Installing temp guage sensor(aftermarket)

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'71 Dart Custom

'71 Dart Custom

Advocate of the Slant
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Palestine, Tx
I have the typical problem with my temp and feul guages. I replaced the voltage limiter but my feul guage registers 5/8 when full or doesn't work at all and the temp is dead. I can live without a gas guage, but a temp is mandatory. I bought a set of mini trio guages and would be perfectly satisfied with that, but the sensor for the temp guage is bigger than the hole where the original sensor goes. So I get to looking, and I can't find a spot anywhere on that 225 to put that sensor. Anybody found a way around this? My car runs cool and has never overheated, but I don't like not having a temp guage.
 
pettybludart said:
Go to your local hardware store,plumbing area should have some adapters to help.Good luck.
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I did this a couple of times...sometimes it works and sometimes it doesn't. I have drilled out the hole and retapped it. Others have welded nuts on to the radiator or thermostat housing.
JMO
Frank
 
Like Charile & Frank above said, if you have the right tools. Pull the thermostat and stuff the hole with paper to catch the shavings or use a shop vac in the T-stat hole while you drill and tap.
 
Check to be sure an adaptor isn't already screwed to the 3/8" NPT. I spent a very fustrating afternoon trying to install my gauge looking for reducer adaptors until I realized a 5/8" NTP adaptor was provided and installed already. Boy did I feel stupid.
GregH
 
I've tapped into the heater hose with a "T" fitting before but If it were me, I'd fix the factory setup. Sounds like your gauges got fried when the old voltage limiter crapped out.
 
IF you decide you want to fix the factory setup like cudamark said, I have a set of working temp and fuel gauges that I haven't gotten around to posting for sale. Let me know if you want them. Check your gauges first before asking for replacements... I learned that the hard way (I thought my gauges were dead but they were fine).
 
Here's how I did the 'Cuda

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Ok, I'll try to say this without writing a book. 2yrs ago when I bought the car both gauges worked intermittently but I thought the temp was reading low, not even registering hardly. Then, after killing the motor the temp gauge would slowly begin to rise almost to halfway mark. Bought the trio gauges and finally went the pipe fitting route, but was never satisfied with the results. The new gauge starts at 130 degrees and just like the old one, when I'm driving, it doesn't register at all. I kill it and come back 15 minutes later and it's reading 170-190.
So, last weekend (2yrs later) I decided since the new gauge reads like the old, why not get a new orig sensor and just try to fix the old gauge. But now the factory gauge is completely dead, I tried grounding the wire going to the sensor, but nothing. Shouldn't that peg the needle if it's working? My gas gauge is still working just like it always has. I would rather fix the factory gauge, but I've never even pulled the gauges out of the dash, and won't until I know what I'm looking for. Also, all this makes me wonder if my engine is even warming up to normal operating temp? The heater doesn't blow very hot.
And why is it heating up after I kill it? I understand that heat rises and the sensor is at the top of the motor, but I've never noticed one heat up that much after shutdown.
One other thing, when it sets and gets hot like that, it's hard to crank and the lifters clatter if I put any strain on the motor. It doesn't seem to run good hot.
Sorry, I'm no good at diagnosing. I'm one of them "tell me what's wrong and I'll do the labor" types. Thanks for all the input.
 
