Leaking Speedometer Cable Cap

[Joe M.]

The end that screws into the PG tranny is leaking a lot. When I removed the tranny crossmember, I tried to tighten it and did so a little, but could not get any type of pliers in place to be certain it was as tight as possible. I am not certain what creates the seal under the cap.

Is this common? Is there a solution?

[John H.]

Re: Leaking Speedometer Cable Cap

The end that screws into the PG tranny is leaking a lot. When I removed the tranny crossmember, I tried to tighten it and did so a little, but could not get any type of pliers in place to be certain it was as tight as possible. I am not certain what creates the seal under the cap.

Is this common? Is there a solution?

Joe -

Later speedo "bullets" (fittings) had an internal lip seal to keep trans fluid from getting past the speedo gear; don't know if Powerglides used the same fitting as manuals - maybe someone else does.

[Ray G.]

Re: Leaking Speedometer Cable Cap

Hello Joe;
There is no pressure in the rear housing where the speedo. fitting is housed.
Only the over high fluid level will "a lot" of fluid leak.

Probably other seal leaks in the transmission and converter allow air into the transmission permitting the fluid in the converter, which is entirely full, to leak down and overfill the transmission.

Ray

[Joe L.]

Re: Leaking Speedometer Cable Cap

Joe -

Later speedo "bullets" (fittings) had an internal lip seal to keep trans fluid from getting past the speedo gear; don't know if Powerglides used the same fitting as manuals - maybe someone else does.

John------


They did not originally use the same fitting. However, the same replacement fitting works for both applications and this fitting is GM #345215 and remains available for about 20 bucks, GM list.

Also, the original fittings did include a seal as does the 345215. The seal currently available which will fit all of the fittings, original and 345215, is GM #3869910. This seal installs INSIDE the fitting

The fittings also use an O-ring seal on the outside periphery of the fitting. This seal is GM #10054241. Degradation of this seal will also cause a leak but not one that emanates from the cable coupling.

If any leak is found, it's a good idea to replace both seals. It's very inexpensive and easy to do.

[Joe M.]

Re: Leaking Speedometer Cable Cap

Joe, you provided so much info that I am confused. I don't plan to remove the transmission. Is removal required to replace the seal/o-ring?

I am trying to picture what you are talking about; a seal inside where the speedo gear is located? and an o-ring on the outside? I have searched the 1961 passenger car manual and it does not show the details that I am looking for. Shows a beautiful cutaway, but does not show the side covers.

In summary, what stops the fluid from coming out of the speedo fitting?

One of the previous posters indicated that there should be no fluid back there if everything was sealed correctly, but that is not my case.

[Joe L.]

Re: Leaking Speedometer Cable Cap

Joe, you provided so much info that I am confused. I don't plan to remove the transmission. Is removal required to replace the seal/o-ring?

I am trying to picture what you are talking about; a seal inside where the speedo gear is located? and an o-ring on the outside? I have searched the 1961 passenger car manual and it does not show the details that I am looking for. Shows a beautiful cutaway, but does not show the side covers.

In summary, what stops the fluid from coming out of the speedo fitting?

One of the previous posters indicated that there should be no fluid back there if everything was sealed correctly, but that is not my case.

Joe-----


There is no need to remove the transmission. I believe the speedometer fitting is located on the extension housing of the Powerglide (it's been a LONG time since I've done anything with a Powerglide). The fitting is retained to the extension housing by a small "trapazoidal"-shaped retainer and a small 1/4" hex head bolt. Remove the bolt and you can pull the fitting out of the housing. Be careful that the speedometer driven gear does not fall out of the retainer and into the transmission.

Once the fitting is out, you remove the speedometer driven gear from the fitting. Then, stretch and remove the o-ring seal on the periphery of the fitting and install a new one so that it fits completely into the fitting groove and is not twisted in any way.

Lastly, pull out the internal seal from the threaded end of the fitting. This seal has an outer metal shell and is a press fit in the fitting. Then, drive in a new seal.

Install the speedometer gear in the fitting, re-install in the transmission, insert the retainer, and install the bolt. Done.

Tip: if it were me, I'd also replace the speedometer driven gear with another one of the same configuration, color and tooth count.

[Joe M.]

Re: Leaking Speedometer Cable Cap

Thanks for the advice. With the tranny crossmember removed and the tranny supported with a jack stand, i had difficulty even getting a pair of small pliers on the speedo cap so that I could tighten it. Maybe it would have been easier to remove the retainer from the side of the tranny and replace the seals as you describe and tighten the cap at the same time.

When I pull the retainer, should the speed gear be inside the retainer?

[Joe L.]

Re: Leaking Speedometer Cable Cap

Thanks for the advice. With the tranny crossmember removed and the tranny supported with a jack stand, i had difficulty even getting a pair of small pliers on the speedo cap so that I could tighten it. Maybe it would have been easier to remove the retainer from the side of the tranny and replace the seals as you describe and tighten the cap at the same time.

When I pull the retainer, should the speed gear be inside the retainer?

Joe-----

The speedometer driven gear is inserted into the FITTING. The fitting is the round, "bullet-shaped" piece that inserts into the transmission extension housing. The RETAINER is a small, flat "trapazoidal-shaped" piece that fits into a slot on the fitting and, thereby, retains the fitting to the extension housing. The short 1/4" hex head bolt fastens the retainer to the extension housing.

And, yes, I think your best bet due to access problems would be to remove the bolt and retainer and, then, pull the fitting out of the transmission with the cable still attached. It will then be easier to remove and re-install the speedometer cable from the fitting. However, I want to re-emphasize that you have to be extremely careful that the gear does not fall out of the fitting and into the transmission when you remove the fitting.

[Joe M.]

Re: Leaking Speedometer Cable Cap

I found an archive post where a 55 owner talked about a large amount of ATF coming out the speedo shaft. Roy Bratz told him to see if the air vent was clogged. Does the 1960 PG have an air vent?

As was stated earlier, I may have seals that are allowing air and ATF to go into the rear of the PG where is it not supposed to go. I don't know enough about the internal workings to understand that.

I did find the small hex head bolt that holds the speedo attachment to the side of the PG.

I am still not sure where the drain plug is located. On the bottom of the front of the PG is a blue plug with square hole in it, but the manual says it is an inspection port. Is the drain plug pointing toward the rear of the car and horizontal?