modulator valve leaking? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

19mike69 · 03-12-2003, 01:31 PM

my mod valve seems to be leaking right where it goes into the side of the transmission....how do you fix this?....mine seems to twist from side to side,are they supposed to do that?....any help will be appreciated

71-longbed · 03-12-2003, 01:39 PM

sounds similar to how mine is.... i put a hose clamp on it ... im not sure how to trouble shoot if it's gone bad .... mine had lots of oil around it...sorry i couldn't help more

JimKshortstep4x4 · 03-12-2003, 07:47 PM

There is an "O" ring that seals the part of the mod body that slides into the transmission. It is pretty easy to change the "O"
ring. If you jack your truck up on the passengers side it will move the transmission fluid to the drivers side and minimize the amount of fluid you lose. (Always use stands under the truck).

There is a clamp held on by a 5/16-18 bolt with a 1/2" hex head.
Remove the bolt and clamp and the modulator will slide out. I always put a pan under the mod as some fluid will come out.

Remove the modulator, replace the "O" ring and lube the "O"
with transmission fluid and reinstall.

When you pull the vacuum line off, if you see any oil in the metal tube, you will want to replace the modulator.

Jim

19mike69 · 03-12-2003, 08:34 PM

Jim...thanks alot....thats exactly what i needed to know....im guessing you can get this O ring at any parts store?

19mike69 · 03-12-2003, 08:38 PM

hey,i have another question....on the drivers side on the radiator support that runs all the way across the fron,there is a bolt on either side of the radiator on the bottom....on mine,the bolt on the drivers side is loose but the top of the bolt is round like a carriage bolt....how the hell do you either replace that or tighten it?

OLDCHEV4X4 · 03-12-2003, 09:11 PM

19mike69..the carrige bolt is in a 1"x1" flat piece of steel with a square hole in it. That will keep it from turning. Hold down on the head to keep it from poping up. Good luck finding a 7/16 carriage bolt.
Randy

JimKshortstep4x4 · 03-12-2003, 09:41 PM

Mike,

If the parts store is a problem most transmission shops will help you out.

If you know someone in machine maintenance, they usually have a selection of "O" rings and would probably give you one.

Jim

bobs409 · 03-13-2003, 08:41 AM

In addition to replacing the O-ring, clean the area well with brake or carb cleaner and put a bead of RTV around the part that goes into the transmission (above the O-ring) before installing. This will help seal it better.

If there is any sign of transmission fluid in the hose, the modulator is bad and should be replaced.

03-12-2003, 01:31 PM	#1
19mike69 Registered User Join Date: Jul 2002 Location: pottsboro,tx Posts: 513	modulator valve leaking? my mod valve seems to be leaking right where it goes into the side of the transmission....how do you fix this?....mine seems to twist from side to side,are they supposed to do that?....any help will be appreciated

03-12-2003, 01:39 PM	#2
71-longbed Its Magically Delicious Join Date: Jan 2003 Location: oregon Posts: 2,398	sounds similar to how mine is.... i put a hose clamp on it ... im not sure how to trouble shoot if it's gone bad .... mine had lots of oil around it...sorry i couldn't help more __________________ 71 C10 LWB 350sbc -TH350 12 bolt 3.42 Posi Of all my favorite things to do, The utmost is to have a brew. My love grows for my foamy friend, with each thirst-quenching elbow bend. Beer so frosty, smooth, and cold it's paradise pure liquid gold. Yes beer means many things to me that's all for now cus I gotta pee.

03-12-2003, 09:11 PM	#6
OLDCHEV4X4 Registered User Join Date: Apr 2000 Location: Chester County PA, USA Posts: 1,228	19mike69..the carrige bolt is in a 1"x1" flat piece of steel with a square hole in it. That will keep it from turning. Hold down on the head to keep it from poping up. Good luck finding a 7/16 carriage bolt. Randy __________________ 72 k/10 short wideside 72 k/5 Blazer 72 K/5 Blazer - obstacle course racer 72 custom/10 8' bed 70 K/5 Blazer 67 C-30 GMC Flat bed 86 GMC K2500 Plow Truck 85 GMC K3500 84 M1008 85 M1008 77 G30 Motor Home 72 Sears 12hp Tractor Glenmoore, Pennsylvania

03-13-2003, 08:41 AM	#8
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	In addition to replacing the O-ring, clean the area well with brake or carb cleaner and put a bead of RTV around the part that goes into the transmission (above the O-ring) before installing. This will help seal it better. If there is any sign of transmission fluid in the hose, the modulator is bad and should be replaced. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

03-12-2003, 07:47 PM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	There is an "O" ring that seals the part of the mod body that slides into the transmission. It is pretty easy to change the "O" ring. If you jack your truck up on the passengers side it will move the transmission fluid to the drivers side and minimize the amount of fluid you lose. (Always use stands under the truck). There is a clamp held on by a 5/16-18 bolt with a 1/2" hex head. Remove the bolt and clamp and the modulator will slide out. I always put a pan under the mod as some fluid will come out. Remove the modulator, replace the "O" ring and lube the "O" with transmission fluid and reinstall. When you pull the vacuum line off, if you see any oil in the metal tube, you will want to replace the modulator. Jim

03-12-2003, 08:34 PM	#4
19mike69 Registered User Join Date: Jul 2002 Location: pottsboro,tx Posts: 513	Jim...thanks alot....thats exactly what i needed to know....im guessing you can get this O ring at any parts store?

03-12-2003, 08:38 PM	#5
19mike69 Registered User Join Date: Jul 2002 Location: pottsboro,tx Posts: 513	hey,i have another question....on the drivers side on the radiator support that runs all the way across the fron,there is a bolt on either side of the radiator on the bottom....on mine,the bolt on the drivers side is loose but the top of the bolt is round like a carriage bolt....how the hell do you either replace that or tighten it?

03-12-2003, 09:41 PM	#7
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Mike, If the parts store is a problem most transmission shops will help you out. If you know someone in machine maintenance, they usually have a selection of "O" rings and would probably give you one. Jim



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