Speedo Cable Leak @ Tranny - The 1947 - Present Chevrolet & GMC Truck Message Board Network

stllookn · 07-09-2004, 02:00 PM

I just noticed that my speedo cable is leaking at the tranny. Is there an o-ring seal on the cable or does it just need to be tightened up more? Looks like the fluid is slowly leaking from inside the connection fitting. Is the speedo cable for a PG, TH350 and TH400 interchangeable?

XXL · 07-09-2004, 02:12 PM

[QUOTE=stllookn]I just noticed that my speedo cable is leaking at the tranny. Is there an o-ring seal on the cable or does it just need to be tightened up more?QUOTE]

Yep, there's an o-ring in there. Just pull out the unit that plugs up into the transmission body and swap it out.

stllookn · 07-09-2004, 03:55 PM

I detached the speedo cable and it is leaking from inside that part with the oring. The o-ring does not seem to be the problem. Thanks in advance. Maybe I just need to tighten the speedo cable nut more...but it does not seem right that it should leak with the speedo cable removed. I thought there might be another o-ring between the speedo cable flange and the nut. I might try looking at the one on my TH400 that does not leak to see what is going on there. I was hoping to avoid crawling under another truck out in the pasture...LOL!

70c10 · 07-09-2004, 06:11 PM

I just replaced my bullit recently and I still have a leak. I didn't realize there was an internal seal as well. I only replaced my outer o-ring. I didn't really notice the inner seal condition. Here is a pic of one off ebay.

stllookn · 07-09-2004, 07:43 PM

That is exactly the part that I was looking at and it does look like there is an inner seal. I will bet mine is leaking too since it is coming from the inside. Where can you get the inner seal?

Fred T · 07-10-2004, 03:40 AM

Most any auto parts store that's worth its salt will have the o-rings. Also, check the shaft on the speedo gear for a groove where the seal is. You probably need to replace it, too. Another source for the parts is a tranny shop. I got the gear and both o-rings for under $10 last summer.

roadking · 07-10-2004, 11:06 AM

i had same problem with mine leaking with new o-ring, called my tranny guy(very reputable) he told me they always put alittle silicone around the o-ring after a rebuild because this is a common problem. thats what i did hasnt leaked since.

70c10 that is the only o-ring in your picture that keeps tranny fluid from leaking.

i just recently had a leak in my tranny slip yoke, kinda a wierd deal leaking out my front u-joints. posted a question on the board about it, sure enough a common problem with gm yokes i had a small pin hole in it, jb weld did the trick.

70c10 · 07-10-2004, 11:11 AM

I also used a little RTV in the groove and around the o-ring which helped but I never realized there was an inner seal as well. Mine is leaking slightly out the back end of the bullit where the cable goes in.

roadking · 07-10-2004, 11:22 AM

yes, the plastic gear inside also has a small o ring.

07-09-2004, 02:00 PM	#1
stllookn Saving 1 truck at a time! Join Date: Aug 2001 Location: Kent, WA Posts: 6,465	Speedo Cable Leak @ Tranny I just noticed that my speedo cable is leaking at the tranny. Is there an o-ring seal on the cable or does it just need to be tightened up more? Looks like the fluid is slowly leaking from inside the connection fitting. Is the speedo cable for a PG, TH350 and TH400 interchangeable? __________________ '68 C20 Longhorn 50th Anniversary 400/TH400 '68 C20 Longhorn 50th Anniversary 468/TH400w/buckets '72 C20 Halfhorn (Longhorn w/o cab and front clip) '69 Flxible Cruiser (look up ugly in the dictionary)

07-09-2004, 02:12 PM	#2
XXL Señor Member Join Date: May 2002 Location: Edge of the world Posts: 5,367	[QUOTE=stllookn]I just noticed that my speedo cable is leaking at the tranny. Is there an o-ring seal on the cable or does it just need to be tightened up more?QUOTE] Yep, there's an o-ring in there. Just pull out the unit that plugs up into the transmission body and swap it out. __________________ Craigslist \| ebay \| Engrishtees \| www.myattitudesucks.com \| Follow me on Twitter

07-09-2004, 03:55 PM	#3
stllookn Saving 1 truck at a time! Join Date: Aug 2001 Location: Kent, WA Posts: 6,465	I detached the speedo cable and it is leaking from inside that part with the oring. The o-ring does not seem to be the problem. Thanks in advance. Maybe I just need to tighten the speedo cable nut more...but it does not seem right that it should leak with the speedo cable removed. I thought there might be another o-ring between the speedo cable flange and the nut. I might try looking at the one on my TH400 that does not leak to see what is going on there. I was hoping to avoid crawling under another truck out in the pasture...LOL! __________________ '68 C20 Longhorn 50th Anniversary 400/TH400 '68 C20 Longhorn 50th Anniversary 468/TH400w/buckets '72 C20 Halfhorn (Longhorn w/o cab and front clip) '69 Flxible Cruiser (look up ugly in the dictionary) Last edited by stllookn; 07-09-2004 at 04:09 PM.

07-09-2004, 06:11 PM	#4
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	I just replaced my bullit recently and I still have a leak. I didn't realize there was an internal seal as well. I only replaced my outer o-ring. I didn't really notice the inner seal condition. Here is a pic of one off ebay. Attached Images __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

07-09-2004, 07:43 PM	#5
stllookn Saving 1 truck at a time! Join Date: Aug 2001 Location: Kent, WA Posts: 6,465	That is exactly the part that I was looking at and it does look like there is an inner seal. I will bet mine is leaking too since it is coming from the inside. Where can you get the inner seal? __________________ '68 C20 Longhorn 50th Anniversary 400/TH400 '68 C20 Longhorn 50th Anniversary 468/TH400w/buckets '72 C20 Halfhorn (Longhorn w/o cab and front clip) '69 Flxible Cruiser (look up ugly in the dictionary) Last edited by stllookn; 07-09-2004 at 07:46 PM.

07-10-2004, 03:40 AM	#6
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	Most any auto parts store that's worth its salt will have the o-rings. Also, check the shaft on the speedo gear for a groove where the seal is. You probably need to replace it, too. Another source for the parts is a tranny shop. I got the gear and both o-rings for under $10 last summer. __________________ Fred There is no such thing as too much cam...just not enough engine.

07-10-2004, 11:06 AM	#7
roadking Registered User Join Date: Nov 2003 Location: kc Posts: 229	i had same problem with mine leaking with new o-ring, called my tranny guy(very reputable) he told me they always put alittle silicone around the o-ring after a rebuild because this is a common problem. thats what i did hasnt leaked since. 70c10 that is the only o-ring in your picture that keeps tranny fluid from leaking. i just recently had a leak in my tranny slip yoke, kinda a wierd deal leaking out my front u-joints. posted a question on the board about it, sure enough a common problem with gm yokes i had a small pin hole in it, jb weld did the trick. __________________ 71 C10 SWB BLACK AND WHITE 350 CRATE TH350 ENJOY LIFE Last edited by roadking; 07-10-2004 at 11:20 AM.

07-10-2004, 11:11 AM	#8
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	I also used a little RTV in the groove and around the o-ring which helped but I never realized there was an inner seal as well. Mine is leaking slightly out the back end of the bullit where the cable goes in. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

07-10-2004, 11:22 AM	#9
roadking Registered User Join Date: Nov 2003 Location: kc Posts: 229	yes, the plastic gear inside also has a small o ring. __________________ 71 C10 SWB BLACK AND WHITE 350 CRATE TH350 ENJOY LIFE



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