1hz overheating up hill and at 100kms (1 Viewer)

Joined
Feb 25, 2020
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11
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Australia
Basically as the tital says. My rj70 bundera with hzj75 firewall forward (panels and motor changed) is getting to 90 to 95 degrees when going up longish hills or slight uphill at 100kms. Highest temp I've got to has been 97 degrees. Pulled over let it cool down at idle.

Has no issue at speeds under 80kms unless it's a long laboring hill that slows the car down.

Looking for what to test next or pay to get done. as I'm conserned I'll cook it on a long drive.

Things I have done so far:
New upper and lower radiator hoses.
New genuine thermostat.
New adrad 4 core radiator. And cap
New toyota red coolant
Flushed engine block with hose and no thermostat until water run clear. (No chemical flush just water)
Second hand genuine clutch fan off known hzj75 with no cooling issues. (Tested fan when car running at 90 degrees after a hill pull over open bonnet shut off motor and fan stops instant and is tight.)
Removed spot lights from in front of radiator.(No difference)
Removed a.c. condenser from in front of radiator.
No oil in coolant / coolant in oil. Oil is clean
No bubbles in radiator running with no radiator cap.
Not loosing any coolant from system.
New fuel filter and prefilter
New air filter.
New oil filter and oil.
No blow by. (Upside down oil cap check)
Aftermarket temp gauge checked against calibrated gauge and is correct.
Has good oil pressure both factory gauge and aftermarket.

Other changes since the motor transplant from hzj75 at 255kms:

3" stainless snorkel into factory airbox
2.5 " exhaust and extractors with factory muffler.
34" tyres and diff ratio change from 4.11 to 4.3
2400 rpm at 100kms 5th

Is it worth looking into pump / injectors
Or is the problem more likely to be head / pre combustion chambers? Any thing else to check myself before paying to fix? Water pump has done less than 10k. Wanting to turbo once heating issues are resolved.

Thanks all in advance
 
Joined
Jul 22, 2003
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18,230
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Perth Western Australia
Does it still have the tunnel on the radiator? 97c is not that bad. I used to let mine get up there all the time. You know the thermostat doesnt open till 88c?
If its making black smoke, turn the fuel down.
Dropping back to 4th gear cools them down.
 
Joined
Feb 25, 2020
Messages
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Location
Australia
Does it still have the tunnel on the radiator? 97c is not that bad. I used to let mine get up there all the time. You know the thermostat doesnt open till 88c?
If its making black smoke, turn the fuel down.
Dropping back to 4th gear cools them down.
Yea still have the radiator shroud. It has the 76 deg thermostat sits at 82 for normal driving I'm assuming this is where the thermostat is open. I've noticed a small amount of black smoke, need to check at higher speeds and up hill. Are these motors good to sit at higher rpm in 4th. I haven't noticed any temp change between 4th and 5th both gears let the temp creep up on slight up hills at 100kms. I wouldn't think cooling a 96kw diesel would be this big of a problem. Everyone says they run hot. I think adding a turbo is only going to make it worse.
 
Joined
Feb 25, 2020
Messages
11
Location
Australia
Higher as in below 3000 rpm.
Higher rpms allows more air to pass through the engine.
The other thing to check is radiator pressure. You should have nice firm radiator hoses when fully warmed up.
Yea hoses are good pressure at temp worried there is to much pressure at 95 plus degrees. Rpm would be bellow 3000 in 4th at 100. Just seems like a lot when driving
 
Joined
Jul 22, 2003
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Perth Western Australia
1HZ can sit on 2800 all day. Ive done a few 1000-1500klms a day trips through the northern Goldfields and Pilbara at that rpm. You know when they are going too fast when some fresh oil suddenly appears in the air intake tubes. I think I got mine from overtaking 2 road trains at a time at a 130 :grinpimp:
Most of the time I do 110-115, but hills should be cut back to 100 in 4th.
My coolant at the outlet was around 90-100c most of the time . Maintaining pressure is the most important thing IMO.
I think you are doing everything right.

