max safe water temp (1 Viewer)

[colby1979]

Good idea, that will definitely help. Ive read were folks removed obstructions such as winches, lights and other stuff from the front to increase airflow and that brought temps down a few degrees.

Does your 75 have hood louvers? The turbo adds tons of radiant heat to the engine bay that helps heat soak the system.

 

[fitzmooney]

Mine is a HJ60.
Here are a few things to check.
Fan - Can you feel resistance when you turn it by hand?
Check for bubbles in the radiator with the engine running and up to temperature.
Thermostat may not be opening fully.
If it has been overheating the radiator may be blocked with debris from the engine.
Finally the water pump may be an after market one with pressed metal blades which have corroded away.

 

[coldtaco]

engine was rebuilt about 2yrs ago, turbo installed a year later.
fan has resistance, don't know what good or bad resistance would feel like.
couple of weeks ago got the rad redone, got a new core, the old did have some blockage
assuming got a new thermostat when rebuilt. I put a new one in two days ago, tested the old and seems to work fine
don't know what kind of water pump was used, new or old one put back in, assuming new one
I spaced the hinges to raise the rear of the hood up about 1/2 in

 

[fitzmooney]

Something is not right here. I would borrow or buy an IR temp gun to get another cross check on your gauges.
Have you checked the radiator for bubbles?
Take the cap off and run the engine until the thermostat opens. Run the engine at 1000rpm topping up with water to the top of the filler neck.
Then check for bubbles. If there is, then you have leaking head gasket.
There is also the remote possibility that an incorrect head gasket may have been fitted.

 

[GTSSportCoupe]

Something is definitely not right. Under those conditions the motor should have no problem running at whatever temp the thermostat opens at. A viscous fan clutch that is not working right (as mentioned above) could cause issues. However even with a fan not working i'd think it would run cooler.

To check your fan, pull off on the side of the road when it's at those high operating temps, Let the EGT's (turbo) cool down a minute and then shut the motor off. Get out and move the fan with your hand. At those temperatures, the internal mechanism will have moved the oil inside to the clutch surface and there should be a huge amount of resistance when you try to spin it. If there isn't, you can service it, or just buy a new Toyota OEM one.

Other checks you can do on the viscous fan, before you start your motor in the morning, spin the fan. It should spin free, then catch, then spin free, then catch. This is because all the silicone oil is settled into the bottom.

Then start your engine and let it run for a few minutes, but not long enough to warm up much. Shut it off and spin the fan. At this point, the fan should spin easily, as the internal mechanism is keeping the silicone oil out of the clutch surface.

 

[mudgudgeon]

At the speeds you mention, airflow without a Fan should keep temps under control IMHO.

Definitely worth checking the viscous fan hub, if it's 100%, it will help. But I think you have bigger problems.

I recently had overheating issues with my hzj105, changed everything, did a fan hub rebuild, replaced the fan hub, thermostat, rad cap etc. eventually cooked the motor and found I had a cracked head.

For what it's worth, I'd just replace the fan hub.
Finding the silicone oil was a PITA, I spent several hours stripping; cleaning, testing and adjusting the operation of the viscous hub, putting it back together I found the main o ring had stretched which made it hard to get it sealed. A week afterward and all the oil had leaked out and I had to replace the hub anyway.
The replacement was better than the one I re-oiled anyway. Can really hear it when it locks up.

 

[coldtaco]

Ok, took cap off and ran engine at 1100rpm till thermostat opened. Could not see any obvious signs of air bubbles.
Found two tubes of fan clutch oil, 6000ctsomethingoranother . From my reading seems I should have 3 tubes?
As to the fan, when cold it has a slight drag. When you start the fan is running at what seems full power then goes "off" I have never noticed the fan noise during driving, of course with all the other noises I don't know if I would be able to hear it come on.

 

[fitzmooney]

As stated above the fan air flow though the radiator at cruising speeds should be sufficient to keep it cool.
I would get it checked with an IR gun before you go any further.
Another way to check the water pump and radiator, is when you are doing the bubble check, make sure the radiator neck is full to the top and rev the engine.
If the level drops and then comes up again, the pump is working OK.
If the level overflows, you have blocked radiator.

 

[ozcrusier]

Have you guys got any dyno diesel tuners in Canada because having the engine tuned can save money in the long run.

 

[coldtaco]

checked fan after shut down, more resistance than when cold, don't know if enough don't have any prior knowledge of what it should be like.
removed radiator cap and set to 1100rpm then rev'd the engine and water level stayed the same.
I did try and take IR readings after warmed up and seems to be approx 20degrees cooler on the side farthest from the inlet/outlet.
Tomorrow I might try and do a flush, then remove the radiator and take it back. Then try and service the fan coupling.
No idea of how to tune a engine even if I could find a dyno.

