Ford/New Holland 6.6L / MT-643

[Diehard]

Anyone have the Ford/New Holland 6.6L with the Allison MT-643 tranny combination? My ‘88 Ford/Ward has the AT-545 and I have some questions before I purchase an MT- 643 that I found to upgrade mine. Any help is much appreciated. Thanks in advance.

[brokedown]

I've got a friend with the 7.8L ford/new holland with the mt643 in it. I understand the 7.8 and 6.6 to be mostly the same engine but a different stroke. I can pass your questions along if you like.

[PNW_Steve]

Do New Holland tractor dealers work on the old 6.6/7.8's?

[Diehard]

Brokedown, I had wondered if I’d need an adapter plate to mount the MT-643 to my 6.6L? Today, I had a chance to pull off the floorboard panel covering above the bellhousing on mine and found the answer I’ve been searching for. Since my 6.6L/AT-545 has a SAE #3 bellhousing, and the MT-643 I found has a SAE #2 being larger in diameter, I figured there had to be an adapter plate somewhere. Answer: the adapter plate is already mounted on my engine to attach the AT-545. I just have to remove the adapter plate to install the MT-643. Problem solved. And thanks for offering to pass on my question. If in fact I do come up with any questions about the 643, I will message you. Thanks again...

[Diehard]

PNW STEVE, I can’t answer your question about New Holland tractors, but to say, I wouldn’t think so. I would think an older diesel mechanic would be your best bet. If you’re a do-it-yourself kind of guy, google it and jump right in. YOUTUBE has a lot of videos as well. Good luck.

[Booyah45828]

The flywheel housing adapter plate is just the beginning of the difference. Since the at545 and mt643 have different torque converters(because of the lockup clutch), most swaps will require a different flexplate/spacer/flywheel arrangement. Check into that as well before you rip everything apart, get stuck, and need to move the bus.

[Diehard]

Will do. Thanks for your input.

[Ninjakitty]

Anyone have know the location of the oil pressure sensor on the 6.6? I had a flood come in the dash thw othwr day amd now my gauge isn't working. I was thinking of juat bypassing the old gauge and adding a new one but I'm not quite sure where the gauge is located. I've already searched google. Thanks!

[Diehard]

l will look at my engine manual when I get back home this weekend and see if I can help you out. Sorry, I haven't been on the forum for a while and just saw your question tonight.