Question about 22RE and broken timing chain

I should add that I pulled the chain cover without removing the head . . . I wonder if a compression test would be diagnostic?

Scotty I assume you only replaced the chain,guides and cover? if so your timing chain tensioner could be worn,read below for full details & do a leak down test to see if you bent the valves but I suggest you remove the head for full inspection and to prevent headgasket leakage in future:

Most engine wear on any engine occurs at startup with that said the R series Toyota engines such as the 18R,20R and 22R all use a timing chain which it's tension is supplied by hydraulically driven timing chain tensioner which has it's oil pressure build up few seconds after the engine has started therefore the timing chain rubs on the driver's side brown colored nylon/plastic timing chain dampener or guide and after so many miles (140-170 000 miles in the city with the average 4 starts per day) the driver's side guide breaks through causing the chain to rub on the timing chain cover for the first few seconds upon startup and when driving in 5th gear and letting off the gas.

Usually by this point the other timing components such as the camshaft sprocket,crankshaft sprocket and chain have their specs out of tolerance and hence must be replaced as well.The tensioner sometimes sticks due to dirt build up and other problems arise as well and must be replaced as well,all of those parts are sold in the aftermarket world as a "timing chain kit" which also include gaskets and a front oil crankshaft seal.Toyota on the other hand for some reason does not sell the parts as a kit but as individual parts which would cost around $400+ and from all of the reading I have done on many Toyota

4-Runner/pickup discussion sites I have come to the conclusion that many experienced off-roaders who cannot afford to buy all of the genuine Toyota timing parts instead buy the chain and tensioner from Toyota and the other parts from aftermarket as a kit but of course don't use the aftermarket chain or tensioner.

The best brand of aftermarket timing chain parts to use on the 20R &

22R series Toyota motors are:

and if you choose to buy from Toyota these places have the best prices in the USA & probably the whole world:

(10% shipping by Fed Ex orfree shipping with $100 & over speak to Roger at 1-888-271-3948) (free shipping with $100 & up) Other ways to check timing chain wear are:

you can also remove the valve cover and take a flashlight and see if the driver's side timing chain dampener or guide wore through.

You can bend 1 to all 8 valves and have timing cover eaten through if you wait and then coolant and oil mix together to give you butterflies in your stomach.You can do a fluid analysis on your engine oil by going to any Caterpillar and buying a fluid analysis kit for around $15-20 and taking a sample of your old oil.

Finally these sites explain the timing chain replacement well:

Sidney=AE =99 Repairs tv's,vcr's,home/car audio out of my home E-mail: snipped-for-privacy@yahoo.com Dartmouth,Nova Scotia Canada

1985 Toyota 4-Runner,solid front straight axle,factory cruise control,sunroof,22R-E,W56,RN60LV-MSEK,rusted rear step/towing chrome bumper with 251 000 KM

Hi Sidney,

Thanks for the great info! I was just deciding to replace the chain with a Genuine part as opposed to a mystery brand: I'll assume the higher price will assure longer life! Anyhow, I'll check into the links you provided.

As for the tensioner, I previously installed an aftermarket kit, and I believe it included all parts. (The guide had worn out, and the chain worked throught the housing, so I ended up replacing the cover and all other parts. Since all parts were changed about 30k miles ago, I was suprised to have the chain break last week!)

To clarify, is it your opinion that valves get bent EVERY time a chain breaks, even if it happened at startup and ran at low rpm for literally

1 second?

Thanks again,

Scott

Scotty,

The 22RE is an interference engine, meaning that if valve timing is interrupted the pistons hit the valves.

Let's say that your idle speed is ~700 rpm. That's about 12 revolutions per second. So for that one second, each open valve will have taken 24 separate hits from its respective piston.

Now, you might have gotten lucky and the cam stopped turning at such a position that no valve extended far enough into any of the combustion chambers to be hit by a piston.

So, cross your fingers, knock wood, rub that lucky rabbits foot, and do a leakdown test as Sidney suggests. You may find that you're the recipient of karma from leading a good and virtuous life. Be prepared to send the head to a machine shop, though.

-- Mike Harris Austin, TX

Hi Mike,

Thanks for the reply. I called a shop today and the guy said I most likely have some valve damage. However, he DID say the rocker arms would/should have extra play if the valves were bent. At first wiggle, the rockers seem about normal. Fingers crossed . . .

Scott

The 22RE is a non-interference engine. It's unlikely you have any valve damage.

Q

Scotty wrote:

This may be of interest to you.................... particularly the reference to interference versus non - interference bit in the first link.

That is incorrect, sir.

My understanding is that some - not all - of the earliest 22R series from the '70s were (barely) non-interference. They had low compression heads and notched pistons. By the time the E series came out they were most definitely interference engines.

Unless you find yourself with a NOS early series block or the PO deliberately overhauled it with low compression (either a purist, or with the intent of adding a turbo or supercharger), chances are that even an early engine would have been rebuilt using higher compression heads and/or pistons from a later model.

-- Mike Harris Austin, TX

I can attest from personal experience 81 22R THE valves can get bent, you may be lucky since it happend when trying to start it. DO a leak down test or temp install the new chain & do a compression test

Quite often one of the valves gets bent when the rocker arms get torqued down.

Thought I'd offer an update on my broken timing chain. I decided to order replacement parts (Toyota), and replace the chain without tearing into the head. (Hoping I lucked out and didn't ruin a valve when the chain broke) I finished up last night, and . . . it runs like crap: Barely idles, no accelleration, and smelly exhaust. I did a compression test this afternoon, and found the following (after 4 cranks):

1 -155 2 - 120 3 - 150 4 - 152

First crank yields 90 pounds for all cylinders. When I repeat with a squirt of oil, all cylinders gain about 30 pounds.

So, does #2 suggest a tweaked valve, or did I simply screw up my timing when I re-assembled with new parts?

Thanks,

Scott

Sounds like you didnt get your timming quite right. Your compression readings are only really good with a warm motor.

Scotty (the other one)

Thanks for the reply; I'll inspect my chain and TDC settings tonight. I was sure I had it right the first time, but it runs so badly that it has to be more than a busted valve or two!

Cheers,

Scott

Yep, I failed to sync the distributor gear properly with the cam gear: runs fine now! ;>)

As for "broken chain" = "busted valves", not true in this case. I noticed when I began the repair that the chain had wedged, freezing the cam sprocket into the 10 'o clock position. Since it broke instantaneously when I tried starting the engine, I hoped that this meant no valves were stuck out as the pistons cycled. Looks like that was the case!

Thanks for all the help,

Scott

Now its able to get to full running temp have you done another compression test yet?

Yes, it looks good when tested at higher temp. And the oil added to the cylinders during the test made a lot of smoke, which made apparent an exhaust leak at the manifold/head area: turns out one of the stud bolts is broken off. Don't look forward to extracting the sheared remains . . .

Scott