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ramigojag

Member Since: 29 Oct 2018
Location: Sydney
Posts: 17

2003 Range Rover HSE 4.4 V8 Ipanema Sand

Transmission Overheat: Real Problem or a Glitch?

I've owned my FF for about a month now. I went into it with my eyes wide open and coming from an old P38 I like to think I'm pretty familiar with Range Rover's and there small glitches and foibles.

The car seemingly randomly throws a split second "Transmission Overheat" warning on the dashboard and I saw split second because it flashes barely enough for me to read it then its gone; very occasionally I get a downshift followed straight away with an upshift and off it carries on without a trouble.

It's never gone into a fail safe program.

It doesn't seem to occur in set circumstances or situations, It can happen on a cold morning drive to work cruising with no traffic, but then it won't appear on a 40+ Degree C day here in Western Sydney sat in traffic driving up a mountain.

I am pretty privileged to have good mechanical background and access to plentiful scan tools and scopes.

The first time I saw the problem was when the car was stone cold accelerating away from a roundabout (not from a stand still) it momentarily flashed "Transmission Overheat" then for the rest of the 300KM journey it was fine.

Straight away I thought typical Range Rover glitch.

It started happening a little bit more common so I thought maybe there is a problem, I ordered the correct fluid and a new transmission cooler.

The car had a brand new box 2 years ago and a complete overhaul of the cooling system 12 months ago (new radiator, coolant, water pump and hoses etc.) I'm happy with the state of the engine cooling system, but the trans cooling system was a bit of an unknown.

I followed a post from RRPhil and checked the trans temp sensor resistance at the ECU it measured 1400 Ohms about an hour or so after a drive which equates to roughly 70 degrees C. which was matched by the scan tool showing 68 degrees c.

I monitored live data with my scan tool on a drive to work and this is what I found.

The top graphs are engine speed, the middle graphs are engine temp, the bottom graphs are AT oil temp.

Click image to enlarge

The car is a 2003 M62 RR.

At one point whilst cruising no change to engine load or speed the AT oil gains and loses around 50 degrees c in temp in a couple of seconds.

This can't be write can it, this has to be indicating a bad sensor?

The majority of the time the sense measures accurately, but sometimes glitches explaining why when I tested it it measure correctly.

The trans service gear hasn't arrived yet so I haven't done the service yet, but now wondering if I should order a temp sensor also.

What do you guys think?

Thanks

7th Nov 2018 8:56pm

northernmonkeyjones

Member Since: 24 Mar 2012
Location: derby
Posts: 8523

2016 Range Rover Autobiography SDV8 Santorini Black

can't see how on the last graph it can go from cold to 140+ deg then back to cold in a minute..... it could be that the sensor is starting to break down.

looking at the traces the coolant temps seem to be increasing nicely, apart from the spikes, which would indicate that its working as it should.

if you can get at it I would start with that There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

7th Nov 2018 9:17pm

ramigojag

Member Since: 29 Oct 2018
Location: Sydney
Posts: 17

It goes from around 90 degrees to 140 degrees back to 90 in around a second. Thats a zoomed in version of the highest spike in the previous graph.

The engine coolant temp is stable throughout the whole warms up nicely to 105 and stays there for the entire journey.

Yes thats, what I'm thinking has to be a bad sensor, they are a pain to get out here will have to shop around from the UK unless I can find a local ZF supplier. Current:
------------
2003 Range Rover V8 HSE
2014 BMW 125i

Previous:
-------------
2005 VW Golf GTI
2001 BMW E39 M5
1991 Peugeot 205 GTI 1.6
1995 Range Rover P38 4.6 HSE
1991 Suzuki SJ413

Too many others to mention

7th Nov 2018 9:32pm

northernmonkeyjones

Member Since: 24 Mar 2012
Location: derby
Posts: 8523

looking at the description in RAVE it looks like the sensor is part of the internal wiring harness in the pan

1058 227 019 Valve body harness 5HP24

might be worth swapping it out if you are doing the oils and filter.... There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

7th Nov 2018 10:00pm

RRPhil

Member Since: 22 Aug 2011
Location: Blackburn, Lancashire
Posts: 968

In case it helps, the internal wiring harness should be available from a Land Rover, BMW or Jaguar parts department. The part numbers are :

Land Rover = YMD001500
BMW = 24 34 1 423 719
Jaguar = JLM20218/LNC3380AA

Click image to enlarge

Phil

7th Nov 2018 11:26pm

ramigojag

Member Since: 29 Oct 2018
Location: Sydney
Posts: 17

Thanks Ill try ringing around them to see who does the best price as well as trying to find a local ZF distributor. Current:
------------
2003 Range Rover V8 HSE
2014 BMW 125i

Previous:
-------------
2005 VW Golf GTI
2001 BMW E39 M5
1991 Peugeot 205 GTI 1.6
1995 Range Rover P38 4.6 HSE
1991 Suzuki SJ413

Too many others to mention

7th Nov 2018 11:35pm

ramigojag

Member Since: 29 Oct 2018
Location: Sydney
Posts: 17

Do you manufacture the harness RRPhill?

Looks like you have a few in that picture thats all.

