Thinking of wiring in back-up radiator fan switch

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Old 04-24-09, 06:25 PM
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Thinking of wiring in back-up radiator fan switch

My new junk car's temp gauge suddenly started to climb today(for first time). The fact it got to 88 today has nothing to do with it. I made it to the lot where I was heading, quickly opened the hood, noted the radiator fan not working(it should have been, based on gauge and temp it was at), but also noted the upper radiator hose was not all that hot.

A couple thoughts came quick to mind: Either thermostat stuck, or coolant level real low in radiator even though level up in reservoir just fine. The fan came on, but was short lived. Another possible issue I started to think about. Actually I have thought about this with my last pretty trustworthy car.

It's a scary thought knowing that you can take pretty good care of a car (don't raz me about not changing oil), only to have a head gasket blow, which is fairly common for these kinds of newer style engines to do, with a little overheating.

I let the car cool down, and then headed down the road, hoping. Whoop. There it went again. Had to quickly pull onto a side street and whip open the hood. Radiator fan not going. Hmmm. THIS time the upper hose WAS hot and I infrared temp aimed at spark plugs = 230F. I started gently whacking on fan motor and fender relays. Nothing. I even had key to "ON".

Then I decided to start the car and see if the fan would come on then. Yes.

Why? Why not when on ON? I proceeded on my way and drove several miles to where I had to go, and so far no more problem.

Not sure if thermostat stuck, and possibly this affected the sending unit signal to realy? Maybe an air pocket? (Any theories?; car does not lose coolant and level up to top of radiator, as I just went out and checked just now and came back in -and no prior behavior like this.) More pondering.

Have any of you contemplated or actually installed wiring fan direct, thru proper size fuse, and into the cabin to a say a toggle switch that maybe even has a light that will verify a current flow? It just seems like a good idea to be on the safe side. This will not cure a bad thermostat. But, with an electric fan system, you are at the mercy that the sending unit and relay are doing it's job.

Any thoughts on this?

And any comments about a new thought that perhaps the design of a thermostat can possibly lead to the inner disc, that moves, becoming pinned inside the part that does not, due to expansion? I've looked at stats and can't figure out why they design them so the inner disc fits inside the outer housing and simply does not push flat up against it. It seems like a recipe that could allow for that disc to become hung up, like mine may have. Odd, it do it, but then go away.
 

Last edited by ecman51; 04-24-09 at 06:37 PM. Reason: added last paragraph
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Old 04-25-09, 08:15 AM
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What about the engine temp sensor? This is what turns your fan on and off.
 
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Old 04-25-09, 09:17 AM
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Originally Posted by HotinOKC View Post
What about the engine temp sensor? This is what turns your fan on and off.
Oh good, a response.

Anyway, I am not sure of anything anymore. Oddly the coolant level is full in radiator and reservoir. No previous problems like this.

Then I caught the fan running for a short bit. But at the same time while the gauge(no reason to suspect a malfunction with it as infrared temp taken confirmed engine was hotter) was registering near hot, the upper radiator hose was only warm, not hot. Then after I let it cool in that lot for about 1/2 hour, then drove back down the road, as I said yesterday, it started to get hot on the gauge again (I watch my gauges all the time when driving), so I quickly pull over. Only this time the radiator hose was hot (which is good) but the fan did not work at all when I pulled over and quickly raised the hood on that side street with the engine still running. So then I quickly shut off the engine to let it cool down (one good thing about these wide open little 4 cylinders is they cool down fairly quickly) and with the key left to ON, the fan did not work.

The sending unit.? Yes, could be. One more ingredient with the puzzle, I guess. Since my post last night, I have driven 50 miles and no more trouble. Gauge remained steady. When I have problems it seems they are odd and sporatic. They cause me to review in my head the whole scenario and requestion myself as to what I really found that was happening, almost out of disbelief. Especially when mulitple things seem to be occuring at once (radiator hose temp and radiator fan).

Now here is a good one: Out of my paranoia of being stranded on the road (I don't have that many friends that I'd care to call), I was rooting through my supply of left over and used old car parts and found 2 old thermostats that possibly still may be good. Oddly, one has that center disc in contact metal to metal with the stationary part of the stat. And the other stat that I had specifically marked '91 Spirit also had a rubber gasket around that disc!, and that rubber was distorted and squeezing past the seal of the disc on one side to the stationary part! Who and why the heck would they design something like that! Maybe that is the type I have in my car, and that rubber gets distorted and grabs hold of the spring-loaded disc and causes it to hang up?

I'm going to check with auto parts store on these 2 types of stats. Do you know WHY they put that rubber in there? On some and not others? Is it to create a perfect seal when closed? If so, why? Why would they need to seal it 100% on a car that is going to get hot unless it opens? You'd think a little seepage past that seal between the spring-loaded center disc and the stationary part would actually be a good thing.
 
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Old 04-25-09, 09:30 AM
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If you do have to change the fan eventually, you might find it easier to skip about 8 steps according to the Haynes manual. You might be able to pull out the fan assembly out wthout taking off the front end of the car i.e. bumper, fenders grille, and radiator is what I think Haynes said. Found this extremely funny since the fan unit is normally attached to the radiator itself. Oh yeah I forgot the part written by lawyers, disconnect negative battery cable. My question on that is if the car hasn't been started in several days, why would the fan turn on. I mean DUH!!!!
 
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Old 04-25-09, 09:52 AM
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Originally Posted by nightowlpunk View Post
If you do have to change the fan eventually, you might find it easier to skip about 8 steps according to the Haynes manual. You might be able to pull out the fan assembly out wthout taking off the front end of the car i.e. bumper, fenders grille, and radiator is what I think Haynes said. Found this extremely funny since the fan unit is normally attached to the radiator itself. Oh yeah I forgot the part written by lawyers, disconnect negative battery cable. My question on that is if the car hasn't been started in several days, why would the fan turn on. I mean DUH!!!!
The reason I am starting to collect this brand of car now is because how in the open it is to work on engine stuff. And also you run into many backyard mechanics who say stuff like, "Oh ya, I've changed out the head gasket in one(or some) of those. Nothing to it!" Me: "Good, I'll call you up then!")

I already changed out the radiator in my '91 (just so you know, the one I have now is the '90), in 07. A piece of cake. Very little dismantling. My radiator fan and fan motor are right there easy to get at. A piece of cake. (Especially since the a/c unit has been taken out)

Even if you take a car like mine to a service garage, you get cheaper bills because the labor is easier than on many models of cars. Especially the more new cars where they pack stuff in like sardines in a sardine can and hide the battery on you because it can't fit in the normal location.

I woudn't want a car like that if they gave me one. Not unless I built up my bank account first to afford the repairs. I would rather have easy to work on stuff to own, rather than have to have a high paying, long hours, boring job, to pay for these expensive toys that require more complex repair work. How silly working your life away(since you die anyway) for such stuff, when you could be on a beach instead, basking in the sun with no stress, looking for sea shells and at nice scenery.
 
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Old 04-28-09, 06:36 AM
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Update

I've driven a couple hundred miles, give or take, since my thread - and it has not done it once since. It has only done that one time. Something apparently got stuck. Some one-time occurance like that could cost a less observant or knowledgeable person (like my mother) an engine!

My concern is with the thermostat more than anything, since I discovered the upper hose only mildly warm, when the engine was hot, on that first occassion in the parking lot.

This problem is rather disturbing, since on these type cars, and maybe other 4-banger Chryslers, is that often when idling about town, the temp gauge goes up to half-way before the fan comes on. That means, that if something did get stuck (whether it is the thermostat, sending unit or relay, or ?) that you have a small window to determine if the car is overheating, if it creeps up any further from that halfway point.

That is why I think it would be a good idea to have the fan on a back up wiring system so that anytime the temp on the gauge got higher than the 1/4 mark area(or somewhat higher), how it is when cruising down the highway, that you can flick on the switch and have the fan come on.

A possible project if I have nothing to do, which seems never.
 
