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Home > Puma (Tdci) > Overheating in 6th gear going uphill (SOLVED)
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Greyman110



Member Since: 29 Sep 2017
Location: London
Posts: 327

United Kingdom 
Thanks!

This is the number one suspect at the moment and it’s cheap and easy to do so fingers crossed it makes a difference.
Post #866366 9th Nov 2020 7:32pm
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Greyman110



Member Since: 29 Sep 2017
Location: London
Posts: 327

United Kingdom 
UPDATE

Heating valve changed. It did make a difference, however hasn’t completely solved it.

After changing and topping up the coolant I did a drive which took about an hour and included motorways. I drove with the temp on cold.

Generally the temp stayed within the working limit 87-105c. Pulling off at lights generally saw the temp go down. Hard acceleration the temp would start to go up before settling back down.

I drove in 6th up hill at 50mph in a place I know where I have had the fuel cut off before and it was fine holding temp at mid 90’s.

All was looking good until I really pushed it hard through all gears going from 30 to motorway speed. I had the same issue happen - the temp climbed and fuel cut off for a few seconds.

Now the caveat to that is that I don’t normally drive this car as hard as that but for testing I wanted to see how it was. Throughout the rest of the drive, while I drove it a little harder than I would normally, it behaved absolutely normal.

I’ll check the coolant level today as it would have released some from the cap and I’ll test it out doing a longer motorway drive when I have a work-related trip.

Overall changing the valve has made a big difference. I’ll have a look through the nanocom in case I need to reset something but at the moment I feel like I’m close to solving this problem.

One thing I’m curious about - how long should pressure be stored the coolant system for? If I take my cap off 24 hours after my last drive, I still get a big hiss. I don’t remember that happening before but then I have been checking more in the leat few months!
Post #867261 14th Nov 2020 10:32am
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 17372

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
I can take the cap off several days after using the vehicle and still get the hiss, all that tell me is that the system isn't leaking under pressure and it is, I feel, a very good sign.
Post #867270 14th Nov 2020 11:50am
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Greyman110



Member Since: 29 Sep 2017
Location: London
Posts: 327

United Kingdom 
That’s good news then!

I’m now looking at changing the water pump. Apparently the spline wears and doesn’t drive it properly. Usually works fine on the flats and you’d only notice a difference going uphill!
Post #867271 14th Nov 2020 11:58am
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Greyman110



Member Since: 29 Sep 2017
Location: London
Posts: 327

United Kingdom 
All parts ordered from Paddocks so should arrive this week.

Thanks Blackwolf for the info on O rings and gaskets required.

I’ve gone for the pump and connector assembly which I think is Britpart.

Think I might need to get some ramps or axel stands for this one. Also does anyone know if I’d need to remove my steering guard?
Post #867656 16th Nov 2020 7:45am
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Kevlar



Member Since: 28 Oct 2020
Location: Prague
Posts: 78

Czech Republic 2010 Defender 90 Puma 2.4 SW Santorini Black
Hey Greyman, if you are only changing the coolant pump, you wont need ramps or stands.
The pump can be removed from above access.
Post #867719 16th Nov 2020 2:41pm
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 17372

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
You may find that it helps if you stand on the ramps or axle stands - it makes it easier to reach down into the engine bay to get to the water pump! Rolling with laughter
Post #867761 16th Nov 2020 6:17pm
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Greyman110



Member Since: 29 Sep 2017
Location: London
Posts: 327

United Kingdom 
Rolling with laughter I noticed Laughing

I bought the Haynes Online just to get an idea so I'm ready to go! Laughing
Post #867764 16th Nov 2020 6:25pm
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Greyman110



Member Since: 29 Sep 2017
Location: London
Posts: 327

United Kingdom 
So I made a start on replacing the water pump. This is the first time I have ever done something to an engine so its been an interesting learning curve!

Sooooo....brake vacuum pump....I was screwing the brass screw back on and I thought it was catching on something inside. I put my finger in and could feel something but when I took it out, whatever it was popped out and who knows where its gone now! Anyone happen to know what it was and if I can get another one? And was there an o ring for this? if there was, thats gone too! Rolling Eyes Laughing
Post #868894 22nd Nov 2020 5:36am
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Ianh



Member Since: 17 Sep 2018
Location: Essex
Posts: 1997

United Kingdom 
Post #868922 22nd Nov 2020 9:51am
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Greyman110



Member Since: 29 Sep 2017
Location: London
Posts: 327

United Kingdom 
Thanks for that.

Crawling around the floor in daylight, I found a tiny spring so removed the vacuum pump, refitted and put everything back.

Will do a proper test tomorrow so fingers crossed!
Post #869028 22nd Nov 2020 7:03pm
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Greyman110



Member Since: 29 Sep 2017
Location: London
Posts: 327

United Kingdom 
So wasn’t the water pump! Big Cry
Post #869105 23rd Nov 2020 11:20am
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Defenderdredd



Member Since: 05 Oct 2010
Location: South Hams
Posts: 10

England 1992 Defender 110 Td5 Black LE Java Black
Hi Greyman110.

Ive had the same problem over the life of my 2.4 puma, like yours mapped but I also have cruise control and it only seems to happen when towing heavy loads uphill. I have learned that uphill, whilst the engine is willing, the temp suddenly shoots up and cuts power, not ideal when you have a big trailer or large boat on the back!

To combat this I take the car out of cruise and drop into 5th or 4th (steepness dependant) open the windows, turn off the aircon and put the heater on full! often this is enough to prevent the problem but not always!

Really would love to find a cure? My 2.2 model is absolutely fine as is my Brothers 2.4. Whilst I cant contribute a solution, I do understand the frustration and also thought about changing the rad for an Ali Sport aftermarket radiator to improve the cooling to see if that is the fix.

Ive read that holding 6th with a chipped engine puts it under significant load therefore extra heat is generated and dropping a gear reduces that load. Eessentially 6th is an overdrive gear but regret to inform that mine happens in 5th and 4th if a big hill such as telegraph hill off the M5

Will continue to follow your thread with interest, thank you for raising the issue.
Post #869601 25th Nov 2020 6:46pm
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Greyman110



Member Since: 29 Sep 2017
Location: London
Posts: 327

United Kingdom 
So today I did an 80 mile round trip.

Motorway driving at a steady 56mph at around 1900rpm in 6th gear. The temp on average was around 105c.

Had the heat on full and I noticed the following:

As the temp went up and down, it had no impact on the heat.

What did seem to have an impact were hills - Going down hill the heat would get really hot and the temp would drop. Going up hill and the heat would go cold and the temp would rise.

Does anyone have any idea what would cause this to happen? It certainly does feel like something is off with the circulation!?


On level ground the heat felt about right although I did notice it was blowing cold when I got home which was on level ground. The temp had also dropped to 92c.

When I came off the motorway and stopped, the temp immediately dropped from 105c to mid 90's in about a minute.

I don't think it's the CHT sensor as I read somewhere that when this goes wrong you should start to see fault codes coming up.

I'm not convinced its the thermostat as I've seen large fluctuations in the temp at different times.

Radiator i'm not too sure about. I can feel its hot at the top pipe and cold at the bottom pipe but I am considering changing both this and the thermostat.
Post #870205 29th Nov 2020 12:18am
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Kevlar



Member Since: 28 Oct 2020
Location: Prague
Posts: 78

Czech Republic 2010 Defender 90 Puma 2.4 SW Santorini Black
This is down to your coolant not filling the heater matrix. If the coolant level is low or you you air in the system then you get inconsistent cabin heat. Try bleeding the coolant again.
Post #870218 29th Nov 2020 7:15am
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