3ltr BT50 Transmission Hot.

Submitted: Thursday, Oct 10, 2013 at 17:01
ThreadID: 104667 Views:8889 Replies:5 FollowUps:6
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Has anyone installed a larger transmission cooler or is the standard one ok in very hot weather?.
I noticed mine was a tad hot today when towing 2 ton against a very hot and strong head wind . :irked:
If you have please advise why and where you got it plus the price if you can. :confused:
I used to have a handle on life, but it broke.

Cheers Dodg.

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Reply By: Ross M - Thursday, Oct 10, 2013 at 19:20

Thursday, Oct 10, 2013 at 19:20
Any towing at all would require a transmission cooler
The OE system only has a small amount of reserve capacity and that is really for empty running on a hot day.Towing creates far more heat input to the trans fluid and requires a dedicated cooler in addition to the OE cooler so trans temps don't get too high and shorten the autos life or cause a failure because of overheating.
with a cooler fitted after the trans and before the radiator heat exchanger it is then able to dissipate the maximum heats to the atmosphere and not deliver it to the radiator water.
I don't own a BT50 and have not towed with one, but the principles involved are the same for any auto vehicle.

PS A strong tail wind on a hot day is worse.
AnswerID: 519506

Follow Up By: Ron N - Friday, Oct 11, 2013 at 01:19

Friday, Oct 11, 2013 at 01:19
Dodger - Ross has nailed all the points well. All automatics should be fitted with an oil cooler for towing, particularly long distance towing, or towing in hilly country.

I understand the current Mazda BT-50 6 speed auto transmission is the Ford 6R80 model transmission, as fitted to the current model Ford Ranger and the F150 in the U.S. - and the Americans manufacture an aftermarket transmission oil pan for the 6R80 that is cast alloy, and which holds another 2.8L.

Both the extra oil capacity and the cast alloy pan help greatly with heat dissipation.

An automatic tranny shouldn't exceed a temperature of more than 250 deg F or 121 deg C, or you will find seals becoming hardened and leaks starting.
On these electronic transmissions, overheating will melt the plastic insulation on the solenoids and wiring, resulting in solenoid failure.

One U.S. transmission repairer recommends a maximum of 200 deg F (93 deg C) for the 6R80 - and claims that every extra 20 deg F (over 200 deg F) in operating temperature, reduces transmission life by a factor of 2.


All OEM designs utilise the minimum amount of oil that the engineers reckon is good enough for average operating conditions, with a small portion of extreme operating conditions included.

Towing a big van a substantial distance on a hot day, is called constant extreme operating conditions - and this is operating conditions way outside Mazda engineers calculations.

Cheers - Ron.
FollowupID: 799665

Reply By: John and Regina M - Thursday, Oct 10, 2013 at 20:05

Thursday, Oct 10, 2013 at 20:05
They are meant to get hot.
What is more important then the temp of the cooler is the temp of the fluid leaving it.

But heavy loads and high ambient heat place additional requirements on the transmission and TC so borrow an infrared temp gauge and check out the temp of the fluid on the exit of the cooler.

Many times it's not an issue and if you maintain a regular and methodical approach to fluid replacement and general servicing you can negate the need for many of the expensive bolt ons.
AnswerID: 519509

Follow Up By: Ross M - Thursday, Oct 10, 2013 at 22:08

Thursday, Oct 10, 2013 at 22:08
Yes they do get hot and normally run hot, but, when towing, the temp of the fluid leaving the auto torque converter is often in excess of 100Deg C and that will boil water.
In hot weather the bottom of the radiator, normally cool, is quite hot purely from cooling the engine heat. This leaves little left to cool the auto fluid heat also being added to it.

The auto which is working hard will/can/often does overcome the system and overheating results.

If an average person has noticed it is HOT then it would be very reasonable to assume the system is near it's limit. With no reserve left, any additional loads or heat will cause a failure.

