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Temp Gauge rising!


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Hey Faq friends hoping some of you can lean in here...

 

my temp gauge has been riding high the last couple days despite full coolant and oil level.  Today it happened within just a few minutes of driving on cooler day in Seattle. The needle actually hit the red so I pulled over to further investigate again.  The radiator cap was still cool to the touch and coolant seemed full. No obvious coolant or oil leaks that I could see.  The gauge is also really jumpy.

 

I had my car in for service last month and my local mechanic felt that based on some oil leakage that I might be due for head job but I wanted Patrick and Midnight Motor Sports to handled that later in the year.

thoughts anyone?

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Edited by rdeeble
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Probably a faulty gauge/ground as sydneyTii said, but if it’s actually getting hot then a failed water pump or thermostat that has stuck closed. Do you have an IR thermometer? Go for another drive and compare the temp of the sensor housing to the radiator. 

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Check the following:  (presuming coolant level is good, and there are no air pockets in the cooling system from a recent coolant change--are you getting hot air from the heater?)

  • When driving and the gauge reads high, touch the upper radiator hose and radiator tank--carefully!  If they're both cool(ish)--i.e. not too hot to touch--then I'd suspect a stuck thermostat.
  • Also while driving and the temp starts to go way up, turn your heater on full blast (heat lever to full hot, blower full blast) and see if that drops the temperature.  If it does, there may be a more organic problem than the ones mentioned here.  If it has no effect, then it's probably not a cooling system problem ('stat excepted).
  • unplug the wire that's attached to the temp sender (left side, front of the head), and clean both the terminal and the female plug.  They get corrosion on 'em.  And while you're at it, take a close took at the threads where the sender screws into the coolant pipe.  You have dissimilar metals (aluminum and brass) and since the sender grounds through those threads, corrosion can affect gauge readings.  Remember that if you remove the sender to clean the threads, you'll need to drain some coolant.  And don't use sealer on the threads when you reinstall!
  • If the gauge itself tends to be jumpy, look at the gas gauge.  If it's also jumpy, then it's almost positive the problem is a deteriorated ground at the gauges themselves.  Look for a post on "grounding gas and temp gauges" in the archives on how to do this.

Let us know whatcha find.

 

mike

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  • 2 weeks later...

Plus one on all of Mike Self's suggestions

I did them all on one car and in the end the gauge was faulty and unreliable. 

It's very uncomfortable to see that needle hitting Red all of a sudden even when you know the car is not overheating

Try swapping out the gauge and see if it behaves the same way. For me the needle went down to 3:00 O'clock max 

Plop Plop Fizz Fizz   What a relief it is

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  • 2 weeks later...

Hey everyone thanks for the good advice... heres my not-so-clear findings report ...

>Clean your earthing/ground points, you may need to ground you cluster, it’s not uncommon.

Got it! Got the male end nice and shiny (anyone have a good tip on cleaning the female connector?) Also noted this heat gauge wire sheath was pretty frayed and I might just want to replace it.

 

On 8/17/2021 at 6:51 AM, bluehills2002 said:

>I was in the same boat as you last summer- no jumpiness, just a slow rise towards the red, very unsettling.  What got me right back to 3 o’clock were new alternator bushings from Blunt to eliminate the play + a new belt.  Tom

This is intriguing because i do get a very slight flicker on the L light on idle which might have something to do with the bushings... curious how this would change heat gauge though? Is it just a matter of load on the electrical system?

 

 

On 8/17/2021 at 8:00 AM, Mike Self said:

Check the following:  (presuming coolant level is good, and there are no air pockets in the cooling system from a recent coolant change--are you getting hot air from the heater?)

 

Coolant level is good and I do get hot air from the heater

 

On 8/17/2021 at 8:00 AM, Mike Self said:
  • When driving and the gauge reads high, touch the upper radiator hose and radiator tank--carefully!  If they're both cool(ish)--i.e. not too hot to touch--then I'd suspect a stuck thermostat.

Sort of... Tank is hot but not too hot - hose is cool to the touch

I replaced thermostat  - this seems to have lowered the temp gauge to about 2:00 but not back to 3:00 where it was previously...  I suspect more than one issue might be at stake

 

 

On 8/17/2021 at 8:00 AM, Mike Self said:
  • Also while driving and the temp starts to go way up, turn your heater on full blast (heat lever to full hot, blower full blast) and see if that drops the temperature.  If it does, there may be a more organic problem than the ones mentioned here.  If it has no effect, then it's probably not a cooling system problem ('stat excepted).

 

indeed with the heater on my gauge (following thermostat replacement) drops from 2:00 to 3:00

Radiator was rebuilt 5 years ago (along with water pump and all hoses) but I'd like to get a temperature on the radiator to see if its not doing what it used to

 

On 8/17/2021 at 8:00 AM, Mike Self said:
  • unplug the wire that's attached to the temp sender (left side, front of the head), and clean both the terminal and the female plug.  They get corrosion on 'em.  And while you're at it, take a close took at the threads where the sender screws into the coolant pipe.  You have dissimilar metals (aluminum and brass) and since the sender grounds through those threads, corrosion can affect gauge readings.  Remember that if you remove the sender to clean the threads, you'll need to drain some coolant.  And don't use sealer on the threads when you reinstall!

Partially done - male terminal is clean.  Going to further assess the female terminal and the sender screws soon

On 8/17/2021 at 8:00 AM, Mike Self said:
  • If the gauge itself tends to be jumpy, look at the gas gauge.  If it's also jumpy, then it's almost positive the problem is a deteriorated ground at the gauges themselves.  Look for a post on "grounding gas and temp gauges" in the archives on how to do this.

Yes I do notice jumpy gas gauge but only temporarily then its solid while temp gauge stays jumpy. MORE IMPORTANTLY I HAVE JUST DISCOVERED THAT THE TEMP GAUGE JUMPS UP A QUARTER WHEN I ACCELERATE this make me think that on top of other issues i have some electrical grounding issues.

 

On 8/17/2021 at 8:00 AM, Mike Self said:

Let us know whatcha find.

 

mike

 

So the general report is I had Patrick Oneil replace the thermostat and it helped but not where I want it.  Im going to get it back into his shop in a few months to have my electrical completely cleaned up (one of patrick's favorite things) and have the cooling system further assessed.  For the time being Im getting used to the heater being on and at least the needle isnt hitting red... but I tell you nothing makes you more nervous than not seeing that 3:00 mark. To be continued!

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