22R timing chain guides?

[nuclearlemon]

after talking to a toy mechanic at petersons toyota in the fort, i did clampy without pulling the pan or the head. the pan was going to be a possibility dependant on the condition of the guides, but the head is rarely pulled according to him.

once you unbolt all the front cover bolts, (including a couple going in from the backside and one under the chain under the valve cover on the head), you slide the front cover off. if damage to the head gasket occurs, then you pull the head and replace. if the guides are missing chunks (or something else appears to be missing chunks), then you pull the pan.

shortly thereafter is where i documented a 22r doing 95 mph through idaho, without even skipping a beat or dripping a drop, so i'm pretty dang sure it worked

 

[Red_Chili]

The key is what happens 20K miles from then...

 

[DaveInDenver]

The key is what happens 20K miles from then...

This is what I saw in my own engine. I left the head in place at the 125K timing R&R and the HG at 187K didn't have a whole lot of life left in it (although nothing to indicate impending failure, it was showing signs at #3). Supposing someone else was not as anal as me (Toyota Red, distilled water, annual flushes, etc.), I'm fairly confident that the HG would have been in worse shape. We've talked about it before, I think the design service life on the 22R HG is prolly something like 200K km (125K miles) and being Toyota that means you have 1.5x or 2x margin, so 300K km (185K miles) is reasonably safe to assume for most engines. But beyond that it's borrowed time. So I think the service interval and procedure is by design, HG and timing components at some set mileage, probably 200K or 250K km, which works out to about 125K to 150K miles.