400 turbo shift differences and issue

[rs74]

The 400 trans behind my 85 diesel won't shift into drive. Not sure if it is me or just getting used to this diesel but second gear shift seems a little late and no drive. It will hit second and keep pulling but when you let off then give it some pedal then its like it is revving up to match the road speed if that make sense. I had a 350 turbo that acted something like this and it had a burnt nylon gear on the govenor. I will look into that tomorrow on this one.

Also this 400 and the one behind the 454 (84 K30) are different in how they shift. The 84 shifts real quick and is at a low rpm when it does. The 85 will rev a bit before it shifts. Not sure if this is the making of a bad trans or what. Need to figure out why it is not shifting. It was a couple quarts low on fluid but I topped that off and still nothing. No burnt smell from trans either.

[crashz]

The 400 is controlled by vacuum as you know, so there is a device on the IP that regulates vacuum based upon throttle input. If the vac lines are degraded, it could start there.

However one of you posts mentioned that this truck might have had a 4 speed? If thats the case, the vacuum lines and such might not have been installed correctly (or at all) and the transmission might be from a gas truck. The torque converter is also suspect.

The previous owner of my 87 put a junk yard transmission in my truck shortly before selling it to me. I have identical symptoms as you. Lately shifting, erratic shifting, only seems to work when manually shifted. I suspect that my 400 had come from a small block powered truck, as I have to floor it to get the truck to move in either direction, and once going it shifts crisp and tight but the diesel is screaming. I'm sure my PO changed the converter and all.

This winter I'll be pulling the trans (been sitting for 4 years, another won't hurt) and rebuild with the proper diesel governor and diesel torque converter.

[rs74]

Ended up tracing the vaccum lines on this. The rubber hose had a big hole in it not allowing for it to shift. So now that this is fixed I need to fix a brake line and replace all the vacuum hoses as they are all rotted. Getting closer to driving it.

[Greenlee]

Fyi. If it's stock, most of your vacuum line should be metal with just a short rubber hose on each end. When I was swapping a th400 in my truck I read somewhere not to use rubber hose for the entire vacuum line.

[rs74]

Originally Posted by Greenlee

Fyi. If it's stock, most of your vacuum line should be metal with just a short rubber hose on each end. When I was swapping a th400 in my truck I read somewhere not to use rubber hose for the entire vacuum line.

Yeah it has the metal line. The rubber up on the rear of engine was rotted pretty bad. Not sure what they was thinking when whoever routed teh vacuum lines. The had a Tee in line and the far end of the vacuum hose they just stuck over a valve cover stud to block off. I am coming into more work than I thought due to half assness.