Thanks Current:
------------
2003 Range Rover V8 HSE
2014 BMW 125i

Previous:
-------------
2005 VW Golf GTI
2001 BMW E39 M5
1991 Peugeot 205 GTI 1.6
1995 Range Rover P38 4.6 HSE
1991 Suzuki SJ413

Too many others to mention

11th Nov 2018 8:52pm

fisha

Member Since: 25 Sep 2009
Location: Scotland
Posts: 1368

2015 Range Rover Autobiography SDV8 Aruba

Quote:
very occasionally I get a downshift followed straight away with an upshift

Thats the gearbox ECU reacting to the high temp reading as well as the transmission overheat message displaying. On overheat, I think I'm right in saying that the gearbox drops to a lower gear in order to raise the rpm of its oil pump pushing fluid to the cooler so it can shift more of the hot fluid out to get it cooled.

As aside on cooling ability for the gearbox:

I see its a 4.4 BMW unit, and from the temp readings its holding 105°C ... which it should. That is working correctly. That being said, a number of people (including myself) felt it was beneficial to modify or fit a lower temp stat to the engine to bring it down to ~90°C operating temp. There are plenty of threads on this forum and others about it. Some modify the existing housing with a spacer and different stat within. I changed the whole stat for a lower temp one which was a case of 4 bolts to remove and refit.

The benefit of lower engine temp is also that it gives the gearbox fluid more cooling too cause the gearbox fluid dumps its heat into the engine coolant. 90°C coolant is going to suck more heat out of gearbox fluid than 105°C coolant. V8 or else ...

13th Nov 2018 8:58pm

ramigojag

Member Since: 29 Oct 2018
Location: Sydney
Posts: 17

Yes, I know why it downshifts which is what I expect it to do.

I've read the posts about the thermostat mod which I am considering, but for the time being the cooling system is new and healthy and I believe these A/T temp spikes are a glitch in the sensor rather than an actual fault of the trans overheating so I am not overly concerned with getting the temps down more just replacing the sensor. Current:
------------
2003 Range Rover V8 HSE
2014 BMW 125i

Previous:
-------------
2005 VW Golf GTI
2001 BMW E39 M5
1991 Peugeot 205 GTI 1.6
1995 Range Rover P38 4.6 HSE
1991 Suzuki SJ413

Too many others to mention

14th Nov 2018 12:51am

fisha

Member Since: 25 Sep 2009
Location: Scotland
Posts: 1368

No worries, its just a personal opinion that 105°C overly stressed the components in the system and lowering its running temp makes it stay healthier for longer.

Back to the spikes, to me, it reads as though your sensor is sending out the right signal all the time, but that something is getting in the way of it.

My gut feeling is the connector where the chassis loom attaches to the internal harness of the gearbox. ( That molex multi-connector round thingie ) You may just simply have a poor connection ( corroded etc ) between the terminals on it.... much in the same way trailer socket pin terminals seem to degrade sometimes and the lights begin to flicker etc.

If you had a poor connection at that point which was sometimes breaking or degrading, then that would increase the resistance of the circuit and spike the reading ... just like your seeing.

Have you disconnected the plug and checked it over ? Simple things first n all that. V8 or else ...

14th Nov 2018 9:48am

ramigojag

Member Since: 29 Oct 2018
Location: Sydney
Posts: 17

I agree with you, it is a job for the future though. Maybe in 6 - 12 months time. What I mean is the hoses, rad, pump etc are all in good condition and relatively new so I am not concerned with them letting go soon, but I agree in the next 12 months at some time I will try the thermostat mod to relieve pressure on those components.

I have removed the connector and re seated it in the hope it was a bad connection, I have also tried it at the AT ECU.

I was originally going to order the sensor then do the trans flush and new oil cooler, but now I am thinking I will do the trans flush and oil cooler first and inspect the internal loom then and hopefully I can see something, if not and after the work it is still glitching then I will order the loom and do another flush because the likelihood of me having to do it twice to get the majority of the old fluid out is high anyway. Current:
------------
2003 Range Rover V8 HSE
2014 BMW 125i

Previous:
-------------
2005 VW Golf GTI
2001 BMW E39 M5
1991 Peugeot 205 GTI 1.6
1995 Range Rover P38 4.6 HSE
1991 Suzuki SJ413

Too many others to mention

15th Nov 2018 8:48pm

ramigojag

Member Since: 29 Oct 2018
Location: Sydney
Posts: 17

I'm updating this more for my own future reference and incase anyone else has the same glitchy problem as me.

Today I did just a trans oil and filter change.

When I removed the pan the fluid had definitely not been overheating, it didn't smell burnt and was nice and clear.

The temp sensor was covered completely under one of those black bands which tie the loom together (not sure if it should be or not) I pulled it back from out of the band so it can measure the fluid not just the fluid inside the band.

It was also a little grubby so i cleaned lightly with some degreaser put it all back together with fresh fluid.

The transmission wasn't shifting badly before, but it is ultra smooth now, can't really even feel the change you only know because of the change in engine tone.

Gave it a pretty hard drive for 15 mins on a hot Sydney day and it got to 85 - 90 degrees and stayed there, but time will tell next time I take it out on a long journey. Current:
------------
2003 Range Rover V8 HSE
2014 BMW 125i

Previous:
-------------
2005 VW Golf GTI
2001 BMW E39 M5
1991 Peugeot 205 GTI 1.6
1995 Range Rover P38 4.6 HSE
1991 Suzuki SJ413

Too many others to mention

30th Nov 2018 6:34am

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