I had a customer with an overheating 7 series Toyota (out of warranty) Informed Toyota. They sent free of charge a new counterweight with bigger air flow opening, a new radiator, new fan, fan shroud, ,fan pulleys and belts. New hood with vents installed. They sent a new hydraulic oil dipstick for a higher oil level (thus more cooling capacity.) They also paid the labor of installation. 7FGCU25

Be sure and check the hydraulic pressure and flow. Typically the Toyota trucks run very high - especially if you are running forklift attachments on them. Typical truck will kick out 28gpm, when the attachment only needs 10. This excess flow has a negative effect on the truck and often causes overheating.

A larger fan with more fins?
Lift Truck Manufacturers are doing much to reduce sound/heat to the operator and many units have a pretty airtight hood on the motor. This may not allow heat to dissapate as quickly and could aggrevate a problem.
Lift Trucks having a long run do allow for a greater air flow, but short trips don't supply as much of an airflow to the engine.

Zerex also manufactures a "super Cool" engine coolant which increases cooling system efficiency by 25%. It does not have antifreeze properties so make sure the truck is not subjected to subzero temperatures at any time.

No one has addressed the possible issue of an out of adjustment inching pedal wich is also a common cause of overheating. I have not seen a big problem with Toyota's overheating. One possible problem you may have is with the new 3 way cat they didn't have a heat shield at first. Now they do.

The first item I like to check is temperature differential between the radiator tanks. This checks cooling capacity of the radiator. The coolant may flow to quickly thru the radiator ( not giving the coolant enough time inside the radiator core to cool sufficiency ). There should be about 12-15 degree difference. A couple things come to mind while reading all the posts. Here in Arizona we are aware of the cotton type radiators. These do work well in an enviroment such as cotton gins or cotton processing. They still need to be maintained. But When we have an enviroment that has overheating issues. We will recommend at least a four core type radiatior. This will usually take care of any high heat problems here. When the ambient temperature reaches 115-128 degrees; as it does here in the summer, this type application can be severe.
Working for Yale dealership we have limited access to Toyota & Nissian units. But I believe these water pumps also have a bleed valve to bleed the air from the system. I would also check to make certain there is no air trapped in the water pump. This might cause reduced or no coolant flow. I hope this input is of some use.

Thanks for the reply. I'll check it out for future use.

The Evans NPG product is a waterless coolant, which besides being non-toxic, has a boiling point of 375 degrees vs. 260 degrees wih the standard coolant. It is a lifetime coolant as well. The coolant was tested in Yuma AZ by the army and will now be used in all new humvees manufactured for the armed forces starting this month. Has very good application in diesel trucks as well.

The Evans NPG product is a waterless coolant, which besides being non-toxic, has a boiling point of 375 degrees vs. 260 degrees wih the standard coolant. It is a lifetime coolant as well. The coolant was tested in Yuma AZ by the army and will now be used in all new humvees manufactured for the armed forces starting this month. Has very good application in diesel trucks as well.

Can you give us the details on the Evans Cooling product? I have not heard of it but it sound like old Wynn's Super Cool which was effective in the late 70's.

Gentlemen,

I am fully aware of the overheating problems that have occured with the Toyota and Nissan trucks. I have found a solution to the problem which is using a coolant manufactured by Evans Cooling.

I was able to confirm with some contacts on the inside at Toyota they did indeed have a counterweight design issue on a couple of the 7 series models. I would suggest anyone having cronic overheating problems on these units contact their dealer and discuss this issue with them

There are many reasons for overheating, some of which are covered in the previous discussions. Standard checks are fan belt, radiator cleanliness, fan shroud engagement and radiator cap for sealing. However, it is very important to keep the coolant mixture at the right concentration all year round, ensure that the transmission clutches are not slipping (operator driving practice?) and that if an attachment is fitted, the hydraulic flow from the truck might need to be reduced through a flow divider. Advancing timing slightly can also help significantly.

There are many reasons for overheating, some of which are covered in the previous discussions. Standard checks are fan belt, radiator cleanliness, fan shroud engagement and radiator cap for sealing. However, it is very important to keep the coolant mixture at the right concentration all year round, ensure that the transmission clutches are not slipping (operator driving practice?) and that if an attachment is fitted, the hydraulic flow from the truck might need to be reduced through a flow divider. Advancing timing slightly can also help significantly.

Have numerous customers with the new L series Nissans, not only getting raves about power and fuel efficiecy but have 0 over heating issues and 0 warranties to date. They have certainly raised the bar.

Listen to Liftman, check those corners under the shroud. Also, there is a dead air space directly in front of the fan hub that will clog and will go undetected. The radiator that LOOKS clean is not always clean and can sometimes only be detected when removed. Nevertheless, I think you have an air flow problem

Glad to hear you are having good results.
As I said, I heard they would not be as good, I have not had any experience with the new units.
I would not call Overheating a quirk but more a problem and it can be a very costly one if you are the one who has to pay the bill and try to run a company with all that that includes.
Unfortunatly the Hysters here are not getting very good results and also have overheating issues and require holes and slots in the hoods to try to minimize the issue.

I have found the same thing here, Hysters Toyotas and Nissans all at the same location, only the Toyota's overheat. All forklifts have quirks, Toyota's seems to be heat management.

Have quite a few New L model Nissan's with "0" heating issues; unless you had an example of heating issues why would you suggest they do? Also have older Hysters that do not overheat, only the Toyota's.

I disagree on the comment on the new Nissan's, the changes to the new Nissan are not simply cosmetic and shape. This new engine has significant improvements, they changed the routing of the coolant flow to create a more even temperature dispersion, the water pump and fan blades have been modified to increase coolant and air flow. This engine through managing heat, has provided some astoundingly low emissions, and fuel consumption while increasing performance substantialy.
If you don't believe me, try a fuel consumption test, it will blow your mind.