'71 Dart Custom said:
Ok, I'll try to say this without writing a book. 2yrs ago when I bought the car both gauges worked intermittently but I thought the temp was reading low, not even registering hardly. Then, after killing the motor the temp gauge would slowly begin to rise almost to halfway mark. Bought the trio gauges and finally went the pipe fitting route, but was never satisfied with the results. The new gauge starts at 130 degrees and just like the old one, when I'm driving, it doesn't register at all. I kill it and come back 15 minutes later and it's reading 170-190.
So, last weekend (2yrs later) I decided since the new gauge reads like the old, why not get a new orig sensor and just try to fix the old gauge. But now the factory gauge is completely dead, I tried grounding the wire going to the sensor, but nothing. Shouldn't that peg the needle if it's working? My gas gauge is still working just like it always has. I would rather fix the factory gauge, but I've never even pulled the gauges out of the dash, and won't until I know what I'm looking for. Also, all this makes me wonder if my engine is even warming up to normal operating temp? The heater doesn't blow very hot.
And why is it heating up after I kill it? I understand that heat rises and the sensor is at the top of the motor, but I've never noticed one heat up that much after shutdown.
One other thing, when it sets and gets hot like that, it's hard to crank and the lifters clatter if I put any strain on the motor. It doesn't seem to run good hot.
Sorry, I'm no good at diagnosing. I'm one of them "tell me what's wrong and I'll do the labor" types. Thanks for all the input.
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Hmmmm.....quite a bit to comment on here....I think I would start by putting a good live gauge on the oil pressure to see what that looks like. If it's low at operating temperature, there is no use going any further with anything else. If it's good, install a new 180 degree thermostat ( I suspect you don't have one) and see if the temp gauge (either one) works now. You may need a new cam and lifters if they clatter and you have good oil pressure. Also check the rockers and push rods for wear.
As you have done already, you can test the factory gauges by connecting the sending unit wire directly to ground and then turning on the ignition for a second or two to see if the gauge comes up. If not, there could be many reasons, from sender to wiring to circuit board to the gauge itself. Those instrument clusters are not too bad to pull. I like testing them out of the car. That way you can test several things at the same time. I've had many of those clusters with just bad connections on the circuit board. Loose nuts or a bit of corrosion and the gauge won't get a good connection. A simple icepick test light and a couple of jumper wires is all you need to McGiver a test bench. Same with the fuel sender. With it out of the car (very important!!! Do not do this with the sender in the tank!!!!) connect 12 volts to the sender connection and then connect your test light wire to the battery ground and the pick end to any part of the sender housing. The light should come on and get brighter or dimmer as you raise or lower the float arm. If it doesn't light up, the sender is bad. Sometimes you can fix them but new ones aren't too bad in price. That should keep you busy for a while... :toothy7:
Let us know your progress.
 
Thanks, cudamark. 45lbs oil pressure going down the road, 10-20 at slow idle. I replaced the t-stat as part of my initial thorough tune-up soon after I bought the car. Made no difference and the old one looked pretty new. I considered going to a hotter one, but didn't think that was the answer. Seriously, when I first crank the car it runs good for a forty yr old engine that I suspect has never been rebuilt. I can go thirty miles and it'll run fine. I stop and go in a store 15 - 20 min, come back and temp reads 170, it's hard to crank and clatters like hell climbing a hill.
Tomorrow I'll try to pull the cluster and check it out. If I can't get the temp to work I'll probably wind up drilling the head. The new temp works, it's just that I had to fit a tiny nipple in the orig sensor hole, then use fittings to basically make an external chamber for the new sensor to set in. Didn't seem very efficient to me. I just wasn't sure about drilling the hole. The idea had occured to me but I was scared that might be a drastic solution and experience has taught me that if I'm not sure, then I shouldn't go doing anything stupid.
 
Your oil pressure isn't great but should be enough to get the job done. If you have a good 180 degree thermostat, there is no way it should read 130 if you've driven more than 5 miles or so. I'd put a thermometer in the radiator cap hole and see what it really reads. Don't do any drilling on a cylinder head. If you need to modify something to mount the sender, drill into the intake or get a thermostat cover with a fitting option already built into it. How many miles are on that engine? You sure the noise you hear is not an ignition ping? You may need to back off the timing a bit. That might help the slow crank also.
 
