Cooling System woes....

[ChrisCrowie Junior Member Find all posts View Profile Close ChrisCrowie]

Hopefully some of the more mechanically minded forum members can help me with this issue. :lol:

Bascially I have done all that I can think of with the cooling system to stop an ongoing issue. At the first sign of a hill or under load at 110kph the temp guage jumps up to the red.

I have replaced radiator, clutch fan, thermostat, radiator cap and coolant to genuine with no resolution in sight. Chemical flush of block done as well.

Where this has me beat is over the weekend I tackled Straddie down main beach in softish sand 3rd gear 2200rmp for about 20mins and the temp guage did not move at all, come off the beach, air up and drive back to the otherside of the island and the first hill sees the guage go into the RED :evil:

I have even replaced the sender unit to no avail....

The other concern is the radiator is pushing about a litre and a half of fluid out into the overflow continously but not taking back into the radiator on cooling down.

Where it also gets even harder to figure out is when I pull over with the temp in the RED I sit idiling for about 30 secs and then temp is back to normal, comming down a steep hill under no load and the temp goes down to only about 1/4 hot....

I can't figure it out and don't know what to do. Next step I am looking to put an aftermarket temp guage in

Why would this be happening and what have i overlooked? Also why is the coolant getting pushed to the overflow but not flowing back on engine cool down?
I have towed moving trailers to Mackay and back previously without the temp guage moving a cm, but now I don't trust it, this is all happening after I had the engine stripped and rebuilt about 2 years ago.

Any thoughts?????

[Prado BB Advanced Member Find all posts View Profile Close Prado BB]

Re: Cooling System woes....

I had a similar problem in my Patrol - similar to the overflow issue not the gauge issue. It turned out to be a hairline crack in the head that would expand when really hot and contract when cold. Had the head off and no one could find it. Finally when a heat test was done (not the right term), they found the crack. It's all good now. I believe one way to test for this condition (a good indicator I'm told) is to open the radiator cap in the morning when engine is cold (sitting over night) and if you notice pressure in the radiator, then you have an exhaust gas leak into the cooling system, which causes the overflow issue and hence the crack in the head somewhere. I didn't have any of the usual symptoms, e.g. milky oil, bubbles in the radiator, just the overflow issue and loss of power when hot or on a hot day.

[fishfinder Advanced Member Find all posts View Profile Close fishfinder]

Re: Cooling System woes....

Where it also gets even harder to figure out is when I pull over with the temp in the RED I sit idiling for about 30 secs and then temp is back to normal, comming down a steep hill under no load and the temp goes down to only about 1/4 hot....
The temp sender can take a reading off hot water and will show a cooler reading on air - it is possible you may have not blead the cooling system for air and that you have an air lock in the system and also mentioned is there maybe a crack in the cylinder head .

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Re: Cooling System woes....

Just a little outside the square.... have you added the winch or driving lights or bar recently & its overheating since then?

Hope you find the answer.....for what its worth i have an aftermarket temperature sensor on my TD. The sensor is mounted under the bolt that holds the engine diagnostic plug on. Its on the top radiator hose.

General cruise it sits on 73 degrees working up to 83 on a longer hill - I haven't yet had a chance to test on a long hill climb but I could only get it to 90 once @ Fraser in the very soft sand aboce the high tide mark & a good 10 minutes of pushing hard in high range. The OEM gauge still hadn't even moved.

Can you hear the fan coming on when its hot, it should be roaring it head off & should be quite noticeable over the engine noise.

Cheers

[HeathNZ Junior Member Find all posts View Profile Close HeathNZ]

Re: Cooling System woes....

Dont trust the factory gauge (get another fitted). Have you replaced the water pump? You seem to have done everything else.

Maybe the pump isnt working right. Is there any corrosion around/on the thermostat mounting surfaces?

It does sound like its being pressurised by something though.

Disconnect the water pump belt, remove rad cap and run it up looking for bubbles. If it bubbles my guess is the head some where. If not hook the belts back up and see if the flow improves, might be water pump not flowing coolant well and it's boiling some where causing steam to push the water out. Having said that it should draw it back on cooling...

Get a pressure test done too on the coolant system. Glow plugs out, pressure test for 30 mins and then crank it over. any water will squirt out of the cylinders meaning head or gasket stuffed.

Sorry not sure.

[ChrisCrowie Junior Member Find all posts View Profile Close ChrisCrowie]

Re: Cooling System woes....

Thanks for the replies guys, so far:

1. No bubbles in cooling system with cap off and engine running, and no pressure in the system when taking the cap off after sitting overnight.
2. Rebleed system and it did take about another half litre of coolant in doing so, but with cap off and engine running all would be smooth and then every so often water would rise out the top and then go back down, doing this randomly at irregular intervals :?: :?: :?:
3. With the new fan in i can hear it kicking in when very hot, but on general driving doesn't kick in at all. (after parking car and then coming back after say 5 mins and starting again you can hear the fan working for a couple of mins until airflow cools it down)
4. Water pump was replaced during rebuild along with timing belt. How do I tell if the water pump is working correctly or not? Is there an easy test to do besides pulling the whole system apart again?
5. Winch and lights has been on the car since day dot and never had any issues before the rebuild.

What did confuse me this morning on opening the radiator cap is there were shards of hard clear plastic on the inside of the cap that have never been there before!!! Can't figure out where this stuff would have come from!

but since rebleeding the system not as much coolant has been getting forced to the overflow, but there is still some heading that way. On shutdown after driving you can hear the overflow bubbling away....

StormyKnight, any chance you have some photos of your temp gauage install I can use to base mine off?

