FMS mechanical temp gauge comes with wrong fittings??!!?

garystocker · Sep 2, 2005

Directions say to remove sending unit and install a 'mounting adapter'. Theirs is 1/2" where is would thread into the block. It says 'aftermarket adapter required for engins with 3/8" sending unit hole diameter.

I guess home depot will have a 3/8 adapter...right? Is that what they mean by 'aftermarket"?

HISSIN50 · Sep 2, 2005

They also sell a kit (Seems to me that FMS gauges are made by Autometer, and AM sells an install kit for their temp gauges because the same issue exists). They default the gauge to fit a SBC for some reason IIRC.

Like you said, I also would just hit the home-store if that is easiest for you. Or grab the adapter from AM or from the parts store (they often have fittings like this in the gauge section/aisle at the store).

Good luck bud.

sgarlic · Sep 2, 2005

Any local Ace Hardware usually has the fitting you need.. in no logical order.. you'll probably have to ask them.

TheUser · Sep 2, 2005

I had the same problem and I read to NOT go to the hardware store as the fittings there won't allow the thing to reach down in there; I can't confirm this, but what I did was I went to O'Reilly's and got a bag of fittings in the gauge section like HISSIN said and it was only like $6 for the bag. I'm sure NAPA and other places have similar fittings or could order one for you.

garystocker · Sep 2, 2005

Got one from Downs Ford. The shipping will cost as much as the gas would have been...

I went to the 2 big home stores and my hometown hardware store and could not find a fitting in 3/8 with a lip to accept the sensor.

Thanks

HISSIN50 · Sep 2, 2005

Good deal. I did not think the home store would have anything that would work right, since I know exactly what lip you are talking about. But I have read a few threads about people using brass from the hardware store, so I figured I was missing something or being too anal.

You guys did it right.

joelliott · Sep 2, 2005

I got the 3/8 adapter for my gauges I just installed. It fit in perfect and the sender does get a nice bit into the water passage. On my old deigital temp gaugeI used the homedepot route for the adapter. The sender was about 1/8 inch inot the water passage. Thus temp readings were spuradic. I say go with the AM kit. It was like $6.00 total.
Joe E.

HISSIN50 · Sep 2, 2005

joelliott said:
On my old deigital temp gaugeI used the homedepot route for the adapter. The sender was about 1/8 inch inot the water passage. Thus temp readings were spuradic. I say go with the AM kit. It was like $6.00 total.
Joe E.

Joe, can I ask how the gauge read erratic with the old set up? I have a similar issue on a trans guage and have wondered how inaccurate it is.

joelliott · Sep 2, 2005

Well Im definitly no expert. it was a electric gauge to start with. So that makes it alittle quirky. But the hardware store adapter I bought was so thick that the sender that came with the temp gauge barely hung into the water passage in the intake. Maybe a 1/8 inch. So as fluctuations in the coolant flow, or minor temp changes due to normal driving, everything showed up on the gauge. Id be one minute at 185* in a traffic jam then get on the highway open the stang up good for a minute and the temp be at 240*. Just not possible. The car never puked, just the gauge moved.

The new adapter with the autometer mechanical gauge I just installed is shorter than the pervious hardware brand. So the sender slide further into the coolant passage thus getting info from more water and a truer reading. Not just hot spots in the flow.

Again Im no tech. But just a rednek observation. Good Luck
Joe E.

HISSIN50 · Sep 3, 2005

joelliott said:
Well Im definitly no expert. it was a electric gauge to start with. So that makes it alittle quirky. But the hardware store adapter I bought was so thick that the sender that came with the temp gauge barely hung into the water passage in the intake. Maybe a 1/8 inch. So as fluctuations in the coolant flow, or minor temp changes due to normal driving, everything showed up on the gauge. Id be one minute at 185* in a traffic jam then get on the highway open the stang up good for a minute and the temp be at 240*. Just not possible. The car never puked, just the gauge moved.

The new adapter with the autometer mechanical gauge I just installed is shorter than the pervious hardware brand. So the sender slide further into the coolant passage thus getting info from more water and a truer reading. Not just hot spots in the flow.

Again Im no tech. But just a rednek observation. Good Luck
Joe E.

I appreciate your observations Joe. With my set-up, I have the probe barely at the end of the 'tee' and was worried that the readings might be slow (almost being a radiative reading, rather than real-time from being truly in the flow) since the sender is sort of shrouded.

Again, thanks for the feedback.

garystocker · Sep 4, 2005

Update

So I had finished the project last Thursday night as I planned, except fot the mounting of the temp sensor since they include a 1/2" mounting adapter for a 5.0 with a 3/8" opening. So As I mentioned earlier I could not find one in the home stores and ordered one overnight from Downs FORD in Toms River NJ (2 hours away)

It never arrived.

