Over heated going up a steep 5 mile grade (1 Viewer)

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I have a 97 with 170,000 miles. Truck has never had a heat issue until yesterday. I drove to the mountains and on a steep 5 mile grade the AC stopped blowing cold and the temp gauge (normally runs dead center of the gauge) was halfway between center and red. As soon as I topped the grade temp came back town to normal and had no probs on the hour and a half ride home.

Fluids are good and no leaks, Flushed a couple months ago and rear heater bypass was done. Ive had the truck a year and its completely stock. Any suggestions on where to begin on trying to avoid this from happening again. I have been reading thru fan clutch threads but more than a bit confused
 
I went through cooling issues when I first bought my 80 too.
Ask yourself a few questions;
Do you have any thing obstructing the radiator?
How old is the radiator? Even though it might not be leaking, it could be clogged/corroded up enough to limit optimal cooling.
Are the cooling fins all straight, clean and clear of dirt, mud and dead bugs?
Is my fan clutch engaging?

I first had to remove my lights for better cooling. I later modified an old blue hub fan clutch by adding 10,000CST oil and added hood vents in order to put the 10" lights back on while keeping coolant temps normal.

Hope that helps. Good luck!
 
Half way between center and red is a non issue especially when pulling a grade. Well within normal. If you are concerned start with fan clutch.
 
Oil analysis time too...
 
FWIW my opinion is it was probably the transmission heating up so much that it heat soaked the radiator and therefore coolant. Assuming you check all the usual suspects. These transmissions are slushboxes. Strong and have big internals. I have encountered this same issue. Did you have the OD off ? I have 35's on stock gears and on long steep grades I will put in 2nd and keep rpm up around 3-3500 and go at that speed. This keeps heat out of transmission as best as possible. But the converter is not locking up like this and can drastically heat up the trans fluid. I'm actually going to try adding an additional cooler as I have a spare stock cooler from a part-out I did just to see if it brings the temps down.
 
I went through cooling issues when I first bought my 80 too.
Ask yourself a few questions;
Do you have any thing obstructing the radiator?
How old is the radiator? Even though it might not be leaking, it could be clogged/corroded up enough to limit optimal cooling.
Are the cooling fins all straight, clean and clear of dirt, mud and dead bugs?
Is my fan clutch engaging?

I first had to remove my lights for better cooling. I later modified an old blue hub fan clutch by adding 10,000CST oil and added hood vents in order to put the 10" lights back on while keeping coolant temps normal.

Hope that helps. Good luck!

Nothing obstructing the radiator, radiator looks to be original and not many dead bugs....did find a mud dobber had built a nest on it and cleared it yesterday and washed out the fins as best I could.......The original owner was a "its a toyota, no need for PM" kinda guy so I doubt it was ever flushed before I got it. I just ordered a new aisin fan clutch off amazon to give it a try.
 
FWIW my opinion is it was probably the transmission heating up so much that it heat soaked the radiator and therefore coolant. Assuming you check all the usual suspects. These transmissions are slushboxes. Strong and have big internals. I have encountered this same issue. Did you have the OD off ? I have 35's on stock gears and on long steep grades I will put in 2nd and keep rpm up around 3-3500 and go at that speed. This keeps heat out of transmission as best as possible. But the converter is not locking up like this and can drastically heat up the trans fluid. I'm actually going to try adding an additional cooler as I have a spare stock cooler from a part-out I did just to see if it brings the temps down.

I hadn't thought about the tranny heat, it was a very winding road and the tranny was working hard, its also the only fluid that hasn't been flushed and replaced with syn. I didn't take it out of OD but I dont think we hit OD but it was stupid of me not to turn it off. I think im gonna order amsoil tranny fluid and do a flush and replace the filter along with replacing the fan clutch and see what happens
 
Half way between center and red is a non issue especially when pulling a grade. Well within normal. If you are concerned start with fan clutch.

I just ordered the aisin off amazon
 
Considering the monster transmission cooler that is on all US market rigs, I would not really think transmission heat soak to be a big problem. IIRC, that is considered part of the Towing Package. Lots of us have upgraded the silicone fluid in the fan clutch, even in new Blue ones.
 
I doubt trans. heat would cause such a rise as you were probably in 3rd gear most of the way up your grade but any thing is possible. Especially, if you trans fluid is old.

While driving on soft beach sand recently, I have seen 250+ degrees F coming out of the transmission going to the radiator cooler and my coolant temps never rose above approx 205-210 degrees F (as read by my ScanGauge II, OBDII reader).
Not a bad idea to change you ATF fluid and filter though. Should be done about every 30,000 miles or so to keep your transmission in optimal condition.
 
