Valve tap under minor load

My 83 toyota has been running great aside from the occasional part here and there going bad. I drove it from Los Alamos to Albequerque Friday and it ran great. However once I got into town and below freeway speed I noticed some tapping. The tapping only happens when I apply minor acceleration, i.e. when I very first shift into a gear or when I'm driving around town, 35 mph or so, and don't need to have the pedal to the floor. At freeway speeds when I've gotta have the throttle all the way open just to keep up with traffic it doesn't tap, same with when I'm coasting, but when I just apply a little accelerator I get the tapping. Suggestions on what I should check/do first?

Reply to
Fowie
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If the valves need adjusting, that is an easy fix. I had an '83 and I set the valves down .002 tighter than spec, and with 0-30 synthetic oil I had no valve burning and noticeable performance boost from longer cam duration. I use the same method on the 86 fuel injected model I have now. Works great. I don't remember if fuel injection was available in the 22-R in '82, but if yours has injectors, they can sometimes be mistaken for valve noise when they get old. One thing about a Toyota cam is that they are about as hard as diamonds, and they rarely wear out. I have seen rockers wear into the rocker shaft though, and that makes a sloppy mess out of your supposed precision adjustment.

Reply to
Long Ranger

The noise you describe could be timing chain slap. The plastic guides are known to fail. They can be inspected with the valve cover removed.

Reply to
Jeff

Thanks for the tips, I'll check it out today. I lost my Haynes manual though. What are spec valve clearances for an 83 toyota, 4wd, 4 cyl.

22R carbureted engine?
Reply to
Fowie

Without looking my memory is 8-11 thousandths, exhaust and intake repectively. It is normally printed on that little picture of your vacuum lines that is pasted on the underside of the hood.

Reply to
Long Ranger

I removed the valve cover to check things out and realized my valve check gague had rusted in my toolbox. I checked the timing chain guides though and they're doing great (good thing, since I replaced the entire chain 3 years ago). Any other ideas? I've never had valve tapping so I'm just assuming that's what it is, it only happens when I mentioned it does. Even just idling it's hard to make the sound while revving the engine, it has to be put under a light load, like when you just barely push on the accelerator. If I push hard on the accelerator the tapping goes away. I've gotta make another 2 hour drive Friday and I'd rather not throw a rod or something in the middle of the New Mexico desert.

Reply to
Fowie

Could your valve cover be torqued down too much? Apparently these 22R's can have rocker arm clearance issues.

Reply to
Jeff

It's not valve noise from your description. You have a "spark knock" - most likely caused by a lasy or inoperative EGR system. Could also have carbon build-up in the engine. My bet is if you put 91 octane fuel in the noise will all but dissappear. I'd buy a can of combustion chamber cleaner and follow the instructions on the can. Get a can of BG 44K if you can find it and put the can's contents in the fuel tank.

Between the two you will remove all traces of carbon deposits from the intake and combustion chamber.

This used to be a COMMON problem on the R series Toyota engines - with the EGR and Carbon about evenly split as the cause. The carbon is the more likely cause on a vehicle that has not been driven reasonably aggressively.

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Reply to
clare at snyder dot ontario do

I suspect the problem is piston slap, not valve tapping.

Reply to
Jeff Strickland

Ding ding ding! 2000 points to the spark knock diagnoser. I disconnected plug #4 wire and the tapping went away completely. So....what's the fix for this?

Thanks for all the help from everyone.

Reply to
Fowie
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Combustion chamber cleaner and 44k for carbon deposits, and make sure the EGR is operating properly.

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Reply to
clare at snyder dot ontario do

Try techron fuel system cleaner or technron concentrate plus:

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Use NGK Iridium-IX (or Laser-Iridium with platinum ground pad) spark plugs.

And as suggested, keep the engine tuned up -- clean EGR, new PCV valve, valve clearance, the usual works.

Reply to
johngdole

I pulled the EGR valve out and it was over 50% closed up from carbon deposits. Cleaned it out really well so it was completely open and reinstalled it. The truck smoked like a mother when I started it back up--must have got some oil in the intake or maybe it was just from all the carburetor cleaner that got in there. Problem is, it's still tapping! Any other ideas? I'll check timing as soon as I get access to a timing light, but it would seem like timing would be apparent all the time, not just in the middle of acceleration and go away under load or when coasting. I checked the plugs and they all looked ok except that number 4, which is the one that seems to be causing the tapping, had a little oil residue on it, but that might have got on it when I was pulling it out of the engine, since the socket down there is a little dirty.

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Reply to
Fowie

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Have you run the combustion chamber cleaner yet?

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Reply to
clare at snyder dot ontario do

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Yes, I put in a bottle of valvoline combustion chamber cleaner (didn't have the BG44K) and got a bottle of octane booster that should have put it around 96 octane, but didn't see any improvement from that. I figured I'd keep putting in cleaners though while I'm driving it.

Reply to
Fowie

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You really need to use something like Toyota or GM's "combustion chamber cleaner" which is sprayed in through the intake with the engine at a fast idle, choking the engine off just before you empty the can. Let it sit for about 15 minutes, then start and accellerate several times - it will smoke like the dickens, but if carbon is the cause, it WILL be gone. No guesswork that way.

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Reply to
clare at snyder dot ontario do

Any idea where to buy some of that? Just from the dealer?

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Reply to
Fowie

Are you asking where you buy Seafoam combustion cleaner from Advance Auto Parts? It is sitting on the shelf about eye level at the local Advance Auto Parts. Any auto parts store should have a combustion cleaner product. The challenge with those products is getting the stuff in each cylinder. Removing heads and cleaning stuff up is a little more accurate.

On my truck a new timing chain solvd one source of ticks. A new exhaust manifold will solve another source of noises. I removed the egr and cleaned all the carbon out of it that was blocking it. I also washed and dried the filters in the black egr modulator.

My old truck also has mechanical lifters so pr>Any idea where to buy some of that? Just from the dealer?

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Reply to
Jim Behning

The dealers virtually always carry it and their prices will be competetive.

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Reply to
clare at snyder dot ontario do

Ok, washed and cleaned the EGR filters, added oil detergent, filled it up with 91 octane plus some Lucas fuel system cleaner. Warmed the truck up and poured 1/3 pint of seafoam down the carburetor. It actually didn't smoke as much as when I first cleaned the EGR lines, though it did smoke a bit. Still taps. I did the seafoam again and it smoked more, but I'm still getting the tap. Any other ideas? I'm drawing a blank.

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Reply to
Fowie

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