QuestionHi again,
Thanks for the info - so am I correct that, like motor oil, the viscosity of the tranny fluid increases with temperature and thus the psi increases? Also, am I correct in assuming that it is unlikely both the modulator and governor are bad since the tranny operates fine after warm-up? I would think that the modulator and governor either work or do not? I know that it is tough to nail down a problem like this, and appreciate your help. Is there a good way I can flush all the fluid before installing the new valve body? I would rather have everything fresh, if I can. Thank you! Dave
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Followup To
Question -
Hi, there is a similar question/issue on the site, but not exactly, so here goes: I have a 1972 Pontiac Ventura II and have owned it for about 3 months. The car has a big block Pontiac 400 in it, and according to the seller it came out of a mid 1970's Firebird or TransAm. It has a THM350 tranny with a B&M top-loader shift kit. The problem is that the tranny will not shift out of first gear for approximately 3 miles at cold, after that, it's as if a valve "releases" and all is fine from that point on (no sluggishness or slippage, etc). Of course, geared as high as the car is (4.10 rearend), I cannot drive it faster than 20 mph (4K rpm) until that point. I have replaced the vacuum line to the modulator, which appears new, changed the vacuum source around on the intake/brake booster etc., replaced the tranny filter and oil, all to no avail. I did read on-line that some of the Pontiac 400's had a vacuum delay - but there seems to be ample vacuum at startup. Any ideas PLEASE?! Thank you, Dave
Answer -
Dave, it could be the trannys valve body thats in it ,when the fluid is cold it will not have enough psi to shift , a new or differnt valve body should fix it.
AnswerDave;
Yes you are right ,when the fluid warms up it changes the trannys atf psi. and when you say it is fine when warm , than it could be the B&M valve body. as far as cleaning it I would drop the pan / & screen - get a new screen than get a can of starting fluid and spray all of the parts that you can on the inside of the tranny it dries clean , than replace the screen, thats the fastest way to clean it pretty good , but if real dirty than you would have to clean it better / remove it and rebuild it..
