| DougB |
| (Roll Me Over) |
| 06/06/04 02:10 PM |
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Automatic transmission: Hot A/T problem-solving, and changing fluid & filter
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Well, after months of experiencing overheating problems on my '89 A/T I seem to have found the solution and have come up with a working theory as to why this problem has been plaguing the operation of my vehicle on the highway.
Symptoms:
A/T Temp light repeatedly lit up while traveling at normal highway speeds in 4th gear (O/D on). There was no specific interval for this occurance, but it began to occur more frequently over a period of months. Occasionally, fluid would boil-over through the breather plug. Turning the O/D off and driving in 3rd gear would prevent the problem happening. There was also some lost power which was not immediately apparent due to the length of time it took for the problem to develop and other engine troubles.
Background:
This is a 4-gear non-lockup Automatic Transmission on an '89 Dodge Raider.
It was winter of 2002 the last time I had my transmission filter changed out by a transmission shop. Last Fall, I had a local transmission shop flush out my old ATF and replace it with Mobil 1 fully synthetic ATF. Expensive to say the least. I call it the "Keith Richards" treatement.
Until last Fall, I'd never had my A/T Temp light come on. Then, one day while driving through a headwind strong enough to fold my mirrors back and a tow strap tied around the front of my bumper, the A/T light went on. It would seem like that was an isolated event due to the conditions I described.
After the first few events, I did an ATF drain & fill in hopes that it might remedy the problem. No luck.
Earlier this year the A/T Temp light began popping on more and more frequently during long trips until finall it got to the point where I could only operate in 3rd gear at highways speeds to keep from overheating. Obviously, this was not a cost-effective/fuel-efficient means of travel. Luckily, the Mobil 1 ATF isn't as prone to breaking down as normal ATFs might be; it was not burned or discolored even after many overheating episodes.
After the last incident of it happening, I decided that I'd crack open the pan and have a look at the filter screen...
Once I got the pan off, I removed the bolts holding the screen to the valve body and popped it off. I was startled when about 1/4 of a quart more ATF spilled out. I hadn't expected that to happen so I got ATF everywhere. It was a mess.
Theory:
As it turns out, the flush & fill combined with the extra detergency of the new synthetic ATF must have washed out some deposits throughout the system. After a period of few months, these micro-fine particles eventually filled the pores in the filter screen making it difficult for fluid to pass through the mesh. With less fluid being able to flow at higher speeds and higher temperatures, fluid was not able to pass through the cooler at a normal rate. This is what led to the overheating.
The debris in the filter screen was not immediately apparent until I wiped a shop towel over a section and it became black.
I did a comparison between the old filter and new filter by pouring some used ATF on each filter screen using a turkey baster. The new filter allowed fluid to pass through while the old filter just let most of the fluid run off the sides. A subsequent test drive at highways speeds led to no overheating. 
Anyways, problem solved: the Raider's runnin' well again. Hope this helps someone out someday. Happy driving!
-DougB
| Anonymous |
| (Unregistered) |
| 06/06/04 02:19 PM |
Re: HOT A/T: Problem solved!
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Thats great! I am glad you fixed it. Shows Mobil 1 Tranny fluid is good @ cleaning deposits!
| Lloyd Swartz |
| (Web Wheeler) |
| 06/06/04 02:51 PM |
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Re: HOT A/T: Problem solved!
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This is an often neglected item, that can lead to a burned out transmission. Best to pull the pan and clean the filter every couple of fluid changes to be safe.
| MarkG |
| (Body Damage is Cool) |
| 06/06/04 03:18 PM |
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Re: HOT A/T: Problem solved!
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This is the kind of information that someone should archive.
| Anonymous |
| (Unregistered) |
| 06/06/04 04:09 PM |
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Re: HOT A/T: Problem solved!
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My dads 1997 Corolla has 170k on original tranny fluid and filter. Still workin ok. I am sure it would benefit from a fluid change from he is old style and believes in the myth that a old tranny w/ new fluid will case more problems.
| FrankR |
| (Web Wheeler) |
| 06/06/04 04:46 PM |
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Re: HOT A/T: Problem solved!
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Good work, Doug!
It sure gets fixed faster when you take it apart to see what's wrong instead of standing around kicking the tires and cussin', doesn't it? Of course, it helps to have the experience, confidence and energy to get the job done. The first 2 come the hard way, but by the time most of us gain those, the 3rd one's shot!
Good goin' and thanks for the tip...
Frank
| Anonymous |
| (Unregistered) |
| 06/07/04 03:27 AM |
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Re: HOT A/T: Problem solved!
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Lately my A/T temp light has been coming on at start up when the engine is cold, but not any other time. could this be the same problem. I have changed the Tranny fluid twice, but never removed the pan and changed the filter.
Same problem in the early stages maybe?
| Anonymous |
| (Unregistered) |
| 06/07/04 01:09 PM |
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Re: HOT A/T: Problem solved!
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Quote:
Lately my A/T temp light has been coming on at start up when the engine is cold, but not any other time.
This could be caused by a bad or intermittantly failing TPS. Check with a scan tool to see if you have any stored DTC's. If so, use a DVOM to measure the resistance in the TPS as it's swept from closed throttle to WOT.
Joel, CA
| NathanC |
| (Roll Me Over) |
| 06/07/04 08:12 PM |
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Re: HOT A/T: Problem solved!
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Way to go Doug!
| Houston |
| (Mudrunner) |
| 06/07/04 08:33 PM |
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Re: HOT A/T: Problem solved!
