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Discussion Starter #1
Been yaking to me mechanic chappy and I mentioned aboot the gearbox's overheating and stopping issues on this forum.
One idea that we came up with was to fit an external oil cooler to the system thus eliminating the lack of cooling when the rad starts missbehaiving.
I would like your views and thoughts on that idea.

i.e. take a lead from where the oil feed goes to and from the radiator and affix to an external cooler tank in front of the rad thus making use of the fans to cool the oil doon.

I know that ford hads a problem with the Sirras over here where the high powered models with the body kits on had gearbox failures due to the aerodynamic changes caused by the bodykits.

with these delicate systems one never knows, it could be a way forward.
I appear to have a new box on my car so would like it to last for a few thousand miles.

Thoughts and ideas please..

cheers

Bill
 

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Re: Thots on an idea to 'prevent' gear box overheating

Similar topic on teh Classic forum right now.

On a few of my rigs I have bypassed factory tranny coolers and fitted RV coolers. RV coolers are normally designed to be fitted in line with the factory setup, but I never had any difficulties. Visit your local RV/Motorhome/Travel trailer shop and get the biggest unit offered with standard tubing... no threaded fittings. These usually have a small flair for input and exit allowing for flex lines to be worm clamped in place. A couple of long nylon fitting "zip tye" the unit to and through your radiator and A/C.

Back up note, flush your tranny before starting all this so that you have fresh fluid in your convertor before dropping the pan.
 

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Re: Thots on an idea to 'prevent' gear box overheating

ace, so it wisnae such a hair brained idea after all......
I would be changing the oil even although it is, or appears to be, a new unit.
that would let me inspect the oil.

thanks for the reply
 

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Re: Thots on an idea to 'prevent' gear box overheating

The problem is not whether you can/should mount additional cooling, but WHERE to mount it?

On my 2003 HSE, there's no room in front of the radiator without taking the grill out. I am going to have my fabricator make me a high clearance grill for just this purpose.

Good idea!
 

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Re: Thots on an idea to 'prevent' gear box overheating

jdholder said:
The problem is not whether you can/should mount additional cooling, but WHERE to mount it?

On my 2003 HSE, there's no room in front of the radiator without taking the grill out. I am going to have my fabricator make me a high clearance grill for just this purpose.

Good idea!
Is there any room behind the "Power Vents" for something small, maybe one on each side:


Oil Cooler Small by d86cfv, on Flickr

I'm thinking as an additional cooler, in line rather than a replacement.
 

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Re: Thots on an idea to 'prevent' gear box overheating

The oil cooler isn't actually in the coolant radiator is it, but the little heat exchanger down by the bottom RH side of the radiator if I am not mistaken?

Or is that for something else I am missing?
 

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Re: Thots on an idea to 'prevent' gear box overheating

Barry's right the gearbox oil cooler is a heat exchanger type box and is about 8"x6"x4" in size and sits down behind bottom left corner of the radiator as you look at the front of the car.

Again , not personally a design i'm a big fan of , bit like the thermostat system on the main cooling. Engineering probably are pushing the oil temp upto its max and trying to maintain it there at the upper levels of its working temp.

Dont see why you wouldn't be able to add in an oil cooler. I'd say the place with the most space is in front of the radiator at the very bottom ... may be visible though.
 

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Discussion Starter #9
Re: Thots on an idea to 'prevent' gear box overheating

Noo, thats intresting.
I am lead to believe that the oil is cooled as part of the water rad.
I have even tried to look for an oli cooler as a standard part and none listed.

mmmm more food for thots?

Time to dig further
 

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Re: Thots on an idea to 'prevent' gear box overheating

I am lead to believe that the oil is cooled as part of the water rad.
Its a bit of a yes and no to that. The oil is cooled by the water coolant that passes through the radiator ... but the heat exchanger box is fed by the pipes that run to the radiator, and the oild doesn't go through the radiator itself.
 

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Re: Thots on an idea to 'prevent' gear box overheating

Fisha is dead on. The actual fluid cooler/heat exchanger is part#7A095 in the new release of Microcat.
 

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Re: Thots on an idea to 'prevent' gear box overheating

:think: My wife has 65k miles on hers and never had an issue with the gear box overheating, and we live in Fresno where it's over 100 degrees for on average 30 days a year. It was 110 degrees here yesterday.
 

