auto meter mechanical temp guage

[fairlanegt427]

ihave been having problem with autometer temp mechanical guages.  anyone else have this problem?   it doesnt seem to read anywhere near where it should.  i have sent it in to autometer and they sent me a new one,  still the same thing,  i also check temp with a laser themometer and i was reading 20 degrees cooler than the autometer guage,  questioning my guage i borrowed one from a shop neighbor and it was right in line with my laser thermometer.  i am thinking about pulling out that mechanical guage and trying out an electrical guage.  anybody else have this problem?  and or any guidance?

[mlcraven]

Not very helpful to pose more questions than answers, but here goes: What is it reading?  What were you expecting?  Where is the sensor located?  Did you do a pre-check in a pot of boiling water?

I have the poor man's AutoMeter mechanical water temp gauge: AutoGage.  Sender is in the usual location in the front of the intake manifold.  No matter what the outside air temp range between 60F and 95F the gauge reads 200F.  It rises to 215F max at long red lights during the dog days of  a southern summer.  And in the late-winter/early-spring when air temps are well under 60F never indicates less than 195F. All this with a refurbished rad, water passages in block cleaned, 38 degrees timing all in at @ 2200 rpm.  Engine doesn't seem to have any complaints so I don't worry about the gauge...just use it as a relative reference point.

[427Fastback]

I use a laser thermometer at work all the time....They are easily fooled....I would just check your gauge using a pot of water and bring it to a boil...You can always put a cooking thermometer in the pot as well as your 2nd gauge and compare them...When the water comes to a boil you know what they all should say...

[fairlanegt427]

the mechanical sender is where it is suppose to be.  front of intake behind thermostat housing. it is reading 195 at idle in my shop running for 15 minutes i have never had an fe run that warm at idle,  i have checked plugs also thinking it might be lean but they look great.  timing is set at 34 total.   i think i am going to just buy the old style mercury filled thermometer and stick that in rad tank.  i am running a dual pass aluminum radiator with 2 fans and a shroud so i know it has plenty of radiator.  this car is just a street strip 428, 12:1 compression.  their is no thermostat,  i run that dove adjustable thermostat housing and have played with adjustment on it with just no luck.  i do have meziere pump on it, i think i am going to get jays adapters and try the cvr pump.and cross my fingers.

[cjshaker]

Ditto on the laser temp gauge. They are not always perfect readings. Also, what you are reading is the SURFACE temperature of the intake, not the coolant running inside it. There can be a big difference when dealing with thick pieces of aluminum. Thin copper or steel is different.

Also, like anything that reads pressures, temps etc., unless it is a scientific or medical quality instrument, or has been recently calibrated, the readings are not guaranteed accurate. You could take 5 different gauges and likely get 5 different readings when comparing them. 20 degrees seems a bit far off, but that was with the laser gauge which was reading surface temp.

I run two Autometer mechanical temp gauges and both work fine for me. While I admit I have not checked them in water with a cooks thermometer, they still work fine and seem to be accurate enough. In my Mach, it'll run 180 cruising, then creep up to 190-195 max on hot days in town. I know that's where it runs, so if it's a few degrees off, it doesn't really matter. If it starts shooting up from where it normally runs, then I know I have a problem.

[fairlanegt427]

cj shaker.   i am wondering where did you put the other water temp guage at on  your car?   i am  sure i know but i really am drawing a blank in my head.   i also think that i am going to my local drug store and buy a good thermometer.   also i bought those adapters from jay,  i am gonna take off that meziere pump and try that cvr.   i am going to video the water flowing inside the tubes with the meziere and also with the cvr.  ill put them up here if i can figur it out and or if it even takes a good video.  plus this is not the first auto meter guage that i have had fail on  me.   i have had a tach crap out on me and also 1 other mechanical water temp guage (same car).   plus if you think about it,  lets say autometer makes 100,000 water temp guages per year for example.   lets say that their failure rate is 2%   thats still 2000 bad ones.   i am not beating up autometer but it is also something to think about,   plus maybe i am just an unlucky person when it comes to these mechanical guages:)

[cjshaker]

Sorry I missed your reply.

I meant I have 2 gauges in 2 separate cars, or one gauge per car. I do run the factory gauge in the stock intake location on each car, and then I run the Autometer gauge in the thermostat housing using the factory units with the bung cast in. They give me very accurate readings compared with the factory gauges, and using both gauges I know instantly if anything funny is going on with the thermostat.

You can see in this image where it's plumbed at on the housing.

[fairlanegt427]

i didnt even think of putting sender in the thermostat housing but i dont need too i have the dove adjustable thermostat housing. it is basically a gate design, even though when i have it adjusted closed all the way, i would guess that at its closed point you could take 4,   1/8 inch holes and put them side by side and that would be as far closed as it gets.  i am just going to boil some water and check my guage and go from their.

[machoneman]

Don't let the probe touch the bottom of your boiling water pot! Suspend it in only in the water.

[fairlanegt427]

i did go and buy a thermometer at the store to double check  the temp in relation to the guage.  the guage works.  i guess i think i have another problem.

[machoneman]

O.k. but what is the problem?

[fairlanegt427]

i think i have a head gasket possibly leaking and or air in the system.  i fill the stytem under vacuum so it gets pretty much all the air out.  i have bought a test kit to check for gases in the coolant.  still waiting for that to show up.   also i borrowed a stant pressure kit to check the sytem with coolant in it under pressure.  that guage didnt move had it on for 2 days.  also when i filled the sytem under vacuum it checks for leaks that way too.  i am thinking possibly overfilled and or still  an air bubble in the system that wants out.  also maybe i just have a car that runs a little warm with the hood on.

[cjshaker]

If you have any air in the engine, just jack the front end up and it should escape towards the radiator easily.

But initially you were concerned that it was running at 195 while idling. That is certainly not hot, and if that's as high as it goes while sitting still, idling, then it sounds to me like you have a very GOOD cooling system. If it's a bit warmer than other engines you've had, it may be because it has thinner cylinder walls, tighter engine compartment or maybe just the weather itself. But that is certainly not a temperature I would be concerned with.

[mlcraven]

That last possibility (runs hot with hood on) would be fairly easy to investigate and put to bed one way or another.

[fairlanegt427]

i do agree on the hot engine compartment with the hood on and the 428 does definitely fill the engine compartment up in a 1965 comet.  i think that sometimes i definitely do over think myself and or overstress myself over this stuff. because i know all of you guys in here are as picky as i am and i just want it perfect as do all of you.  thanks for the posts on this subject  team.