temp gauge not working

Vmxhunter · Post by **Vmxhunter** » Mon Feb 08, 2010 6:30 pm

Well rode most of the day sunday. And this has been the second time out with my 86. But the temp gauge isn't working (well it's not moving). I know I got antifreeze moving. Since there is steam coming off the rear heat exchanger when I stop the sled for a rest. The snow is melting off it. The level in the radiator is just fine.

Now, if I want to remove the sending unit for the temp gauge from that "T" fitting. Do I need to drain alot, or just a little antifreeze? Or can I just remove the sending unit. And let the antifreeze drain from that spot into a container? If I do that, how much can I expect to drain out from that "T" fitting that the sending unit is screwed into?

Bob Vehring · Post by **Bob Vehring** » Mon Feb 08, 2010 7:18 pm

I don't think many of them do, mine never moved, replaced it with a known good car gauge, never moves. Both respond to heat if I hold a lighter under the probe. On mine the small hose never gets warm, I have the engine out an put it back together today, I made sure nothing was plugging the line, it was clean. I think, probably because of the Banjo bolt on the top, it just doesn't flow much threw there. I thought about just taping the whole on the top for a fitting and getting rid of the banjo bolt, but not sure if I care that much

Post by **Vmax540** » Tue Feb 09, 2010 7:51 am

There have been tons of discussion on the gauges..... there seems to be a flow problem created by restriction. One member simply cleaned out both nipples with a drill bit with good results.

Garage
Monday Jan 18th
Speaking of temp gauges

Vintage classifieds
Wednesday Jan 20th
Temp gauge wanted

Vmxhunter · Post by **Vmxhunter** » Tue Feb 09, 2010 7:29 pm

Maybe I'll try that drilling. But IF I removed the sending unit...How much antifreeze can I expect to come out? So I can have the right sized container to hold it while it drains.

Bob Vehring · Post by **Bob Vehring** » Tue Feb 09, 2010 8:12 pm

You won't lose much if you just take the top bolt off. I have mine apart on the bench now, looked at this yesterday My guess is the banjo bolt, it only has a maybe 5/32 hole in it and has to then go threw the fitting.
Sorry to say but IMO the whole setup is kinda dumb. The bottom has a cast in fitting right next to the main big hose. Unless there's enough restriction in the big line, the water has no reason to want to go up that little line. Then you have the probe for the gauge that just sits in a plastic tee, sio it doesn't really get water flowing past it much. then theres the restriction on the top end. I think the answer is to splice a tee that holds the gauge into the bigger line, but haven't tried it yet. So far, even with the thermostat, it hasn't showed any sign of getting hot

Joe · Post by **Joe** » Wed Feb 10, 2010 2:36 am

The only time my VMAX shows any heat is when the engine is running and the sled is not moving for quite a while (like idling 15 minutes). Once I start moving, the needle comes way down to the bottom of the scale and stays there.

In my opinion, taping an the remote sensor of an indoor/outdoor thermometer to the upper hose and putting the display on dash would be a great (cheap) solution. You could read the temperature to a tenth of a degree even below zero. You will probably even get to choose US or Metric units. Without a penetration in the hose, there will be minimal chance of a leak. If it fails, you can buy another one and tape it on the same way. One of the displays has an internal LED illuminator so you can read it in the dark when you push the button. My digital thermometer batteries last about a year.

brjr540 · Post by **brjr540** » Wed Feb 10, 2010 4:27 pm

i.m.o. you NEED the thermostat installed to PROPERLY warm the engine, with the t-stat removed it over cools and causes cold sieze conditions depending on the coolant mixture,jetting outside temp. i used a 140deg t-stat and drilled a .015 hole in it to remove air bubbles i have never had it go over 150deg.a warm engine require less fuel than a cold engine. i know i may have opened up a can of worms here but i will give up a couple of h.p. for reliability any day.

Post by **tyler440** » Thu Feb 11, 2010 8:33 am

its not the horsepower i am looking to gain... its the fact that if you have a thremostat stick closed (like i did) you wont know it until your motor is hotter than hell and there is steam coming from everywhere... mine stuck closed while cruisin at midrange... thank god the guy ahead of me pulled over just before a mile of WOT... when i slowed down i was suddenly surrounded in steam... i looked at the guage needle and it was climing rapidly.... needless to say i got towed home from there... tore everything apart and found nothing... put the thermostat in boiling water and it stayed motionless in the closed state.... honestly how the steam was coming out of the motor and out of where ever it was coming from is beyond me but i got really lucky!!