Hey guys, I have a Gear Vendors in my truck that I purchased back in 2016 and from day one that I’ve owned it, it has always leaked fluid from where the speedometer cable screws onto the speedo gear assembly and makes a huge mess underneath my truck.

I ran across a post on this site while posting about a different problem with my GV regarding the installation of a Maximum Overdrive deep sump oil pan https://www.ford-trucks.com/forums/1...overdrive.html). In this article it addresses the oil leak issue from the speedometer cable and provides a picture & part number of the o-rings needed to resolve the leak (post #3). So I ordered the o-rings, but when I went to install them, when I pulled out the speedo gear assembly I discovered my speedo gear is about 2” in diameter, where the speedo gear assembly in the article was only about 1” in diameter. That means the o-rings I ordered don’t fit because they’re way too small. The author of the article mentions he has a J-Type gear vendors unit, which must be the older style? I believe I must have a P-Type gear vendors; newer style????? Is that why my speedometer gear housing is larger???

So my question is this….is there a different sized o-ring that will seal better than the factory sized o-ring that came in my GV? If so, can someone post a part number and a location to buy it from? I would appreciate it. I’m sick and tired of this oil leak and would like to resolve it once and for all.

Thanks for the help….

 

I have a high boy so my speedometer still comes off the transfer case. but the speedometer cable adapter on my GV was leaking ,so I pulled it out and cleaned it up good and put TRS on it and it has never leaked since.

 

What is TRS???

 

The Right Stuff. probably any silicone would work but TRS is the best of the best.

 

I wouldn't use any sealant. If it gets loose in the unit it could cause problems. Just get the right size "O" ring.

 

I never found the right O ring.

Also make sure it's not leaking on your cable itself, the GV seems to put more oil there than most stock hook ups.

 

So it seems to be shooting oil up into the cable and then leaking out the threaded screw-on cap that attaches the cable to the speedo assembly. On the end of the cable tube it's got a flared end that mates up against the speedo assembly. And I also noticed there's a small o-ring that sets just inside that assembly where the flared cable end mates up to the speedo assembly. I'm assuming it's leaking past that little seal and shooting up into the cable housing and then leaking out the threaded cap that screws onto the assembly and then it leaks down onto the oil pan and makes a mess (hope that made sense). Because the threaded cap on the cable sets vertically higher than the speedo assembly, I'm assuming it's not leaking past that 2" o-ring that is on the speedo assembly itself, otherwise it wouldn't be on the screw-on cap. But who knows, maybe it's leaking from both places.

So when I looked in the GV manual at the parts list, it doesn't even list that tiny little o-ring where the flared end of the cable mates to the speedo assembly. But it does list that 2" o-ring for the speedo assembly. So the point of the article I referenced in my original post was that the factory o-rings in the GV were too small and that's why it allows oil to leak. The guy found the correct size o-ring, which was a little bit thicker than the factory o-ring, and it solved his oil leak problem. I was hoping to do the same thing, but I need someone to tell me exactly what size 2" o-ring to buy because I have no idea. But I also need to find a little thicker o-ring where the cable mates to the speedo assembly. Any ideas guys?

 

So here's where it's leaking. This is after I wiped it down the day before. The oil was also on the bottom of the tailshaft and dripping from the bottom of the oil pan. I'm assuming it's running from this spot??? Or maybe it's also leaking from where the speedo gear assembly goes into the tailshaft. Not sure.

Also, here's what that little o-ring looks like. It looks more like a valve seal than a simple o-ring. But I think it's leaking past this seal and up into the speedo cable. I need a seal that fits tighter than this one does to hopefully stop the leaking. Any ideas?

 

Not an uncommon problem even on standard speedometer cables. I have sealed them with TRS but you need to make sure the cable turns a few times before it dries. I suspect it would work for you too, but if it doesn't, you'll have a mess that no fun to clean up.