Yompkins

After getting my great-grandpa's old 1985 Toyota Pickup (4x4 22r 98,000 mi) back up and running I had been having some issues with the truck getting too hot. During normal driving the gauge would sit almost exactly in the middle, but while on the turnpike (75mph 3200rpm) the gauge would approach 3/4 of the way to max. Not quite in the "red" range but close. If I turned the heater on it reduced this down closer to the normal halfway point.

I decided to do a full coolant flush to get all the chunky green stuff out and refill with Toyota Red. I had some loud whining noise coming from the front of the engine when warm, near the water pump and oil pump and after pushing the truck hard the area around the water pump and oil pump would be wet. Because there is so much oil and wheat dust still coating the bottom of the engine, I have not been able to tell if the wet is actually oil leaking from the main seal or coolant leaking from the weephole due to a blown seal making all the old oil wet. (Maybe both) I figured while I had it drained, I would go ahead and install a new Aisin water pump, gasket and Toyota thermostat and gasket. Flushing the system took a long time but it went faster after I removed the thermostat, and I didn't have to wait for the truck to heat up each time to fully circulate the distilled water. After about 10 flushes with distilled water the drained fluid finally looked clear.

I installed the new Aisin water pump and gasket according to the service manual, but no torque specs were listed. I found a video on YouTube that suggested torquing the large bolt on the water pump to 9 ft lbs and the other smaller bolts and nuts to 6 ft lbs. The large bolt that goes through the timing cover tightened to those specs as did the nuts but all but one of the bolts just spun in the holes before getting to 6 ft lbs.

Maybe 6 ft lbs was too much or maybe the bolts have been overtightened before, but it seems that all but one of the bolts are stripped. As the water pump is still held tight by the one large bolt, one small bolt, and three nuts I took it for a test drive and it appears to be holding and running without leaking. It does make me wonder if those bolts were already compromised, that could have caused the water pump to leak at high rpm causing the fluid I've been seeing on the bottom half of the engine.

I'm sure I could attempt to drill out the bolt holes in the timing cover and attempt helicoils to try and fix the issue but I'm considering replacing/upgrading the timing chain assembly and just replacing the whole timing cover as well.

The truck has just about 100k miles which I believe is the service life of the timing chain and tensioner. I have read that many people upgrade to the two-row timing chain and/or metal guides. When inspecting the chain guides during my valve adjustment it appears they are both present, but I have not checked to see if they are broken at the mounting holes. Under deceleration I do hear a slight rattle I've heard described as marbles in the timing cover that leads me to believe my chain is stretched.

I'm looking for any help or recommendations from you guys.

If the water pump bolts are stripped out in the timing cover, should I go ahead and replace the cover rather than try to repair it.

And if I'm going to replace the timing cover and am due for a new chain and tensioner, should I just replace the chain and tensioner or upgrade to the two-row chain system with metal guides?

13Swords

Good work on the coolant system flush. Where does your temp gauge read now that it's been flushed? Did you replace the thermostat while you were at it?

Here are the torque specs for the timing cover bolts/nuts courtesy of LCE.



I believe that the thread pitch on the bolts is 1.25 but it would be wise to check them with a thread pitch gauge to be sure.
The threads the bolts "grab" onto are in the block, *not* in the cover, so replacing the cover won't help with stripped threads. Frankly if the new water pump is not leaking coolant I wouldn't worry about it. As for any oil leaks (or coolant leaks) from the timing cover, I'd wash off all the old oil, grease & wheat dust from the engine, then run it to see if it's actually leaking oil or coolant anywhere. That makes leaks easier to spot & fix.

I agree, 98K miles is about a limit for a timing chain set. The fact that you are hearing "marbles" from the area of the cover means that either the chain is stretched or (more likely) one or both chain guides are broken, most likely the driver's side guide (quite common on the OEM guides).
You can check this with the valve cover off, a long flat-bladed screwdriver & a strong light. You can look at that guide & pry on it a bit to see what kind of movement it might have. There is a good video about this on Youtube here:
IMO, for a stock unmodified engine, the double row timing chain isn't necessary & is more headache than it's worth. I do recommend that when the entire timing set is replaced that you get a kit that has the steel backed guides. These are much better than the OEM style plastic backed guides.
There are quality single row timing chain sets available with the steel guides, not just the double row sets. I have a single row set with steel backed guides on my 20R, made in Japan by OSK. Don't cheap out on the timing set, only buy quality.

When you do the timing set there are some specific things to look out for. You can get the cover off & back on again without removing the head but you have to be careful of several things.
There is a vertical bolt in the head, in front of the distributor drive, that's usually hidden under a pool of oil (see diagram above). This bolt secures the head to the top of the timing cover. Make sure you don't miss this one or you will break the top of the timing cover when you go to pry it loose from the engine.
There are 2 bolts at the front of the oil pan that bolt into the bottom of the timing cover.
There is a rectangular part of the head gasket between the head & the timing cover. You can get the timing cover off without damaging it but you have to go slow & careful when removing the timing cover.
I very much recommend that you replace the oil pump gasket (gasket between oil pump & timing cover) and the crankshaft oil seal (located on the front of the oil pump).
3 bolts in the cover *may* require a bit of RTV sealant to prevent oil leaks. The sealant needs to be on the shank of the bolt, very near to the head, and/or on the side facing of the bolt head that contacts the cover. Locations shown & circled in pic below.



The water pump does not have to be removed from the timing cover in order to get the timing cover off the engine, but the one larger bolt circled in the pic below does have to be removed to get the timing cover off the engine.


The smaller bolts on the water pump can stay in place, & the water pump will come off with the cover as a unit.

That's all the tricks I've learned about this that I can think of.