"LO" temp?

[rrubel]

Was mucking around with the cooling system yesterday, installing a lower-temp fan switch. Refilled the radiator and overflow bottle (filling to top of neck with engine warm). Went for a drive. Temp gauge never goes off "LO". Oil temp climbs normally, but not coolant temp. I checked after the engine had cooled off and the level is still to the filler neck so I don't think there's an air bubble. I guess the thermostat could have suddenly decided to stick open. I know how to check the thermostat for proper operation, but how does one test the temp sender? And am I correct in thinking it's the wire just below the overflow hose on the filler neck? Are there multiple senders? I'm worried about driving it - if the coolant isn't actually flowing for some reason, will it overheat the engine without my knowing it?

I guess there's always the chance I replaced the wrong sensor, though I kinda doubt that. I took out the one between the last two cylinders on the passenger side, which is where both the Haynes and the new switch's directions said it would be... The fan doesn't run at all, which is to be expected if the temp is low.

Thanks...
[RICHR]

 

[warren s]

Rich-

Some manuals list the resistance measured in Ohms of the temp sender at various imersed coolent temps temparatures.

Short of removing and terting the sender, try and ground the connecter or lead to the block and see if the guage swings.

I would drive a shot distance and than pull over and check the engine. Just buy putting your hand around the valve covers and manifold and the hoses I bet you can tell if all is normal or running hot. Not very scientific but I think anyone who had the same car for a while could tell if all is the same as usual. I doubt from what you discribed that you affected the actual coolent circulation.

On my 95 the oil temp goes to the same zone and stays there even though the coolent temop may have a 30 degree variance.

 

[rrubel]

One thing making it harder to tell what's going on is that today is the coolest it's been in a while... ambient was about 75 this afternoon and maybe 65 this evening.

Went for a drive tonight; the engine (except for exhaust area) was cool after driving a couple miles. I could rest my hand comfortably on the plenum. Upper and lower radiator hoses were warm but not hot.

After that, went out for a longer drive and whaled on it a bit. Got home and the plenum was warm but not hot (but it IS only in the 60's right now). Radiator cap was warm but not hot. In fact, I carefully took the cap off (letting pressure release first) and the coolant was steaming but not boiling - I could touch it without getting burned, though it was uncomfortably hot. Oil temp didn't get above 209 even when pushing hard and actually cooled down at first while I was stopped at a light.

Something tells me the thermostat is stuck open...

Oh, I tried grounding the sensor to a known ground (the horn ground) and got no reading. Also tried grounding out the fan temp switch and got no fan. Perhaps I'm doing something wrong there.

[RICHR]

 

[Top]

Rich,

The sensor below the radi cap is the ones that tells the Driver's Info center "Low Coolant". "LO" on your dash cluster is controled by the temp switch between the cylinders. See my earlier post.

http://www.corvetteactioncenter.com/forums/showthread.php?postid=114429#post114429

Hope this helps.

 

[vigman]

Oh Rich

What color wire was on the sender you replaced.. and what style connector was on it?


I think you goofed!

and replaced the cooling fan switch with the temp sender......


Yikes



Vig!

 

[rrubel]

Vig, the sensor I replaced had a single black wire with a square plastic flat connector at the end. The new one had an adapter wire with this type of connector (with a flat piece of metal) at one end and its own round connector (just like the knock sensor) at the other end for the sensor itself.

My Haynes manual showed the fan switch being just behind the oil dipstick. I only saw one thing back there; are the multiple sensors in that area?

Argh! If I replaced the wrong one I'm going to feel like SUCH an idiot.

Thanks.
[RICHR]

 

[vigman]

Senders & switches cooling system

" installing a lower-temp fan switch"

The fan switch wire is Dark Green/White with a ROUND pin female connector.

"My Haynes manual showed the fan switch being just behind the oil dipstick"

For an 84 thats correct ( rutt-row )

On my 88 it's on the drivers side between 1&2.

"Temp gauge never goes off "LO""
I assume this worked before?

"the sensor I replaced had a single black wire with a square plastic flat connector at the end."

So far so good....

The new one had an adapter wire with this type of connector (with a flat piece of metal) at one end and its own round connector (just like the knock sensor) at the other end for the sensor itself.

ALARM_ALARM_ALARM


The coolant sensor gauge wire is dark green.

So me thinks you did put the switch where the sender goes.
AND
When the new sender hits temp, the switch will close sending the temp gauge to OVERHEAT ( Do not panic )!

I hope you didn't chuck the OLD sender...put it back!

The other way you can tell, is ground the dark green sender wire and watch the gauge ( key on buddy behind wheel)
one will send the gauge to OVERHEAT...

If you ground the Dark Green/White this will click on the fan.

The fan sender is a switch so at a certian temp CLICK the Bi-Metal moves and closes the crkt to ground.

The Temp sender is a heat variable resistor 1500 ohms ( ish ) cold
75 ( or lower ) OVERHEAT

( The Grim Reaper stirkes again... bringing bad news)


Vig!

 

[rrubel]

Argh. So the prize goes to Vigman... again... and the booby prize goes to Hypertech for their directions.

Yes, the sensor I removed was the temp sender. Apparently only cars (of my year, at least) with BOTH FANS installed at the factory will have a fan switch. Otherwise, the ECU turns on the fan. I saw a plug in the block between cyls 1 & 2, but as my main fan isn't connected there and my aux fan is manual there's no point in installing the fan switch.

Vigman, you're correct when you say that 84 has the switch back where we have the sensor. The Hypertech directions said that all 84-96 Vettes have it there... The Haynes says nothing about a switch for 85-87 cars.... just the ECU turn-on in the diagram.

Anyone want the switch? Free plus shipping. It'll turn on your fans at 200 and off at 185 - but you need to know where your fan switch IS before installing! It's new but has gouges in the housing from de-installation.

Thanks for the help, guys. Again...
[RICHR]

 

[searay270]

Advice at it's best

This thread exchange just demonstrates the true value of having a board such as this available to all Corvette owners.

Many thanks to the contributors and super-experts (we all know who they are) who take the time to share their knowledge for others to learn, and for persons such as myself - the ability to get up to speed with common problems before they actually occur as the new owner of an old vette.

Keep up the participation!

Jack

 

[Fiddler's Gold]

Yikes!

Yikes! YIKES Y-I-K-E-S!!!

good luck,
Fiddler