I pulled the valve cover off the 4Runner today. and had a look at the timing chain, and the driver's side has a ton of slop in it. I could easily take a long screwdriver and pull it 1/2" or more away from the chain guide on that side.

the bolts aren't chewed up at all....so I don't know if that was the cause....but it sure doesn't look healthy.

thoughts? that's not normal, is it?

 

They're famous for breaking the plastic guides. I would be safe and replace it.. Pony up for metal guides if you can. It probably won't jump timing but if it slaps around long enough it will wear through the timing cover into the water jackets and start dumping coolant in your oil.

 

yeah bro i'd replace it to be safe. do the metal guide kit from engnbldr.com


if it breaks or does somehow skip a tooth, it could mean major engine damage, 22res are interference engines

plus what the guy mentioned above...it could saw through the timing cover into a coolant passage, if it breaks the guide, and you don't want that....coolant in your oil. mine was almost there when i replaced it...it had already started cutting grooves into the timing cover

if its that loose, it won't be long now before it tears that plastic guide to shreds

 

so, no, that's not normal. there isn't a hydraulic tensioner or something? it's so loose, that I would have assumed to find serious damage around it. but not seeing any....I assume there's something I missed.


I've heard of the metal guides, and intend to use them if/when it comes time...I was just hoping it wasn't time yet.

 

well, yes, there is a tensioner. it's powered by oil pressure i believe. there's definitely a possibility that it died on you, leaving that slack in the chain. if that's the case, maybe it happened recently, so no damage has been done yet
i would think that if it is the tensioner, and not just a horribly stretched chain, there is more of a possibility of it skipping a tooth...this isn't based on any special knowledge or anything, just what feels like common sense to me. without the tensioner keeping up the slack, it will be loose on both sides (well, depending on whether your accelerating or coasting...if you know how all that stuff works)
get a long screwdriver or something down there and try to push the tensioner if you can. its pretty far down there and impossible to see, so good luck. i'd say that if the slack in the chain concerns you, go ahead and go for the whole deal. its only like 75 bucks shipped for the kit with steel guide (here: http://engnbldr.com/ToyotaHotLicks.htm )...if your motor's got high miles on it, theres a good chance its stretched. whatever the culprit, you should go ahead and do the thing sometime soon. how many miles on the motor? if over 100, its probably time

 

well....if it's powered by oil pressure....it wouldn't work with the motor off. would it? obviously I wasn't sticking my screwdriver down in there with the engine running. this is why I asked, like I said, with so much slop, and no damage, I was thinking there would be a tensioner of somesort that doesn't do anything with the engine off. I've been tempted to start it up with the valve cover off for a minute to see if the slop went away....but I thought I'd ask first

the PO replaced the head and turbo about 25k miles ago. I'm assuming the timing chain were new then too. the truck has about 180k on it total.

the PO is a fellow member of a local ORV club, and a very talented mechanic. so I trust it was maintained pretty well.

 

Hmm when I replaced my head gasket my chain was still very tight with the engine off.

Rob

 

i don't know the details of how the tensioner works


the bottom line is, there shouldn't be any slack, and if there is as much as you say, something is wrong. why don't you ask the previous owner? it sounds like you're still in contact with him. find out when he did the chain and ask him what is normal and what is not. that's the first thing i'd do


and don't start it with the valve cover off....boiling hot oil everywhere

 

he's in MOAB for the EJS....and won't be back for a couple weeks. I'd like to make some progress before then.


I was tempted to start it up....but I really do know better


I've been studying the FSM I have on pdf....and cannot tell how the tensioner works. but all the evidence I can find says that it's not normal....so I guess I'll take things apart and have a closer look

 

The tensioner has a spring in it, but oil pressure is the main way it works. You can see if the guide is still there by looking with a flashlight. He might have changed the head and not even taken off the timing cover, meaning that the chain could be stretched or the guide could be broken. There could also be a problem with the tensioner if it was not installed correctly. If the bolts were not torqued and are too tight then it could jam the tensioner and it would not work properly.

 

Yes you can have slack on the drivers side. That side has a set pitch between the two sprockets. If you push on the drivers side chain you will be turning the cam forward a bit causing slack. The oil pressure (on the passenger tensioner) of the engine running and the fact that the crank is pulling the chain off the cam keeps it tight on that side. If you have a diesel rattle sound then it is probebly the tensioner is gone. But don't just assume that you have a problem because you have some slack on that side with the engine stopped.
Grab the crank and turn it backwards a little bit, you will see what I mean.

 

WOW! that's EXACTLY what it has. It almost sounds like a knock, but doesn't change if you disconnect any of the plug wires, and with the hood closed, it sounds exactly like a diesel.

OK, I'm definitely pulling the chain cover now.

 

Check that plastic guide on the drivers side. They always break 1st, around the bolt on the upper side.

Next, get a factory tensioner, and be sure to torque it to EXACT specs. Overtighten it, and the tensioner will not work correctly.

 

Crap!!!! I noticed mine sounding like a diesel today. I just put the LCE header and 2.25" exhaust on. Also started the intake/battery swap today. I couldn't finish it, can't seen to mount the air filter to the AFM. Looks like there's a timing chain in my future.

 

I knew they were prone to breaking the chain guides, so I was looking for that. and it didn't look like either one was broken. but it's hard to tell from that angle. if the weather this week cooperates, I'll pull the chain cover off and have a look-see.

 

And remember, the bolt right under the timing mark tag on the cover MUST be the shortest bolt. It goes right through and will stop your tensioner from working if to long. When you have the cover off select the bolt and put it in. You will see what I mean. You can get a cheaper (price not quality) tensioner from Ted at Engbldr.com. Toyota wants $100 for them, I think ted is around $30. But some thread locker on the bolts for the tensioner and hardly tighten them. If to tight it will not work right or not very long. You might want to do the oil pump while you have it apart. Oil Presure effects the tensioner.