Trans leak caused by bad ground??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

DevinM · 06-08-2002, 09:29 AM

I had a tranny leak (TH350) and the mechanic replaced my pump unit. Then w/ in 2 months it was leaking again. The mechanic investigated deeper into the problem and advised me that the engine had never been grounded to the transmision, Therefore the "brass bushing" (by the torque converter) was grounding out and melted. Does this make any sense to anyone? The mechanic grounded everything and assured me that I won't have anymore problems.

tom hand · 06-08-2002, 09:44 AM

If the engine block was not grounded and the starter was grounding thru the transmission maybe. It would be very difficult to install a transmisssion and it not have a good ground to the motor thru the mounting bolts. I have installed hundreds of transmissions without making any attemp to ground them with no problems. I sure would like to see that bushing.

Longhorn Man · 06-08-2002, 04:56 PM

Kinda sounds crazy...but I've seen worse things.

bigvinnie · 06-08-2002, 05:16 PM

I have a friend who rebuilds trasmissions who told me the same thing about the grounding problem.... lack of strong grounding can do some very strange things... I use numerous grounding straps between the engine and frame, frame and body (front and rear), core support to frame, etc.....

lofly'a · 06-08-2002, 06:19 PM

ya learn somethin' new everyday. thats why i read and participate in this board regularly.

71GMC_3/4T · 06-09-2002, 10:50 AM

6 bolts to hold the transmission to the engine and none of them were making contact? Hmmmm, something just doesn't make sense. I could see maybe the tailshaft bushing (grounding through the rear axle via the driveshaft), but not the pump bushing.
Could you go into more detail as to what he did to fix the problem? Where did he run the wires to/from? What gauge were they? Did he use star washers? Thanks!

mikep · 06-09-2002, 01:56 PM

Thats the dumbest thing I have ever heard. Your transmission is securely bolted to the engine block which is in turn grounded to the frame and firewall.Grounding the transmission to anything else is not going to accomplish anything. I think your tranny guy is too used to explaining things to female customers. They'll believe anything.The real truth here is probably he used crappy parts or just did a bad job so he's looking for some excuses.Go elsewhere next time. He's trying to snow you.

GMCjunkie · 06-09-2002, 02:24 PM

Stand corrected mikep, not ALL women will believe ANYTHING that a so-called "mechanic" tells them

Just F.Y.I.

Super Chevy · 06-09-2002, 04:21 PM

i may sound dumb ,but arnt the bellhousings on the th350 alluminum ,i dont think alluminum conducts electricity very good?

Super Chevy · 06-09-2002, 04:24 PM

btw , even if you had a bad "bushing" why would it leak?,i know the front seal is the thing that actually seals not a bushing

71BBK10 · 06-09-2002, 04:54 PM

i might be wrong but i think he's talking about the little "cap" on the front of the torque converter

Paul Clark · 06-09-2002, 05:18 PM

Didn't mention where it was leaking. A little dye in the fluid and then a check with an ultrviolet light might help pinpoint things. Lots of places where those things can leak. I know, 'cause mine leaks at all of them.

Longhorn Man · 06-09-2002, 07:20 PM

Aluminum conducts fine. In the 70's houses were wired with it.

DevinM · 06-09-2002, 08:47 PM

Well, the mechanic told me that since the bushing "melted", the torque converted got sloppy which caused the problem. Initially, he didn't know what the problem was and suggested getting the whole thing rebuilt. When he called the local tranny shop the first thing they asked was "is the engine grounded properly?" I know the mechanic very well and he know the tranny shop people very well at all. So, I find it hard to believe that he's giving me the "run-around". He grounded 3 spot. Battery to Inner-fender, intake to firewall, and a 3rd place?

chevy72402 · 06-09-2002, 08:55 PM

I believe on my th400 it was grounded also through a bolt that held the tranny on...

06-08-2002, 09:29 AM	#1
DevinM Registered User Join Date: Jan 2002 Location: Deerfield, MA USA Posts: 198	Trans leak caused by bad ground??? I had a tranny leak (TH350) and the mechanic replaced my pump unit. Then w/ in 2 months it was leaking again. The mechanic investigated deeper into the problem and advised me that the engine had never been grounded to the transmision, Therefore the "brass bushing" (by the torque converter) was grounding out and melted. Does this make any sense to anyone? The mechanic grounded everything and assured me that I won't have anymore problems. __________________ '71 Chevy C-10 - Current '62 Imapla SS - Traded for my current '73 Nova Hatch - traded for ATC-350X '73 Chevelle Deluxe - First car (R.I.P) DEERFIELD, MA

06-08-2002, 09:44 AM	#2
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	If the engine block was not grounded and the starter was grounding thru the transmission maybe. It would be very difficult to install a transmisssion and it not have a good ground to the motor thru the mounting bolts. I have installed hundreds of transmissions without making any attemp to ground them with no problems. I sure would like to see that bushing. __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

06-08-2002, 05:16 PM	#4
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	I have a friend who rebuilds trasmissions who told me the same thing about the grounding problem.... lack of strong grounding can do some very strange things... I use numerous grounding straps between the engine and frame, frame and body (front and rear), core support to frame, etc..... __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project

