Would you worry about running a separate trans fluid cooler on a stock daily driver? Is it the optimum thing to do? Or is a radiator integrated cooler good enough? I have a 64 Riviera with a low mileage rebuilt ST400. I want to make that trans last for as long as possible. Here in the desert, it's usually around 100F for 4 months or more, and I'm worried about heat causing accelerated wear. I was told by a pro transmission guy that too cold fluid is just as bad as overheated fluid, and that external coolers weren't a great idea except for trailer haulers. It gets down in the 30's here in the winter, so I'm concerned about screwing the transmission by running too cold fluid. Is that a reasonable concern, or bullshit? I'm getting ready to order a radiator, and I'm debating going with an external cooler and possibly gaining more cooling capacity in the radiator. Good idea? Not worth it?
I ran a th400 for 7 yrs with no trans cooler . However it depends on a persons driving habits, in the seventies I worked at a bone yard and our delivery truck had a 400th trans with no cooler and it worked fine around town, however I have had 400 ths in tow vehicles and keeping them cool enough is a chore. My avatar has a 425 nailhead and a 400st and I did drive it with out a cooler for a couple of summers, but I found on long mountain hills the trans heat would cause the oil to foam and come out the breather tube on top of the trans and cause smoke when it sprays on the passenger side exhaust ( a major factor when you see burnt vehicles on the side of the freeway ) so I put a finned aluminum 2pass trans cooler on the frame rail. I have been told the st 400s run hotter than the th400s because of the busy torque converter. In short , yes a trans cooler is not a bad thing to have, although you should have a factory one in your rad.
In CA, yes of it's anything like here in Ozland. Even in cooler climates you need to get the fluid up to operating temperature so the transmission can do it's job. I always run a radiator with transmission cooler and a separate stand alone cooler as well. Based on advice from reputable transmission shops, the consensus is to run transmission coolers in a series, from pressure outlet of transmission through radiator first and then through an auxiliary cooler before going back to transmission. Firstly, the reasons for this is that if the transmission fluid is hot, it will be cooled more quickly and efficiently by the radiator. Secondly, if it is cool it will be warmed up and yes they can run too cool. When they run cool condensation that may be in the system remains there, NOT GOOD. The transmission needs heat for self preservation but not too much. If the fluid is too hot after it leaves the radiator it will be cooled by the auxiliary cooler before going back to the transmission. Auxiliary coolers needs to be mounted where airflow isn't impeded as it needs to dissipate or radiate the heat, air flowing through and over does the job. If stuck for space a small slimline auxiliary coolers with a fan as you propose is the go. In colder areas and on short trips, the transmission may not get hot enough to reach optimum operating temperature. By being routed through radiator firstly it will be heated to a better temperature. I checked my OT in the garage and this is the way the big manufacturers now do it. They spend $M on R&D so why not take advantage of their expertise, it's free. I wouldn't recommend just running an auxiliary cooler, my opinion, but definitely use your radiator. Why, because the transmission generates the second greatest amount of heat beside the engine. I always use coolant rather than water. It costs a little more but has a lot more advantages. Water has contaminants that may lead to blockages and corrosion. Coolant also lubricates your water pump. A good quality radiator also helps. I personally prefer to run fluid line through the radiator first and then back through auxiliary transmission cooler. I've seen small air deflectors used to push air over and/or coolers in some instances where space is an issue. Don't have it too low so that you run the risk off loosing it due to road clearance issues. Last thing you want to do is grenade your transmission due to heat buildup as heat will eventually kill it. I've never been a fan of just a stand alone transmission cooler in isolation. Normal transmission range is between 180F- 250F with pan temperature @ 60mph being 180F. Any more that 20mins @ 300F and you could need some repairs. When towing a load the temp can easily rise to 250F. Good fluid is pink, red means used, Brown or with a red tint means too long. Temp fluctuation is normal however prolonged high temps will definitely shorten the life expectancy of your trans. For optimum performance change the fluid, purge the system and change the filter every 15k miles (24k klms). For longevity use a quality trans cooler and mount it in a suitable location with good airflow. I wouldn't run any automatic without a cooler sans cooking it and be up for an expensive rebuild.
