2F running hot

[Travis22]

G'day guys, i seriously need some help.

I really wanted to finish putting together my last trip report as seen here:

https://forum.ih8mud.com/40-55-series-tech/461762-australian-photos-4.html

as im not much good at contributing with my mechanical skills so enjoy giving back with some photos etc! But the old girl is killing me.

Basically, from the start.

Engine was running 100% fine, then 'overnight' it just started running warmer. Literally the day we left on the above trip, i noticed the temp gauge climbing a little higher then it had ever done before. (Gauge is good, and i have confirmed temps with a laser thermometer)

Basically what happens is she warms up as usual but the temp rises to around 200-210maximum. If i let it idle the temp drops to around 190, but no lower. Previously the engine has run at 180 and it never ever ever climbed above this no matter what the driving conditions were.

Engine is running perfect. Zero smoke on startup or when running. It seriously feels perfect.

Originally i figured it might have been related to the cooling system as the water pump was weeping a little (had been weeping in the passed, between the pump and engine block seal) but now i believe this to be unrelated.

Waterpump, thermostat, all hoses, radiator cap and the radiator have all been replaced with new ones.

With the new radiator, it does run a little cooler or should i say it takes a little longer to get as hot, and when i pull up and let it idle it does come back down to around the 190 mark quicker but in hindsight... i think i bought a new radiator which really wasnt needed!

Since then ive had a leakdown test done on all the cylinders which all came up fine. AND, my mechanic did a hydrocarbon? test on the cooling system which came up negative for any combustion gasses.

However, IMO the radiator hoses are bulging a little. I believe there is excess pressure in the cooling system now. The coolant isnt spewing / boiling over, it seems to function as per normal, the coolant level rises and falls in the overflow bottle as the engine heats up and cools. It does not appear to be 'using' any coolant.

With the engine cold, i can squeeze the hoses but within 10-20seconds of starting the engine they become quite firm, i cannot squeeze them.

Looking for answers here i found comments suggesting possible problems with the PCV valve and have checked mine and it appears good. Timing is good, so i dont think the engine is leaning out.

All spark plugs look good. After a longish drive the coil does feel VERY hot to touch, you can touch it but its bloody hot. Cannot remember if this is its normal operating temp or not... But the engine idles and runs absolutely perfect hot or cold.

I put a can of carby cleaner through the carby, this has improved throttle response but thats all. Runs perfect as always. I also sprayed the carby cleaner around the manifolds looking for a leak but got no response.

Coolant looks 100% fine. Ive drained the system 4 times! since this started and its always looked like new, zero signs of any contamination.

Engine oil was changed out prior to the trip - so it was new at the start of the trip and has been drained out and replaced again at the completion of the trip. The old oil looked like perfectly good old oil.

Engine oil pressure has remained unchanged.

Since returning home i have a small oil leak which has developed. Maybe a small drop of engine oil per 1-2 hours from the back of the engine somewhere.

Any and all help would be greatly appreciated!


Kind regards
Travis.



***edited to add*** i forgot to mention the FAN is a fixed 8 blade type so that is all good.

 

[Fast Eddy]

You replaced the cooling system recently, and now it's having problems?

Did you "burp" the air out of the system? If not, park it on an uphill slope and run it a bit with the radiator cap off and top it off as necessary.

If you didn't buy your new parts from Toyota it's entirely possible you got a new part that is bad. You might test the thermostat in a pot of water on the stove.

It could be that the cooling passages in the block are clogged. You can find info around on how to remove the block drain and dig around inside with a piece of wire to clear it out.

 

[Travis22]

Thanks for the reply Fast Eddy.

No, nothing was changed prior to the engine 'running hot'.

It just started running hot all of a sudden. The thermostat, hoses and radiator had not been touched for some 15-16years and were all still fine. I had however changed / flushed the coolant some 12months ago but i think this is all unrelated.

If there was a blocked cooling passage (or even oil passage???) do you think this would cause the engine to run hotter with no other signs.

When i drained the system, i use both the petcock at the back of the engine and on the radiator. Both drain fine, show no signs of blockage. Ive become an expert at draining and refilling the cooling system lol Pretty confident there are no air locks in there.

