Hi, My MT643 has the trans temp sensor installed by the chassis manufacturer (Spartan) on the "to the cooler" line.
Mark
hzjcm8 wrote:
Jarlaxle wrote:
hzjcm8 wrote:
Jarlaxle wrote:
hzjcm8 wrote:
Jarlaxle wrote:
hzjcm8 wrote:
Hi all,
I've just joined Good Sam Club. I was the former Transmission Fluids Engineer at Allison Transmission. I held that position from 1990 until my retirement in 2009. Let me know if you have questions about TranSynd, the TES-295 specification or just anything to do with automatic transmission fluids. I'm here to help.
My Genesis has an MT643 trans behind a DT466 engine...Dexron III, right?
Nope !!! I no longer recommend anyone use DEXRON-III. Use TranSynd or another TES-295 for the best possible performance and durability. DEXRON-III is an obsolete spec so anything these days is being manufactured under the label D3/M meaning DEXRON-III/MERCON. These fluids are manufactured and sold but have no license and are no longer approved by either GM or Ford. I used to sit on the GM DEXRON-III committee and I can tell you that these fluids are no longer evaluated by anyone at GM. So, it's sort of like "buyer beware" when it comes to any DEXRON-III (D3M) products on today's market. Also, do not use DEXRON-VI due to possible seal issues with your older MT transmission.
PS: D3M fluids (DEXRON-III) tend to lose viscosity so cooling won't be as good due to lower cooling circuit flow. Unless you change it every 25,000 miles. So, just put in TranSYnd adn you should be good for at least 100,000 miles. Don't forget to change the filters too.
It's wound up 307,000 miles (filters changed annually, roughly 25K) on D3...honestly, I'm leery of switching it at this point! Is TranSynd compatible with D3? Flushing all of the old fluid out at this point is just not feasible short of component replacement. (This thing has the biggest trans cooler I have ever seen!)
Also, what (if anything) can you tell me about the oddball AT500?
If you've had success with DEXRON-IIIH, it's because you've been changing it and paying attention to the filter changes too. However, these fluids are no longer licensed products and I'm leary of them. The AT500 is an older Allison automatic with 4 speeds. It has hydraulic controls. Most every school bus in America had an AT500 at one time. It's a good transmission but a little low on cooler flow at idle. No electronics and it has a mechanical governor (no speed sensors).
Actually, by the records I got, they NEVER did a full ATF change...just an annual filter change. The fluid is clean & bright red (it is definitely Dexron III), it shifts perfectly.
I have to admit that I have looked at LOTS of school buses and have NEVER seen an AT500. Most (T444E, Cummins 5.9, Ford 6.6, Cat 3116, DD 8.2, DT360, IH 9.0 litre) had the AT542 or AT545 light-duty, non-lockup transmissions...3208 Cats or DT466 engines usually had MT643's (though I saw one DT466/AT545, and cannot fathom why someone would spec THAT out!), some pushers had T444E's and MD3060's. As I recall, the AT500 is essentially a lockup AT545...isn't it? I've only seen a few, all behind 5.9 Cummins engines in Freightliner chassis shuttle buses & delivery trucks.
My bus doesn't have a trans temp gauge...where should the sensor for one go on a 643?
Jaraxle,
Not sure how you know it's definitely DEXRON-III if you have no records. So, keep doing what you're doing ... sounds like it works for you. Good Luck !!!
PS: You asked about the AT500 so I thought you meant the AT500 Series which includes the AT542 and AT545. I did not differentiate between model types. In general, the AT500 Series was the fore runner to the 1000 Series. I'm not sure about placing the MT643 temperature sensor. That's out of my area of expertise but I'd say the best place would be the return line from the cooler if you can't catch the sump temperature anywhere.
I would rather drop the DEXRON-III conversation at this point because these fluids are getting very old now and who knows who's mixing them and with what ingredients.
