Smiths Water Temp fitting

SantaFe66 · #1 (**permalink**) 03-17-2006, 07:35 PM

I have analog Smiths guages in my car (bought a roller) and am trying to fit the water temp sender into the intake (Ford PI alum 4bbl) and the stupid thing won't screw down so it won't leak. There must be some kind of washer that fits up inside the nut and slides over the bulb but I haven't found where to get such a thing.

Does anyone know how these are supposed to be installed and what type of washer or gizmo I need? Thanks to another member, I found the fitting that screws into the manifold and it's identical to the one the previous owner sent me after I asked him how I was supposed to install the sender but when I screw it in to the fitting, it doesn't bottom out so there's a lot of slop and it will leak.

The Oil Temp fitting has the same thing but there's a rubber thing in there (can't get it out) and I don't have a bung welded on my Canton yet so can't use it anyway.

Thanks for any help.

Paul

Tongue Pirate · #2 (**permalink**) 03-17-2006, 08:33 PM

Sounds like we have the same guage. If so the correct fitting for the manifold should be taperd in the bottom as to seal the temp sensor between it & the top nut. If you are getting the top nut to bottom out & there is still slop you have the wrong bottom fitting. If the top nut is tight & there is no slop yet it is not sealing up it is possible that your sensor could be bottoming out before the nut can get 100% tight. If you look here you can see my sensor & manifold fitting. It has a 3/8" pipe thread into the manifold.

SantaFe66 · #3 (**permalink**) 03-18-2006, 04:43 PM

I'm pretty sure that the fitting that screws into the manifold is 3/8" pipe, same as yours. However, the top part of the fitting that the nut on the sender fits on is probably not long enough so the nut doesn't bottom. The sender still moves when I screw the nut on as tight as I dare.

I'll take a pic and see if I can make this clearer.

It's really a stupid problem and it's preventing me from starting up the motor since I'm sure it will leak big time.

Thanks for your reply. I'll post a pic tomorrow.

Paul

Tongue Pirate · #4 (**permalink**) 03-18-2006, 05:50 PM

I hear ya! Those last few odds & ends can be a pain. That was one of them for me.

vettestr · #5 (**permalink**) 03-18-2006, 07:46 PM

Turn the adapter fitting over. I think you have it installed upside down. I saw this as the threads are close and will start but will also need to be filed to repair if tightened down much.
If we are talking 2 different fittings then ..... never mind ! In all seriousness I have seen this be it a while ago but might be worth checking.

SantaFe66 · #6 (**permalink**) 03-20-2006, 11:49 AM

You're right about it being two different threadings. One side of the fitting is straight threads and that goes into the adapter I have in the manifold. The other side is pipe threads and the nut on the sender screws on to that. There is only one way for this to fit together as you can see from the picture I attached (whoops, guess it's too big for this, go to my profile and it's the first picture).

Problem is, the nut that's on the sender doesn't bottom on the adapter fitting so the sender moves up and down and won't seal. It looks like there should be some kind of washer in the sender but I don't know what that would be. There is a shoulder on the bulb of the sender and the adapter will only go on one way. The inside of the adapter has been machined out to fit over that shoulder.

Paul

Tongue Pirate · #7 (**permalink**) 03-20-2006, 12:08 PM

That definately "not" the same as mine. Now that I see what you are talking about I'm unsure as to what ftg you would need. I would suggest contacting Smiths to find out what type of adapter you may need unless someone here is familiar with your unit http://www.caigauge.com/index.htm

Zoom This · #8 (**permalink**) 03-20-2006, 12:46 PM

What is not present for your fitting is a brass washer that goes inside the brass housing for the sender. It is about 1/16 - 3/32" thick and just nestles up inside the large brass nut that screws onto the intake manifold. It must have gotten lost along the way. Go to your local Orchard Supply or Home Depot hardware store and go over the collection of washers. I'm sure you'll find a replacement. It looks to be a very common brass washer.

mylesdw · #9 (**permalink**) 03-20-2006, 12:48 PM

It looks like you have the male/male adapter the wrong way around. The sender nut screws onto the straight thread side (it is a BSP thread). The ridge on the bulb just sits on the edge of the adapter. I have seen a thin copper between the bulb and the adapter but mine seals just fine without it. For a neat job you can buy an ordinary NPT/AN adapter and have the AN end machined. I can give more details if you are interested.

SantaFe66 · #10 (**permalink**) 03-23-2006, 07:52 PM

Myles,

I would like to know more about the NPT/AN adapter. Please send me any info you have on those.

I'm going to try the brass washer solution at Home Despot and see if I can get something to fit there.

It sure seems like I'm missing the washer that should snug up to the fitting on the inside of the nut. That is the exact fitting the previous owner of this car had on the 427 SO he had in it but the car has traveled many miles from Washington to New Mexico since then and it may have gotten lost.

I didn't buy his motor since he wanted $25,000 for it. He's since lowered the price to $14,000 so maybe I should buy it. He claims it's good for 600hp but it doesn't have any of the current hop-up goodies so ??

Maybe I should buy the motor and get this over with.

Thanks for your help.

Paul

Rick Parker · #11 (**permalink**) 03-23-2006, 08:16 PM

If the nut will screw onto the straight threads then I think Mylesdw is correct in saying the threaded brass fitting is turned around on the temprature bulb incorrectly. The tapered thread (shown near the nut) goes into the manifold and the nut creates a compression seal on the shoulder of the bulb against the straight threaded portion of the threaded adapter.

SantaFe66 · #12 (**permalink**) 03-24-2006, 05:45 PM

What you can't see in the pic is that there is a machined shoulder on the inside of the fitting so it only goes onto the bulb all the way in one direction. If you turn it around, it doesn't go all the way onto the bulb. It would really leak if I turned it around.

I emailed the british firm that sells Smith's gauges. We'll see what they say about the picture.

Thanks, guys.

I'm also going to Home Despot tomorrow and see what they have.

Paul

mylesdw · #13 (**permalink**) 03-26-2006, 01:36 PM

Maybe we are talking at cross purposes; on mine the bulb passes through the adapter and stops when the collar on the bulb hits the top of the adapter. The collar does not go inside the adapter but sits on top. It is not completely clear from the picture but if one end of the adapter is a tapered thread, it is definitely NOT the end that the nut goes on. I have not found a way of compressing my adapter drawing and still have it visible yet! Can you take a .DFT (draft) file of the drawing? Basically you buy a -12AN to 1/2" NPT straight adapter SUM-220246 from Summit and have the -12AN end machined to 3/8" BSP and a square end (no flare).

SantaFe66 · #14 (**permalink**) 03-27-2006, 05:35 PM

You are right. That's the way my fitting and adapter go together. The bulb shoulder will bottom on the fitting but the nut will not screw all the way down. Guess it is the wrong thread problem. I will try that Summit part and get it machined.

Thank you.

Paul

mylesdw · #15 (**permalink**) 03-27-2006, 06:46 PM

The correct adapter IS available I have seen it discussed before on this forum but if you have no luck, machining the summit part is an option. You need to check that your manifold IS 1/2" NPT.