Thread: What is an acceptable coolant temp for a Defender 300tdi?

Originally Posted by Dougal

Is 100C a problem?

It is when you are only just maintaining 100c by nursing it any push and it climbs further, and that on flat roads! A larger cooling system could still have the operating temp at 90c, but deal with load and ambient temp better.

Do you think a 2070kg truck should go over 100c maintaining the speed limit, what would I have reached if towing my trailer on a hot day up this range? And that is with no AC condesnsor in front, a lower cracking t/stat and a large vent cut in the left guard.

Originally Posted by uninformed

It is when you are only just maintaining 100c by nursing it any push and it climbs further, and that on flat roads! A larger cooling system could still have the operating temp at 90c, but deal with load and ambient temp better.

Do you think a 2070kg truck should go over 100c maintaining the speed limit, what would I have reached if towing my trailer on a hot day up this range? And that is with no AC condesnsor in front, a lower cracking t/stat and a large vent cut in the left guard.

I see your problem now.

Have you got a flow/pump problem or problem with the flow bypassing the radiator?
I'd rig up a thermometer lead in the engine bay you can shift from place to place. Put it on each radiator tank in turn and see if you are getting that 100C water to the radiator and if the radiator is cooling it down enough on the way through.

IMO it is a common problem that most dont know about as the stock gauge masks it. I still had this problem when I installed a brand new 2.8tgv with brand new t/stat and brand new radiator. (t/stat was changed for another to rull it out)

Maybe my 2 inch spring lift does not help? Maybe my low profile winch and winch bar does not help? But these are common items that should be able to be installed without pushing the limit to failure.

The LR Defenders need the A/C fan as the stock viscous and engine bay air flow will not push enough air through the radiator.

Installing the 82c t/stat made a small difference. Cutting the vent hole made a greater difference.

Remember the LR radiator is only 2/3 width of grill. I doubt many small trucks/4x4 have a radiator as small as LR.

Originally Posted by uninformed

IMO it is a common problem that most dont know about as the stock gauge masks it. I still had this problem when I installed a brand new 2.8tgv with brand new t/stat and brand new radiator. (t/stat was changed for another to rull it out)

Maybe my 2 inch spring lift does not help? Maybe my low profile winch and winch bar does not help? But these are common items that should be able to be installed without pushing the limit to failure.

The LR Defenders need the A/C fan as the stock viscous and engine bay air flow will not push enough air through the radiator.

Installing the 82c t/stat made a small difference. Cutting the vent hole made a greater difference.

Remember the LR radiator is only 2/3 width of grill. I doubt many small trucks/4x4 have a radiator as small as LR.

This is a disco solution I found to the needle problem, but it might apply to yours too: Google Translate

I think some quality time with a thermometer you can read while driving will show the best areas to improve. It's very easy to spend time applying fixes which will help a little but not solve the actual problem.

The three big questions would be:
1. Coolant flow through the radiator.
2. Airflow through the radiator.
3. Fan.

I'd go for the radiator outlet tank tempearature first. If that's hot then the radiator isn't getting the heat out.
If it's cold, then you don't have enough water flow through.

My Defender is getting older and towing on long trips the standard gauge gets up towards the red. I wonder if the radiator is getting old as most cars this age have probably had them replaced, so am contemplating an Allisport radiator for better cooling when towing.

On other threads some have modified the bleed hole in one of the tanks, not sure if this will help.

Jeff

Well folks I am happy to report that I just completed an 80km highway test in 30 degree heat. Coolant temp on the VDO gauge stayed at 90 degrees. Even when pushed to 110km/hr up a hill only rose to 91 or 92.

I am happy now...highway temps have dropped by nearly 10 degrees!!

Sorry about the picture quality...the whole multitasking thing is not one of my strong points

Originally Posted by 86mud

Well folks I am happy to report that I just completed an 80km highway test in 30 degree heat. Coolant temp on the VDO gauge stayed at 90 degrees. Even when pushed to 110km/hr up a hill only rose to 91 or 92.

I am happy now...highway temps have dropped by nearly 10 degrees!!

Sorry about the picture quality...the whole multitasking thing is not one of my strong points

What did you change?

Well Wednesday I installed new radiator, new viscous fan, new larger air con fan and new coolant. I only got a chance to drive around the streets at 60kms/hour that night.

Out on the highway was where I was previously really worried about coolant temps around 100 degress, so today was the first time I had a chance to drive at 100km/hour since installing new radiator etc.


Difference is huge!