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Re: Thots on an idea to 'prevent' gear box overheating

fisha said:
Barry's right the gearbox oil cooler is a heat exchanger type box and is about 8"x6"x4" in size and sits down behind bottom left corner of the radiator as you look at the front of the car.

Again , not personally a design i'm a big fan of , bit like the thermostat system on the main cooling. Engineering probably are pushing the oil temp upto its max and trying to maintain it there at the upper levels of its working temp.

Dont see why you wouldn't be able to add in an oil cooler. I'd say the place with the most space is in front of the radiator at the very bottom ... may be visible though.
Why would it be bad for the transmission to get up to operating temperature sooner? The existing cooler still should work fine, really the only issues are that the fluid is shared between the main radiator and the transmission cooler, so if one heats up the other will too.... and that the main radiator can have blockage issues near the bottom where the transmission cooler connects. Adding a separate cooler would basically be to address those two issues, not because the existing system cannot provide adequate cooling.

Personally, I think if you maintain the cooling system you'll probably be fine either way.
 

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Re: Thots on an idea to 'prevent' gear box overheating

My comments are more based towards the temp that the engine is maintained at, a secondarily at the gearbox side of things.

Perhaps its just me and my old rover V8 roots, but I dont like how the engine is kept up at 105°C temps as opposed to more normal temps like 85° and 90°like you would get if the stat were a normal style one. I also dont trust ( and maybe its unfounded ) that in order to provide extra cooling by the engine stat, you rely on a bimetallic style, electrical controlled valve ... with most things like that, if you have them on all the time ( like in hard working environments ... towing ) then it could burn out, thus losing the extra cooling. I just think that in general, the temperature envelopes are pushed a little too hard and that long long term ( i.e. beyond warranty, at which point LR dont care anymore ) that it could be accelerating issues.

So if you're keeping your engine high temp, and relying on that to cool the gearbox oil, are you really getting much cooling from it? A quick trawl through the web seems to show that temps above 120°C for transmissions can reign in and reduce the lifespan of your oil. So in a hard work load, and the trans temp rising, would the gearbox oil get much cooling from something thats already at 105°C ? ( than factor in that there would be thermal resistances, so the heat would never transfer over, and so you wouldn't get 105°C perfectly anyway )

As I say, maybe my thoughts are un-founded and incorrect speculation on my part, but i think it would all just be a little easier if things were running a fraction cooler. I'd sacrifice a fraction of efficiency for a more reliable engine.
 

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Re: Thots on an idea to 'prevent' gear box overheating

linuxfreakus said:
Why would it be bad for the transmission to get up to operating temperature sooner? The existing cooler still should work fine, really the only issues are that the fluid is shared between the main radiator and the transmission cooler, so if one heats up the other will too.... and that the main radiator can have blockage issues near the bottom where the transmission cooler connects. Adding a separate cooler would basically be to address those two issues, not because the existing system cannot provide adequate cooling.

Personally, I think if you maintain the cooling system you'll probably be fine either way.
The existing cooler does NOT work fine. From my gauge that monitors trans temperature, the transmission fluid in the sump regularly reached 230 degrees. As I have been told, this is unacceptable. My vehicle is maintained properly, new radiator and new transmission cooler - it still gets too hot.
 

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Re: Thots on an idea to 'prevent' gear box overheating

Remember high temps shorten the life of ATF, not the transmission itself, so just make sure you keep everything serviced. I used to own a Ford F-250 and the transmission on that beast regularly topped 230 degrees (had a separate gauge for the transmission temp) even with an auxiliary cooler on it. Didn't stop it from lasting 175k miles (and for all I know still going since the guy I sold it to was a mechanic). I did a lot of towing/plowing too.
 

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Re: Thots on an idea to 'prevent' gear box overheating

And then I had an F-150 which both engine and transmission went at 70k miles.... never towed or plowed or wheeled or anything, it had an easy life.
 

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Re: Thots on an idea to 'prevent' gear box overheating

Right, but remember, Range Rover calls their transmission fluid "lifetime fill" - therefore, 230 degrees + lifetime fill = dead transmission.

So - get some cooling on their and you can extend the service intervals to "lifetime" - if not, service it anytime you get up near 235 degrees. Cooling is cheaper though in the long run.
 
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