Cool Transmission Q's

[Agent M79]

I have had a number of Ford products over the years and I have developed a bit of paranoia about transmissions.

I put 2 transmissions in my '90 Mark VII LSC (still running for my Father-in-law).

I put 3 transmissions in my '94 T-Bird LX (sacrificed itself to save both in-laws).

In a couple of cases I was told the failures were 'probably' because of heat.

Since then, I discovered that there is a subset of drivers who are so bold as to change the specifications of their cars by 'modifying' them. Gasp!

So my first tranny mod was not on my car, but my wifes, and I had a tranny cooler installed to hopefully help keep the temperatures reasonable and extend the lifespan of it.

I have watched carefully and have learned that one way to help with temps is to increase the amount of available fluid by getting a higher capacity tranny pan. Of course, another way is what I did for my wife's car, and that is go with a cooler.

If I've been paying attention, then the cooler is probably the more effective option, yes? Would it be overkill to do both a pan and a cooler on a car that is driven hard over-the-road by not taken to the track?

[BruteForce]

I did both. :D

[Agent M79]

Do you have a temp gauge? What has been the differences in temp?


I did both. :D

[BruteForce]

I don't have a trans temp gauge. The idea isn't to get it to have lower temp. The idea is to keep it from exceeding the optimal temp for extended periods.

[Agent M79]

So how do we keep it in the optimal range?

Is the cooler 'always on' or is there a thermostat like device that would open and close based on fluid temps?

[BUCKWHEAT]

If I've been paying attention, then the cooler is probably the more effective option, yes? Would it be overkill to do both a pan and a cooler on a car that is driven hard over-the-road by not taken to the track?


I have both and a Trans oil temp guage. Runs about 150 to 170 normally.

[03SILVERSTREAK]

I have both and a Trans oil temp guage. Runs about 150 to 170 normally.
I also have both except for the trans temp gauge. thanks Buckwheat for the temp reading...:cool:

[Parts Man]

I ADDED A TEMP GAUGE BEFORE I UP IN MY COOLER THE TEMP WOULD STAY AT ABOUT 170 BEFORE AND WITH COOLER PLUS A 10 INCH ELECTRIC FAN NOW STAYS AT AROUND 125...:banana2:

[merc6]

what cooler size and pans are you guys running? Also does anyone have pictures of what the return lines look like and where located for when I decide to install a tranny cooler on this car?

[fastblackmerc]

See this post for pics of my trans cooler install. PM me if you have any Q's....

http://www.mercurymarauder.net/forums/showthread.php?t=20136&highlight=trans+cooler

[David Morton]

So how do we keep it in the optimal range?

Is the cooler 'always on' or is there a thermostat like device that would open and close based on fluid temps?To the 1st question, don't deliberately stall the convertor for too long, or keep it out of lockup when under a load by, say, driving with a trailer in 4th gear.

To the 2nd question, all coolers are always on. There's no thermostats but there is a type of cooler that cools hotter fluid more efficiently. It's design bypasses most of the fluid when it's cold and thick but when it gets hot and thin it flows though the smaller passages faster, so it acts as if there was a thermostat. I suppose you could say the design uses thermal expansion and hot fluid dynamics to make the whole cooler a kind of natural thermostatic cooler. This would be good for northern climes to speed warm-up on those cold mornings.

To interject a caveate about coolers, most automatic transmissions take lube straight from the convertor where it is hottest directly to the cooler and from the cooler to the lube circuits inside the transmission. Many transmission failures occur when this flow gets restricted, limiting the amount of lube that makes it to the bearings, gears and bushings. This fluid is not only lubricating but also cooling those parts, and many of those bearings may have plastic races that hold the needles in place, so lube oil has to be cool enough and has to flow in enough volume to keep things cool.

So the biggest concern when putting on an extra cooler is making sure there is enough flow of lubricant to keep the lube circuits adequately supplied with fluid. Extra cooling is gonna happen with an extra cooler. Where guys mess up is getting one that doesn't have adequate flow. In this area, bigger is better for the lines.

1/2 inch lines would not be too big.

