640 temp sender leak

[William Fissell]

Hi, All,

replace temp gauge and sender unit with new one form this site. As discussed before, not an easy job to get the new nut tight enough to seal. In fact, I don't think it will. I used a brandy-new special-bought flare wrench and it ain't happening. Got to the point where it was leaking and wouldn't come out and wouldn't go in.

I resorted to the hack of using a drift and a hammer to impact-loosen and tighten the brass fitting a bit tighter. It now leaks a drop every few minutes. I ran the tractor up and down the hill a few times ot get the temp up a little and the coolant circulating and it never spewed, just a little drip.

Option 1- take out the 'land-of-almost-right' temp gauge and sender, kiss the money i spent on it goodbye,a nd get a replacement from CNH. Run risk of repeating this all over again.

Option 2 - back the fitting out one more time with the drift and mallet, slip an o-ring on it, and tighten again. Risk getting it so kermungled that I revert to Option 1.

Option 3- live witht he slow leak under pressure

Option 4 - barsleak or another additive that will seal the slow leak.

Opinions?

Also, dumb question: to get at the gas tank, is it possible to loosen the rear hood mounts, and just swivel the whole hood and grille forward on the two mounting bolts at the bottom of the nose? Or do i ahve to take the whole thing off and on?

thanks!
 

[awhtx]

The nut must be really tight to prevent the water leak. I have had to remove the battery tray in order to get good access to it. On one tractor I even had to grind some metal off of the head to get the wrench on the nut good. If you are using a drift and mallet to tighten it I suspect you're not getting it tight enough.

I haven't tried tilting the hood but it must not work because I've never read on this forum of anyone doing it.
 

[William Fissell]

thanks for the perspective on how difficult this is... it took me all of about 5 minuts with a conventional open end box wrench to get the old one out. The replacement on, the flare wrench even rounds off the soft brass nut. Hence my recourse to caveman tools
 

[WayneIA]

Can't remember the sizes but here is basicly what I did in your situatioin. Used a drill bit and drill that just fit inside of the threads in the head and cleaned the champer in the head..Also used a drill bit to clean the hole in the head the temp prob goes into. And , used a bottom tap and cleaned the threads in the head. Worked for me. Good luck
 

[kgrove78]

i replaced the temp gauge and sender on my 62 2000 diesel and it wouldn't stop dripping either turned out the sender was hitting the cylnder in the block and made it sit on a angle so i returned it and found one with a smaller diameter sender also heard of useing fitting to space it out from block also