Hilux81

I have a '81/'82 4WD Toyota Pickup (Gas). The engine and some other parts are from an '82. I am by no means a mechanic, but I've owned this truck for over 10 years now and have done a lot of work on it. This is the first time I've haven't been able to fix something. Any advice or suggestions on this would be appreciated.

I noticed a rattling noise coming from the engine, at first very mild but after a week or two it grew to be loud. It was a metallic noise like metal on metal slapping that was loudest at startup and seemed to get faster/more steady with the increase of rpm but faded away once the engine hit 2000 - 2500 rpm.

I removed the valve cover to take a quick look down at the timing chain and guides and noticed the two bolts holding the drivers side guide were worn almost have way through on the chain side. I assumed the chain had stretched and was making the noise. So I picked up a new dual timing chain and assembly(sprockets, guides, tensioner, gaskets) from ENGNBLDR and got some advice from the guy there.

I then installed the new timing chain with the FSM making sure to mark all the timing chain cover bolts so they go back into the correct spot. I double checked the bolt that goes through the oil pump that it wasn't too long and hitting the chain tensioner. Torqued everything to spec and put it all back together. Engine started first try but after about 30sec of running it seemed like the chain skipped or something happened and the same noise came back with the same symptoms... noise started to fade out past 2000 - 2500rpm. I adjusted the timing and tried it slightly advanced and slightly retarded but didn't affect the noise.

I noticed a few things when the engine was apart. The timing chain cover had some wear marks around the bottom of where the crankshaft sprocket was (looked like the chain was slapping a bit). I measured the old chain(I don't have a caliper, I used a ruler for rough length) and 17 links measured approx 147mm. So didn't seem like it had stretched too much. The old guides and tensioner didn't look to have excessive wear either.

I assumed I had done something wrong when installing the timing chain so I took it apart, looked over everything and installed it again with fresh gaskets. The same thing happened, started first try and then shortly after the noise started. So I got some advice from a professional and then pulled it apart again. Everything looked to be in order, so I put it back together. This time putting the passenger side guide on using the extra bolt hole for the top bolt, pushing the guide in towards the chain making it tighter. But same thing happened when I started it.. can't seem to get rid of the noise.

Could the new tensioner be faulty? Is there a way to test the tensioner? Probably easier to just get a new one?

Could it be the valves? I did a rough cold measurement with a feeler gauge and they looked to be fine.

About six months before this I put in a new oil pump seal, water pump and thermostat. I regularly check and change the fluids. Not sure if any of this could have had an effect on the timing chain.

Yotafarts89

When I read your post I instantly felt for your brother. So I also replaced my timing chain about 2 months ago from engnbldr. I did not do the duel timing kit but rather the single. Either way everything installed perfectly and ran like a dream for about a month until I also started hearing a rattling metal sound over the course of a few days. I pulled the valve cover thinking it was the valves. Checked the valve clearance but she still was rattling. It was not a catastrophic rattle but still I noticed it. Then two days ago I heard one loud rattle and the 4runner died. Had it towed home. Got it to start again but loud loud rattle. Checked the timing and it was 5 degrees btdc so the timing didn't jump. Again pulled the valve cover and noticed the chain was loose on the drivers side when I flicked it with a flat head screwdriver. I instantly though the tensioner must be wonky. I tore it down literally hours ago from writing this and sure enough the tensioner failed. Engnbldr said its a life time warranty so I boxed it up and its in the mail already back to them. Bummed I'm out the time and extra money other expenses not covered in warranty that will need to be done to redo the timing chain but it is what it is. This is the only issue I've ever had with them and their knowledge is second to none. Bummed either way. Check out this video I made earlier today. Your not alone buddy!!!

gillesdetrail

iTrader: (1)

I replaced my timing chain tensioner last summer but did not pay attention to the torque specs, it always rattled for a couple of seconds at startup, after some research apparently the torque on that tensioner is important for it to function properly. I don't remember the specs but in the video posted above it says 12 lbs-ft. Did you replace the guides as well or did they not look worn?

Hilux81

Yes, I replaced the timing chain, tensioner, sprockets and guides even though the old guides and tensioner didn't look overly worn. I torqued the tensioner bolts to FSM specs, pretty sure it was 12lbs-ft. I did notice that the metal plug on the back of the new tensioner wasn't air tight. Once it was covered in oil and you compressed the tensioner in your hand you could see air bubbles coming from around the metal plug on the back. Not sure if this is normal?

My tensioner was acting the same as the one in the video above, but I was under the impression that the tensioner is powered by oil pressure. So it wouldn't have much effect on the chain until the motor is running and oil pressure has built up. But either way looks like I should order a new tensioner just in case.

engnbldr

Hi, troops. Been awhile since I have been by, got directed here with a customer concern.
Over the years I have had some "defective" tensioners in my hands. Now other than one with a couple of hundred K on them and worn out, I will say at this point that I have never seen a "defective" one, other than some we had 10 years ago with the mounting pin too large. Those got gathered up and sent back, just 3 got shipped before we discovered that.

The tensioner is just a shock absorber, all there is to it. There is a spring that holds the arm out when the engine is shut off, it's ONLY function. During operation, it fills with oil, continuously, and the bleedoff hole is so small there is not time for the arm to retract. A shock absorber action is internal, the tensioner action is of course external but the principal is the same. So, there is nothing to even BE "defective." This means something else is happening.

Over torqueing the tiny tensioner body is one sure way to stop the arm.

What usually happens is a tiny bit of debris, like metal particles from previous wear, (Like the metal shavings off the previous bolts that were worn) or from the engine block machining process get in there. The clearance at the tensioner shaft is measured in the 10 thousandths of an inch. So, a few bits of metal, carbon, swarf get in there, the arm sticks, and presto!

"Defective tensioner". We see this in perhaps one out of several hundred sales or so, I have opened them up when returned to check and this is what I find most of the time. Easy to see from the small scarring on the tensioner shaft.
Or we find them that operate with zero resistance, checking the oil inlet we find bits of silicone or sealer plugging them.

Since we supply somewhere in the area of a few thousand of these kits every year, it really isn't a problem unless it happens to you. Then it's a PIA, I agree. Our answer is to replace the rare problem and hopefully that works.

Just MHO,
*EB

Yotafarts89

And let me tell you this. My original plastic timing chain guide literally blew up into a million pieces so if tiny debris can clog a passage then I can imagine that being the case 100%

engnbldr

Here is another classic example of what I mentioned earlier. The tensioner body must fill with oil, unless it does, it cannot maintain tension. It works because the oil in the chamber cannot be pressed out by chain loading and unloading which is what happens with any vertical cylinder design engine. The operation is simply too rapid for there to be time to expel it.
Now IF this example did have the chamber oil filled, it could not be pressed back.
Without oil pressure filling it, it takes a LOT of effort to press the plunger back. Clearly, no oil inside of it.
Sort of like the other user who mentioned working the arm back and forth creates bubbles? Of course! Operating it without being oil filled draws air inside, pressing it back expels the air, thus, a bit of oil residue creates bubbling.
That would be normal.
*EB