I've got a 1989 B250 conversion, 5.2L TBi that I aquired about a year ago. it runs fine but sounds like it's staying in 1st gear a little bit longer than it should, and was wondering what I should do about it. Should I have the tranny flushed, and bands adjusted? My friend said on older vans its better not to flush the transmission because it may be preventing some gears from moving that would otherwise fall off. Any suggestions?
landyacht318
08-16-2007, 12:02 AM
Although I wont tell you that you should not bother to have a tranny service done, I can point you toward an easy possible solution. On our year vans, there is a steel arm (throttle rod) that runs from the throttle body to the transmission that controls the shift points. The linkage could be worn. The connection on the throttle body is designed to slide, and could be fouled or stuck.
If you follow this rod to your tranny you will find where it can be adjusted. There is a half inch bolt that you can loosen (Sharpie the original position). It is spring loaded, so when you loosen the bolt you will lose the current setting.
According to the haynes manual you just remove the slack on the swing arm, slide the adjuster up to the spring, tighten the bolt and your done. In reality, so much slop develops in the linkage that this method probably only works on a newer vehicle(IMO).
I can't remember if you move it forward or backward to make it upshift earlier. I got mine adjusted just where I like it through trial and error. It was about 3/16 of an inch difference from the Haynes manual method. Do note that if you make extreme adjustments and keep it there for many harsch late shifts, or accellerate hard when it's shifting too early you will ruin the tranny.
I reccommend keeping a 1/2 inch socket or wrench with you and drive it making small 1/8th inch or smaller adjustments until you get it where you like. Careful not to burn your forearm on the cat. converter. Do this after you've cleaned and lubed the slidey part by the Throttle body.
I had good luck with a $$$ tranny flush (dealer)with the right fluid after Aarip off joint dropped the pan for a service and refilled it with their econo brand universal type fluid. My torque converter clutch chatter dissappeared immediately after the flush. Aaripoff joint told me I needed a new tranny, 1 month after their warranty expired.
Our trannies can only use ATF +3 or ATF+4. +3 has been phased out but +4 is synthetic and although pricey, is the fluid of choice. Do not trust any quik lube joint or even a national tranny shop chain to use the right fluid. If you do opt for having the pan dropped and the filter changed, bring your own name brand ATF +4 with you and watch them put it in. 4-6 quarts. A tranny flush requires 12-13 quarts.
I think that the reason people reccommend against flushing older transmissions is that the procedure does not require the pan to be dropped and the filter changed. Pumping in fresh fluid can loosen gunk and varnish in the tranny and the radiator and lines and plug the filter and other things. People tend to have a flush only when they detect a problem, and then flushing it just magnifies the problem, or starts a new one.
Good luck, keep us posted
LiveFromHeaven
08-16-2007, 12:29 AM
Thanks for the detiled response, I'll look through my chilton and look under the doghouse tomorrow to see if I can find what you're talking about. Just to make sure I understand, this linkage controls the shift from 1st to 2nd? I'll take a look tomorrow. Thanks!
PS: What might this be called in my Chilton?
landyacht318
08-16-2007, 12:55 AM
Yes, the throttle rod adjusts the 1-2 and 2-3 shift. I dont think it affects the overdrive or Lock up but am not sure. I never noticed a difference when I would do the adjusting, but rarely did I ever get up to those speeds. Once I had the rod fall completly off the TB end and it would almost immediatly shift into 3rd at 5mph and stall the engine.
You really cant miss it (TR) when you have the dog house off. The linkage by my throttle body frequently gets caked with dirt and dust and then doesn't slide properly. Then it doesn't downshift properly.
I've driven thousands of miles on washboarded roads and had a ridiculous amount of play on mine. I had to spend a while getting it so that it would not bind or rattle fiercly. The 1/2 inch bolt for the adjustment will require you to slide under the drivers side of the van. Running boards and a belly can make it a hassle. I've never seen a chilton for our year van, is it any good?
