[ke123]

I wonder if i could get some opinions on this - recently took my 04 4 runner (4L V6 1GR-FE) on it's first camping trip with me as the owner.. After a couple of hours of highway driving, after a coffee stop, had high temp problems.. Turned her off at a hotel parking lot just before she got to the red zone. Under the hood I saw coolant had blown out onto the engine, mounts, etc.

After she cooled (overnight-we just stayed the night at the hotel) i opened the rad and it was low by about half a gallon. Actually there was a garage next door and we pressure tested the cooling system and it held 16 psi for like 10 min. I filled up the rad and was fine for another hour drive deep into the woods. I noticed though that the overflow tank would fill but not siphon coolant back into the rad. I went back to town and replaced the rad cap. This did not fix the problem.

Before coming home i topped up the rad again, and had overheat issues again after about 2.5 hours of highway driving. Overflow tank had filled and coolant had shot all over the front passenger wheel well in particular.. Filled up the rad again to make it home... Coolant still isn't siphoning back from the overflow tank to the rad...

I did an oil change the day before leaving and there was no evidence of coolant in the oil.. Dipstick is clean now too.. No white smoke in exhaust, or rough idle on startup...

Ideas where to go from here? I'm thinking head gasket obviously... So testing for HC from exhaust gas in the coolant.. But maybe there's something simple i'm missing..?

Thanks for looking
Kris

[preacher35]

Originally Posted by ke123

I wonder if i could get some opinions on this - recently took my 04 4 runner (4L V6 1GR-FE) on it's first camping trip with me as the owner.. After a couple of hours of highway driving, after a coffee stop, had high temp problems.. Turned her off at a hotel parking lot just before she got to the red zone. Under the hood I saw coolant had blown out onto the engine, mounts, etc.

After she cooled (overnight-we just stayed the night at the hotel) i opened the rad and it was low by about half a gallon. Actually there was a garage next door and we pressure tested the cooling system and it held 16 psi for like 10 min. I filled up the rad and was fine for another hour drive deep into the woods. I noticed though that the overflow tank would fill but not siphon coolant back into the rad. I went back to town and replaced the rad cap. This did not fix the problem.

Before coming home i topped up the rad again, and had overheat issues again after about 2.5 hours of highway driving. Overflow tank had filled and coolant had shot all over the front passenger wheel well in particular.. Filled up the rad again to make it home... Coolant still isn't siphoning back from the overflow tank to the rad...

I did an oil change the day before leaving and there was no evidence of coolant in the oil.. Dipstick is clean now too.. No white smoke in exhaust, or rough idle on startup...

Ideas where to go from here? I'm thinking head gasket obviously... So testing for HC from exhaust gas in the coolant.. But maybe there's something simple i'm missing..?

Thanks for looking
Kris

Well, you have one of two problems: Either your thermostat is toast OR you are leaking coolant and just not seeing it (probably through the water pump bearings). I had this IDENTICAL problem with my wife's POS GMC Acadia. In fact, ironically, the problem reared it's ugly head at 3AM, on a road trip, waaayyy out in the middle of nowhere in the Texas panhandle. Talk about a puckered butthole. It was 22 degrees Fahrenheit outside and I had three little children in the car with my wife and damned near a hundred miles from any town with a mechanic. Anyway, the truck kept overheating and blowing coolant out of the overflow, which made me think the that maybe the thermostat was dead. I kept refilling coolant every thirty miles until I got to Colorado Springs and got it diagnosed. Coolant was leaking out of the water pump, but you couldn't see it unless the motor was running at high RPM's. Anyway, sorry about the novel, but you're going to have to distinguish between thermostat or leak. GOOD LUCK!

[ke123]

Hey thanks a lot for the reply preacher

Well, the previous owner replaced the thermostat not long before I bought the vehicle.. both the top and bottom hoses from the rad are hot when she's at operating temperature, and in regular city driving (stop and go, shorter freeway drives) I've never seen this problem before. I guess I can pull it and test it...maybe it's sticking intermittently?

The coolant seems to be shooting out of the coolant reservoir overflow hose... Not sure how a leaking water pump at high rpm would lead to all the coolant being pushed to the reservoir and not siphoning back when the system is cold again, but I will try to check that out.

I need to flush the whole system anyways as the prev owner was running standard green coolant instead of the toyota red, and I think the heater core is plugged on one side as I only get heat on the driver's side. Maybe these are a few other clues to keep in mind.. hrmmm..

Thanks!!

[cmoua]

I am going through similar problem on my Honda Civic. I went through the normal diagnostic process:

- replace radiator cap
- replace radiator hoses
- ensure thermostat works properly
- check for milky substance in radiator
- check for coolant in engine oil dipstick
- pressure check coolant system


I didn't see any oil to coolant contamination at all in the radiator or oil. Oil is clean and coolant is green. Thermostat works fine. I am able to see water flowing in radiator once hot and thermostat opens. Temperature has not reach the red zone for two weeks since the overheat incident but I still notice a small leak after each drive.

