Register now to get rid of these ads!

Technical Lets talk temp gauge theory

Discussion in 'The Hokey Ass Message Board' started by Roothawg, May 27, 2017.

  1. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    So, I was on the way home form the SWMO HRH a month or so ago and 650 miles into the trip, the temp gauge started climbing. It was a rapid increase to 250 degrees. I immediately hit the first exit and checked the head with my hand and it was warm but not super hot.

    Anyway, exited off the highway and limped it home on Rt 66 at about 40 mph. As long as I kept it under 40 it was happy. Any thing above that and it would creep upwards. Pull over and it would immediately drop back to normal. I used my infrared temp gun and it shows 185 on the radiator water necks, heads and water pump.

    I suspected the temp sender, so today I changed it. No change. I can only assume it is the gauge, which is only a few months old. I am afraid I have to buy it in a kit and not separately.

    I release the resistance is measured across the sender, but component makes the gauge act up? It's just reads voltage across 2 poles correct?

    So any suggestions?
     
  2. onetrickpony
    Joined: Sep 21, 2010
    Posts: 753

    onetrickpony
    Member
    from Texas

    I have no faith in electric temperature gauges. Start with a mechanical gauge and trouble shoot from there.
     
  3. Blues4U
    Joined: Oct 1, 2015
    Posts: 7,589

    Blues4U
    Member
    from So Cal

    Working as a mechanic I always kept a mechanical gauge in my tool box, or on my service truck, and that is one of the first things I'd do to confirm if I had an actual problem or not, temporarily swap out the gauge with the mechanical one and test it to see if the mechanical gauge also showed it running hot. If not, I knew the problem was with the gauge, not the cooling system.
     
  4. Blues4U
    Joined: Oct 1, 2015
    Posts: 7,589

    Blues4U
    Member
    from So Cal

    It's a variable ground. Full ground pegs the gauge, fully open circuit shows no gauge movement at all, all points in between are equal to the variable resistance.
     
    loudbang likes this.

  5. 19Fordy
    Joined: May 17, 2003
    Posts: 8,025

    19Fordy
    Member

    If it's a flathead Ford, your temp senders could be shorted or bad
     
  6. Got a few more details? How many wires are connected to the gauge? Do you have a ground strap between the engine and the frame AND body? What's the ohms range of the gauge, i.e. does it read 10-250 ohms cold-to-hot or the other way around? (note these values are just an example; different brands can use different values).

    Electric temp gauges have been standard equipment on almost all cars since the mid 50s, they've proven to be accurate and reliable if installed right and of good quality.
     
    Uncle Bob likes this.
  7. So the gauge is part of a "kit"? .......and it's only a couple of months old? There should be some sort of warranty. It would be very bad karma for the seller if there isn't. Do contact the seller and give him a chance to make things right. (I understand that we can buy stuff for our projects months, sometime years before we install them. This won't help your case.) If you hit a dead end and it's been less than a year then you can flex your credit card muscles and have the credit card co make the money part of the deal slip back in your pockets.

    But primarily you just want to establish that you don't in fact have an overheating issue and you have a working gauge. Start with the simple stuff first. Check the connections, the ground(s) in particular, then the sender (don't use teflon tape, etc.), then beg or barrow a known, working gauge to cross check, and so on up the ladder. 90% of the time it's one of the simple things.
     
    Last edited: Jun 4, 2017
  8. Moriarity
    Joined: Apr 11, 2001
    Posts: 30,773

    Moriarity
    SUPER MODERATOR
    Staff Member

    I had the same problem with my 61 corvette and my off topic 66 396 chevelle. both cars were actually running hot at higher speeds and as it turned out they were both missing the spring inside the lower radiator hoses. Hoses used to come with those springs but no longer do, you are supposed to transfer them from the existing hose to the replacement one. Without the spring, at speed the hose sucks flat limiting flow. Both of mine were fine after I installed the hose springs.....
     
  9. Good info^^^^^
     
  10. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    Mark, I can't find anyone that has a spring. Where did you find yours?

    I bought a kit from Speedy Bill. It's been a few years, but only installed for a few months. It was the only kit I have ever found that would fit a 36 Ford pickup speedo hole without modifying, so thats why I bought it.

    Guys, I am a ground freak. Every gauge gets its own ground. I have a remote post that grounds the battery to the frame, the gauges to the battery, and the battery to the starter. All separate.

    It's not a flathead. It's just a common run of the mill sbc crate engine. It has the biggest Walker radiator, cooling components electric fan with shroud, flow kooler high flow water pump, high flow thermostat.
     
