Turbo 400 delayed shift

[Rockinpcranch]

I have an 84 K 20 4X4 with the 350 and a turbo400 and when you shift from park to reverse it takes a bit to shift and engage, it does the same going to drive from park or from reverse to drive. Is there a was to adjust this? I only see the shift linkage and a vacuum line going to the transmission. I' m usually a manual guy but I couldn't pass this truck up and the chance to save it. Since my Duramax went down I will be needing it to move a few tractors I have scheduled to work on, and was wondering if there is anything I can do or an adjustment to make. The truck runs and pulls well but the way it shifts into gear from a directional change has me worried. Thanks For the help.

 

[towjoe]

You check fluid while engine was warmed up? Could be low on trams fluid. I know mine shifts slow when it gets low

 

[Rockinpcranch]

I did check the fluid it is in the operating range but I'm not sure the dipstick and tube is correct. It is in two pieces and could be wrong knowing the kid that put the last engine in it. I will be getting the proper dipstick tomorrow on my way home to see if that makes any difference. Thanks Joe

 

[towjoe]

That's a cheap thing to start with. After that it goes to valve body cross leak, torque converter loose inside, line pressure leak internally ect.... One in my 89 v3500 is real hesitant to go in reverse. It blows fluid out the dipstick once in awhile so it's prone to get low on fluid. If it's all the way full of fluid it works fine till its low. My dad has done auto transmissions for almost 40 years now and as he says" won't be long till it goes out. " but I pull a 48' 3 car trailer with it and it's went 30k miles like it is. I'll just keep checking fluid and driving it till it goes out. I got 4 spares Atleast.

 

[HotRodPC]

It's not Vacuum related if your shift points are OK. It does sound like a low fluid or low pump pressure situation. How is the fluid color? Could be a dirty filter or filter has come loose and dropped in the pan since the filter works as the pick up also.

 

[Rockinpcranch]

The old truck seems to shift okay. I haven't got the new dipstick installed to get a true reading, but the fluid seems to be okay. It still looks clean and red. It doesn't smell burnt but that doesn't mean anything. I wanted to run it and get it warm to get the moisture that might have accumulated from sitting since 2010. I do have fluid and a filter that will be going in this weekend. If I get done with a field service call done with on Saturday. Besides it can never hurt to change it. Thanks for the help!

 

[HotRodPC]

The old truck seems to shift okay. I haven't got the new dipstick installed to get a true reading, but the fluid seems to be okay. It still looks clean and red. It doesn't smell burnt but that doesn't mean anything. I wanted to run it and get it warm to get the moisture that might have accumulated from sitting since 2010. I do have fluid and a filter that will be going in this weekend. If I get done with a field service call done with on Saturday. Besides it can never hurt to change it. Thanks for the help!

Ahaaa, so it's been sitting for 2 years. Either you didn't say that before or I missed it. Chances are the seals are hardened up. I am not a believer in additives to fix transmissions except in this case. Get a good Trans Conditioner to soften and swell the seals, and chances are after a couple to few hundred miles and it'll be just fine. Also, run the gear selector alll the way down into L1 and let it run fluid through that passage for a few seconds and do the same for L2 also. Be sure to open up all channels in the valve body this way.

 

[Rockinpcranch]

You caught me on the missing information HotRod. I failed to mention the truck sitting in the first post. Do you have a favorite additive that you like that works well?

 

[HotRodPC]

You caught me on the missing information HotRod. I failed to mention the truck sitting in the first post. Do you have a favorite additive that you like that works well?

NO, not really. I know Lucas is a good product. You don't need to get the most expensive product either. But, that doesn't mean to get the cheapest. Just be sure one of the specific claims the products make is that it conditions seals and/or swells seals. Just for a seal conditioner and give it a few hundred miles of use and a few trans fluid warm ups and if they are not hardened past the point of now return, then the trans should start to function normal again, provided it's not a worn clutch issue.

 

[Rockinpcranch]

I Serviced the transmission and transfer case Sunday. I used Lucas in it like you suggested HotRod. I have used Lucas in my engines and power steering system but never tried it in the transmission. They have some good products. It seemed to help but time will tell. I used it to check fence and water last night and it seemed to shift a bit better but time will tell I don't think I ran it enough to really give it a chance to work in.

 

[HotRodPC]

Yes, it takes a couple hundred miles and some warmth to work. It should eventually soften the seals a bit and hopefully they swell a tad too.

 

[Rockinpcranch]

Got some good news and some bad. The good is I found a transmission for the Duramax and its on its way. I'm hoping to install it this weekend. I got all my hauling done. I changed fluid in the transmission in the 84 twice drove it loaded and unloaded approximately 1,500 miles. but last night I delivered some wood to a friend and on the way back home it started slipping in third. So I think its time to rebuild the transmission. I can't really complain since it made it through and got the work I needed done. when it started slipping I checked the fluid and it was full but in the dark I really couldn't see if there was clutch material in the fluid. so I'm going to try my hand at rebuilding this tranny after I get a clutch in dad's tractor and the High low clutches built for my tractor.

 

[HotRodPC]

Usually when fluid is dark, that is the clutch fibre that has burned up and away that has diluted the fluid. Sounds to me you've made the proper diagnosis. Don't forget to get a New refurbbed converter. You don't want that sludge in the converter to contaminate your new build.

 

[Rockinpcranch]

Yup the tranny is toast I checked the fluid and it's a bit dark. HotRod you bring up a good point with the contaminants trapped in the converter causing problems. I wouldn't dream of reusing the converter it's cheap reassurance to just replace it. since it could fail and take the fresh rebuild with it. Do you have any recommendations on a rebuild kit and converter? When I had the 4L60E rebuilt in my Z-71 a gill younger transgo kit was installed when it was rebuilt. Is there any thing like that to upgrade with or is a stock rebuild going to be stout enough to tow and work?

 

[HotRodPC]

This is a Turbo 400 right? Naww, not much need to do it. Just a basic rebuild kit and run with it. There are like 3 different upgrades I'd do, but those don't even start til about 500-600hp. Even just a B&M stage 2 shift improver kit is about all you need to firm up the shift for about $40. I'd have to check into for certain cuz I don't remember which holes in the plate to drill, but I think you can actually drill a couple holes in the separator plate and couple other little mods and make you own shift hit if you feel the need. Th400's are tough just as they are.

Do let me know if you have any broken hard parts. I've got plenty of Th400 parts. Flat Rate shipping USPS boxes work great for shipping Trans parts since they are heavy, but yet small enough to fit in the boxes.