Need some help/ideas. (Cooling Problems)

robb1887

robb1887

New member
Bought my 4Runner May 11th. I needed a car to commute and something bigger to haul things. Always been a fan of them, with easy maintence, and low repair costs etc., etc... I found that it would be my best choice.

Well after about two weeks of driving I got home and heard a strange noise from under the hood. Seem the 4R had been running a little warm and I hadnt noticed so the expansion tank was boiling. No biggie, topped of the fluid the next day and thought that was the issue. Drove to work the next day and was fine, but while driving home it got a little warm again. So, Cooling system 101: Replace the thermostat if you are having small issues, I replaced the thermostat and in doing so did a dump and fill with the fluid.

For the last three weeks it was running great, no cooling issues, ran strong, no smoke, oil looks fine.

After driving home the girlfriend and I drove across town to do a little shopping, mostly on the highway. Got to the other side of town and sitting at the first light I immediately smell radiator fluid and look at my temp gauge and its red hot. I immediately turn off the engine and on the heater to pump some of the heat out and push the car off the side of the road where a cop was able to get me into a parking lot.

I let the car cool, we had dinner and got our shopping done. I bought a gallon of distilled water and topped off the fluid I lost so I could get home. I checked the system this morning for air and no bubbles appeared so I drove it to work (20 mins) to see if it would start to overheat again.

It didnt...

So from what I've seen driving it and it getting over heated only happens when the car is ALREADY at operating temp, and I am driving for a while long distance on the highway then hit city streets.

From the PO, I was told the timing belt, water pump, thermostat, and aux belts were all replaced ~1000 miles ago.

I hope to be able to get up with my mechanic buddy tomorrow but its kind of short notice for him. I am thinking of replacing the upper and lower hoses and assoc. clamps and the radiator cap this weekend with a system flush and refill.

Any other idea of what I might need to look at would be appriciated. This thing is driving me crazy.

Thanks in advance for any help you all have to offer. Also, is there any good online parts sites, for oem replacement, that I havent been able to find yet?

-Robb
 
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I would guess your fan clutch is not working properly since you are fine at hwy speeds and air flowing through it. You have a problem once in the city and the air flow stops.

Also how old is the radiator cap? That would be something cheap to replace.

Hopefully you haven't overheated enough times to cause other issues like head gaskets.
 
kball said:
I would guess your fan clutch is not working properly since you are fine at hwy speeds and air flowing through it. You have a problem once in the city and the air flow stops.

Also how old is the radiator cap? That would be something cheap to replace.

Hopefully you haven't overheated enough times to cause other issues like head gaskets.
Click to expand...

Is there a way to test the fan clutch? From the looks leak of the overheat last night it might have started on the highway though. The frame was wet and the inside of the front driver side tire, and the first light was maybe 30 seconds off the highway.

I dont know the age on the cap, but thats one of the next things Im replacing.

Head gasket still seems to be fine (knock on wood). There's no funny smoke, the engine is still running strong, and last I checked the oil it looked good but at this point I have no idea still.
 
robb1887 said:
Is there a way to test the fan clutch? From the looks leak of the overheat last night it might have started on the highway though. The frame was wet and the inside of the front driver side tire, and the first light was maybe 30 seconds off the highway.

I dont know the age on the cap, but thats one of the next things Im replacing.

Head gasket still seems to be fine (knock on wood). There's no funny smoke, the engine is still running strong, and last I checked the oil it looked good but at this point I have no idea still.
Click to expand...

Definitely do the cap to rule that out. The best indicator of a bum fan clutch--aside from overheating in traffic but not at highway speed--is the absence of that fan roar at cold startup that lasts a few seconds then goes away. You can also try stopping the fan with a rolled-up magazine or newspaper when the truck is really hot and should be needing the fan. If you can then you need a new clutch.

Here is a link on YT from last summer with a lot of info:

1998 3.4 Auto 4Runner, Overheating Issue, Suggestions? - Page 3 - YotaTech Forums

Link is to my change write-up post, but lots of good stuff in there. If it is in fact dead, time to overheat after leaving highway can be very short, less than a minute if hot with A/C on. Ask me how I know.
 
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TheDurk said:
Definitely do the cap to rule that out. The best indicator of a bum fan clutch--aside from overheating in traffic but not at highway speed--is the absence of that fan roar at cold startup that lasts a few seconds then goes away. You can also try stopping the fan with a rolled-up magazine or newspaper when the truck is really hot and should be needing the fan. If you can then you need a new clutch.