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give the block and rad a good flushing using some parts store rad cleaner, test to see your fan clutch is working properly or just replace. I see no reason for an "oil analysis" in this situation.
Oil analysis? For the money, there is no simpler and easier and smarter means to know the health of an engine. IMO, it's a no-brainer. I know I beat the horse with this. Blackstone and a good A&P mechanic identified an impending engine failure in an airplane I regularly fly in. Furthermore, my first 80 had no signs of HG failure when I bought it other than a weepy radiator. But, especially for the money, I wanted to do some real baselining particularly with the age of that long cast iron block and aluminum head. Sure enough, there was enough potassium in my oil to indicate that my gasket was on its last legs. I didn't want to get stranded in some US-Mexico border crossing with an overheating or fully blown gasket. And, oil analysis gives you so many different measures other than coolant levels. Let's say the OP's engine suffered zero damage and is in fine running condition, then oil analysis is SO much cheaper, faster and easier than removing the thermostat, buying parts store rad cleaner, and flushing the block and rad. If it's showing signs of HG failure then that flush is a complete waste of time and money.
 
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Oil analysis? For the money, there is no simpler and easier and smarter means to know the health of an engine. IMO, it's a no-brainer. I know I beat the horse with this. Blackstone and a good A&P mechanic identified an impending engine failure in an airplane I regularly fly in. Furthermore, my first 80 had no signs of HG failure when I bought it other than a weepy radiator. But, especially for the money, I wanted to do some real baselining particularly with the age of that long cast iron block and aluminum head. Sure enough, there was enough potassium in my oil to indicate that my gasket was on its last legs. I didn't want to get stranded in some US-Mexico border crossing with an overheating or fully blown gasket. And, oil analysis gives you so many different measures other than coolant levels. Let's say the OP's engine suffered zero damage and is in fine running condition, then oil analysis is SO much cheaper, faster and easier than removing the thermostat, buying parts store rad cleaner, and flushing the block and rad. If it's showing signs of HG failure then that flush is a complete waste of time and money.


I think the whole "oil analysis" thing here on mud is overblown. That's my opinion, so just take it as that. I am not saying it might not be a useful tool but it may very well of been that your land cruiser would of gone many more miles just fine even though it was showing some coolant in the engine oil. Mud OCD.

Personally I think a good compression and / or leak down test is going to tell you more about the health of your engine. If it runs well and has good compression just drive it and have fun. Everyone is so freaked out about their PHH and head gaskets.

In his particular situation (warm on a hill), note I said warm and not overheating as he actually never did "overheat", it was a cooling issue and I don't see the value in doing a lab test on engine oil. His symptoms point to something in the cooling system not working correctly.

Now if he would of had a large loss of power or was losing coolant somewhere that could not be identified then an oil analysis might make sense. another easier way to check to see if there is gasses in your coolant system is a rad gas tester thingy, available at any parts store to loan for free.
 
I hadn't thought about the tranny heat, it was a very winding road and the tranny was working hard, its also the only fluid that hasn't been flushed and replaced with syn. I didn't take it out of OD but I dont think we hit OD but it was stupid of me not to turn it off. . . . .

another option is to downshift on steady and steep inclines
 
Oil analysis? For the money, there is no simpler and easier and smarter means to know the health of an engine. IMO, it's a no-brainer. I know I beat the horse with this. Blackstone and a good A&P mechanic identified an impending engine failure in an airplane I regularly fly in. Furthermore, my first 80 had no signs of HG failure when I bought it other than a weepy radiator. But, especially for the money, I wanted to do some real baselining particularly with the age of that long cast iron block and aluminum head. Sure enough, there was enough potassium in my oil to indicate that my gasket was on its last legs. I didn't want to get stranded in some US-Mexico border crossing with an overheating or fully blown gasket. And, oil analysis gives you so many different measures other than coolant levels. Let's say the OP's engine suffered zero damage and is in fine running condition, then oil analysis is SO much cheaper, faster and easier than removing the thermostat, buying parts store rad cleaner, and flushing the block and rad. If it's showing signs of HG failure then that flush is a complete waste of time and money.


It had signs you just couldn't tell because of the leaky radiator.

If you had fixed your radiator you would have still been losing coolant which would have been a sign you had a gasket issue.

Not saying an oil analysis is ever a bad idea but if you aren't losing coolant then its not needed IMO.
 
Nothing obstructing the radiator, radiator looks to be original ...

Original radiator, likely time for replacement? We have been impressed with the performance of the TYC 1918.

... I just ordered a new aisin fan clutch off amazon to give it a try.

Depending on where/how the rig is operated, the blue hub may not be enough. If it still has the original clutch, with a little work maybe a better unit.
 

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