If the cooling system is perfect, is it possible that maybe something is wrong with the oil, maybe a component is not being oiled and thereby running hotter causing the whole engine to get hotter which in turns caused the cooling system to run at a higher pressure?

Seems logical to me, except for the fact as i mentioned above... that when i start the engine cold, the radiator hoses feel like they 'pressurize' so is it fair to say this isnt simply because the coolant inside them is hotter, as its still cold so something else has to be pressurizing them ie. combustion gasses??? But the leakdown and hydrocarbon both come up good......................... i dont get it!

........................

One thing i really dont get is how a cooling system works / pressurizes. When it is cold, i assume there is no pressure. As it warms up, it builds up pressure as the liquid expands? Eventually the pressure rises above that which the radiator cap opens then some of the coolant purges out into the overflow bottle.

As the engine cools, a negative pressure is created and this then causes the other part of a radiator cap to open and it sucks back in some fluid...

So when i feel the radiator hoses, at any time the pressure cannot be higher then what is required to 'open' the radiator cap?

So i guess under normal operating conditions there shouldnt be much pressure in the hoses but at some point there will be as it heats up, but once the radiator cap opens and purges out some fluid does the pressure remain at or just below what it takes to open the radiator cap?????

I guess what im saying is in the passed i vaguely recall squeezing the radiator hoses with the engine hot, and believe the hoses were fairly soft and squeezable. But now with the engine running (hot, or even when cold and just started) the hoses feel firm. But the coolant still purges and sucks from the reservoir so i guess that means while the cooling system is pressurized it is still within the limits of the radiator cap but higher then 'normal'.

And im hoping all this is somehow related to the engine running hotter lol!!! Im really just looking for a problem, maybe looking to hard and making something from nothing as i was really expecting the leakdown test and or the hydrocarbon test to show me the problem and as they didnt im now stumped!


Travis.



***Edited to add*** Not sure if its important but also keep in mind that ive traveled almost 7000km / 4350miles on our holiday since this started happening. Symptoms havent really changed over that time... maybe just maybe it is getting a little hotter sooner but its hard to say with the different driving conditions around town / v's out on the highways, so im not sure if im correct in thinking that if it was the head gasket etc. it would be well and truly stuffed by now, surely/?????????

 

[desertpat]

Good account Travis,
Looks like your system functions well enough to remove heat at an idle, but not when there is a demand.
You mentioned having a laser thermometer.
With engine running, you might survey radiator tubes looking for a temp diff indicating blockage.
Also check water jackets, cylinder head temps and all cooling system components looking for abnormalities.
Suggest you also check the ignition timing and water pump output (flow).
You might see this with rad cap off and the thermostat open.

Do the rad hoses get hard instantly after starting engine, or does it take time as in until the engine gets hot.

good luck (and let us know what you find pls)

 

[Bigcity25]

I can say my 2f was running hot due to a blockage of crude in my block. The shop then added a chemical to my system and let it sit overnight. I think they did a half assed job flushing it and ruined my radiator. But after 2 treatments and a new radiator it never overheats.

 

[Roboosfj40s]

Possible that the water pump is cavitating? That will create excessive heat and can be caused by an abnormal impeller diameter. As in a regular well pump. You can change the gpm by changing the impeller diameter and if you changed the water pump but has worn the impeller for what ever reason it would cause more heat. Just a thought. Hope you find the problem.
Rob

 

[rkymtnflyfisher]

I fought a similar issue a few years ago on a dodge ram, turned out that it was the radiator cap, twice I replaced it with a new cap from napa, only to find out a few months later that the cap was my problem.

I'd rather be fly fishing

 

[Travis22]

Thanks for the comments guys, i really need all the help i can get.

DP - Yes, it would be fair to say the cooling system works reasonably well to remove most of this overheating at idle but once hot, it does not come back down to what was before the normal operating temp.

Was 180, now gets to 210+ and when left to idle drops back to around 190, but no lower.

The rad. hoses pressurize very shortly after starting the engine from cold thereby i assume it is NOT the normal case caused by expansion as the liquid warms up.

The radiator is brand new. It works perfectly. The water pump is identical to the water pump it replaced ie. same brand made in Japan, and visually identical when i compared them before installing.

When checking the temps with the laser thermometer i get the following sort of readings:

Back of the block, manifold side, head bolt-head near the temp. sender unit = 210 to 220.