Here is a link on YT from last summer with a lot of info:

1998 3.4 Auto 4Runner, Overheating Issue, Suggestions? - Page 3 - YotaTech Forums

Link is to my change write-up post, but lots of good stuff in there. If it is in fact dead, time to overheat after leaving highway can be very short, less than a minute if hot with A/C on. Ask me how I know.
Click to expand...


Thanks for the info, after he pointed out the fan clutch I looked into it a little bit more... what are thoughts on replacement vs. overhaul it?
 
Ordered a new fan clutch yesterday overnighted. We'll see in the next day or two if that was the big problem.

Thanks for the help guys
 
....

Replaced the fan clutch yesterday, it was definitely bad, and drove it to work today to see if it was fixed.

Obviously wasnt my only issue since I am posting something more... fan is definitely working, but I still started overheating on my way home today.

Need to run by the dealership to grab a radator cap.... thinking it might not be staying pressurized is my only next guess.

Anyone else have any better thoughts?
 
Pick up a thermostat and a thermostat O ring while you are there.

If you used just water after overheating, there may not be enough antifreeze to keep the water from boiling over. Keep a close 50/50 mix. This happened to me on my first car. Lesson learned. Pick up the Prestone $7 antifreeze tester if ya want to.
 
LittleCaesar said:
Pick up a thermostat and a thermostat O ring while you are there.

If you used just water after overheating, there may not be enough antifreeze to keep the water from boiling over. Keep a close 50/50 mix. This happened to me on my first car. Lesson learned. Pick up the Prestone $7 antifreeze tester if ya want to.
Click to expand...

Added full strength antifreeze when I got home to try and level it out, just placed the thermostat and gasket ~3 weeks ago

WHORERUNNER said:
where are the leaks coming from
Click to expand...

Seem to be coming from the expansion tank boiling over from what I can tell...
 
Is the radiator original? I wonder if the cooling passageways could be partially blocked to where your radiator cannot keep up with the cooling demands the engine is placing on it. Maybe the previous owner used Bars or the like in it to stop a leak. IMHO, the radiator in the 4runner could be a little bigger.

See if the new cap is the silver bullet. Hope it is.
 
LittleCaesar said:
Is the radiator original? I wonder if the cooling passageways could be partially blocked to where your radiator cannot keep up with the cooling demands the engine is placing on it. Maybe the previous owner used Bars or the like in it to stop a leak. IMHO, the radiator in the 4runner could be a little bigger.

See if the new cap is the silver bullet. Hope it is.
Click to expand...

Driving it again today to see if the cap is the answer. If not I'm taking it to a buddy, my mechanic, Tuesday to do a little more technical trouble shooting. He has an infrared thermometer and toys to check to see if the radiator is the issue etc., etc.. Would be nice not to have to replace it, but if I do it will be the Koyo OEM replacement and an external cooler to nip the milkshake in the ass
 
I'm wondering if that new thermo you put in is a dud?? Sounds like it might be sticking closed. I also think LittleCeaser's suggestion of a blocked radiator or coolant passage (inside the engine) is worth looking into.
 
Ever figure out the problem? I'm having overheat issues as well. It started a couple days ago pulling a 2600Lb boat.
Replaced the thermostat, and gasket and still have issues.
 
robb1887 said:
Well after about two weeks of driving I got home and heard a strange noise from under the hood. Seem the 4R had been running a little warm and I hadnt noticed so the expansion tank was boiling.
-Robb
Click to expand...

Nobody has considered the head gasket since June??

So long as the water pump is moving coolant, it shouldn't boil unless you literally covered the radiator. If you are seeing bubbles in the overflow tank, that is the hallmark sign of a cracked head or blown gasket pressurizing the system. Take it in to a good mechanic while you can still save the engine.
 
Different truck, but same things happened to me on my Nissan Armada. Turned out the radiator cooling passages were blocked. I also had bubbling in the expansion tank but it was caused by boiling water due to the immense heat. I would replace radiator and run a solution through your coolant passages and check on the heater core as well to make sure it isn't blocked.

While doing all this, remove the thermostat you bought and test it in a pan of boiling water.

Once all these are done, you should have covered all your bases.
 
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