I called and it was "rescheduled for September 6th delivery.
They won't leave it without a signature and I will be at work 9/6 so I will NEVER see it! I can't even pick it up at the UPS office as it is as far as the FORD dealer. They say they were here, but we did not hear them and they left no note on the door!

So I resolve to drive up there (Downs FORD) yesterday...they are open to 5:00. So I call to confirm...No...Motorsport and parts dept. went home at 2:00

So I go to my local pep boys in despiration (who don't have it either, of course) and I get them to open a mechanical gauge package for some sun-pro gauge set and the guy took out the 3/8" adapter I needed and put in my 1/2 adapter into the package and called it even.

It fit and worked like a charm.

Now when I took out the sender to install the mounting adapter it did not leak at all. So I started it up and watched the gauge climb to 240* in a matter of seconds...not close to enough time to warm up. So then I watched it puke out the overflow. I killed the motor and lifted the red lever on my cap to relieve the pressure...I heard none...I opened the cap and BOOM! A gallon of (not too hot thankfully) coolant splashed up onto the hood and all over the engine and fenders.

I guess that little bit of air I introduced into the system while removing the sender caused the problem...it needed a burp!

So I cleanned it all up and added a gallon of 50/50 as I drank a consolation beer.

Works like a charm. When warm it reads 195* all the time.

HISSIN50 · Sep 4, 2005

You live on the edge Gary. Bottom line is that I am glad it all worked out for you. And I hope the guy that buys that gauge from the parts store has a Chevy (chevies use the 1/2" adapter IIRC).

BTW, You have the most guts of anyone I know. NOOOOOO way would I remove a rad cap on a car reading 240*F. Seriously, that could have scalded your face and upper body really badly (info for next time). I just had to say something or I would kick myself for not having said it.

garystocker · Sep 4, 2005

I knew you would say that...but the car ran for at most from a dead cold 1 minute or so. The thermostat did not open (the rad hose was cool to the touch)

I assumed the mounting adapter was wrong and let the sensor go in too deely causing a blockage...I was looking for coolant flow.

I thought the thermostat had to open for there to be pressure.

I also wanted to correct this before the engine got damaged.

The lever was supposed to vent pressure...but it must have been low pressure, not enough to compress the spring in the cap enough to vent I assume.

I dunno...what would you have done...waited a while I guess?

TheUser · Sep 4, 2005

what i've done before when I didn't have a pressure release cap when the stang was hot was I grabbed a rag and slowly opened the cap letting the pressure release by holding the cap very slightly open...this can sometimes take a few minutes. You can also pull the overflow hose and let it vent that way to speed things up.

At least you didn't pull the sensor out w/ it hot. I did that one time (no idea what I was thinking) and OMG, coolant shot all over the place...all over my bro's truck, my car and I'm just lucky it didn't get me...that was seriously one of the stupidest things I've done.

Yep, you always wanna burp the system.

Glad you finally got it all sorted out

HISSIN50 · Sep 4, 2005

garystocker said:
I knew you would say that...but the car ran for at most from a dead cold 1 minute or so. The thermostat did not open (the rad hose was cool to the touch)

I assumed the mounting adapter was wrong and let the sensor go in too deely causing a blockage...I was looking for coolant flow.

I thought the thermostat had to open for there to be pressure.

I also wanted to correct this before the engine got damaged.

The lever was supposed to vent pressure...but it must have been low pressure, not enough to compress the spring in the cap enough to vent I assume.

I dunno...what would you have done...waited a while I guess?

If the motor was essentially cold and the stat was closed, I guess I am not sure why so much fluid could shoot out. But with a basically cold motor, I probably would have done the same. Also be real careful of the steam that comes out - it can be quite hot too.

garystocker · Sep 5, 2005

I think the stat was just starting to open, generating the pressure without much waterflow...which is why the hose was cold.

I should have treated it as a hot motor.

joelliott · Sep 6, 2005

Good way to check flow is to bleed alittle coolant outa the rad. Open the cap and start the engine with the cap off. Watch the cores of the rad on the upper parts and see if coolant flows freely.

I did this and it burped the system and allowed me to see the flow. Worked great.

I just ran my stang on a 4 hour highway trip last night. My car ran just right. (between 170*-180*) depending on how I was driving. Mostly traveling 75ish. And thats with 3.45 gears @ 2400-2500 rpm. The gauge was very steady and never sputtered.

I got the mech AM gauge and their 3/8 adapter. The sensor sita about 1/2 into the intake and everything seems to be great. I HIGHLY suggest ordering the AM adapter. No fitment issues, no leaks, etc. Just a nice trustworthy install.
Joe E.

FMS mechanical temp gauge comes with wrong fittings??!!?

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