Just replacing the fluid regularly , which isn't ever done on BT50's, doesn't guard against or prevent problems with heat loads or hot ambient conditions.

It is very expensive to "suck it and see" when a the modest cost of a cooler can ensure control of fluid heat is handled.
FollowupID: 799660

Reply By: sjp - Thursday, Oct 10, 2013 at 21:10

Thursday, Oct 10, 2013 at 21:10
hope the link works ,its from the ozmazda site ,should solve the problem.
AnswerID: 519511

Follow Up By: Ross M - Thursday, Oct 10, 2013 at 21:57

Thursday, Oct 10, 2013 at 21:57
What is being discussed is a transmission cooler, not an air to air turbo intercooler.
FollowupID: 799659

Follow Up By: sjp - Friday, Oct 11, 2013 at 05:56

Friday, Oct 11, 2013 at 05:56
opps ,shows how much of what i read actually gets processed by my brain .
FollowupID: 799667

Reply By: Ron N - Friday, Oct 11, 2013 at 18:54

Friday, Oct 11, 2013 at 18:54
Dodger - I'm reliably informed by a Ford transmission technician, that if your BT-50 transmission got excessively hot, it would produce a fault code that would show the transmission oil had exceeded a maximum temperature set by Mazda or Ford (when the transmission ECU was programmed).
I'm not privy to what that actual "maximum safe operating temperature" actually is, because I don't have any 6R80 transmission technical or overhaul literature, and I wasn't told by my source, what that precise safe temperature is.
These transmissions are used in a wide range of vehicles and applications, and the transmission ECU's are programmed upon installation of the transmission by the manufacturer. Alteration of the programming can produce a wide range of changes in transmission operation.
It's entirely possible the Mazdas use a different programming software and parameters to Ford, according to what the Mazda engineers have specified for their selected transmission performance.

Cheers, Ron.
AnswerID: 519555

Follow Up By: Rockape - Friday, Oct 11, 2013 at 20:24

Friday, Oct 11, 2013 at 20:24
it is an older 3litre bt50 and I don't believe they had the 6R80 transmission.
FollowupID: 799700

Follow Up By: Ron N - Friday, Oct 11, 2013 at 21:01

Friday, Oct 11, 2013 at 21:01
Thanks, Rockape. The OP didn't specify the model and I just presumed it was the current model.

So - Dodgers transmission will be the 5 speed Ford 5R55W that was a product of the Bordeaux Ford transmission plant.
Ford sold this plant to a French steel forging company in 2009 (the HZ Holding France SAS company).

HZ Holdings only continued to produce this transmission until 2011, when Ford ceased using the 5R55 transmissions, and the factory was turned over to making wind turbines.
FollowupID: 799704

Reply By: Ron N - Saturday, Oct 12, 2013 at 02:04

Saturday, Oct 12, 2013 at 02:04
The 5R55W transmission maximum operating temperature is 200 deg F (93 deg C).

If this temperature is exceeded, a fault code (P1783) is produced by the Transmission Fluid Temperature sensor (TFT).
The TFT sensor also plays an important part in shift scheduling. The shift schedule is altered when the transmission fluid is cold.

Here's another useful webpage on the 5R55W transmission. A heavy duty cast-aluminium oil pan is also available for the 5R55W transmission.


Also - another little FYI - the transmission drain plug, actually contains the fill level plug, as well (in the centre of the drain plug).
There's a pipe stem protruding from the transmission oil pan drain plug, that projects to the correct level height for the transmission fluid.

Removing the centre plug only (the oil level check plug), just drains oil that is above the correct oil level.

To fill the transmission, the centre plug is removed, oil is added via the fill plug (located on the right rear of the transmission case) - and the oil level is correct when oil starts to trickle from the centre of the transmission drain plug.

The only fluid that should be used in this transmission is Mercon V transmission fluid.

Cheers - Ron.
AnswerID: 519571

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