Allison ht740 output seal - Printable Version

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+--- Thread: Allison ht740 output seal (/showthread.php?tid=8731)

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RE: Allison ht740 output seal - [email protected] - 11-07-2025

(11-07-2025, 02:28 PM)Richard Wrote:  What Jeff said !!!!!!!  You may have to make a tool by heating and bending a screwdriver into a right angle at the tip in order to extract the rest of the seal. Be careful not to score the bore with a sharp tool.

For what it’s worth, I have done the same thing on seals a couple of times, and scratched my bald head as to why the new one obviously didn’t fit.

Thanks to Jeff, good eye.

Yup, been in same boat that's why it occurred to me after seeing those pictures. Sometimes those are really no fun to get out. 

I have resorted to using a screw in the seal and actually using a claw hammer to pull the seal out. Its either that or a chisel to cut the seal to relieve some pressure so it will come out, just have to be careful not to damage the bore surface if you go at it with a chisel.

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RE: Allison ht740 output seal - Richard - 11-08-2025

Yep, used the screw trick also. Have to be careful with the metal shavings the self tappers make.

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RE: Allison ht740 output seal - Dystrakti0n - 11-25-2025

I just put everything back in again, because I need to limp 1 mile down the road to get water and dump. But I'm 80% sure that is part of the housing as its after the weep hole. And the seal sits much deeper inside the housing on the yoke based on what was still shiny but I am perfectly happy to be wrong. I'll be pulling it again come Saturday. I'm getting quite proficient at it!

Aside, if anyone needs the part number for the low pressure sensor between the drive axle and tag, it's a Bendix 283029N.

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RE: Allison ht740 output seal - Dystrakti0n - 04-18-2026

OK, apologies for the long delayed response. Gentlemen, I am here to humbly report that y'all were right, there was a dust cap in the way that had been dirt welded in place. After several hours with brake cleaner and engine cleaner, a torch and a bit of colorful vocabulary I ended up drilling out two holes, inserted two screws and got that thing out of the way. I have the part that was spec'd and will be installing it shortly. I had to crawl out from under the coach to catch an appointment with Apple tier 3 support. 3rd call, can't get them to understand that there is a database flag issue preventing me from updating that I've accepted ToS so I can activate my new iPhone. Coming from android this whole thing is absurd, but I digress. I will report back as soon as I get it installed and let you know if the leak stopped. So far I have never been so happy to be wrong about something, since I'm now making progress on the coach.

Thank you Jeff for the screw tip. As always, you guys are awesome, thank you for all the help and patience.

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RE: Allison ht740 output seal - [email protected] - 04-18-2026

(04-18-2026, 05:02 PM)Dystrakti0n Wrote:  OK, apologies for the long delayed response.  Gentlemen, I am here to humbly report that y'all were right, there was a dust cap in the way that had been dirt welded in place. After several hours with brake cleaner and engine cleaner, a torch and a bit of colorful vocabulary I ended up drilling out two holes, inserted two screws and got that thing out of the way. I have the part that was spec'd and will be installing it shortly. I had to crawl out from under the coach to catch an appointment with Apple tier 3 support. 3rd call, can't get them to understand that there is a database flag issue preventing me from updating that I've accepted ToS so I can activate my new iPhone. Coming from android this whole thing is absurd, but I digress. I will report back as soon as I get it installed and let you know if the leak stopped. So far I have never been so happy to be wrong about something, since I'm now making progress on the coach.

Thank you Jeff for the screw tip. As always, you guys are awesome, thank you for all the help and patience.

No worries, you are doing the hard work and I know how frustrating it can be at times. Special words sometimes seem to help. I need to do this same job on my bus and I am not looking forward to it. 
Go easy putting in the new seal, easy to damage them. 
Glad you are getting it sorted.

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RE: Allison ht740 output seal - Dystrakti0n - 04-18-2026

I ended up lubricating the seal before sliding the yoke back into place, I felt it make contact then add some smooth resistance as it seated. Too dark out here on BLM outside of Truth or Consequences to do a test run, but we have to do a pump and dump tomorrow anyway, so I will check it out as the coach is airing up and the engine comes to temp.

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RE: Allison ht740 output seal - Dystrakti0n - 04-20-2026

OK, roughly 30 mile round trip, 20 of it highway and the transmission is shifting strong, zero leaks or drips and I feel like I got 30% power back to the wheels now that everything is working properly again.

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RE: Allison ht740 output seal - Richard - 04-21-2026

Thanks for closing the loop!

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