I purchased the Aux Tranny cooler from pfyc.com. I installed it per the instructions (none) and made sure all my fittings and hoses are tight, re-filled her up to normal fluid levels. However, now my car seems to make a grind noise when it shifts from 2nd to 1st (slowing down). It is a very quiet grind. Also it doesn't want to shift into overdrive at normal speeds. I am going to check my fittings again tommarow, but I just want to make sure I did everything right. Also, the cooler gets VERY hot to the touch. Any ideas? BTW, I am running synthetic (Amsoil/Mobil 1 Tranny fluid)

Also I noticed that I followed the directions of that pfyc has (the picture), and have the cooler in the feed line, and not the return. Ugh, looks like I will have to go under there again.

Okay, re-did my fittings, no leaks. The car now shifts into overdrive after I let it warm up a little bit (normal). However, it still grinds, like a squeeky door hinge, when it goes from 2nd to 1st. I do have the feed line going from the tranny to the bottom of the aux cooler, forcing up (backwards of the picture) then from the top of the aux cooler, to the bottom of the radiator, from the top of the radiator to the tranny return. My question is, do I have to much resistance since I am going up, up, through the coolers? Also I wanted to have it before the radiator cause I live in a cooooold climate. Am I harming anything by having this geeeeer sound? All other shifts are firm and fine, downshifts from OD to 2nd, OD to 3rd, no problem. (Mod PCM).

Hi,
I posting mostly for moral support and to let you know that someone actually read your post. I'm going to assume that the grinding noise wasn't there prior to the cooler being installed? I'd be surprised to find that the addition of a cooler would have that drastic an effect on your tranny if it wasn't already going south (if that's what it's doing). Even if the lines were reversed to begin with. Other than that... I don't know what to tell you. Good luck!

Marc

Only thing I can think of is to completely drain all tranny fluid and check to see if there are any metal flakes in it, or does the fluid smell burnt. I would replace the tranny filter and use new fluid and also make sure you added the correct amount of fluid (will take a little more with the cooler, I know a no-brainer) . Check all those and see if it sounds any better. Also make sure you have no sharp bends or kinks in the aux lines. The tranny should put out enuff pressure to handle the lower rad inlet. Good luck and let me know.

Welp, I drained a little bit of tranny fluid out of the bottom of the tranny feed line, and examined it. The fluid is the same color as the new stuff, smells the same too, however there is tiny little metal specks in the fluid. Looks kinda like the glitter found in some makeup (girlfriends) but even smaller (are these friction material?). The filter was changed around 10,000 miles ago, and the tranny itself isn't much older, 15,000 or so. I broke one, thanks for the warranty. However, I will replace the filter. This never did it before, and it seems as the fluid warms up, it almost disapears. I am sure I have good pressure, because all gears shift strong and there is no sign of tranny probs, except when I go from 2nd to first, and its only if I am slowing down. It goes right into 1st, like normal except the sound it makes. If I am in 2nd and hammer it to the floor, it shifts right into first strong as ever then back into 2nd when its supposed to. If I bring up the car to OD, and let off the gas and let it ride from OD to 3rd, no grind (probably couldn't hear it over the road noise anyway), 3rd to 2nd, no problem, but then 2nd to 1st, errr... Could it just be bubbles in the system? Heh, I am pulling at straws.

Original statement: I do have the feed line going from the tranny to the bottom of the aux cooler, forcing up (backwards of the picture) then from the top of the aux cooler, to the bottom of the radiator, from the top of the radiator to the tranny return.

Comment: I may be all wet here, but, that's never stopped me before. From the description you provide above, it sounds to me like you've plumbed your add-on transmission cooler it such a fashion that it'll do no good whatsoever. Here's why I stink that.

First, the radiator. All radiators, whether top to bottom or cross flow, receive the heated coolant from the engine at the top of the radiator, and discharge the cooler fluid from the bottom of the radiator. It's done this way because of the coolant's propensity to drop as it cools. For the same reason, transmission fluid should flow from the top of the heat exchanger inside the radiator to the bottom to take advantage of the cooler coolant at the bottom of the radiator (if you introduce the transmission fluid at the bottom of the radiator, you lose heat transfer capability as the transmission fluid encounters ever higher temperatures on its rise instead of ever cooler temperatures on its way through the heat exchanger).

Next there's the add-on cooler. By placing it before the radiator in the flow path, all you're doing is reducing the amount of heat the radiator is required to dissipate. The transmission fluid, however, will never be cooled below the temperature of the hotest phase of the engine coolant. What you want to do with the add-on cooler is drop the temperature lower than what comes out of the radiator heat exchanger.