After driving it and continue to check for overheat condition, the only leak I found is from the overflow reservoir. After a half hour at highway speed I am able to see leaks from the overflow reservoir due to air bubbles. My guess is that during combustion there's a slight leak from the head gasket that pushes air out through the radiator cap to the overflow reservoir.

The Civic has over 230K miles so I went ahead and order parts to replace the head gasket.

Every situation is different. Do a thorough diagnostic and do the head gasket as a last resort. Hope your situation comes out better than mine.

[JEL]

Now knowing it's had green in there, I'd lean on a plug somewhere in the system, perhaps the thermostat after all. I have read a lot of reports about green stuff and Toyota red/pink sludging up and not playing well together. I know t-stats are supposed to fail open, however it can happen the other way, that's what did in my parent's old Suburban with a 350, the "fail-safe" t-stat failed the wrong way, overheated, and popped the engine.

[ke123]

Thanks for all the suggestions guys.. I'm having a hard time understanding how the T-stat would cause this, as the cooling has been fine all the rest of the time (non-long highway trips) and the path for fluid from engine to the rad is obviously open if the coolant is being pushed into the reservoir..

Although I have no issues replacing the thermostat just in case.... I will do it while I flush the green crap out! and flush the heater core..

[ke123]

Yeah so got home last night from the trip and let the 4runner cool until now (about 20 hrs). When i removed the rad cap it was still pressurized.. And it smells like exhaust. Aaaaaargh

[JEL]

That sucks, what is the mileage on it? Could have been overheating it did it in, the 1grfe head gaskets seem delicate and susceptible to failure easily if over heated.

[ke123]

Originally Posted by JEL

That sucks, what is the mileage on it? Could have been overheating it did it in, the 1grfe head gaskets seem delicate and susceptible to failure easily if over heated.

Just 130k miles. It never got all the way to the red before i pulled it over, but close.. This problem is what caused that incident though.. Again, only showed up after hours on the highway.

[ke123]

I mean could anything besides a leaking HG cause this?

[ke123]

Update : got ahold of a block tester kit.. No exhaust in the coolant, even after a long trip. Thank God...
I think it just boils over on a long highway run because the rad isn't up to the task.. No leaks in the system. So i may just replace the rad (it's still on the original), flush the system and replace coolant with the correct red stuff

[gm350reratliff]

Make sure nothing is blocking the air flow through the A/C condenser and radiator. It's amazing how much stuff can get trapped in between the condenser and radiator. It could also be that the radiator is restricted internally as well. Also, if the fins on the condenser are really beat up and flattened down, you may try an A/C condenser fin comb like this: Amazon.com: Mountain 8300 AC Condenser Fin Comb: Automotive

If the fins are beyond repair, you may have to get a new condenser.

To me it sounds like it can't effectively exchange the heat when driven on the highway. Does it overheat any other time?

[ke123]

Nope, doesn't seem to overheat any other time. I'm guessing the cooling system just isn't up to the task with the combination of the heat from the tranny on a long high 75 mph highway drive, plus "hot" weather (84 degrees F, Canada hot ).

That's a good point about the AC condenser "comb" though, although I've looked and haven't seen much restriction.

Cheers,

[Aquanius]

Hi, I had this exact same issue with my 1990 nissan 300zx. I had mulitple times had the coolant come flying out of the overflow bottle through the overflow hose. I tested everything and replaced all of the easy parts, including the thermostat. What ended up being the problem was two fold. When the car got up to operating temperature the cap on the radiator is suppose to open at a certain pressure to let coolant go into the overflow as needed and return as it cools down. What I had found was that my radiator had a plastic neck where the metal cap was placed. Over time, the metal had scored enough of the plastic away that the cap was not sitting correctly at operating/high temperatures and would malfunction when releasing and returning coolant to the overflow. The second problem was that in the radiator, which was the stock one, there had been fairly bad corrosion that had taken place which had caused a blockage of the coolant flow in the radiator itself. To alleviate this I replaced the stock radiator with a new radiator with a metal fill neck and replaced the cap, just in case.

[radlynx]

I would think that the fan clutch is not doing its job. it should engage when it needs to cool the engine down. give it a try and let us know the outcome.

also, it could be that your coolant overflow tank hose is clogged, could not push or suck liquid in the tank.

Originally Posted by ke123

Nope, doesn't seem to overheat any other time. I'm guessing the cooling system just isn't up to the task with the combination of the heat from the tranny on a long high 75 mph highway drive, plus "hot" weather (84 degrees F, Canada hot ).

That's a good point about the AC condenser "comb" though, although I've looked and haven't seen much restriction.

Cheers,