds like it's worn(kind of a 'grating' noise).

Both of these sounds are barely audible to the unaided ear (in my driveway), the stethoscope allows you to hear 'under' the general 'white' noise of the engine.

I replaced the fuel filter and checked the hole at the bottom of the fuel pump for obstruction. I cut the old fuel filter in half, nothing unusual.


The sound is a distinct, sharp ticking sound, just like a loose valve, but I adjusted the valves to a 'firm' .008/.012.

The noise is making me crazy! <img src="/forums/images/graemlins/scared.gif" alt="" />


Any ideas? Fuel pump? Idler pulley? A faulty head rebuild?

I think you've located your problem... exhaust leaks are almost ventriloquist like....

<img src="/forums/images/graemlins/cheers.gif" alt="" />

This does seem the most likely explanation, however...

The 22R fuel pump can be VERY noisy. I was absolutely shocked when I replaced mine recently at how much quieter the new one is. Mine still pumped just fine, although the one way valve was shot.


I know when I had an exhaust leak, it was much much more noticeable when the truck was cold, before the metal expanded and sealed the leak somewhat.

stock87 "The 22R fuel pump can be VERY noisy. I was absolutely shocked when I replaced mine recently at how much quieter the new one is. Mine still pumped just fine, although the one way valve was shot."

stock87....Do tell, was it a ticking noise?

I'm fairly certain ,like about 90%, it's not an exhaust leak. It's always the most likely and easiest to explain. I'll go over the exhaust system again, this time without the exhaust manifold heatshield in the way.

Anyone else have any ideas?

Did you replace your valve adjustment screws when you redid the top end? They're convex shaped; when they wear a few flat spots into them, they'll get clackety too.

Yes Sir, new studs and nuts from the dealer. <img src="/forums/images/graemlins/smile.gif" alt="" />

It most certainly was a ticking noise, bordering on tapping. I don't know about yours, but when I put my hand on the pump while the truck was idling, I could actually feel the gnome on the inside hitting the metal part. That guy was pissed!

Actually the new one I can feel the tapping too, it just isn't nearly as loud. Both OEM pumps.

Well, it's not the fuel pump, I dropped in a new toyota factory fuel pump. Now I have a spare! <img src="/forums/images/graemlins/shiner.gif" alt="" />

I swear it's louder driving home at night than going to work in the day, probably just less traffic noise at night.

I am now fairly certain that I'm coming completely unglued. <img src="/forums/images/graemlins/scared.gif" alt="" />

Anyone want to crawl around on/under my truck to locate the noise? I promise I'll keep the speed down below 50mph....
<img src="/forums/images/graemlins/smile.gif" alt="" />

I've had 2 similar noises lately: First one was the number one plug unscrewed itself anough that a tapping noise was coming out the plug hole. Second was after I did the TC, etc and it turned out to be the air pump (A piece of keyway had been lodged in it and when I R&R the pump while doing the TC, it came unlodged).

Good Luck.

I finally figured it out. It was the timing. My FSM says under the "ignition system" chapter:
"ignition timing
5' BTDC at idle (950) rpm max)
(with vacuum advance cut)"
The picture next to the instructions shows a hand turning the distributer with both vacuum lines disconeccted at the distributer. I took this to mean (between the picture and instructions) that you should just disconnect, or "cut" the vacuum lines.

I was looking through the arcives about timing and saw a post about the sticker under the hood with some engine specs on it......I thought, hmmmmmmm...I've never really looked at that.

So I took a look at the sticker and it said the same as above, but in addition it says "with vacuum lines plugged"...

I guess the new (slightly retarded) cam timing since the top end rebuild was enough to make the diffrence, as I never had a problem doing it the wrong way before. <img src="/forums/images/graemlins/notooth.gif" alt="" />

I set the timing to 7' and presto! no more clicking sound at low speed on acceleration! and bottom end power! <img src="/forums/images/graemlins/shiner.gif" alt="" />