2.5L Diesel Overheats While In Neutral With A/C Running...

[Ahnsahn]

Two interesting points here.

If the radiator has been replaced, it could possibly have been replaced with one of a smaller capacity, and therefore being under-dimensioned for your engine.

Also you mention having changed the thermostat twice. You should be able to buy a thermostat that opens up fully at a lower temperature. I don't remember the range on top of my head, but it's usually something like 68 to 72 degrees Celsius. So why not look into getting a thermostat that opens up at the bottom of the range, somewhere around 68 degrees. You might currently have one that opens at a higher temperature.

As I noted earlier, the thermostat I removed from the engine was a 82 degree model. I just referenced the Toyota service manual again and it stated: "The thermostat in this engine operates at a temperature of 88 degrees".

Would using a 82 degree thermostat (in place of a 88 degree model) affect this overheating problem in any way?

Could be a few things, viscous fan coupling came to mind as not responding, but l feel the rad replacement could have less veins than it should have to flow and cool the water.

I hope a larger radiator or even a new water pump solves this problem.....or even another fan.......

[transam]

Two interesting points here.

If the radiator has been replaced, it could possibly have been replaced with one of a smaller capacity, and therefore being under-dimensioned for your engine.

Also you mention having changed the thermostat twice. You should be able to buy a thermostat that opens up fully at a lower temperature. I don't remember the range on top of my head, but it's usually something like 68 to 72 degrees Celsius. So why not look into getting a thermostat that opens up at the bottom of the range, somewhere around 68 degrees. You might currently have one that opens at a higher temperature.

As I noted earlier, the thermostat I removed from the engine was a 82 degree model. I just referenced the Toyota service manual again and it stated: "The thermostat in this engine operates at a temperature of 88 degrees".

Would using a 82 degree thermostat (in place of a 88 degree model) affect this overheating problem in any way?

Could be a few things, viscous fan coupling came to mind as not responding, but l feel the rad replacement could have less veins than it should have to flow and cool the water.

I hope a larger radiator or even a new water pump solves this problem.....or even another fan.......

The engine should run cooler with an 82 if the rad and pump are doing their job.

[MTH]

Two interesting points here.

If the radiator has been replaced, it could possibly have been replaced with one of a smaller capacity, and therefore being under-dimensioned for your engine.

Also you mention having changed the thermostat twice. You should be able to buy a thermostat that opens up fully at a lower temperature. I don't remember the range on top of my head, but it's usually something like 68 to 72 degrees Celsius. So why not look into getting a thermostat that opens up at the bottom of the range, somewhere around 68 degrees. You might currently have one that opens at a higher temperature.

As I noted earlier, the thermostat I removed from the engine was a 82 degree model. I just referenced the Toyota service manual again and it stated: "The thermostat in this engine operates at a temperature of 88 degrees".

Would using a 82 degree thermostat (in place of a 88 degree model) affect this overheating problem in any way?

Could be a few things, viscous fan coupling came to mind as not responding, but l feel the rad replacement could have less veins than it should have to flow and cool the water.

I hope a larger radiator or even a new water pump solves this problem.....or even another fan.......

Sorry I was a bit low in my initial statement about when the thermostat should open. Either way, an 82 degree Celsius, would open earlier than an 88 degree and therefore provide more cooling for your engine. So if you're going to replace the thermostat, don't go up in degrees.

As for the radiator, it could be under capacity, as you mention it has been replaced by the previous owner. Some cooling fins could have deteriorated, or there might be dirt clogged up between some of the fins preventing air to flow and cool it properly.

Water pump could also be a culprit, even though it's not leaking, the impeller could be corroded and therefore not pumping enough water through the system.

The radiator cap could be faulty, and therefore not keeping the correct pressure in the system, but letting water overflow to the expansion tank too early.

And yes, there could be some problems with the fan, but you seem to have already tested that it works properly.

[Kwasaki]

We are running out of ideas here so has you truck/car got an ECU, if so sensors or connections to to sensors could be at fault.

[MTH]

Of course the sensor could be off, however if the problems only occur at long time idle or during high load in steep terrain, then a sensor problem is probably not what to look for.

Then again, it's a very cheap an easy part to take out of the equation.

[Kwasaki]

Of course the sensor could be off, however if the problems only occur at long time idle or during high load in steep terrain, then a sensor problem is probably not what to look for.

Then again, it's a very cheap an easy part to take out of the equation.

Well his problems aren't solve yet so many questions have to asked in the process of elimination.

Sorry with respect you are incorrect if sensors are not read correctly by the ECM ( ECU ) ( PCM ) assuming he has one then the 2 situations where the engine overheats could occur.

The other question would be, if it has a ECM was it adjusted and compatible with the re-con engine.

Adjusting fuel supply etc, the air intake temperature the coolant temperature at idle or under load could cause the problem.

Regardless off what people say oil pump and pressure can contribute to this type of problem as well.

I would of said that the fan is OK even if it was only checked with a book.

He has already eliminated the thermostat.

What type of ECU, is it compatible is it set up right.

The radiator efficiency still to be resolved.

The water pump efficiency also.

The oil pump efficiency

All these things have to be checked out.

Edited November 26, 2011 by Kwasaki