[BillyGman]

It seems to me that having the transmission flushed, changing the fluid (and the filter as well!) more frequently than the 24,000 mile recommended interval would go a long way toward preventative maintainence. Since my transmission is stock, and I've been puting 160 more HP through it than a stock Marauder engine would, I have the transmission fluid flushed out and changed twice per year (every 6,000 to 8,000 miles) and I have the filter changed atleast once per year. So far I have 36,000 on it, and w/out any problems. And many people here can tell you that I don't baby my car while I'm driving it at all. Fluid breaks down after awhile from the constant day to day heat cycling, and can lose it's ability to lubricate parts. I think that increasing the fluid change intervals would do more than a bigger or better cooler. I don't see anything wrong with allowing the fluid temperatures to routinely reach 175 degrees. that's perfectly normal. It's when they exceed 200 degrees that you can significantly reduce the longevity of the transmission. But if the fluid in your transmission hasn't been changed in 25,000 miles, then I'm sure that it wouldn't lubricate the transmission as effectively as it should even at temperatures of 175 degrees.

[ctrcbob]

When I lived in Western New York State, (Cold and Snow), I had transmission coolers in my 1992 Camry and my 1994 T-Bird as I would use both those cars for towing. With both of them, in the Winter, I covered the cooler with a vynal cover that I made, in order to not overcool the fluid.

Note that the 92 Camry only holds half the fluid of the MM. Never had any problems with it. Only changed the fluid once in 98,000 miles and the transmission tech said the inside of the transmission looked like new.

[BillyGman]

When I lived in Western New York State, (Cold and Snow), I had transmission coolers in my 1992 Camry and my 1994 T-Bird as I would use both those cars for towing. With both of them, in the Winter, I covered the cooler with a vynal cover that I made, in order to not overcool the fluid.

Note that the 92 Camry only holds half the fluid of the MM. Never had any problems with it. Only changed the fluid once in 98,000 miles and the transmission tech said the inside of the transmission looked like new.Uhmm, and you would recommend that people let their cars go for 98,000 miles without changing the trans fluid as long as they have a trans cooler? I think there are other factors. Perhaps the Camry simply had a better transmission, or it wasn't under as much stress for the rest of the time other than the instances of towing. Either way, I still think frequent transmission fluid changes will help matters.. I'm not saying it's a cure-all. Just that it would be a good preventative measure.

[David Morton]

I've been to school on automotive lubricants as well as several schools on automatic transmissions and this is what I've learned about ATF and AT filters.

ATF is red because they put a temperature sensitive red dye in it. The dye breaks down from heat. ATF is also a mineral oil base. Very durable if not overheated. The dye is there to tell us when the oil is starting to break down, the two go bad at the same time so, if the fluid is still nice and bright red, the fluid is still good. As the fluid breaks down though, it doesn't turn into anything a filter can catch. Engine oil filters are necessary because the cylinders are making soot all the time from combustion, big particles of carbon, very abrasive, need to be removed. The only reason they put filters in transmissions is because of the clutch material that will flake off during break in. The gears of course make very fine slivers of metal for quite a while but a magnet is there to catch that and after 5,000 miles or so the gears should stop making those fine slivers. One filter should last the life of an automatic transmission.

The problem with the old style "drop the pan" fluid change is that it only gets about half the old fluid out. We used to do that in the old days because they used to put screens instead of filters in them. Made from stuff just like in those permanent coffee filters you can get, fine mesh plastic or stainless steel. The problem with those was that as the mineral oil breaks down it makes a varnish-like substance and this gluey stuff would plug up those screens. I fixed many a "problem" TH350 just by replacing the screen. Also, occasionally, since they didn't hold the material they were screening out, this clutch material would float back out into the pan on shutdown and sometimes it would wash up into the valve body and stick a valve.

Billy, I commend you on a wise maintenance philosophy, but you really don't need to replace filters. Doing a line flush gets nearly 100% of the old fluid out and if done every 25,000 miles will eliminate any possibility of failure due to bad fluid.

[BillyGman]

Very educational post Dave. Thanks. ;) As far as my transmission, I have it flushed every time I have the filter changed, and also once or twice between filter changes. So the filter never gets changed w/out the transmission being flushed out first. The dealer gets $150 for that service, and so I don't really mind spending $150 twice per year to always have fresh fluid in the transmission.

My point is, that there's never any old fluid left behind in the torque converter, because it always gets flushed. I won't argue with you about the need, or the lack of one to have the filter changed. But it cannot hurt, and with my stock transmission having so much extra power put through it, who knows, maybe there's more clutch material floating around in that fluid than would otherwise be with a 300 HP Marauder.

But in light of what you've pointed out about the dye in the fluid, I think that if people aren't going to make it their personal policy to have the fluid changed more than every 24,000 miles, then they should atleast be checking the color of that fluid once every couple weeks like clock work! And for those like myself who occasionaly race their Marauders, they definately should be getting the transmission flushed out more often. Particularly those who load up their torque converters at the starting line before each race. Because that DOES heat up the fluid BIG TIME, regardless of what type of transmission cooler they have.