Question about leaking transmission drain plug

[Vortec_4300]

Hi,

I have a 2005 Chevy Silverado basic work truck with a manual transmission. Although my maintenance schedule dictates a fluid change at 100K, I had a local garage perform that service at 50K by swapping out 3.5q of GM Syncromesh Fluid (as recommended by the owner's manual.) At $20 per quart plus labor, this wasn't cheap.

Now (approximately 6 months and 27K miles later) the transmission drain plug is weeping slightly, and the fluid is collecting onto the exhaust pipe so that a slight odor can be noticed. I currently have over 67K miles on the truck, most of it primarily highway commuting (with a few trips to the fishing hole thrown in!)

I asked a local technician at a transmission shop (not the garage that initially performed the transmission service) to check the problem and try to rectify it, and he informed me that it is very hard to keep this weeping/leaking from occurring just due to the thin nature of the synthetic Syncromesh fluid. He removed the plug, put his thumb over the hole to stop all the fluid from draining, put on some JB Weld, and replaced the plug with approximately 1/2 quart of new fluid, until it reached the appropriate fill level (1/4" below the fill plug). He also recommended that I disregard the owner's manual and have the transmission serviced at approx. every 30K miles, which I can certainly do, although I would want to try and stretch that interval out if possible.

Can anyone out there comment on this? Does his observation that there will be slight leakage no matter what I do seem correct? Does shrinking the maintenance interval to 30K sound reasonable, or would it be overkill? I am really concerned because the amount of transmission fluid in the pan is only approximately 3.5q and I am planning on keeping this truck long enough for my 4 year-old niece to use it for driving lessons in the future (her mother will be buying her a BMW, no doubt, so that girl will need some good country driving sense that will be helped by a slow-moving, full-sized truck with a 5-speed and a long clutch throw.) Plus, I really like the truck!

I am, as always, grateful for any helpful advice I get in this Forum. Thanks in advance!

 

[another Todd]

I would not go back to a guy who put JB Weld on your drain plug. You might not get it out next time you try. A better choice would have been Hylomar sealant. I use hylomar on all drain plugs and pipe threads, even on some gaskets. It never dries out, its tacky, similar to "form a gasket" non hardening, but not as messy, and a cool blue color. And best of all, no leaks ever.

 

[mikeinaustin]

is this vehicle supposed to have a gasket on the transmission plug? was it replaced with a new one when the original service was performed? could the bolt have been overtorqued when put back on?

 

[Vortec_4300]

Quote:

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I would not go back to a guy who put JB Weld on your drain plug. You might not get it out next time you try. A better choice would have been Hylomar sealant. I use hylomar on all drain plugs and pipe threads, even on some gaskets. It never dries out, its tacky, similar to "form a gasket" non hardening, but not as messy, and a cool blue color. And best of all, no leaks ever.

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LOL I made sure and pointed out to him (the shop owner) that the truck would be coming right back to him in about 30K so he had better be comfortable with wrenching on that plug when he next sees me.

This guy was pretty good - he saw me on an emergency basis first thing Saturday morning (I needed to make a long distance trip and was afraid that I didn't have any fluid left in the transmission pan) and he worked on my truck despite recovering from a shattered ankle from a previous motorcycle accident.

I will print and save this post and get the recommended sealant you mentioned at the auto parts store this afternoon to use the next time. Thanks!

 

[Vortec_4300]

Quote:

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is this vehicle supposed to have a gasket on the transmission plug? was it replaced with a new one when the original service was performed? could the bolt have been overtorqued when put back on?

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No gasket that I could see (the shop owner allowed me to stand underneath the truck while he performed all of the maintenance.) The drain plug was on kinda tight, but the fill plug was WAY too tight (although that's not where the leaking was coming from.)

I guess that a new plug in 30K (by then the truck will be at almost 100K) would be a good idea anyway.

 

[Papa Bear]

A little teflon tape on the threads would help.
If it doesn't have a gasket, I assume it's a tapered pipe thread ??

 

[Matt_S]

GM's oil pan drain plugs have a rubber gasket built into the head of the bolt itself. Are the trans pans similar? If so, a new bolt would cure this. I suspect, though, it's probably a tapered pipe thread and, if so, I'd say a little teflon tape would be just the ticket.

 

[Tosh]

Maybe I'm talking out of my bum here, but I've noticed what appeared to be leaks from a drain plug actually coming from above and just collecting as a drip on the drain plug because it's the lowest point.

 

[Merkava_4]

The drain plug either has a separate seal or the drain plug has an integral seal. The use of JB Weld on a drain plug should be a clear sign that you need to find a different shop.

 

[cousincletus]

The NV3500 transmission has a pipe thread plug on the drain and fill. If it's leaking, I would use silicone Permatex RTV on it, or #2 Permatex. Maybe you have a bad plug? I never had any problems with mine (2001 Dodge Ram 3.9 V-6, NV3500 transmission) leaking. I've heard you shouldn't use teflon tape on a transmission drain plug. For what reason I have no idea. I would venture to say also that maybe the leak isn't from the drain plug, but from somewhere else. Have you checked the fluid level recently?