Here is the situation.

I bought a 4Runner about......ummmmm 6 months ago. I got to drive it...ummmmmm 4 times? Anyway, it overheated on the way home from work. I figured OK, no problem. Did the typical stuff:

Replaced Thermostat
Changed out the Radiator TWICE
Replaced the water pump
Replaced the Fan Clutch TWICE

No Oil in the Coolant, no Coolant in the Oil.....

Still........ no dice.

Please help me out here.
1988 4Runner, 5spd, stock 3.0

 

What year? How about the thermostat? Power flush? Are you SURE no coolant in oil/oil in coolant?

 

Perhaps your thermostat is sticking, or not opening properly, --that should've been your first part to look at. Go with the original toyota part it's like $15 bucks but is has a toggle valve that cheaper ones won't have. It's only 3 bolts on the 3.0. Good luck.

 

I edited the top post.

I did replace the thermostat w/factory. I'm an ALL factory person.

I did NOT powerflush.

There is POSITIVELY now oil in coolant or vice/versa.... been there / done that :pat:

 

have the thermostat in my hand now -

When I place the thermastat into it's housing, should it squeeze the seat w/the smaller spring at all? This one does not. It sits in there but it never moves the flat seat on the spring.

 

Just because it has not been mentioned, but what about the water pump?

 

I mentioned it. I replaced the water pump, check the timing, replaced the thermostat, replaced the fan clutch.

 

just a thought, you may have an air pocket that hasnt been purged (?) completely. my old 86 did that for quite a while, finally got sorted out a week before i started parting it out. go figure! hope this helps.

lee

 

Sounds like an air pocket.

 

I'll bet they did a headgasket on it before you bought it and reversed the headgaskets when the assembled it. It happens often it's likely blocking fluid passages causing it to overheat.

 

Try turning on the heater and see what it does. It would be an easy check to see if maybe a bypass hose is clogged. If the heater does not blow hot air it might mean that no coolant is getting to it. If my logic is correct, that would be more proof that the headgaskets are reversed.

 

I'm gonna say reversed head gasket as well.

 

With the heater on, it DOES blow hot air and it brings the temp down.

Not reversed head gasket since it's been running for years after the headgasket was done.

 

Did you replace the Radiator Cap!

Could be the weak link.....

 

when the vehicle is hot and the thermostat is open take your hand and feel around on the rad, the whole thing should be hot, if only parts of it are hot such as the upper and lower tanks its probably partially clogged and not allowing the heat to dissipate to the atmosphere.

PS. does it overheat while driving and at Idle or one or the other??

Blake

 

check your ignition timing.

 

It overheats ALL the time. Driving, sitting still, etc.

timing is good.

Radiator cap replaced.

Frustration!!

 

I just took pictures.

I took the hose off the water inlet and it was cruddy but only where it fits OVER the inlet tube. The upper Radiator hose is "squishy" even when empty and cool. I'll replace all the hoses.

I picked up another factory Toyota Thermostat and gasket.

I might as well replace the belts too. The timing belt looks good and timing is correct.

The check valve in the thermostat, as per the FSM is supposed to be at the top. Now I wish I had looked at it when I took it out. After I get all the hoses and belts, I'll put it all back together, fill the system slowly so as to create as little extra air as possible, and then cross my fingers.

15 Pics: http://members17.clubphoto.com/jonat...72/guest.phtml

 

is the rad hot all over??
are both the upper and lower rad hoses the same temp?

 

That's right Alex, I'll take the air pocket for $100!
Disconnect your upper radiator hose from your radiator, fill the hose going toward engine with coolant here. Re-attatch hose, turn heater on and start your rig, watch her burp!
This is free! Don't throw parts at your rig and waste money! :pat: