High 1984 - High Engine Temp - Elec Fan turns on at 240 Deg

[TnTom]

When I start the car and let it warm up the temperature will continue to rise until the fan switches on at 240Deg's.(by the instrument gauge).

I have not let it idle until the fan turns off to determine what that temp is.

As I drive the temps goes down and holds at 165. If I stop and idle (say a long light maybe) the temp will start to climb and I have raised the hood to confirm the fan is off and as I suspect the fan is not turning. I drive off and the temp goes down to 165.

What controls when the fan comes on and if I want it to switch on at say 195 degs. how can I make that happen instead of 240? I really want to start cooling before the 240 mark.

 

[combustables]

When I start the car and let it warm up the temperature continues to rise to 240Deg's.(by the instruments gauge), at that point the fan comes on and the temp begins downward.

I have not let it idle until the fan turns off to determine what that temp is.

As I drive the temps goes down to and holds at 165. If I stop and idle (say a long light maybe) the temp will start to climb and I have raised the hood to confirm the fan is off as I suspected (and it is, the fan is not turning). I drive off and the temp goes down to 165.

What controls when the fan coming on and if I want it on at say 195 degs. how can I make that happen instead of 240? I really want to start cooling before the 240 mark.

Check your fan relay and fan switch. Are you also certain your temp readout is correct? The original fan turn on number was 228 degrees. Also, look into installing an additional temp fan switch which you can get at mid amierica or any of those places. They sell kits that turn the main fan on at various temps ranging from 170 to 205.

Good luck!

 

[TnTom]

I'll check the instrument and verify the temp and then look into adding a switch.Thanks for the feedback.

 

[CAJUN C4]

I'll check the instrument and verify the temp and then look into adding a switch.Thanks for the feedback.

Might also add a Manual Overide swith under you dash so you can turn the Fans on at will.

 

[TnTom]

Talking to my wife (and we actually do talk ) she told this morning that she read somewhere the dealer can adjust a chip and reset the turn on number.

Actually there was override switch installed in the dash. The previous owner had installed one and I took it off. He had an endless amount of jerry rigging that I have had to un-do. Looks like this un-do may be a re-do as I now have in addition to a hot idling engine a hole in my dash where the switch was :bash.

Looks like there are a number of options.

Regarding the original turn on of 228 degs. If boiling is 212 why would it (original turn on) be higher than that. My wife said because of the antifreeze.

At what temperature would an engine actually be "overheating"?

 

[gmjunkie]

Talking to my wife (and we actually do talk ) she told this morning that she read somewhere the dealer can adjust a chip and reset the turn on number.

Actually there was override switch installed in the dash. The previous owner had installed one and I took it off. He had an endless amount of jerry rigging that I have had to un-do. Looks like this un-do may be a re-do as I now have in addition to a hot idling engine a hole in my dash where the switch was :bash.

Looks like there are a number of options.

Regarding the original turn on of 228 degs. If boiling is 212 why would it (original turn on) be higher than that. My wife said because of the antifreeze.

At what temperature would an engine actually be "overheating"?

The higher lb pressure cap on the cooling system,the higher the boiling point!! These cars are designed to run hotter for a reason!!

Less Emissions,Better Economy,Less Contaminate build up in Engine and longer Exhaust System Life just to name a few!!

Just a thought,Get a Factory Service Manuel!! You need it,or at very least a Haynes or Chilton!!
Believe it or not there is allot of useful information in them,If your working on it,You Need it!! There Well worth the Bucks!!

Hope this Helps!!

 

[TnTom]

Thanks for the info. I do have have the GM Service Manual and the Auxillary Electrical Manual and they both address the cooling fan operation. What they don't have is the detail that I found in the attachment you provided. Would you tell me where you found this? My manuals make no reference to the procedure for testing the switch or relay. The info you provided should get me heading down the right path.
I think I may have the answer to the problem looking me right in the face and I hope tomorrow this thing is put to rest. I can see the switch is not the original (shiny brass). When it was screwed into the head thread tape was applied to the thread. I'm guessing there is no ground or a bad ground at best.
Thanks again, Im pulling the switch out and cleaning off the threads and will also do the ground check as the attachment discribes. I'll check the whole system as discribed.
Again thanks everyone for the feedback. I let you know what happens.

 

[gmjunkie]

Thanks for the info. I do have have the GM Service Manual and the Auxillary Electrical Manual and they both address the cooling fan operation. What they don't have is the detail that I found in the attachment you provided. Would you tell me where you found this? My manuals make no reference to the procedure for testing the switch or relay. The info you provided should get me heading down the right path.
I think I may have the answer to the problem looking me right in the face and I hope tomorrow this thing is put to rest. I can see the switch is not the original (shiny brass). When it was screwed into the head thread tape was applied to the thread. I'm guessing there is no ground or a bad ground at best.
Thanks again, Im pulling the switch out and cleaning off the threads and will also do the ground check as the attachment discribes. I'll check the whole system as discribed.
Again thanks everyone for the feedback. I let you know what happens.

That is out of the Haynes Chevrolet Corvette (84-96) manual,I have most of the GM C4 manuals,but I also have the Haynes and Chilton's too!!I've found that by having the 3 I can usually find what I'm looking for,seams like none of the manuals are quite complete!!Putting thread on tape them isn't uncommon,as long as there tight they will still get a connection there grounded through the engine block!!By it being possibly new maybe it's the wrong sender,or not tight enough to get a ground!!

PS With any electrical problems on any vehicle,FIRST thing I do is find and Clean All Engine,Chassis and Body grounds,and about 80% of the time my job is done!!! 1 bad ground can make electrical systems do Weird and Crazy things,and most of the time it's a ground that you wouldn't think it could possibly be the cause!!

Happy Vetting!!

 

[TnTom]

Dear GMJ,
Ive added the Hanyes to the manual pile. In the past I used Motors like a bible
but have been away from under hood for too many years and some things arent where I thought I left them .

I stepped through the diagnostics per the manual and looks like the relay, The fan did not run when I disconnected and grounded the temp switch connector but it did run when i jumped the relay.

I'll replace the relay and remove the teflon from the temp switch and replace the temp switch as well. Might as well start fresh.

Again thanks for the feedback. This is the first newer ('84) vette that I have had my first was a '63. It ran real good but drove like a BIG car, and no fatigue. This one (the '84) reminds me of when I raced go karts. Love that handling.

Again thanks.
TnTom

Tmn

T

 

[gmjunkie]

This one (the '84) reminds me of when I raced go karts. Love that handling.

Again thanks.
TnTom

Tmn

T

:L Just wait till you step up to a C5,thats like piloting a Space Ship and then the C6,a Space Ship with a Flux Capacitor!!!

Can't have too many manuals!!I have a few Motor manuals,Mostly Collision,Structural Reconstruction and Estimating guides,Have a Crap Pot full of Mitchell's too,dating back to the 60's!!I use a GM Stand alone program for C5's and C6's,boy is it a Quicker way to look things up!!

 

[TnTom]

Mission Accomplished

I determined that even though the sound of the relay gave the impression the relay was opening and closing (and it was) there was still not a complete circuit. Took the cap off the relay and it was visually obvious that the relay switch contacts were not "contacting" a small gap remained. I bent the fixed contact slightly closer to the coil contact point until it was visually obvious obvious that it would complete the circuit when "switched". Put it back together and grounded the temperature switch and the fan ran. I reconnected the temp switch and started it up. It idled to 243 F and the fan turned on, it cooled to 226 F and the fan turned off.

Thanks to everyone for the help.

Tom

 

[vetteoz]

Talking to my wife (and we actually do talk ) she told this morning that she read somewhere the dealer can adjust a chip and reset the turn on number.

You should thank your wife; she was right!

Except in your case on the '84 models only,
the fan is controlled by the temp switch, not the computer as in later years.

 

[Hot Rod Roy]

Don't make the same mistake the previous owner made. Fix the problem properly. Don't jury-rig the relay. It will just fail again. The '84 fan control circuit is pretty simple, and it works fine if everything is in good shape. The original relay is marginal capacity. Since it needs to be replaced, install one with higher amp capacity, and be sure the terminals provide a good connection. I used an 80 amp rated relay when I fixed mine, and have never overheated since! You don't need extra switches or accessory fan control gadgets . . . just good parts.

S.T.W.

 

[ken mohr]

Don't make the same mistake the previous owner made. Fix the problem properly. Don't jury-rig the relay. It will just fail again. The '84 fan control circuit is pretty simple, and it works fine if everything is in good shape. The original relay is marginal capacity. Since it needs to be replaced, install one with higher amp capacity, and be sure the terminals provide a good connection. I used an 80 amp rated relay when I fixed mine, and have never overheated since! You don't need extra switches or accessory fan control gadgets . . . just good parts.

S.T.W.

 

[rascal_rascal_99]

Hiya's TnTom, hope your little bugs are getting worked out for you...really just posting to say hi from right around the corner, Hillsboro/Manchester! Welcome to CAC! Oh, and hope you're staying dry right now!

 

[TnTom]

hiegher rated relay & At what temp should the car operate

HHR thanks for that input. I still wasn't comfortable with the "bend the contact" even though it did "fix" it. not the root cause. Do you have the number on the relay you installed. Ill go to Napa I guess? and ask for a good 80amp relay?
I have always avoided anything that was electrical until I was forced to address it. After I look it over I usually find that it wasn't as complicated as it I like to think is. When I get home I'll find a good relay and put it in.
What should be the correct thermastat temp. I replaced the one that was in the car with a 195 Is I was thinking to put a 200 in. Is 210 too high for the thermastat?

My '96 GM 5.7 Pickup runs at about 195.

Rascal, Actually Im watching it snow in upper state NJ finishing up some work and will head home to Woodbury this coming Friday night where I will officially be retired.

I was looking at Vet when I came home for Christmas for 10 days Ive been in NJ since Aug then came back here to NJ for a few weeks. Wish I was driving the Vet. Id make about a 9 hour trip out of a 14 hour trip

Ive got my Altima with me and 871.2 miles of interstate from Mahwah NJ to the house all on really great interstate. If the roads are dry its a great drive.Its really great drive in the right car and the roads are dry.

Bye Bye New Jersey. Im going back to Tn where a man can buy a gun and a gallon shine and go fishin for less than the the price of a gallon of gas.

I had a '63 about 20 years ago I couldnt believe how it drove. Felt like a big car and no fatigue. Really was cruiser and made a great drive from San Diego to Phoenix. It was a 327 2 speed. "Honest Officer I didnt think there was a speed limit out here in the desrt"

I have only had this '84 a short time. My wife bought it while i'v been out of town (after we talked about it on the phone...sorta of). Needs some paint. Runs pretty good. Interior is good. I have to replace a headlamp gear on the driver side, might as well do them both.

Power antenna needs lookin at .I gotta do that. My wife did the weather stripping and did some interior trim work. She replaced the shifter boot, seats, disassemble the doors and got them working and looking really good.

Any Corvetting going on in Manchester?

 

[rascal_rascal_99]

Not anything going on in Manchester, there's a vette club in Nashville that C5Y2K here could fill you in on. There was also one in Chattanooga at one time that did a fun monthly cruise. I really need to look that one up again and see if it's still active, I lost touch with them due to schedule conflicts when I was looking for a local vette club and just never looked them up again since then even though I'm available to go meet them now.