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-   -   TH350 problems Shifts at 4500+rpms? (https://67-72chevytrucks.com/vboard/showthread.php?t=598947)

TheBlueBomber 10-02-2013 04:16 PM

TH350 problems Shifts at 4500+rpms?
 
So I drove the truck the other day and it ran terrible. felt like i had to floor it to go what other people were going like 2000rpms. cleaned the oily spark plugs and turned the dist just a hair and it improved like crazy!

then I took it for a test drive and now she wont shift into second gear unless im at 4500+ rpms and even then I have to stomp on it so itll shift. Doesnt really work manually either still the same effect. having to stomp on it to shift gears. hit 3rd gear twice today.

Any ideas on what it could be? I figured if it was a vacuum problem it wouldnt shift out of first

OH and the fluid is like a dark red and smells smelly. That smelly smell that smells.... smelly. Prolly could use 1/4qt of fluid so ill start there. Havent changed fluid/filter since I got the truck.





SM465 swap soon but I would like to drive it/four wheel A LITTLE before I do the swap (christmas time)

TheBlueBomber 10-02-2013 04:18 PM

Re: TH350 problems Shifts at 4500+rpms?
 
Backfires once through the exhaust when cranking.

clapage6 10-02-2013 04:51 PM

Re: TH350 problems Shifts at 4500+rpms?
 
I believe this has the kick down cable right? Which would be the most like culprit for what you're describing. I don't have the most efficient way of checking/adjusting it but i'm sure google what.

If i'm wrong about the kick down cable the unlikely cause is the governer which i believe can be access from outside the case but is rarely the problem.

geezer#99 10-02-2013 05:13 PM

Re: TH350 problems Shifts at 4500+rpms?
 
Tranny fluid smells like burnt toast eh!!
And dark red!
It's on death's door! Soon to expire.
A backfire at start up is retarded timing. Check your timing!

kalbert 10-02-2013 05:19 PM

Re: TH350 problems Shifts at 4500+rpms?
 
Have you checked for vacuum leaks? Particularly in the vacuum line that connects to the vacuum modulator on the transmission? Without a way to sense engine load the transmission will not shift correctly, and if the engine has a bad vacuum leak it can neither run correctly nor supply the transmission with an accurate indication of load. If it's been driven alot, or driven hard in a poorly running condition or without the modulator connected the transmission will certainly be damaged, possibly severely.

TheBlueBomber 10-02-2013 06:04 PM

Re: TH350 problems Shifts at 4500+rpms?
 
Quote:

Originally Posted by geezer#99 (Post 6296650)
Tranny fluid smells like burnt toast eh!!
And dark red!
It's on death's door! Soon to expire.
A backfire at start up is retarded timing. Check your timing!

I know... I know. I just need it to last until decemberish because thats when ill start the swap. I parked it for the day cause it started making me frustrated.

TheBlueBomber 10-02-2013 06:32 PM

Re: TH350 problems Shifts at 4500+rpms?
 
Quote:

Originally Posted by kalbert (Post 6296658)
Have you checked for vacuum leaks? Particularly in the vacuum line that connects to the vacuum modulator on the transmission? Without a way to sense engine load the transmission will not shift correctly, and if the engine has a bad vacuum leak it can neither run correctly nor supply the transmission with an accurate indication of load. If it's been driven alot, or driven hard in a poorly running condition or without the modulator connected the transmission will certainly be damaged, possibly severely.

ill check the vacuum leaks.

INSIDIOUS '86 10-02-2013 07:35 PM

Re: TH350 problems Shifts at 4500+rpms?
 
Is your vacuum line to the modulator hooked up? Check the lines
Posted via Mobile Device

motornut 10-02-2013 08:50 PM

Re: TH350 problems Shifts at 4500+rpms?
 
Quote:

Originally Posted by INSIDIOUS '86 (Post 6296880)
Is your vacuum line to the modulator hooked up? Check the lines
Posted via Mobile Device

yup i'd check that first,top and bottom make sure the hose bit is tight and not oily or cracking

INSIDIOUS '86 10-02-2013 10:11 PM

Re: TH350 problems Shifts at 4500+rpms?
 
It may be stuck. It sounds like its shifting on the govener
Posted via Mobile Device

dieseldawg142 10-03-2013 12:51 AM

Re: TH350 problems Shifts at 4500+rpms?
 
yup, if your vac. lines are fine, just replace the modulator. did mine couple yrs ago, was like $15-$18.
my truck pulled this on me last summer, was running up to 3-4 grand before shifting. couldn't find no leaks so i pulled the rubber T fitting off my vac. gauge thinking it mite be plugged, soon as i flexed the T fitting, a huge crack showed up. problem solved

TheBlueBomber 10-03-2013 10:28 AM

Re: TH350 problems Shifts at 4500+rpms?
 
Quote:

Originally Posted by dieseldawg142 (Post 6297418)
yup, if your vac. lines are fine, just replace the modulator. did mine couple yrs ago, was like $15-$18.
my truck pulled this on me last summer, was running up to 3-4 grand before shifting. couldn't find no leaks so i pulled the rubber T fitting off my vac. gauge thinking it mite be plugged, soon as i flexed the T fitting, a huge crack showed up. problem solved

Cool beans. Ill check it out. The first thing I did when it started happening was check it out and its hooked up. Ill pull it off and see if that does the trick.


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