If it makes you feel better, Range Rover v8s are run at a 120c for 24hours under load on a test bed at the factory
 
Joined
Jan 8, 2004
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Johannesburg
Did this change suddenly, or did you change something before this happened, like a temp guage that actually reads temperature???

Not trying to be funny but yes, if you are sure that it always climbed the same hill at the same speed in the same ambient, in the same gear at lower temperatures, and then suddenly went up to 97, then it may be something that broke or gets stuck, but just touching on 97 during a steep climb, especially if you don't change down, is not that bad, and should not kill your engine.
 

Indestructible 47

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Are you sure that your facts are correct? 1hz on a hill pulling 100km/h???

I would check the tune. An old trick on the mine cruisers was to wind the fuel screw and that gave the motor way more fuel and therefore power. Being mine cruisers, the blokes didn't give a stuff about them and ran them hard all day. If your motor is getting to much fuel, it could make it hot under excessive load. That's my bet.
 
Joined
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Australia
1HZ can sit on 2800 all day. Ive done a few 1000-1500klms a day trips through the northern Goldfields and Pilbara at that rpm. You know when they are going too fast when some fresh oil suddenly appears in the air intake tubes. I think I got mine from overtaking 2 road trains at a time at a 130 :grinpimp:
Most of the time I do 110-115, but hills should be cut back to 100 in 4th.
My coolant at the outlet was around 90-100c most of the time . Maintaining pressure is the most important thing IMO.
I think you are doing everything right.

If it makes you feel better, Range Rover v8s are run at a 120c for 24hours under load on a test bed at the factory
Thanks for the info not used to seeing temps that far above the thermostat. Not going to be a good tow car if it gets hot under it's own weight. What you say about outlet temp makes sense as I've removed my a.c. and the a.c. shut off sensor is in the outlet and that's where I put the temp probe for the gauge
Did this change suddenly, or did you change something before this happened, like a temp guage that actually reads temperature???

Not trying to be funny but yes, if you are sure that it always climbed the same hill at the same speed in the same ambient, in the same gear at lower temperatures, and then suddenly went up to 97, then it may be something that broke or gets stuck, but just touching on 97 during a steep climb, especially if you don't change down, is not that bad, and should not kill your engine.
I bought a hzj75 troopie as a donor for the motor and gearbox and front guards. This went into my bundera. I'm now getting this car setup for some decent trips. I have fitted an aftermarket water temp gauge. Yes it's only touching on those temps up hills. All ambient temps have been between 20 and 30 degrees temps up the same hill vary from 90 to 97 depending on how hard I hit it. I'm just reluctant to take it any further than an hour down the highway with the water temp going all over the place. Don't think it should be creeping up on the highway at 110 every time the ground isn't down hill with no load. Just seems something is not right.
 
Joined
Feb 25, 2020
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Australia
Are you sure that your facts are correct? 1hz on a hill pulling 100km/h???

I would check the tune. An old trick on the mine cruisers was to wind the fuel screw and that gave the motor way more fuel and therefore power. Being mine cruisers, the blokes didn't give a stuff about them and ran them hard all day. If your motor is getting to much fuel, it could make it hot under excessive load. That's my bet.
Lol they are two separate occurrences. I'm not pulling 100 up a hill. But anything not completely flat at 100 and it will slowly creep up as soon as accelerating from 80. I don't think my fuel screw is "sent" it still has the tamper tag but I'm not completely against it being to rich. If it is rich and i kept the throttle out under load would it still get hot. It doesn't seem much better if I feather it up the hill at lower speeds
 
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:beer:I ran a B engine in an old Land Rover for many years. One mistake I made was to put a high quality VDO direct temp guage in. Now I know why Toyota damp their guages down so much, probably too much because they are sometimes too slow to catch an over heat situation. But the direct guage was all over the place, you could see the thermostat coming in and out all the time. The only time it was smooth was on long uphills with the thermostat fully open. That when it all becomes very real, and its down to a well maintained system, air flow gearing ect. I don't believe that you have a temp problem, but do all the checks first and remember that my opinion is only worth what you paid me for it.:confused:
beer[1].gif
 

Squash

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You worry to much, a pressurized, glycol infused cooling system will easily handle over 100 C.
I've seen our mining trucks run uphill at +15 percent grades reach consistent 110 C.
I'm talking 15km of uphill.
I love your concern, but don't worry so much.
 