(Sorry i got the conversions wrong before, 220 is the hottest temp the engine has run at (105deg C) - measurement taken at the location as above)

Front of the engine on the top thermostat cover = 194 to 203 (90-95deg C)

Top radiator hose = 194 to 203 (90-95deg C)

Bottom radiator hose = 140 (60deg C)

...........................

So yes, i guess i could say since checking things with the laser thermometer ive always found its hotter at the back of the engine to the front. (furthest away from the radiator so only to be expected i guess......)

BC - re: blockages in the engine. Is there any way to test for this. I flushed the cooling system some 12months ago and replaced the coolant afterwards. This was done simply because the coolant was getting very old, i had no actual issues before or after.

Id rather not flush the lot again right now with the brand new radiator given i wouldnt like to end up with crap moving out into the radiator, HOWEVER if this seems like a real possible cause then i guess i could install a filter on the top radiator hose to catch any crap that flushes out of the engine........... Or can it be flushed with the radiator removed?

Rob, cavitation... I really dont think so. Given the engine started running hot before i started replacing all of the cooling system components.

And the water pump only started weeping between the block and gasket, the pump and internal impeller etc. all looked fine and as above, identical to the replacement pump which i fitted.

If cavitation was happening would it generally be at a given RPM?

And lastly if it was happening, thereby causing the radiator hoses to pressurize when cold - id assume that as soon as the engine temp and cooling liquid rose above the radiator caps opening pressure the overflow reservoir would be inundated with bubbles etc...?

RKY - I did suspect the radiator cap. When i replaced the waterpump, thermostat and hoses i also fitted a new radiator cap.

What i found was the new radiator cap actually opened at a slightly higher pressure (tested once back home) of 15PSI and this was causing a small amount of coolant to actually spray out of the lid on the overflow bottle when it purged. So the old radiator cap was fitted and this 'spray' stopped.

Later i purchased a new radiator and it came with another new radiator cap, one which the radiator dude insisted was much better design and quality then my old one so ive been running that once since. FWIW it as tested and opens at 11PSI.

Thanks again guys..............

Any thoughts re: this being an electrical problem? I wish it was, but cannot think of any reasonable cause given how well the engine still runs both when cold, and hot. I checked the timing many times on the trip, and made very slight adjustments along the way hoping to see any changes in running temp but it did not have any effect.

Travis.

 

[1911]

The thermostat, hoses and radiator had not been touched for some 15-16years and were all still fine.

How do you know they are still "fine" after 15 years? If you haven't tested the thermostat in a pot of boiling water with a thermometer, either do that or just replace it with a new Toyota one on principle.

The radiator can easily accumulate enough calcium sulfate deposits in 15 years (way less time if you don't use distilled water) to block or partially block the passageways and you can't see it from the filler neck.

If it were my truck and these were 15 years old, I would replace both (or at least have the radiator rodded and boiled out by a good rad. shop if not replaced) before I did anything else.

 

[desertpat]

Travis, good troubleshooting again.
Your rad seems to remove heat well and there is some fluid flow, but maybe not enough.
Could it be that your thermostat is not fully opening. It`s the most likey place to have restriction.
A defective thermostat or a piece of scale from the water jacket may be lodged in there as it happened suddenly.
cheers

 

[edwjmcgrath]

When you've tested everything and you don't find the problem, it's probably something that you have ruled out. It's simple enough to remove the thermostat completely as an experiment. I hope it's that simple.

However, your symptoms are the classic 'exhaust gasses getting into the coolant' from a bad head gasket. Overheating under load but not at idle. High pressure on the radiator hoses. Coolant blasting out of the radiator cap and the overflow tank. When you are idling, the pressure is lower and there is only a small amount of exhaust getting in there and the radiator can handle it, but when you run at higher speed, even though you have more air flow, the cooling system can't dissipate the heat. When he did the HC test, did he use a tailpipe sniffer or a block tester? You can buy and do a block tester test yourself. Also, one other thing to try sometime when the engine is cool (and preferably without the thermostat installed) is to warm the engine up with the radiator cap removed then rev the engine and look for bubbles in the antifreeze.
I hope I'm wrong here, but having seen a few bad head gaskets over the years, this problem sounds very familiar.