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Sorry kiddo, score one for your dad. It's NOT a myth that you can create new trans problems you didn't have if you change fluid on an old automatic that has deposits and aging seals/o-rings in it. The fresh fluid will have lots of the detergent additives that ALL ATF's have. This fresh fluid will clean out crud, and it's that "crud" that may have been the only thing sealing a marginal seal or o-ring.
Also, you can get lots of clutch pack or friction disc material ending up in the filter like what Doug experienced.
If you have enough friction material left on the discs, and your filter doesn't clog completly, you keep on driving.
However, it's not uncommon to see a 'borderline' trans with over 100K on it get a filter & fluid change and not move off the shops' rack after they're done. It's happened to me, and to others, not to mention the customer!
Was the trans in great shape before you started, no, it wasn't. I won't include strong,well maintained automatics that didn't have pretty burned fluid or very dirty fluid before the change-over. Well maintained autos aren't usually the ones that suffer. It's your "beaten" and abused automatics that worry me when I'm asked to work on a high mileage unit.That dirty fluid may be all that's keepin the trans together.
So, the point of what I'm saying is that if your dad's auto has long passed the point of being well-maintained, you need to think about Plan "B" if you want to change his fluid in the future, like maybe needed a rebuilt unit after you or a shop is done with it. Esp. if his fluid looks and smells bad. Regular fluid and filter changes ARE called for and ARE needed, but be aware that out here in the working shop world, you have to know when to warn someone that some maint. work just might bite them in the butt if the conditions are right for it.
| DougB |
| (Roll Me Over) |
| 06/07/04 08:40 PM |
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Re: HOT A/T: Problem solved!
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For those of you who are thinking of doing it, dropping the pan on these trucks is a real PITA, but I managed to do it for the first time at night with only a flashlight and a socket wrench set.
Put it back together in the rain too. 
Here's the proceedure I included in another thread:
How to drop the pan on your A/T:
Quote:
1. Use the bottle jack and jack up the tranny by the transfer case. Fit the bottle jack as close to the inside as you can in order to rest the transfer case housing on a jackstand. Once that's done...
2. disconnect the shifter linkage on each side. You'll figure it out. Just remember how it all goes back together.
3. Unbolt the two bolts of the transmission cushion from the bottom. Unbolt the two bolts at the rear of the 2nd member "T", then unbolt the four bolts on either side. It should all drop out after that. The next part is easy.
4. Open the drain plug and drain all the fluid.
5. IMPORTANT: make sure to unbolt the A/T dipstick tube brackets. Yes, the tube is bracketed in two places and is permanently connected to the oil pan. One of those places you won't be able to reach with your arm. You'll have to use a long extension (~2') to get at it. You can see it by looking forward and up from the Oxygen Sensor. Unless the bolt has been swapped, you should be using a 17mm socket.
6. Unbolt the 14 bolts to the transmission oil pan and drop the pan. You might have to wrestle with it a bit, but don't force it. Be prepared for the fluid that will fall out if it that didn't exit through the drain plug - there's more than you think. Once that's done, swing it to the side and say, "Yeah, you liked that, didn't you!".
7. The filter will be visible in the middle of the valve body. I think there's like 5 or 6 bolts holding it in. Unbolt them. The filter screen will drop out with a spacer on the top of it. Be prepared for any residual fluid that may drop from that point, especially if the filter's clogged.
8. Wipe off the pan and magnets.
9. Install the new filter and paper gasket.
10. Installation is the reverse of disassembly.
20. Fill with ~3-3.5qts of new ATF. Check your ATF level carefully! Follow the instructions in your service manual!
Both my parents Toys are cruisin' around with high-milage everything in them, however, I doubt that they've seen quite the service that the Raider has.
I've heard the same "myths" from a few reputable transmission mechanics. I'd have to agree with Houston - I'm now a beleiver.
| Anonymous |
| (Unregistered) |
| 06/08/04 12:38 AM |
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Re: HOT A/T: Problem solved!
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Joel,
Thanks for the info, but help me out with the acronym's, I'm having a little trouble:
TPS?
DTC = Diagnostic Trouble Codes
WOT = Wide open throttle?
DVOM = Digital Volt/Ohm Meter?
Sorry, I'm a little slow tonight and a newbie.
Thanks,
Peter
| TobyB |
| (Rock Warrior) |
| 06/08/04 09:17 PM |
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Slightly off- thread...
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I've heard about similar problems when going to a synthetic motor oil, too-
it flushes out the petro crud, causing problems- apparently it can kill old air- cooled VW's in a few hundred miles...
now back to your regularly- scheduled thread!
t
| Anonymous |
| (Unregistered) |
| 06/08/04 10:19 PM |
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Re: Slightly off- thread...
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Actually, there were several problems with early synthetics that would contribute to failures. Some of them did clean deposits off extremely well, leading to a similar situation. Many lacked the additives that extend the life of older seals (make them swell up, in other words), and there were some problems with lubricating properties matching up with certain viscosities while oil weight didn't. If you're really interested, there have been several very interesting threads of the past few years. Other problems, too, but those were the major ones off the top of my head.
| Anonymous |
| (Unregistered) |
| 06/09/04 02:07 AM |
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Re: HOT A/T: Problem solved!
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TPS= Throttle Position Sensor
My 95 SR flashed an occasional AT light as well as an even more intermittant Check Engine light. Looked into both the engine ECU and the Tranny ECU to find the same TPS trouble code. Also noticed a glitch in the TPS at closed throttle when cold . Replaced the TPS and never had a problem since. I have noticed other SR's with the same DTC and the same intermittent failure when cold.
Joel, CA