Technical Dodge/mopar 318 question

Wiring a 1934 Dodge 4 dr - has an ‘82 318. Trying to figure out where the coolant sensor is/goes!!! I know it sounds basic - but would appreciate a little help.


Thanks

 

It is right behind the thermostat housing.

 

I believe your coolant sensor is right behind the tstat housing in your 2nd pic.

 

Looks like yours is center under the fuel line

 

Looks like a 2nd one under return spring beside thermostat housing
Is’82 the “lean burn” system?

 

Should there be coolant when I remove the sensor? I initially thought that was the sensor but my gauge shows no movement. All other gauges working fine. Was going to replace and thought I might see coolant when I removed but it was dry. Then research showed that could be a “knock sensor” which I didn’t know existed!
Appreciate the help

 

I was trying to help,,,but lost all my concentration !
Good looking old Dodge car,,,,,good looking Mopar alternator,,,,,good looking Dodge engine,,,,,318 is great engine,,,,looks really clean and nice .
Electronic box on the firewall,,,,and then an HEI,,,,, come on ,,,,,,Blasphemy !

You’re right ,,,,that’s not the temp sender .

Tommy

 

Oldtmtech - do you mean the plug? Under the spring toward the front looks like a vacuum fitting.

 

Desoto29hemi - thanks for your feedback. This is only my second time wiring a hot rod. I will come back to you for further advice once I get this coolant question solved. Greatly appreciate the feedback

 

Sorry man,,,,,,just kidding really .
You can remove the fitting that used be used for another purpose ,,,,,look in the lower left of your engine pic .
The fitting beside the thermostat housing with the two vacuum nipples on it is a ported vacuum switch .
You won’t need it for your application .
You can screw a temp sending unit in there .

Tommy

 

Should be water under that fitting

 

Make sure you're using the correct part for a temperature gauge. If Mopar was anything like GM, a "switch" (either open or closed circuit only) was used with a warning light. A temp "sensor" (variable resistance) was used for temperature gauges. Also not sure about Mopar, but GM vehicles of this vintage also used as many as three coolant sensors or switches. One for the I/P guage or light, one for the engine control module and maybe a third for an electric engine cooling fan.

 

That's a vacuum switch That I believe was the ported vacuum switch and is now N/A.

 

Mr 48 is correct - that is a vac port and should be capped - the temp sensor is right under your fuel line and if it were me i would replace it with a mech temp gauge - I don't trust electronic stuff when it comes to engine temp - sometimes by the time it tells you that you have a problem it is to late - just a thought - jaxx

 

Thanks Jaxx
I have pulled the sensor directly behind the thermostat housing under the gas line and there is no sign of coolant? Should I see coolant? looks dry???

 

What does the back side of the sensor look like ?
It should be solid,,,,,because you were right earlier,,,,it’s a knock sensor.
There shouldn’t be any water in that boss there .

On the right side of the intake,,,,,,behind the dipstick area,,,,,where the front intake bolts are .
There is a cad plated plug screwed in there,,,,,,you can remove that and place a temp sender in there if you choose .

Tommy

 

Thanks desotohemi - I thought that might be the case but wanted to get someone to verify before I remove the plug. Appreciate the help

 

You’re welcome,,,,,just trying to help .
There is a vast amount of knowledge here,,,,,,,I am just a slight speck on the windshield compared to the talent here .
Not many Mopar guys here,,,,,but still several ,,,,,everyone tries to help .

Tommy

 

There's some photos online that show the temp. sensor going into the manifold where that square drive pipe plug is, just to the left of the thermostat housing.

Check the length of the temperature probe to make sure it doesn't bottom out in the coolant passage. Some pics showed an adapter/extension being used to raise the sensor maybe 1/2" to 3/4" if necessary, and possibly to adapt to the thread size of the temp. sensor.

 

Thanks everyone- I was able to loosen the fitting that had the vacuum looking fitting on the top and there is coolant there. Just need to drain some out and get the new sensor fitted.
As always the HAMB comes through for someone like me with very little experience in this field. But a desire to build a hot rod!!!!
Thanks - hopefully I’ll post a working temp gauge in the next few days.

 

The little item between the two front right intake bolts is where the temp sensor usually is on the smallblock Mopars. Unless you are going to run a mechanical gauge-then you need one of the larger holes.

 

The temp. sender is located where Lemondana and Desoto wrote. The vacuum switch is temperature controlled and was used to keep your egr valve inop. when the engine was cold and working when operating temp reached.

 

Success! idling at around 155 steady.
again thanks to all for your input.

 

Good job, you don't need the temperature controlled vacuum switch.
I agree with the other suggestions that the first sender right behind the thermostat was probably a knock sensor. If you ever replace the factory manifold with an aluminum aftermarket one, just get a regular nonemission version and it won't have the extra holes.

 

That 318 is going to be a lot more efficient, and will stay in better condition long term, if you change the thermostat to either a new one, or one with a higher operating temp. A steady 180 to 190 will work much better.

 

Are you running a 727 or 904 automatic transmission? If so, it looks like you could possibly use some help on the so called kickdown linkage. Can you post a few more pictures of your throttle bracket and all of the linkage on the side of the carburetor. If you don't have this hooked up and functioning correctly, you will burn your transmission out fairly soon.

 

Lemondana - thanks for the input. Yes 727 and I do NOT have the kick down linkage setup yet. I need to research that. I am “yard” driving now just to test everything and it seems to shift fine but I will look into the kick down linkage. It’s a 727 with a lokar shift.

Gene - I believe the thermostat is a 160 - you are suggesting a slightly higher temp is better for this engine. Appreciate the advice.

Thanks
Pulled it out yesterday - more testing.

 

Rj27 ,
Yes,,,,you need the kick down linkage installed and functional,,,,,,,the transmission won’t last long without it .
You can motor around the house without it,,,,,but not any trips if any length .
Get it done soon .

Tommy

 

Ok thanks - will research and get this done properly.

 

Yeah, the kickdown controls the fluid pressure in the trans, too low and it will burn out the clutches.

The proper adjustment is hard to do with aftermarket stuff, but I normally go until I get a 1-2 upshift about 15 mph with light throttle. Some books call for more or less, But 15 mph can vary in rear gears and tire sizes also. 20 MPH for 2.70 Gears, 15 Mph for 3.73 Gears.