The correct flow, in order to achieve maximum cooling of transmission fluid is from the transmission to the top of the radiator heat exchanger, then out of the bottom of the radiator heat exchanger into the top of the add-on heat exchanger, and out of the bottom of the add-on heat exchanger back to the transmission.

Regarding the sounds your hearing and the shifting problems you're having, the way you plumbed it in is probably of no consequence one way or the other. Since the problem started when you added the external cooler, to confirm it's the source of your problem, suggest you temporarily take the add-on cooler out of the circuit and see if the problem goes away. If it does, you've probably got some sorta flow restriction through the add-on cooler which will eventually damage your transmission.

I'd sure like to hear what your problem turns out to be.

Regards, Gary in Sandy Eggo

Thanks gary, unfortunatly its starting to get cold here in MN, but if I find a garage (with a heater) I will take out the cooler for now. From what I read online, most people recommend to put the aux cooler before the radiator if you live in cold climates cause Very cold tranny fluid is bad for trannys too. However, what I may end up doing is just divert (maybe a valve?) strait to the radiator, bypassing the aux cooler for winter months, then in late spring re-enable the cooler. But you statement on the flow problem really hits home, is there any way to test tranny fluid flow? How is tranny fluid pumped through? BTW, my tranny shifts fine through all the gears now except when it is VERY cold, and I can't get into O/D till it warms up (normal tranny action from what I read in newsgroups). That grind is still apparent when I go from 2nd to 1st de-accelerating, however, I have to "listen for it" to hear it, but it does sound like a flow problem. So, how do we test that? I don't want to blow this tranny up, it'd be my 2nd and I am not under warranty anymore!

YOU SAID: From what I read online, most people recommend to put the aux cooler before the radiator if you live in cold climates cause Very cold tranny fluid is bad for trannys too.

COMMENT: The purpose of an aux transmission fluid cooler is to cool the fluid lower that is possible using only the heat exchanger in the radiator. If you place the aux cooler BEFORE the radiator exchanger, you have accomplished nothing. You've wasted your money on the aux cooler. AND, as I stated earlier, if you run your transmission fluid from bottom to top through the radiator heat exchanger, you'll end up with HOTTER transmission fluid than if you'd just done nothing.

Regarding cold climates, it's not anything to be concerned about. You can start your car and drive off on a cold morning, can't you? Well, the transmission fluid only gets warmer after that while you're driving.

Transmission fluid will operate at around 180F under very ideal conditions. Start goofin off or encounter hot weather, or pull hills, etc., and that temperature's going to start to rise significantly. For every 10F rise in the fluid's operating temperature above 180F, the fluid life is cut in half. OTOH, it's reasonable to expect the fluid life to lengthen if you can drop its temperature below 180F.

YOU SAID: However, what I may end up doing is just divert (maybe a valve?) strait to the radiator, bypassing the aux cooler for winter months, then in late spring re-enable the cooler.

COMMENT: If you're basing this decision on climate, you needn't bother. Even if you had it plumbed correctly, your transmission would remain in a good operating temperature range, and your fluid life would thank you. Since you've plumbed it before rather than after the radiator heat exchanger, the aux cooler will have no affect other than to help the radiator a little (which it doesn't need).

YOU SAID: But your statement on the flow problem really hits home, is there any way to test tranny fluid flow? How is tranny fluid pumped through?

COMMENT: I can't provide any information here.

YOU SAID: BTW, my tranny shifts fine through all the gears now except when it is VERY cold, and I can't get into O/D till it warms up (normal tranny action from what I read in newsgroups).

COMMENT: I believe this is discussed in the owner's manual. I believe it's based on engine coolant temperature. The fuel/air mixture is also affected.

YOU SAID: That grind is still apparent when I go from 2nd to 1st de-accelerating, . . .

COMMENT: I never did ask if you'd changed your fluid. Have you? If not, I can almost guarantee you that if you do, you'll notice an immediate improvement.

Regarding automatic transmissions in general, the more frequently you change (at least some of) your fluid, the longer the transmission will last. When it slip-shifts or slam-shifts, that's the little valves and other sliding devices that are sticking then moving. Changing the fluid will do a lot to clean that up. Changing it frequently will prevent it from happening.

I use a vacuum bottle to suck about 6 quarts of fluid out via the dipstick tube. I do this once a year, in the fall, after the summer heat is over and the worst transmission conditions are over (heat).

I now put about 12,000 miles a year on my car (retired) which means I'm changing half the fluid every 12K miles. The fluid I take out doesn't look anything like some of the descriptions I've been reading on this list. Even though the fluid I take out doesn't look any different from the new fluid I then put in, and I've not been experiencing any problems, the transmission always operates just a litttle bit smoother following each fluid change.