 

[Bigcity25]

Something obviously isn't working right to allow your coolant to do it's job. Cavitation will occur to a pump not moving fluid at all. I am a firefighter and you always make sure water is moving through a pump. Even at idle the water will heat up and boil over a period of time if its not moving. My guess you have limited restriction somewhere. X2 on checking the pressure of the system and testing the thermostat.

 

[tag3]

Fan clutch?

 

[SUMMIT CRUISERS]

Fan clutch?

That was my guess until I saw where he

"***edited to add*** i forgot to mention the FAN is a fixed 8 blade type so that is all good."

 

[Chugging Along]

When you've tested everything and you don't find the problem, it's probably something that you have ruled out. It's simple enough to remove the thermostat completely as an experiment. I hope it's that simple.

However, your symptoms are the classic 'exhaust gasses getting into the coolant' from a bad head gasket. Overheating under load but not at idle. High pressure on the radiator hoses. Coolant blasting out of the radiator cap and the overflow tank. When you are idling, the pressure is lower and there is only a small amount of exhaust getting in there and the radiator can handle it, but when you run at higher speed, even though you have more air flow, the cooling system can't dissipate the heat. When he did the HC test, did he use a tailpipe sniffer or a block tester? You can buy and do a block tester test yourself. Also, one other thing to try sometime when the engine is cool (and preferably without the thermostat installed) is to warm the engine up with the radiator cap removed then rev the engine and look for bubbles in the antifreeze.
I hope I'm wrong here, but having seen a few bad head gaskets over the years, this problem sounds very familiar.

Wouldn't the exaust foul up the anti freeze and possibly discolor it?

 

[huminajumina]

I am curious about this exhaust leak into coolant theory as well, I am assuming that depending on where your gasket is leaking, you can get the exhaust into coolant without loss of compression or water in oil or smoke in exhaust ( of any color) ... just depending on where/how it starts leaking???

I am having the same exact problem on a '76 2F, but I just put it in so I never knew how hot it normally ran, and it is spitting extra fluid out as well...I will have more time to look over everything tomorrow, I'll try looking for bubbles under throttle tomorrow also

 

[Travis22]

1911 - I know the old hoses and thermostat were fine because as ive said right from the first post, i did replace them. IMO they did not need replacing / were not contributing to the engine running hot but were replaced given it was a convenient time, (well hardly convenient out the back of the caravan park in 40degC heat without any shade, but i wasnt going to risk murphys law right before heading into the desert) to do so and i had a full set of genuine Toyota ones on hand.

........................................

DP - I dont think this is related to the thermostat because i have tried 3 different thermostats. That is, the one that has been in their for the last 16years (genuine 85degC Toyota (185degF)) plus i also tried an off the shelf 'Terrain Tamer' 2F-3F thermostat which was stamped 88degC (190degF) then i found a Dayco 2F thermostat rated at 82degC (179degF)........... so i tested them all in a pot of boiling water and came to the conclusion they were all pretty bloody much the same. Hence i concluded the original one - 16year old Toyota thermostat was still operating perfectly, but given the Dayco one was stamped 82deg C i opted to install it 'just in case'.... It appears to function as it should and id say of the 7000km's ive done with the engine running warmer, its been in for around 1000km now. FWIW i have the rubber gasket installed on top of the thermostat too now...

(The 'original' one had the rubber gasket, but when i removed it at the caravan park while on the holiday and put the 88degC one in it was shagged and i wasnt able to get a new top rubber gasket in the town, so the 88degC thermostat ran without that gasket but when i got home i was able to get the top gasket so i opened it up again, then decided to try the 82degC thermostat so installed it with the gasket.)

None of this, has had any effect on the engine running temp. It has been pretty much consistent in its 'running hot' since the day it started, with the exception of that 'new' IMO faulty rad. cap which caused the 'tiny spray' from the rad. overflow bottle while i was running it.

While on the trip we found the engine temp reacted consistently with the ambient temp outside. If we got on the road very early before the sun came up we could travel for some time before the engine would start running hot. By midday as it started getting hotter and hotter the engine would get hotter and hotter etc.......... But, FWIW i doubt that would happen now with the new radiator as i think its that little bit more efficient.