    Last edited: May 27, 2017
  11. c-10 simplex
    Joined: Aug 24, 2009
    Posts: 1,371

    c-10 simplex
    Member

  12. Moriarity
    Joined: Apr 11, 2001
    Posts: 30,773

    Moriarity
    SUPER MODERATOR
    Staff Member



    here....
    http://www.ebay.com/itm/1966-1972-P...ash=item2c798e4f65:g:ajgAAOSw~FJZHGDV&vxp=mtr
     
    kidcampbell71 likes this.
  13. henryj1951
    Joined: Sep 23, 2012
    Posts: 2,306

    henryj1951
    Member
    from USA

    er just get THIS type---->
    .

    hose.jpg
     
  14. henryj1951
    Joined: Sep 23, 2012
    Posts: 2,306

    henryj1951
    Member
    from USA

    like this^^^^^

    and or just STAY Mechanical...
     
  15. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    I believe it's accurate or at least it's working. I can watch it fluctuate when the thermostat open. It follows the full range of motion. I'm starting to think Mark may be on to something. As soon as I drop down in speed, it drops back to normal within a minute or so. The reason I am thinking he may be right is that the lower hose is molded and I was thinking when I installed it, that it was a little flatter than I liked. With the high volume pump, it may be collapsing. It's cheap enough to try. Can't hurt. I ordered the spring, should be here Tuesday.
     
  16. JOECOOL
    Joined: Jan 13, 2004
    Posts: 2,771

    JOECOOL
    Member

    I'm sure you know this but I'm old and like to repeat things ,but I get a reading 11 degrees higher when I use the cyl head for the temp sensor ,instead of the intake manifold.
     
  17. nunattax
    Joined: Jan 10, 2011
    Posts: 3,052

    nunattax
    Member
    from IRELAND

    install a sbc your troubles should fade away
     
    TagMan likes this.
  18. Reading is an amazing tool. You should try it.
     
  19. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    I use the head port for my electric fan sensor.
     
  20. Moriarity
    Joined: Apr 11, 2001
    Posts: 30,773

    Moriarity
    SUPER MODERATOR
    Staff Member

  21. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    Just showed up yesterday. I've been down with the crud, maybe this week I can get back on it.
     
  22. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 12,600

    Johnny Gee
    Member
    from Downey, Ca

    To add to thing's closing off circulation like a missing spring on a lower hose. I had an issue much like that after installing a water pump that had a higher volume flow than stock. It would close my thermostat at high rpm's and the only way to get things flowing again was to stop the engine and let the pressure equalize.
     
  23. stimpy
    Joined: Apr 16, 2006
    Posts: 3,546

    stimpy

    no offense But ... those hoses are about as bad as a flat one , they cause lots of internal restriction and cavitation from the ribbing . if not internal springs then do what we do on industrial and big trucks, use solid metallic tubing and short rubber sections to connect it to the parts ( speedway sells it and its correct as flatheads used them ) the metal also conducts heat and helps cool the coolant .
     
    henryj1951 likes this.
  24. Speed~On
    Joined: Apr 28, 2011
    Posts: 1,607

    Speed~On
    Member

    I run 2 temp gauges in my SBC crate engine. One directly in the intake manifold and the other mounted in my dash. Perhaps you could use 2 as I have done? This would certainly give you an accurate reading and you can use the 2 gauges as a "checks and balances" with your temp readings. I know this doesn't solve your issue, but it sounds like you'll have it resolved once you can install your new parts. Hope you feel better soon.

    20170605_120247.jpg

    And another mechanical temp gauge in the dash.
    20170605_120403.jpg
     
    Last edited: Jun 5, 2017
    BJR likes this.
  25. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    Thanks. I was looking for a direct mount gauge the other day. That one would work just right I think.
     
  26. Speed~On
    Joined: Apr 28, 2011
    Posts: 1,607

    Speed~On
    Member

    I purchased that intake temp gauge directly from Moon Equipment in California. They were great to work with over the phone.
    They are available in a few different face sizes, mine is the larger face. I really like it as it's nice to have.
     
  27. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    I think that's what I will do. I'll have it drained down anyway, might as well mount the gauge at the same time.
     
    mike in tucson and Speed~On like this.
  28. Moriarity
    Joined: Apr 11, 2001
    Posts: 30,773

    Moriarity
    SUPER MODERATOR
    Staff Member

  29. sunbeam
    Joined: Oct 22, 2010
    Posts: 6,213

    sunbeam
    Member

    You said crate engine is it stock? If it has Vortec heads on a pre Vortec block you need a circulation hose or drill the head. Vortec blocks don't have that extra port where the water pump bolts on that let's water circulate in the block when the thermostat is closed.
     
  30. ^^^^^ Yeah, Chris....we've all been sitting on the edge of our computer chairs waiting to see what happened!
     
    Moriarity likes this.

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.