Thermostat cover with fitting option? I like that better than drilling. Where might I find?
Soon as I get one I'll get a new t-stat. Odometer says 93,000, by the way.
I tried pulling the inst cluster today. Finally decided maybe I'll just focus on getting my new gauge sensor mounted for right now. That's a tight little area behind that dash. Everything but the temp still works and the gas gauge reads accurate below 1/2 tank so I'm leaving well enough alone.
A friend adjusted the carb for me and it runs a lot better. He said I had it idled down too low and was running too rich. Now it's holding a steady 45lbs oil pressure even at a red light and he smoothed it out a lot. It had been idling rough. That clatter does sound like ignition ping but I don't understand why it only does it after I've ran the car for a while.
Back off the timing. Turn distributor clockwise or counter?
 
oh this is an easy fix. what you do is you yank those heater hoses out. (who needs a heater) then you put the temp sensor where the heater hose nipple use to go in the head, and you get a plug for the water pump oulet for the other heater hose. after all that. you yank the heater out from under the dash. which saves weight. and if the old lady complains that its cold, you throw her a blanket. hope this helps :cheers:
 
cudamark said:
Don't do any drilling on a cylinder head. If you need to modify something to mount the sender, drill into the intake or get a thermostat cover with a fitting option already built into it. .
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Why not drill the cyl head? I have done it to several heads to use a mechanical temp gauge in place of the electric sender. Just enlarge the existing hole. Drilling to intake does no good, we are talking about a slant six, not a V-8. No water in the intake manifold. The t-state housing option has the problem, that the temp gauge will not show the temperature, untill the T-stat opens. If the stat does not open, the engine could overheat, and it would not show on the gauge.
 
you can get one of these t's for a radiator hose, or heater hose. this is what i have in my toyota. it worked very well.
 

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slantscamp said:
you can get one of these t's for a radiator hose, or heater hose. this is what i have in my toyota. it worked very well.
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That would work fine if installed in a hose that had water flow at all times. EI: heater hose on a Non A/C car. A/c cars have a hot water valve that shuts down water flow in the heater hose in the "off" or "max A/C" settings.
 
Well, I mean no disrespect, but unless someone gives me a plausible reason WHY I shouldn't drill and tap the existing hole and mount the sensor in the most logical spot for it, here in a few days I'm gonna buy a 3/8 npt tap. I cherish this car but I'm more worried about it being functional than keeping it original.
Seriously, if you have a horror story, lay it on me and I'll go buy a T-fitting for the radiator hose. It just seems to me that the temp you're wanting to read is the motor itself.
 
Hey I like the one about throwing the wife a blanket. My wife rode in a sleeping bag as we drove across country in our Dart with a bad heater core.....
 
Charrlie_S said:
Why not drill the cyl head? I have done it to several heads to use a mechanical temp gauge in place of the electric sender. Just enlarge the existing hole. Drilling to intake does no good, we are talking about a slant six, not a V-8. No water in the intake manifold. The t-state housing option has the problem, that the temp gauge will not show the temperature, untill the T-stat opens. If the stat does not open, the engine could overheat, and it would not show on the gauge.
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Sorry, I forgot the OP was working with a slant 6. Yeah, an intake tap won't work but I still would rather plumb a T in the heater hole outlet than drill the head. If something bad happens on the drill job, you may be looking at replacing the head. Of course, if you use the '75-up head, it has the big hole from the factory.....and hard seats to boot....
Oh, and if your thermostat doesn't have a bleed hole in it, get a different brand or drill one yourself. With the bleed hole working, you can get a decent signal for the temp sender in the thermostat cover. Not as good as one before the T-stat but better than one in the radiator hose.
 
there is a plug on the passenger side of the block, to the rear of the oil pump
u can see it up and to the left of the oil filter adapter
 

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I had a friend that attached a sender to a brass freeze plug on a V8 engine and it worked good. Might be a thought.....
 
i had the same problem i just went to the hardware and got a 1/2 inch plumbing tee and
two 3/4 inch long nipples and spliced it in the heater hose the third hole in the tee is for the sensor
 
805moparkid said:
there is a plug on the passenger side of the block, to the rear of the oil pump
u can see it up and to the left of the oil filter adapter
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no need to drill, tap, cut or anything!!!!!!!!!!!!!!!! there is a plug in the water jacket right here!!!!
 
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