Old fluid varnish-coats highly toleranced parts and loses it's lubricating properties. New fluid cleans away those varnish coatings, and provides renewed lubrication.

This whole job takes me about 5 minutes, and I don't even get my hands dirty. Transmission fluid is real cheap when compaired to transmission repairs. When the fluids weren't as good as they are today (25 years ago), I usta do one of these fluid changes EVERY time I changed my oil (every 5K miles). I've never required any automatic transmission repairs (225K was the longest I ever kept a car).

Regards, Gary in Sandy Eggo

I think your slightly wrong...



Clearly shows the fluid goes into the heat exchange through the bottom of the radiator, and the return comes from the top to the tranny.

I do have the cooler before the radiator, I am switching this to after (more efficent). But does top/bottom really matter in a pressurized system?

Well, anyway, got my cooler after the radiator, and my tranny seems to run better, and the grind is gone.

YOU SAID: Clearly shows the fluid goes into the heat exchange through the bottom of the radiator, and the return comes from the top to the tranny.

COMMENT: Whatever picture you meant to include didn't show up. Can you describe what it is you were referring to?

YOU SAID: But does top/bottom really matter in a pressurized system?

COMMENT: Top to bottom or bottom to top won't matter at all with regard to your aux cooler because it's encountering the same temperature over its entire surface. It never hurts to be consistent, though.

Top to bottom WILL matter to the heat exchanger inside your radiator. The reason for this is, as I described earlier, your ever-cooling transmission fluid will be exposed to ever cooler radiator coolant if it flows downward.

I'll try to make this clearer by exhaggerating. Let's say your radiator coolant exits the top of your engine at 195F and cools to 160F on it's way through the radiator before it exits at the bottom of the radiator and goes back to the engine. Let's say your transmission fluid comes out of the transmission at 220F. If you introduce the transmission fluid at the top of the radiator heat exchanger you have a 25F temperature differential. Let's assume instant heat exchange. The temperature of the transmission drops to 195F. But then, as it passes down through the heat exchanger, it encounters ever cooler coolant. At the bottom of the heat exchanger it's exposed to 160F coolant, and it too becomes 160F before going back to the transmission. So, your transmission fluid came in at 220F and exited at 160F - a 60F temperature drop. This is good.

Now let's have the transmission fluid flow the opposite direction. The 220F transmission fluid encounters 160F radiator coolant and cools immediately to 160F. But then, as it rises, it encounters hotter and hotter coolant all the way up to 195F. So, your transmission fluid came in at 220F and exited at 195F - a 25F temperature drop. This isn't as good.

All this having been said, let me now back-peddle a little (or, maybe a lot). In a cross-flow radiator, the big temperature drop doesn't occur from top to bottom, it occurs from left to right. What this means is the temperature of the coolant on the cool side of the radiator won't vary any where near as much (from top to bottom) as it would in a top-down radiator. Consequently, direction of flow (up or down) in the radiator heat exchanger) isn't as significant as I've been carrying on about. Oh well, the day's not been a total loss. You've learned a little about heat exchange theory.

ADDITIONAL COMMENT: I cannot explain why your transmission is acting any better simply because you plumbed the aux cooler AFTER the radiator instead of BEFORE. The flow rate should have been the same regardless.

Regards, Gary in Sandy Eggo

I understand the theory, but my pict (cut and paste this "http://www.geocities.com/fastxtc/gp/auxcooler") stock shows that it flows from the tranny to the bottom of the rad cooler, then from the top of the rad cooler back to the tranny.

"The transmission oil cooler is located inside the right side end tank of the radiator. Two quick-connect fittings on the outside of the outlet tank are connected to a transmission oil cooler located inside the outlet tank. Two transmission oil cooler lines are connected from the transmission to quick-connect fittings. A/T fluid is pumped by the transmission through a transmission oil cooler feed line to the transmission oil cooler lower inlet quick-connect fitting. The A/T fluid temperature is regulated by the temperature of the engine coolant that surrounds the transmission oil cooler as the A/T fluid passes up through the transmission oil cooler. The A/T fluid leaves the transmission oil cooler through the upper transmission oil cooler outlet quick-connect fitting and returns back to the transmission through the transmission oil cooler return line."

Like I back-peddled in my last post, the coolant in the right side radiator "tank" is fairly constant in temperature, so (notwithstanding several minutes of heat transfer philosophy), it really doesn't matter where the transmission fluid is introduced to the heat exchanger, or where it's taken out.

So, you real problem was noises. Have you made the fluid change yet?

Regards, Gary in Sandy Eggo

Well, I lost a little more than a quart when I changed how my tranny cooler was plumbed, and filled her back up and she shifts like a champ, and no more grind. I noticed that my car (coolant temp) runs a little cooler.