Intermittent "low coolant" light........

[Can Can]

Intermittent \"low coolant\" light........

My "low coolant" idiot light has been flashing on and off intermittently for the last few weeks. The rad is full so I'm not quite sure why it's happening.

The wierd part about it is that it seems to flash only when I'm going downhill on very slight grades at highway speeds. It will only flash for a second or two and then go out. Tonight I drove 120 miles round trip and it flashed about 4 times for no apparent reason....... Temp gauge was reading normal at the time./forums/images/graemlins/dunno.gif

 

[tRustyK5]

Re: Intermittent \"low coolant\" light........

Bad sensor? I can't think of what else it could be if the coolant isn't low.

Rene

 

[imiceman44]

Re: Intermittent \"low coolant\" light........

[ QUOTE ]
Bad sensor? I can't think of what else it could be if the coolant isn't low.

Rene

[/ QUOTE ]

Or a loose wire grounding on something.
/forums/images/graemlins/doah.gif

 

[OFFRDK5]

Re: Intermittent \"low coolant\" light........

Check on the passenger side of the rad. Should be easy to see. Mine was solid on and I pluged it back in and it was fine.

 

[JeffHK5]

Old ars post

Yep , I know it's a "older than dirt" post but mine has started doing the same thing!

Canmore, what was the fix?

Thanks, Jeff

 

[Can Can]

Wow, I was surprised to see this post up at the top........

I'm *pretty* sure that the "low coolant" light is being caused by air in the system, either through a bad head gasket/cracked head or a bad/cavitating water pump. Since then I have had some wierd cooling issues, as well some intermittent boilover into the coolant reserve tank.

Regardless, I've put another 20K on the 83 with all this happening, and it's still running fine. The reason I'm not worried is because the truck has been relegated to farm duty status, and doesn't see much road time anymore. One of these days I'll probably end up trying to see if I can solve the issue, but until then I have better things to spend my time on.

Sorry I couldn't offer you any solid conclusions, brother. Are you having similar issues, by any chance?

 

[JeffHK5]

No boiling over but it does have a strange working thermostat, it will go up to 230 degrees before it opens for the first time. The coolant light will come on at all different temps and RPMs , no pattern.

Is the sensor in the overflow tank , where it actually measures fluid level or is an idiot light that works off a temp. sending unit?

I was thinking that a bad temp. sender could give me the impression that the thermostat was opening at 230 and would make the "low coolant" light come on and go off randomly.

I like the old 6.2 but these phantom cooling problems are a little frustrating!

Jeff

 

[jarheadk5]

I'll scan the relevant pages out of my book and post 'em up tomorrow. Might help both of you...

***EDIT***

Scanned and posted in the "6.2 Tech Info" sticky post. Hope it helps...

 

[tRustyK5]

I'm doing the head gaskets and water pump on Paul's old truck right now. FWIW, there were no signs of cavitation with the old pump and no 'smoking gun' with the head gaskets either. Looks like number two cylinder was where the problem was though. That piston is very clean, and that exhaust port on the manifold is the only one with rust spots...

I've never had the coolant light come on with this truck though.

Rene