06-08-2002, 06:19 PM	#5
lofly'a Registered User Join Date: May 2000 Location: Alexandria, LA 71301 Posts: 1,451	ya learn somethin' new everyday. thats why i read and participate in this board regularly. __________________ -02 avalanche (daily driver) -66 gto ragtop 389/400 (garage queen, hand-me-down from dad) -72 Tribute Trans Am (6.0LS/T56 6-speed) in progress -2003 YUKON (Wife's) -71 gmc swb fleet (current project, gonna shave everything, bags, stuff w/ 20's, gen III powertrain) -48 3100 SWB - 12/31/23 LONG TERM Project

06-09-2002, 10:50 AM	#6
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	6 bolts to hold the transmission to the engine and none of them were making contact? Hmmmm, something just doesn't make sense. I could see maybe the tailshaft bushing (grounding through the rear axle via the driveshaft), but not the pump bushing. Could you go into more detail as to what he did to fix the problem? Where did he run the wires to/from? What gauge were they? Did he use star washers? Thanks! __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

06-08-2002, 04:56 PM	#3
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Kinda sounds crazy...but I've seen worse things.

06-09-2002, 01:56 PM	#7
mikep Used to have a truck Join Date: May 2002 Location: port orchard WA Posts: 1,552	Thats the dumbest thing I have ever heard. Your transmission is securely bolted to the engine block which is in turn grounded to the frame and firewall.Grounding the transmission to anything else is not going to accomplish anything. I think your tranny guy is too used to explaining things to female customers. They'll believe anything.The real truth here is probably he used crappy parts or just did a bad job so he's looking for some excuses.Go elsewhere next time. He's trying to snow you. __________________ No truck :-(

06-09-2002, 02:24 PM	#8
GMCjunkie Dude...I'm a CHICK Join Date: Jul 2000 Location: Lakeland Georgia Posts: 6,192	Stand corrected mikep, not ALL women will believe ANYTHING that a so-called "mechanic" tells them Just F.Y.I. __________________ ~~~~~~~~~~~~~* "The unexamined life is not worth living" -Socrates ~~~~~~~~~~~~~* '71 GMC Suburban 4x4

06-09-2002, 04:21 PM	#9
Super Chevy Registered User Join Date: Feb 2001 Location: Ohio Posts: 1,025	i may sound dumb ,but arnt the bellhousings on the th350 alluminum ,i dont think alluminum conducts electricity very good?

06-09-2002, 04:24 PM	#10
Super Chevy Registered User Join Date: Feb 2001 Location: Ohio Posts: 1,025	btw , even if you had a bad "bushing" why would it leak?,i know the front seal is the thing that actually seals not a bushing

06-09-2002, 04:54 PM	#11
71BBK10 Teufelhunden Join Date: Oct 2001 Location: Camp Pendelton Ca Posts: 572	i might be wrong but i think he's talking about the little "cap" on the front of the torque converter __________________ 1971 K10 lwb fleetside 402 T350 205

06-09-2002, 05:18 PM	#12
Paul Clark Registered User Join Date: Apr 2002 Location: Center Point, IA Posts: 502	Didn't mention where it was leaking. A little dye in the fluid and then a check with an ultrviolet light might help pinpoint things. Lots of places where those things can leak. I know, 'cause mine leaks at all of them.

06-09-2002, 07:20 PM	#13
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Aluminum conducts fine. In the 70's houses were wired with it.

06-09-2002, 08:47 PM	#14
DevinM Registered User Join Date: Jan 2002 Location: Deerfield, MA USA Posts: 198	Well, the mechanic told me that since the bushing "melted", the torque converted got sloppy which caused the problem. Initially, he didn't know what the problem was and suggested getting the whole thing rebuilt. When he called the local tranny shop the first thing they asked was "is the engine grounded properly?" I know the mechanic very well and he know the tranny shop people very well at all. So, I find it hard to believe that he's giving me the "run-around". He grounded 3 spot. Battery to Inner-fender, intake to firewall, and a 3rd place? __________________ '71 Chevy C-10 - Current '62 Imapla SS - Traded for my current '73 Nova Hatch - traded for ATC-350X '73 Chevelle Deluxe - First car (R.I.P) DEERFIELD, MA

06-09-2002, 08:55 PM	#15
chevy72402 FARMER/RANCHER Join Date: Apr 2001 Location: SD Posts: 597	I believe on my th400 it was grounded also through a bolt that held the tranny on... Attached Images __________________ 1972 chevy super, long box, 402 big block (2,000 miles on rebuild) 2wd tach, tilt, tool box on bedside, a/c, sliding rear window, orange and white. 1972 Chevy Blazer 2wd, tach, tilt, a/c, my first engine overhauling experience, Orange, with white top 2006 Gmc Sierra, XM, Z-71, dark blue, onstar, leather, rear entertainment (audio only) heated seats, (the wife loves that feature) upgraded tires immediately after purchase to Goodyear Wrangler AT/S (hate those rock throwers that come from the factory) BWC



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