Thanks all for your help so far, let the investigation continue....

[StormyKnight Advanced Member Find all posts View Profile Close StormyKnight]

Re: Cooling System woes....

No worries, i will take some when the rain stops & the suns up.....

re the rebleed, did you have the heater turned on? The engine water also goes thru that system when the heater dial is turned off cold....there could be an airlock in there too...

Instructions for filling cooling system from my Ellery's Book....

1. Adjust heater control to maximum (rear heater also if applicable)
2. Have Coolant Mixture on hand to fill system
3. Remove radiator cap & fill cooling system with coolant mixture
4. Remove top from coolant supply tank and top up system
5. When the coolant is cold the coolant level should be between the LOW and FULL mark. The coolant level will vary depending on engine temperature.
6. Start engine and run it @ 2000rpm for 10 minutes to open thermostat and purge air from system. Fill coolant suppy tank to "full/max" mark.
7. Replace cap

Other than that I can't think of anything else that would cause your issue......

[Leethal Advanced Member Find all posts View Profile Close Leethal]

Re: Cooling System woes....

Couple of thoughts ...

Check the Radiator cap seals (2 off) to ensure it is sealing both the neck and the top on the radiator, plus check for splits loose clamps in the hose to the recovery bottle and INTO the bottle.
Remember it needs to be sealed to ensure only fluid is drawn back into the radiator, any leaks etc will allow air in instead of coolant.

Since the engine cools down readily when idling I would think the water pump is okay.
When you fitted the thermostat did the fit with the bleed "jiggle valve" in the correct position (6 o'clock), this would prevent proper bleeding of air.

From your description that the overheating occurs at 100-110 km/hr it sounds like an air flow issue, I assume you have checked everything in front of the radiator for obstructions/debris, there isn't a loose or bent panel or guard that is deflecting air and preventing air flow across the radiator at high speed ?
That you can hear bubbling into the overflow bottle indictates to me a cracked head or similar as the gas needs to be coming from somewhere (assuming your not boiling)
Good luck.

Lee

[craig Member Find all posts View Profile Close craig]

Re: Cooling System woes....

Did you put the thermostat in the right way

[cranky Lurker Find all posts View Profile Close cranky]

Re: Cooling System woes....

G'day Chris i feel for you i had a similar issue with my 1kz te Prado 2001 model, overheating on long hills towing the camper trailer, like you i replaced everything in the cooling system and it still overheated, to cut a very long story short you say you replaced the viscous fan hub that was the third thing i replaced after the thermostat & radiator, after a year of no resolution to the overheating issue i went back to square one and took a closer look at the viscous hub pulled it apart and found very little oil in it & they are also adjustable internally, purchased a tube of silicon oil 18ml i think from toyota & the adjustment was incorrect the two phillip head screws should sit about mid way my one was all the way off, there was no way this fan was going to cut in, anyway after i readjusted the internal coupling & added the extra tube of silicon oil no more overheating, hope this helps hate for you to go through what i went through, also went back to toyota to complain about the viscous hub at $540 i wanted some sort of compensation for my pain guess what didn't want to know.

[ChrisCrowie Junior Member Find all posts View Profile Close ChrisCrowie]

Re: Cooling System woes....

Been away for work, but got some further progress and the news is not good....

Rebleed of system allowed a little bit more coolant in, but then.... bubbles found when idiling!!! :evil:

White smoke and rought idle on start up, starting to use coolant, and still pushing water out to overflow = either cracked head or blown head gasket.

I am hoping blown head gasket as the car drives normally otherwise with plenty of power, no overheating in city driving only on highway or hill climbs and fast cool down when idiling.

So the question is, are there any defintive ways to tell cracked head from blown gasket before forking out more coin on taking it all apart?

Southside Toyota has quoted $1550 for new bare head which is ok as all other parts were replaced in rebuild so should be fine, just hoping it is only the gasket gone as i can get away with about $500 to have that done....

[Robo76 Lurker Find all posts View Profile Close Robo76]

Re: Cooling System woes....

Just reading this thread for the first time and is pretty much what happened to me. Car was pumping out water into over flow bottle, etc,etc. All of a sudden temp went through roof and engine started running rough. Pulled the head off and all looked ok until we use a snake light to look up in the pre combustion chambers. No. 2 had a crack in it. Un-fixable, new after market head bought with valves, gaskets, head bolts, etc. All good as gold now. Save a fortune doing it my self.

[ChrisCrowie Junior Member Find all posts View Profile Close ChrisCrowie]

Re: Cooling System woes....

Further investigation had me pull the radiator out, under 12mths old but clear bow to side gives over pressurisation theory further weight...





But while doing this, removed glow plugs to check chambers in head and all black and sooty, no indication of leaking coolant.

New radiator in and while bleeding sat glass bulb on top to check for bubbles, ran for 40 mins but no bubbles found....

Next step off to engine rebuilders to compression test and possible leak down test.... thinking now the head itself may be fine but the gasket is gone....

the saga continues....

[cranky Lurker Find all posts View Profile Close cranky]

Re: Cooling System woes....

G'day Chris, have you had the radiator rodded out to see if its blocked, i had the same issue were the coolant would overflow into the bottle and they found the middle of the radiator 50% blocked, the cause of this was i had replaced the coolant with a non toyota coolant and after approx a year started having problems.

[Derb Senior Member Find all posts View Profile Close Derb]

Re: Cooling System woes....

Hi Chris. Chances are better than even you have a duff head. The toyota temp guages are useless. Stormy is onto it with an aftermarket setup. By the time the oem units cry uncle it's all over rover - you are already in trouble. Good luck.