 

[fitzmooney]

Take a reading at the top of the thermostat housing and compare it with your after market gauge.
I wouldn't start playing with the fan clutch as it appears to be working OK.
To flush it properly you have to get it up to temperature with the radiator cap off.
Then undo the top hose and heater hose that goes to the water pump and open the heater valve.
Also the engine and radiator drain plugs. Engine plug is below the turbo.
Then put your flush hose into the heater hose and flush until it comes clear from all outlets.

 

[coldtaco]

Took temp reading at water inlet and compared it to the after market temp gauge they are within a couple of degrees to each other.

 

[Tapage]

dude .. at 200F I'm pulling out and opening the hood to let it cool .. ( running engine ) or if I can, down shifting and let it run in compression ..

 

[Rock40]

I have several extra OEM fan clutches from an HDJ81. I don't know if they're the same but PM me if you want to give one a try.

 

[coldtaco]

"I have several extra OEM fan clutches from an HDJ81. I don't know if they're the same but PM me if you want to give one a try."
I will try and take some measurements to compare, thanks.

 

[coldtaco]

I took the rad back to the shop and had him change some things. He didn't to exactly what I wanted, so I was just gonna see what happened. The inlet pipe that is inside the top cap has a opening that is only a 1/4 the size of the pipe (on the side, the HZ rad I have is the same way). So he ended up opening the pipe to half open. Then he put a plate over the tubes about a 1/2in above the tubes to try and force more water to the far side. Don't know how he thought this would work out compared to my request. Oh well, so I drove it today on my test road, not very good for it though because of all the tourists that cannot drive the speed limit :-( Summer time in AK :-(.
My observations are as follows.
It took quite a bit longer for the temps to stable out at the same temps as before, so no real improvements from before. At 65mph it still climbed to 215F. So I figured I would go a head and try the long hill climb. This is about a 5mi climb with a level off about mid point, then a slightly steeper climb. I was able to keep 65mph easy up to the level off, but temps hovered at 218F. Then the last part of the climb the temps got to 220F, egts stayed at about 850F with boost around 11psi. So I backed off :-( and climbed the rest of the way at about 50mph and 4th gear, temps backed down.
I will pull the rad one more time and have him remove the plate and try that. If that does not help then I will look into trying to get a aluminum rad made that is as long as I can make it, will have to see how much longer I can make it, probably only about 2-3in longer. I haven't tried the ram air to the lower part of the rad, will try this after I get the rad back.
Frustrating to have enough power to climb just about all the hills but the water will not play nice :-(

 

[coldtaco]

put rad back in without doing anything else after all. I did install the fan/clutch I had for my 1HD-FT project to see what it does. When I was running the engine at 1100rpm to bleed the cooling system, the fan would come on when the water temp reached 180F, then off at about 170F, which the old fan/clutch did not come on. So that part was better. Today I drove it at sustained 65mph for about 60mi round trip. At flat sections water temp would be come up to about 210F then the fan would come on and water would drop to about 203F. Sections that had inclines, the water would get to about 215F before dropping down to around 208F. There is one short "steep" climb where I was able to keep the speed all the way up to the top but the water reached 220F, after cresting the temp slowly came back down to the 203F-210F range.
Working on making a scoop of some sort to get more direct air to the lower 4in of the rad to see if this will help any.

 

[GTSSportCoupe]

Try pulling your thermostat out completely and go for a drive. See how it does. I've boiled thermostats in pots of water before and they all act differently. They can have a huge impact on the operation of the cooling system. I run a high flow thermostat from an australian company called Tridon. Off ebay. Works very well.

 

[mudgudgeon]

I would suggest testing a tridon and new oem side by side on the stove top.

I've not been impressed with some tridon products. Rad cap as an example. I had a rad cap fail, tried tridon and ended up coughing up for oem because I wasn't happy with tridon one

YMMV

 

[coldtaco]

Ok, so I removed the thermostat. Driving around town it runs cooler than with a thermostat, which is to be expected. On hwy at 65mph it got up to about 210F driving outbound. on the drive back in it stayed around 205F. Don't know why the difference. So still seems to run hot even without a thermostat :-( I guess I just have to give up on beating the heat. In town it's no biggie, it's if I want to drive out of town with the truck that it will be a pain. Most of our roads have speed limit of 65mph. Then there is the problem of climbing hills, I got the power to climb most hills at 65mph but it get's too hot so I will have to climb hills at about 50mph and 4th gear. Just does not seem right.