My "new" hunting rig, 1993 Toyota pickup

[dorton]

The bumper looks great on there. Keep us updated on the build.

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[DaveInDenver]

Metal timing chain guides are definately on the short list of things I am going to proactively replace

I'm not a fan of DOA guides. I never heard back from them about my lifetime warranty, either.

My set after 45,000 miles.




My original OEM guides were fine at 125K (still have them too) but I replaced them following the Internet wisdom of plastic = junk, metal = awesome. I went back to the Mother Ship, the OEM set I put in during the rebuild have gone 60K already.

Toyota used to use metal guides with the 20R and its double row (some 22R guides are 20R guides that have been machined down). Toyota does not change things randomly. I think when they went to a single row chain they designed the guides to absorb some vibration (metal guides are noticeably noisier) and be the part that breaks first (single row chains definitely need replacement much sooner), the fuse it you will. The original parts rarely disintegrate all at once, but rather fracture, giving you time to fix them. You do your valve lash adjustments when the book says, right?

If you follow the recommended intervals WITH OEM PARTS, the guides are not a problem. That's critical IMVHO, since aftermarket guides and tensioners are generally what fail early. Use Toyota boxed or OSK guides and tensioner only. The parts will be made in Japan and Japan only, otherwise you not getting the correct ones. I cannot stress the importance of this, especially with the tensioner.

Not to mention the rubber on these guides was already hard and cracked, which is part of the reason I think they fatigued and broke. There was nothing damping the vibrations. If you do really want metal backed guides, I'd only consider the double row conversion, again using factory parts only.

[1911]

Hmmm... my experience was just about 180 degrees from yours Dave; original factory guides broke and the chain sawed through my timing cover, no notice or warning and the engine continued to run great until the coolant and crankcase oil mixed. And I kept my valves adjusted too. My D.O.A. guides lasted at least 100,000 miles, after which I sold that truck. Put the D.O.A. guides in Ross's truck too when he did his top-end re-build. (shrug). You may be right; I am a big believer in OEM Toyota/Aisin/Denso parts probably 99% of the time.

[DaveInDenver]

I should be clear, that I have two issues.

One is the tensioner I used was not OSK (it came with the DOA timing kit). It is paramount that the tensioner work smoothly and reliably (particularly at start-up) otherwise nothing will last long in this application. And not just OSK (or Toyota), but OSK that is made in Japan and has the hardened chrome finish on the piston.

Second was that I never heard back from DOA about addressing my guides.

So metal guides might be fine in concept but my experience with them was terrible. I had less warning on impending failure than had the guides just crumbled into the oil pan and let the chain slap the timing cover. At least in that case you have a couple of minutes to shut it down. My failure was instantaneous in the middle of an intersection and resulted in piston/valve interference since the snapped piece wrapped around with the chain and lodged onto the crank gear. It burst open the chain. It actually was D.O.A. :-)



Which is another reason I believe the nylon guides are not all bad, even if their failure is complete and get just a minute's warning you won't get engine seizure right away. Mixed coolant and oil will of course eventually ruin the engine. You get warning, rattling, drop in oil pressure, overheating, at least something. And in most cases you can drain the fluids, replace the timing cover and timing parts and get the engine going again. I think double row chains and metal guides are fine, but I truly believe the design Toyota used for the single row is a necessary compromise. The 3RZ guides are also nylon, although the design is different and more robust.

The reason I mentioned checking valve lash is with the valve cover off it's pretty easy to inspect the driver's side guide for cracks and signs of failure. The little guide ears on the OEM parts will usually break first and when that occurs you know you are on borrowed time.

[huntsonora]

Well, what I thought was an oil pan gasket leak is actually a timing cover leak so it will be off tomorrow and the timing chain and guides will be checked. I'm praying that the guides are still in one piece so I don't have to also drop the oil pan. Regardless, I am left with a decision to "upgrade" to metal guides or not. I was sold on making the change until I saw Dave's post about his experience. Time to do a little research I guess

Drum

[DaveInDenver]

Might be timing cover or look at the front main seal, too. This seal tends to wear a groove into the pulley that weeps oils. Sometimes just a new seal is needed or a Speedi-sleeve if the groove is deep.

Yeah, I might be the only person in Yotaland to have removed the metal guides, header, Air Lockers and crawler gears in favor of stock parts. We like it more the way Toyota built it, quiet, reliable, easy on gas.

[huntsonora]

Might be timing cover or look at the front main seal, too. This seal tends to wear a groove into the pulley that weeps oils. Sometimes just a new seal is needed or a Speedi-sleeve if the groove is deep.

Yeah, I might be the only person in Yotaland to have removed the metal guides, header, Air Lockers and crawler gears in favor of stock parts. We like it more the way Toyota built it, quiet, reliable, easy on gas.

Thanks Dave! I'll check it out for sure!

I agree with you on stock Toyota parts its just hard to believe that plastic guides could be better than metal guides but seeing yor pictures leaves me wondering