  #7  
Old 05-07-09, 09:31 AM
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The fan relay in my 93 buick century decided to quit and I came close to overheating but didn't because I watch the gauges. Living in NYC where I'm often stuck in really heavy traffic I decided not to replace the relay as it often came on after the car was hotter than I liked. I wired the fan directly into the cabin where I could control the fan. Now when I'm in traffic I turn the fan on before I start to get hot and when I'm running the A/C at 60mph I can keep the fan off.
Been like this 5 or 6 years now and I like the system better than factory seup. Only thing is you have to remember to turn the fan off as I wired it directly to the battery.
 
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Old 05-07-09, 04:43 PM
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Originally Posted by easywind View Post
The fan relay in my 93 buick century decided to quit and I came close to overheating but didn't because I watch the gauges. Living in NYC where I'm often stuck in really heavy traffic I decided not to replace the relay as it often came on after the car was hotter than I liked.
You nailed it. That is what I don't like either. Mine comes on often when it is mid way. When it does that, I keep staring at the gauge, hoping it indeed will come on. Back in the good old days with fans that always ran, the temp gauge would always stay put at under the 1/4 mark. None of this up and down stuff, where you wonder if it is going to work, every time it climbs.
 
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Old 05-13-09, 09:12 AM
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4-29-09 update post

Today again, only for the 2nd time !!, I caught the gauge creeping towards hot! I pulled over. No radiator fan going. And felt the radiator hoses. The upper one was warm and the bottom one was cool. So then I began squeezing the upper hose in a rythmic pulsation and all of a sudden the hose became hot. I then restarted the car and then the fan came on and the gauge instantly plummeted from near hot, towards the cool 1/4 mark end.

This is what I think is happening. And this is simply nice for everyone to know - as same principles should apply to your car:

Because I have that small leak in the heater core, when the engine cools back down I am drawing air into the system, instead of coolant out of the reservoir as it should. (In fact, the level in the reservoir never goes up and down as it should.). I think then what happens is the air bubble then heads towards the thermsotat computer sending unit and causes the sending unit and thermsotat to remain cooler than what the actual coolant temp is, as sensed by the other water temp gauge(on dashbord) sending unit. So then neither the thermostat nor sending unit woirk, hence no circulation, and hence no fan coming on. Yet the motor is getting hot. All because of a pin hole leak. Something like this could cost you an engine if yo have airpockets floating around in your engine like this! Blown head gaskets even though minor at first can cause this same scenario.

I had this same sort of thing going on in another vehicle until the gasket finally blew so badly I filled a cylinder with coolant like a fish bowl. And what may have hastened it's demise was the same fact that airbubbles were being trapped in the coolant system, and at the worse place, at the top of the engine where the sending unit and thermostat is, which then causes that double-whammy to cause the engine to overheat.
 
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Old 05-13-09, 01:36 PM
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If these cars are giving you so much trouble, why haven't you called your local auto recycler and ask them to make a pickup? Just wondered.
 
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Old 05-13-09, 02:54 PM
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Originally Posted by nightowlpunk View Post
If these cars are giving you so much trouble, why haven't you called your local auto recycler and ask them to make a pickup? Just wondered.
They did. They made a pickup on my pickup, 2 mornings ago. He gave me $50. Seriously. Was stored in there for 6 years.

Regarding my Dodges? Nah. I like the hassle, to a degree, as long as it is not tooo serious. It brings out the motorhead in me. Plus I'm a cheapskate. It's fun to talk about this stuff with others, also. Sort of like how it is fun to talk about 40 degree below zero days -how miserable it is - and how pipes are freezing up in crawl spaces and stuff. An excitement factor.

I get off on picking these cars up for next to nothing and racking up lots of miles on them, laughing while others go into debt on credit cards and all to impress their friends, and still often have serious troubles with their newer (used) vehicles. Like - I would not want to pay for head gasket replacement on a V-6, or pay for serpentine belt changeouts when they have to jack up the engine, or get charged a hundred dollars like my neighbor where they can't hardly get at rear plugs, or pay for problems with abs brakes, etc., etc. Forget that.

Of any car I have seen, I think my car(s) are the easiest to get at stuff and work on it yourself. Hopefully if I have to changeout the heater core, I can still sing that tune.
 
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Old 05-14-09, 10:14 AM
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If you went to pre-1974 vehicles, no emission controls to worry about.
 
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