transmission Test port thread size - its not 1/8NPT

[JThiessen]

Anybody with an FSM know what the test port thread size is in the 48RE? Tried to thread in my Isspro R8959 (1/8 NPT) temp sender but it doesnt match the thread. Need to know before I return the sender to get a diff. size (noticed in isspro website that they also have metric threaded senders)

 

[ThomasLawrence]

Try again. They're all 1/8" NPT threads. Guaranteed. I've had a gauge in each of them, and always used an 1/8" NPT fitting.



Maybe they gave you a metric sending unit by mistake. Go to a hardware store, and check your sending unit against an 1/8" NPT fitting.



-Tom

 

[JThiessen]

Steve at BD said the same thing (should be 1/8 NPT). I'll do some additional checking on this part to see what it is... ... ... ... .....

 

[stevenknapp]

Some have mentioned that the threads aren't clean, or they aren't deep enough. I forget if it was this board or dieseltruckresource... but a few were using taps to clean up the threads! :O

 

[DieselB59]

I noticed a couple of Isspro sending units were too long to grab threads of the test port and hit the end of the port before the threads would grab, so in the past I used the governor port on the back of the transmission instead, but this is rare, because most of the owners go with a Mag Hytec trany pan.

 

[JThiessen]

Steve at BD recommended using the Overdrive test port on the drivers side of the transmission - that port will allow longer senders to be used - it is also more consistently "in the fluid". When I pulled it out, I had a couple ounces of transmission fluid drain out, as opposed to the other test ports.



I'm still at a loss on what thread size my port plugs are.

Here are the things I checked:

1: I have a 1/8 NPT adaptor that I was able to thread my sender into, the test port plug, and an additional 1/8 fitting. All went in by hand about 3 threads.

2: Ran a 1/8 thread cutter down the sender. It removed a slight amount of material, but not much. Retried the sending unit and still wont even start threading in - if it does catch, it strips aluminum off the transmission.

3: I did manage to get a 10MM bolt to thread into the port about 2 threads. Visual comparison of the 10mm bolt and the test plug would have me believing its a metric standard thread.



Right now, the most logical scenario, based on what has fit and what hasnt, is that I have a transmission with metric threads. This would mean that CC has a dual source on the trannys since most people have reported that the 1/8ths have fit. I did read on another board that someone else is having an issue getting theirs to thread in.



I might try calling the dealer and have them look up the part # for the test port plug to see what the thread is.....