.................................................

ed - The hydrocarbon test was done on the radiator. Twice. The mechanic has some sort of 'test tube' device which is fitted in place of the radiator cap. The engine is then started, idled, revved, and also put under some load... there is a chemical in the tube which is meant to change colour if any gasses are present in the cooling system. Again, the test was done twice while i was there and he couldnt get the chemical to change colour.

............................................

With regards to running the engine with the radiator cap removed to check for coolant flow etc... (ive read this many times) but i dont understand how it is possible. As soon as the coolant starts to warm up it starts to overflow...?????? What do you guys normally do, drain some of the coolant out prior to running the engine?

...............................................

CA - IMO yes id expect to see something in the coolant too if the combustion gas were mixing with it, but the coolant still looks and smells like new.

.............................................

With regards to the bypass hose on the waterpump, is there any 'test' i can do to make sure things are as they should be ie. Operating temp of the bypass hose? I didnt think to check its temperature when i was using the laser thermometer (IIRC once the thermostat is open it becomes HOT) but thinking about it later i wasnt sure if this was right... How does it work?

When the thermostat is closed the coolant is trapped in the engine block while the coolant in the radiator is being pumped around by the waterpump via that bypass hose. So they should all be reasonably cool.

Once the coolant in the engine heats up the thermostat opens, then what happens to the bypass hose?

FWIW, all the hoses pressurize... Including the bypass hose.

..................................................

As ive said im really looking for something, anything to be wrong so yesterday i was trying to look under the rocker cover through the oil fill cap hole with a flashlight... (yes, bugger all to see!) but from what i could see with the engine running i really cannot see any oil moving around in there. Should i? There is oil in there, but there isnt any 'streams' of moving / flowing oil that i can see via the little fill hole anyways.......?

Travis.

 

[desertpat]

"With regards to running the engine with the radiator cap removed to check for coolant flow etc... (ive read this many times) but i dont understand how it is possible. As soon as the coolant starts to warm up it starts to overflow...?????? What do you guys normally do, drain some of the coolant out prior to running the engine"?

It may be that some of the radiator tubes are restricted.
You should be able to remove the rad cap without excessive overflow. There might be some.
The water pump should suck it out of the bottom as fast as it returns the fluid to the rad at the top, but it seems that the rad can't handle the flow = restriction.
Sometimes crud from the block might plug a few rad tubes - that's why I flush and reverse flush engine and rad independently, and that's why I suggested doing a temp survey of the rad tubes.

Cruiser cooling systems have a pretty good volume and can work well cooling the engine when ambient is well above 50 deg C.
At least they do here - same temp summer and winter.

These tech threads are only good if you tell us all what you find in the end.
good luck

 

[edwjmcgrath]

If you want to watch the coolant flow (and look for bubbles), you should remove the thermostat and take out a cup or two of coolant.
That way you start with everything open and flowing and everything cool. When you start the engine, you should see the water begin to flow and you should not see bubbles. You should also not see the level rising until the engine is quite warm. As long as the coolant is not boiling, the level should not be rising very much. If you see bubbles or if the level of the coolant rises quickly, it's an indication that you are getting exhaust gasses into the coolant. You'll want to rev the engine during this test too.

I assume that your mechanic ran a compression leak down test. Another similar test you may want to run on your truck is a coolant system pressure test. This involves a gadget with a radiator cap and a pump on it. You replace the radiator cap with this gadget and pump the pressure up. You then leave it on and see if the pressure drops. If it does, that indicates a leak. A broken head gasket will often show up as a leak.

 

[Bigcity25]

Just want to check; did you burp your system after the coolant changes? Burping, consists of a cool engine and the cruiser sitting on an incline or lifted up in the front. Lots of areas air can get trapped and not allow coolant to move through. Take your radiator cap off and let the engine run. Once it heats it a little the t-stat will open and the air bubbles will travel to the highest spot in the system. This point is the top of the radiator escaping the system. Sometimes it takes a couple of sessions to remove the bubbles. Also what are the chances the water pump just crapped out on you and it's not flowing. I know it's new but there's always a chance something in there isn't working. Or maybe try a backflow kit to clean your cooling system out. The flow is always the same and scale builds in the direction of the flow. The backflow kit attaches to a garden hose and reverses the flow to knock the crude off the internals and flush it our of your engine.