Gun Runner 5

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When I first bought my 77 Series (my first experience with a 1HZ) I had a pyrometer installed. I ran the Cruiser for several months normally aspirated before I followed up with a turbo and Intercooler. On even the mildest of inclines, if I tried to hold speed, the temps would increase rapidly. As those temps went up, the water temps would follow right along. (In the interest of full disclosure, I was running an automatic transmission)
It became clear that I had two options. Back out of the throttle on inclines or install a properly tuned turbo / Intercooler.
 

GTSSportCoupe

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From what I've seen, as long as you own an indirect injection diesel, heat will be a challenge when the engine is fully loaded. Many things can be done to reduce the effects such as bigger fans, bigger radiators, high flow t-stats, etc. But it's always a challenge. Putting a turbo on usually makes it worse. Learning to drive within the limits of the motors is usually what it comes down to. Drive slower up hills to reduce the load, which in turns will reduce coolant temps. All the above advice is excellent. Personally, my next diesel will be direct injection, as they don't seem to have heat issues.

The only thing that worries me on the IDI engines when the coolant temps start getting up there, is localized boiling around the pre-cups. This causes vapor barrier issues and can lead to localized overheating of the cylinder head. Which eventually leads to a cracked cylinder head. As I get my motor regularly too hot while towing, I've gone to a waterless coolant to prevent this localized boiling. My boiling point is now 180C. Thing that sucks about the waterless coolant is it doesn't transfer heat as well as water. So total coolant temps are a bit higher; however at least the cylinder head is at an even temperature - reducing the stress on it, and chances of cracking.
 
Joined
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Rotoiti, New Zealand
Another thing that is often overlooked with radiator swaps is to make sure your fan shroud is well fitted & sealed against the rad. That would tend to cause issues with slow going not highway speeds though.

Cheers
Clint
 
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Another thing that is often overlooked with radiator swaps is to make sure your fan shroud is well fitted & sealed against the rad. That would tend to cause issues with slow going not highway speeds though.

Cheers
Clint
Thanks Clint I've checked the fan shroud seals every bit as good as the factory radiator. Still has the foam around it
 
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I would still be looking at the fan?
easy to modify with little cost of about 15 bucks and 1hr of your time?
mine engages so hard it makes my prado go gutless, makes a big fan noise when engaged that I can hear over my whistley roof racks and 3" exhaust
I thrash the crap out of mine and the hottest it gets is 94degC
Flat to the floor up big hills with way overloaded trailers and stuff on, I usually pull the wastegate hose off if I have overloaded the prado to much just to help with egts a bit-plus Im a bit of a wrecker
On a completely different vehicle my brothers turbo safari also was getting hot even after a new radiator,genuine viscous fan hub etc, used up the last of my 10,000cst oil and overfilled the hub, makes a huge difference, almost runs to cold now
 
Joined
Feb 25, 2020
Messages
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Location
Australia
I would still be looking at the fan?
easy to modify with little cost of about 15 bucks and 1hr of your time?
mine engages so hard it makes my prado go gutless, makes a big fan noise when engaged that I can hear over my whistley roof racks and 3" exhaust
I thrash the crap out of mine and the hottest it gets is 94degC
Flat to the floor up big hills with way overloaded trailers and stuff on, I usually pull the wastegate hose off if I have overloaded the prado to much just to help with egts a bit-plus Im a bit of a wrecker
On a completely different vehicle my brothers turbo safari also was getting hot even after a new radiator,genuine viscous fan hub etc, used up the last of my 10,000cst oil and overfilled the hub, makes a huge difference, almost runs to cold now
I'm thinking of going past toyota and getting a bottle of fluid and doing a top up. I'm not hearing the fan come on not sure if it's because of the bighorns or the exhaust. Like you say for 1hr of my time could be something could be nothing. Worth a shot
 

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