Tennesseestorm

My dad has a '94 Toyota 4x4 with the 4-cyl. It has 293K miles, but the engine was supposedly rebuilt 40K miles ago. Well today he put on a new valve cover gasket and while the cover was off, was looking at the chain. It was taking a tool and was able to move it a great down on down the chain. We are wondering if this was overlooked or if this was even rebuilt at all. I cannot imagine rebuilding the engine at 250K and not replacing the chain while in there.

Is it a crazy job replacing the chains in these? I am assuming these are "interference" engines and when it goes, will bend the valves?

Thanks.

wyoming9

iTrader: (1)

That is about the best way to check is with the valve cover off and look more at the guides then the chain.

It is not hard in a technical way just takes some time.

Some try without removing the head with a good chance at having oil leaks.

Just how much play was it both sides or just the left??

DeclansDaddy

I just did my chain in my 86 22re (which is the same process as yours) without pulling the head and had no problems. I did remove the pan which I would suggest doing. I have no oil leaks at all but I could see how some could have problems at the corners but taking a little time and care and you'll be fine. Also pulling the pan lets you make sure there is nothing weird going on. My guides were still intact but sure enough there was a pile of plastic pieces sitting in my base pan from a previous guide breaking and a PO said F-it on pulling the pan. Probably because with a 4WD the front diff must be removed to remove the pan, just so happens I was lifting the truck at the same time so my diff was already out. I did one when I was 17 with very little mechanical experience and a Haynes manual and it went smooth so I believe anyone who has turned a few wrenches can do it.

wyoming9

iTrader: (1)

That is one of those things if I do the timing chain and all new front parts it is getting a head gasket as well.

Besides pulling the oil pan to me is way more work.

To each there own.

highonpottery

iTrader: (1)

kinda have to pull the oil pan off to remove the bits if you look down your tchain cover and don't see the chain guides anymore

having once done a tchain in the truck without removing the head (valve cover and oil pan removed) I would suggest you take the head off and do it all, it will be easier and less likely to mess up in the end. it was not an easy task getting that tcover back in there with a perfectly horizontal motion so you don't mess up the front crank seal or bunch up the exposed section of head gasket that overhangs where the tcover goes, and before your FIPG/RTV starts setting up. mine ended up bunching the HG and of course resulted in an oil seep there, yay

DeclansDaddy

Guess I was just one of the lucky ones. I did it head on and the front of my engine is dry as a bone. But I do agree that even if you pull the head, pulling the pan is a must. Even if your guides are intact, so were mine but yet my pickup screen was clogged with mangled up plastic from some time in the past. I know this motor was rebuilt so if the guides are there than more than likely the pan is empty but now we wonder how rebuilt it really is. Timing chain in a rebuilt motor shouldn't have slack. Now I have a 4" bracket lift on my truck so dropping the pan is easy. Guess that's one advantage of a bracket lift.

bswarm

If I'm not mistaken the timing chain tensioner is operated by oil pressure. So with the engine off there may be slack in the chain.

JJ'89

As mentioned the chain tensioner needs oil pressure to take out the slack. The chain may seem slack at rest. 293K miles its virtually inpossible that the timing chain job has not been done at least once already. A "rebuild" that's done right would have new chain, sprocket, guides, tensioner, and maybe oil pump. You can hear the rattle from missing chain guides especially when first started. With the valve cover off, look down the driver side of the chain at the wall of the cover. You might see a couple of grooves. Mine had 1/8" deep grooves at 150,000 miles. Eventually it will cut through to coolant and that's the end of the bearings shortly.

Not a bad job, the worst part for me was getting stuff disconnected and parts and surfaces cleaned up b4 reassembly. I didn't have to remove the head or pan. There a couple of links to do-it-urself with pix that I used. I didn't worry about debris in the pan, and 25,000 miles later no problem. I used a Rockauto timing set and new cover, no problem, but if doing it again or next time I'll use Toyota parts.

highonpottery

iTrader: (1)

^not necessarily true ... my dad bought new, an 85 22re pickup and it went 350k with only regular maintenance and one clutch job. Truck threw a rod a week after buying a new bigger truck in 1999.

JJ'89

Interesting case...

More info from wikipedia:

"Toyota swapped the dual-row timing chain used in older engines for a single-row chain with plastic guides in 1983. This system reduced drag on the engine, but is occasionally problematic. Every 80,000 to 140,000 miles, the chain will sometimes stretch to the point that the hydraulic-operated chain tensioner cannot take up any more slack. When this happens, the timing chain impacts the solid-plastic driver's side chain guide, breaking it within a few hundred miles of driving and creating a noticeable chattering sound in the front of the engine, especially when cold. If the engine continues to be operated after the guide breaks, the chain will stretch rapidly (an unfortunate characteristic of single row chains). The loose chain will cause inaccurate ignition timing, which usually results in noticeably rough running. In continued operation, the chain can jump a tooth on the drive sprocket or break entirely, with either case resulting in engine damage from valve/piston collisions. Also, the stretched chain will slap against the side of the timing cover, due to the broken guide, wear through the cover and into the coolant passage behind the water pump. This will cause coolant to drain into the crankcase/oil pan, possibly causing damage to internal engine components such as bearings, crankshaft and valve train, as well as damage caused by overheating due to the lack of coolant (since it has drained into the engine oil). The condition can also render a misdiagnosis of a head gasket failure when, in fact, the head gasket may still be good. The best fix is to buy an aftermarket timing-chain kit (with steel-backed guides) and a new timing cover; 'patching' the hole in a worn timing cover is strongly discouraged."

I think 22Re is double-row chain; my '89 is...

wikipedia: for what its worth...

My $0.02