I recently bought an 88 4Runner to have for my work/everyday truck w/228G on it (it's a 22re). Everything was great for about a month until one day I was rolling to work and noticed it was running just a little bit warm, then the gauge started moving like a seconds hand on a clock towards the red on the temp gauge. I got over as soon as I could in rush hour traffic and as soon as I hit the clutch the engine died. There was the usual boiling coolant going everywhere, but there wasn't any real smoke to speak of. After I got it towed back to my place, I let it sit for a day thinking about how much money I was gonna need to drop into this to get it running. I went to go start it just to see if there was any hope at all. I first checked the oil and couldn't detect that any coolant had mixed in. It started fine (it took an extra second to turn over) and it idled fine. If I gave it a little gas I noticed it sounded like you wrapped a can of spray paint in a towel and shook it to the rhythm of the engine, but it went away after I would let it idle. I then shut the vehicle off after about two minutes cause I didn't have the reserve take filled yet (the radiator was still full). I did the same thing a couple days later but I had to move the vehicle this time so I drove it for roughly 200 feet, and it seemed to run fine, just with that muffled knocking sound.

*Deep Breath*

Now that I have thoroughly bored everyone with that story, my question is do I go straight for a rebuilt engine, OR do I just try and change the thermostat or water pump, flush the cooling system, and ride it out? The reason why I ask is because I'd rather get this done sooner or later and I'd rather not mess around with nickel and dime stuff if it will eventually lead to the same thing. The body and interior are in way too good of shape for me to drive it off of a cliff just yet.

 

start with replaciing the thermastat and than try flushing the system and maybe think about switching to a eletric fan. as for if you want to change the motor i would swap in a davezoffroad performance 22re thoses are nice

 

If you have the tools, pull the plugs check them, and do a compression test.

Replace the thermostat. Get one with a nipple in it (195F) or if it doesnt have the nipple, drill a SMALL hole (one hole) in the metal flange. This is important, it allows water/gas to escape from below the thermostat allowing water (ie heat) to reach the thermostat and allow it to open.

I wouldn't be concerned with an electric fan. You don't need one. You might have a blocked up radiator as well (I've had this)

I replaced mine with a three-row (vs the stock 2 row) and never had an overheating issue since. Water pump should be good unless its leaking then it will need replaced.

I think in the end from what you've said, you might have a fault thermostat, and/or a old eroaded (internally from electrolsis) radiator (common!).

 

Sounds like a spun bearing to me. A knocking sound when given gas is usually a sign of a spun rod bearing. In that case, rebuild it

 

The knocking sound should be examined in depth. A compression test will help. It could be a spun bearing or a valve issue..