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View Full Version : Symptoms of bad tranny vac. modulator?



slick
11-25-2005, 09:19 PM
So, what are some symptoms of a bad transmission vac. modulator? Having a few wierd problems with my tranny as of yesterday(yeah, happened in one day, previous day it ran perfectly fine). Gonna check some vac. lines as well, make sure they are all good.

Thanks.

solid_raiden223
11-25-2005, 10:33 PM
A very HARD Shift would be a very wise guess....

Prospeeder
11-25-2005, 10:34 PM
if it ripped, it would let trans fluid leak out and be sucked into the motor to be burned. Also harsh as hell shifts

THe_DeTAiL3R
11-25-2005, 11:19 PM
Yep, hard shifts mainly from R to 1, 1-2, and 2-1. At least that's how it was when I plugged the vac line on my 2.8.

I suppose the opposite could happen also, really sloppy shifts :shrug:

maybe2fast
11-26-2005, 12:56 AM
shifts slower, revs higher. it can really make a trans act weird (many many different things)

Chris run to an autoparts store, get an adjustable one and give it 2-3 turns in and slap it in (10 min tops) 13mm bolt :twisted:

slick
11-26-2005, 01:00 AM
Hmm.... well, for anyone that has ridden in my car, my car is supposed to shift firm. Like, break the dash in half firm. But, today, it's not harsh shifting at all, and in fact feels kinda slow shifting into gears(and outta park as well), and doesn't want to shift correctly at higher RPM's.

I think Tony and I are going to run to the parts store tomorrow morning while he is here.

maybe2fast
11-26-2005, 01:02 AM
I would bet on the vac mod. remember to give it a few turns.

$15.00 and a 13mm socket is all you will need

Prospeeder
11-26-2005, 01:02 AM
there 20$, BUT they had to order it for me. but it wasnt my problem so i cancelled

maybe2fast
11-26-2005, 01:10 AM
my parts stores usually have them. if one doesn't have it move to the next one.

your probably right 20.00 and a 13mm socket

z284pwr
11-26-2005, 01:14 AM
Me not being the great Auto person....what, just tell them you need an Adjustable one? They universal or how does it work? tell them the trans, they give you an adjustable one or regular one?....wow I feel dumb asking such an easy question... :oops:

Prospeeder
11-26-2005, 01:17 AM
Basicly, Shucks convo : I need a Transmission Vacuum Modulator : what year, car, and model, : 1990, Pontiac, Grand Prix, What trim, duhh LE, SE or McLaren? :Mclaren, make sure it is for the 4T60 Transmission : ok, 21.99 or somthing, but we gotta order it


They dont sell the original anymore, the only one u CAN get is the Adjustable one

JakeMetz63
11-26-2005, 09:13 AM
Stupid toledo freezing cold weather, last night was insane.

slick
11-26-2005, 09:16 AM
Stupid toledo freezing cold weather, last night was insane.

Yep, nice and cold and snowy as hell.

Tony will be here around 11-ish, so we will probably run up there sometime before 3(gotta work today damnit).

slick
11-26-2005, 07:32 PM
Well... the tranny is acting fine now. Guess the cold weather got to it.

maybe2fast
11-28-2005, 12:46 PM
did you replace the vac mod? it maybe screwing up in the cold!

Crazy K
11-28-2005, 05:15 PM
When is the last time you changed your filter and fluid?
Fluid and a filter due for a change can be aggravated by the cold as a dirty filter would reduce the trannys' hydraulic pressure.. in addition to the already thickened fluid.
I've seen trannies act up and not go for two or three minutes simply because of this problem. - Ken
P.S. When they do a "total flush" they don't change the filter! Even if your fluid looks great, it doesn't reflect the filter condition anymore!

slick
11-28-2005, 09:23 PM
My tranny has about 20,000 miles on it. I'll probably do a filter and fluid change here soon.

Crazy K
11-28-2005, 09:57 PM
Hey it might just do the trick. Especially if you've been pushing the envelope with your car. Two things that help are adding a second stronger magnet, and the addition of a transmission cooler if you haven't done so already.

Read on:
http://www.w-body.com/forum/viewtopic.php?t=35977&highlight=

slick
11-28-2005, 09:58 PM
Already have a tranny cooler, no problem there.

I like the magnet idea. Might pick up another one.

Crazy K
11-28-2005, 10:25 PM
I got a bunch while on a job some time ago, I've been putting them in ever since!
(I also run with a magnetic oil plug)

One quick thought.... is your remote trans cooler inline before or after it runs through the basic radiator trans cooler? The reason I ask is theoretically the radiator one would help modulate the temperature to prevent over cooling the fluid, if it was inline after the remote one(and that is how mine is set up). -ken