External cooler on auto trans?

[apierro36]

I was wondering what people's takes are on the necessity of installing a secondary transmission cooler. Preferred models, etc? What's a decent price, and is it worth it, in your opinion?

I have an 87 conquest w 77,000 on a 22re.

Also, does anyone actually use OD even on a straightaway? pulling that much, it scares me a little...

Thanks!

Edited January 3, 2013 by apierro36

[Bob C]

I have a 20 ft 88 Escaper with a 22re and automatic. I do not use the over drive because the engine just does not have the guts. I installed a tach and watch my rpm's. The 22re engines love to spin. You are better off running the engine at 3500 rpm's and not working hard than you are by running OD at 2700 rpm's at the same speed.

My mechanic says that he has never fixed a toyota engine because someone ran high rpm's (not to exceed red line, which I was told is 5200) but he has done valve jobs because people burned the valves up by lugging the engines.

I have a tranny cooler on my MH already (approximately 7" x 7") but I am planning on adding a larger one this spring when I get the unit out of storage. The number one killer of automatic transmissions is heat. I don't think you can cool the tranny to much. I will be putting a Hayden cooler in that measures approximately 7 x 15. O'reily has it for about $45 with the mounting kit.

I also watch my temp gauge carefully. I was driving across South Dakota with a 45 mph headwind. I was going about 55 mph and my temp started to climb a bit. I slowed down to 45 and the temp dropped to normal.

[zero]

I was wondering what people's takes are on the necessity of installing a secondary transmission cooler. Preferred models, etc? What's a decent price, and is it worth it, in your opinion?

I have an 87 conquest w 77,000 on a 22re.

Also, does anyone actually use OD even on a straightaway? pulling that much, it scares me a little...

Thanks!

I doubt anyone would argue the point that high heat is the usual killer of automatic transmissions. Even more true when they lack lock-up torque converters. Without a lockup a converter is an "oil heater" and slips around 15% all the time at highway speeds. So, a good aftermarket cooler certainly cannot hurt and almost has to help to prolong trans life. Only down-side to an added cooler is it can prevent a trans from warming up properly if big and driven in very cold temps. The factory "cooler" in a Toyota radiator is also a "heater" in cold weather. Good aftermarket trans coolers come with optional thermostats. When the weather is cold, the cooler gets bypassed.

[Totem]

I might Argue the usage of Over Drive; no shock there. A motor wont lug going down hill or as long as it can accelerate is what I was taught. Cant see any harm in using it other than floating up a hill and hitting the vector of the point where it begins to decelerate from the hill. hit the button at that point.

[Maineah]

Cooler, after market add on, change the fluid ever 30k with syn. fluid make sure the tail stock bushing is good and the trans will last 150k even using o/d.

[zero]

Cooler, after market add on, change the fluid ever 30k with syn. fluid make sure the tail stock bushing is good and the trans will last 150k even using o/d.

I know little on the specifics of automatic transmissions as used in Toyota motorhomes. That being said, I've had to rebuild and upgrade many automatic transmissions in other RVs. Mostly GM and Ford. The "killer" is often the use overdrive but that is because the lock-up converter is always engaged when OD is engaged. It's often the lock-up converter that fails first and then sends debris through the rest of the trans. My point is -if the Toyota has no lock-up, the OD would not worry me at all as long as it wasn't being lugged. I converted a few transmissions in GM RVs so the lockup can be used in lower gears which is a nice feature. No lugged and no 15% slippage. In the 70s-80s - most big RVs did not use lockup converters. That was mainly because no HD trans was offered with it. GM used the TH400 and Ford used the C6. Then when the GM 4L80 and Ford E40D came out, they started to show up in RVs.

Again - I don't know how many Toyota RVs have a lock-up converter. Without it - there is 15% loss at highway cruising speed. But with it - the converter clutch needs to be sized for the job and never lugged. If gas mileage was important I would not own any RV with a non lock-up auto trans.

[waiter]

I use the OD occasionally on long level straights (usually with a tail wind) If I find the OD popping in and out, I shut it off. It probably annoys me more than it hurts the tranny. OD will not work above about 2500 ft (ECU keeps it from working at high altitudes)

On the 4 cyl, the tranny doesn't have a torque converter lockout (I wish it did). On the 6 cyl, the torqe converter is a lockout type.

My 88 came with an aux cooler, I added another large one, but it probably didn't need it.

John Mc

88 Dolphin 4 Auto

[Totem]

So basically the good word is OD is ok in the 22re but not the V6 providing that you can actually accelerate or keep speed in OD. I would agree with that also.

[waiter]

I think on the 4 cyl, it really is a 4th gear, but on the 6 cyl, its really a torque converter lockout (3 speed with lockout). I'd say if it doesn't pop in and out, then use it.

I use my cruise control a lot, I notice the gas peddle does a lot of up and down as the thing shifts in and out of 4th, so I just turn it off (I think the gas peddle modulating like that is bad for gas millage).

John

88 Dolphin 4 Auto

[stamar]

my 85 dolphin has a pretty standard auto trans cooler installed at the factory. I would almost certainly install one if it wasnt there... national rv wouldnt just throw it on there if they didnt get sued.

switch to dexron 6 fluid, its semi synthetic. Very cheap at walmart but expensive at the auto parts store.