I have towed a travel trailer many, many miles, over the years ........ with my trusty transmission oil temp gauge. NO TRANNY FAILURES. Buy A QUALITY TRANSMISSION OIL TEMPERATURE GAUGE, plumb it in, drive it, watch the temp. A happy, normal operating temp. for your transmission is 175 - 190. MONITOR the gauge. If it runs too high during the 4 months, then add the auxiliary tranny cooler. Click on the link below for a typical chart. http://www.txchange.com/heatchrt.htm
Haven't nearly 100 percent of new cars built with automatics been equipped with trans coolers, for decades? And aren't a high percentage of those coolers built into their radiators? Gary
Given the OP's location and seasonal desert heat, this! ^^^^^^^. Short, to the point and, with the thermostatic bypass, solves the issue of varying ambient temps. The only thing you might add is a trans temp gauge, as a few others have suggested. Ray
Absolutely run Aux cooler plumbed in w radiator.....30 deg isnt anything, drive it easy the first mile or two just like warming up the engine and all is good
a stock TH400 in a car like that without an additional cooler lasted for decades...right? if the trans was rebuilt properly to stock specs, it will last for a few more decades. I would use the stock cooler. But if you dig adding stuff because it's fun to add stuff, the put on an additional cooler, make sure it's plumbed properly.
The thermostatic bypass is a must if the cooler is installed in the return line. The cooler in the radiator will warm the transmission up to engine temperature but the auxiliary cooler will cool it down to air temperature in cold weather. On our tow rigs, we used a transmission cooler with it's own fan under the chassis plumbed between the transmission output and the radiator transmission cooler. If it's put in front of the radiator it heats the air before it gets to the radiator and can add to engine heat in hot weather. The cooler cools the fluid before it gets to the radiator cooler. Going through the radiator brings the fluid to operating temperature before it returns to the transmission. We started doing this after we had a customer come in with a transmission cooler line melted into the plastic fan shroud.
if the radiator is in good condition and is stock with trans fluid lines running to/from it should be fine for regular driving - just change trans fluid according to recommendations by transmission shop that rebuilt it -
School me a lil guy's...... Where is this located in relation to the system plumbing wise, and what is it's job? Say with utilizing the cooler in the radiator, and auxillary cooler, just the cooler in the radiator, OR, a stand alone unit...... I get the thermostatic part= opens at temp, but where would it go, and does it bypass ? I've never see one in a radiator (IE) something we'de put in one of "our" cars, nor in any aftermarket cooler I've ever used.... Just trying to get a lil' smarter here.
Thermostatic bypass. Never heard of it, but now that I have, it's exactly what I'm looking for. Awesome. Alright, so plumb the bypass and cooler inline with the return line? I've read elsewhere here that the finned tube coolers are better? There's several large plate coolers at the local pick-a-part, from dually trucks. I'd like to run one without a fan, and I think the tube cooler would be easier to mount somewhere. One other thing... rubber cooler lines. A high quality chemical resistant rubber hose would be fine? Something like fuel injection hose?
The factory stock one is good. Understand, .... the factories spent millions of dollars failure testing BEFORE they went to manufacturing.
IME with a stock convertor the stock cooler will work fine.If you are running a high stall convertor you must have a separate cooler.I have a 3500 rpm TCI convertor on an OT car with a modified 700R4.I have a trans temp gauge on it and here in Florida it WILL run hot without the cooler.
use steel lines for the cooler as much as you can. They make hose just for cooler lines, don't use rubber fuel line.
Once again, a quality transmission oil temperature gauge will be your best friend, will advise you, as tranny oil temperatures change. High tranny oil temperatures are the enemy of your tranny.
Run a good quality synthetic trans fluid. Gives you a little more protection when it gets hot. Having seen the difference after converting a police training fleet over to Scheaffers trans fluid and watching the amount of failures go down by 75 % just by swapping the fluid type .I am convinced there is a difference. An external cooler properly installed is a good thing if your conditions warrant one.
Ditto, not cold enough here to justify one however I can see the benefits where it gets real cold. Here goes
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