Do I tighten this more? Tractor temperature sender: Super 90 Massey Ferguson

[bradleydavidgood]

 

[Jim.ME]

How does the shoulder on the bulb and the new nut compare to the old ones? Was a bushing removed when the old probe was removed?

 

[bradleydavidgood]

How does the shoulder on the bulb and the new nut compare to the old ones? Was a bushing removed when the old probe was removed?

Good questions Jim, thank you!

I don't remember removing a bushing. I will have to look in there tomorrow more carefully. No new bushing came with the new one.

This other video shows more, and shows the new and old unit.

Skip to half way and its a little further on than half way.

 

[Ray,IN]

New parts can be defective too. Is the new one OEM from a dealer or aftermarket?

 

[bradleydavidgood]

New parts can be defective too.

True. I have a feeling it just isn't seating all the way in there.

I'm going to pull it out and compare more closely to the OG.

Thanks

 

[Jim.ME]

Just looking at your video, the seating surface of the new probe is not the same as the old one. The old one is tapered to fit into a seat the new one has a square edge "collar" instead of a taper.

 

[bradleydavidgood]

Just looking at your video, the seating surface of the new probe is not the same as the old one. The old one is tapered to fit into a seat the new one has a square edge "collar" instead of a taper.

OK thanks!

 

[bradleydavidgood]

Seems to be holding after removing, cleaning, and retightening. Still moves a little.

 

[used red MN]

I don't remember removing a bushing.

Still moves a little.

It won’t hold once it gets pressure in the radiator. Those things need adapter bushings to work properly. The head will have tapered pipe thread (common NPT, black pipe plumbing threads) which the adapter bushing will screw into. The threads on the nut on the thermal bulb are straight threads like a bolt, the sealer you’re putting on there is faking you out when installed properly sealer has no purpose in this part of the connection. The nut tightening down on the raised shoulder on the bulb, the bushing also has a seat that the raised shoulder will set on and seal. When it is in there properly it will not move.
Pull it back out of there I bet there is no shoulder in the head for it the seat on. Without the adapter you are probably pushing the end of the bulb against something down in the hole that is what is allowing it the get somewhat tight and you’re probably on the verge of damaging it.
I’m going to guess that the head has 3/8” NPT threads, because 1/2” the next size up wouldn’t come close to allowing that nut to thread into it, it would just stick in there loosey-goosey.
Example bushing A good auto parts store should have one or be able to get one.

 

[bradleydavidgood]

It won’t hold once it gets pressure in the radiator. Those things need adapter bushings to work properly. The head will have tapered pipe thread (common NPT, black pipe plumbing threads) which the adapter bushing will screw into. The threads on the nut on the thermal bulb are straight threads like a bolt, the sealer you’re putting on there is faking you out when installed properly sealer has no purpose in this part of the connection. The nut tightening down on the raised shoulder on the bulb, the bushing also has a seat that the raised shoulder will set on and seal. When it is in there properly it will not move.
Pull it back out of there I bet there is no shoulder in the head for it the seat on. Without the adapter you are probably pushing the end of the bulb against something down in the hole that is what is allowing it the get somewhat tight and you’re probably on the verge of damaging it.
I’m going to guess that the head has 3/8” NPT threads, because 1/2” the next size up wouldn’t come close to allowing that nut to thread into it, it would just stick in there loosey-goosey.
Example bushing A good auto parts store should have one or be able to get one.

Thanks!

I understand now. The tapered and straight thing... I forced a straight thread with the same thread count into a tapered head. And there is no seat for the bulb shoulder.

The new sender came with an adapter, and I could thread the sender into the adapter, but the OD of the adapter was way too large for the head.
The new sender by itself threaded into the head, so I figured the adapter was for a different model tractor.

Maybe the sender I bought is for the gas engine and I have the diesel. I think I called and verified that it fit the diesel.

Anyway, I'm going to pull it out as you suggested and measure things and find the correct bushing/adapter.

 

[bradleydavidgood]

I can't get to the tractor until Monday since no work at the Amish farm on Sunday, which I'm happy with.
I don't think I have 1/2 so it's either 3/8 NPT or smaller.
So then I came up with this table comparing NPT (female head) to Straight (male sender)

Because I wanted to order every possibility and get it going...

When I came to the 1/4 NPT idea in the first row, taking into consideration that my sender threaded into the head, so they are similar sizes, I could not find an adapter that was 1/4 NPT and 1/2-18 on any auto stores or anywhere online.

The only thing in 1/4 NPT that I found was:

And the problem with that is the OD of the straight would not fit into the NPT.

So I figure I have 3/8 NPT. And ordered just that one. Will be here Monday!

And I am happy I learned all about these old thread types. Was a great lesson. I had no idea.

Thanks!

 

[Jim.ME]

Thanks!

I understand now. The tapered and straight thing... I forced a straight thread with the same thread count into a tapered head. And there is no seat for the bulb shoulder.

The new sender came with an adapter, and I could thread the sender into the adapter, but the OD of the adapter was way too large for the head.
The new sender by itself threaded into the head, so I figured the adapter was for a different model tractor.

Maybe the sender I bought is for the gas engine and I have the diesel. I think I called and verified that it fit the diesel.

Anyway, I'm going to pull it out as you suggested and measure things and find the correct bushing/adapter.

If there was no adapter for the original probe, it had to seat in the head. Can you give us a good picture of the hole in the head? Look at the old and new probes. The new probe does not have the same seating arrangement as the old one, as I posted before.