I have a 1980 L48 with only 17,000 on it. I have been having over heat problems and have done everything I can think of to fix it. I just installed an electric fan, to see if at red lights it would help the car from getting to hotter, which also make the values ping when leaving the red light. I ran the hot wire to the fuse box and connected it to a spade labeled ignition I ran the ground wire to the ground on the alternator. I ran the car for a while and came home and it seems when you stop and idle, it still wants to climb above the thermostat of 160 degress. I shut the key off but the motor still ran for about 3 seconds and my tach swung all the way to the right. Does anybody no what happen and how can I get the tach back to it's regular position. Thanks!!!

 

The correct thermostat would be 195. I would expect your car to climb over 160 at idle. 210 would be about average. What does your temp gauge say?

Engine run on is usually a timing issue and incorrect timing can lead to the car running warmer than normal.

 

The car came with 195 thermostat but it kept going over 200 at red lights. I have set the timing to the specs, but when I did the values would cl adder even more when the car got to temperature. Since I put a lower thermostat in the car it has ran much better, but not all the way correct. What about the electric fan I installed, do you know anything about them, and why my tach did what it did. Thanks!!

 

Most electric fans pull to much current to run thru the existing wir harness in the car. Most of the kits come with a relay that carries all the current for the fan motor. It should he hooked up something like this

Once you have that sorted out, take a look at all your radiator seals, radiator shroud and its seals. It sounds like your car is getting a little warm although 200 is not necessarily to high. Keep in mind your thermostat sets the minimun operating temp on the engine. Other things to look for on your cooling system are missing or dammaged seals, radiator partially stopped up, missing or dammaged radiator shroud, missing or dammaged air dam (this only affects temp while your running)
When you put the electric fan on, you deleted the engine driven fan?
Post some pics of your setup and tell us where you are

 

Running a 160 degree thermostat can cause some of the temp switches to malfunction that will cause poor performance.

I have heard that is not a good idea to run anything cooler than a 180 degree thermostat.

You should look into grounding your fan to something other than your alternator, this could be causing interferance with the tach.

 

I will take some pictures and post them. I mounted the fan on the inside of the radiator and left the clutch fan on as well. I took the hot lead off the ignition and the tach is still all the way to the right. Any ideas how to get it back to position, or do you think I fried it. I hope not the car is all original.

 

The thermostat temp. is the temp. it opens and allows the coolant to start cooling the engine, so the actual temp will be higher. It is not uncommon for mine to hit 210 in town and I have a 195* thermostat. Look at other threads, there is some good information out there.

 

My 80 L48 has a 195 in it and it runs 200-208 at red lights in SoCal 95-103 degree summers which is normal.

Whats your temp with the A/C on?

Your Tach mey still be ok,it could just be stuck.with the engine running give it a few blunt blows right under the tach(be careful not to break anything) I've seen this work more than once

Take pictures of your mounted the fan setup.

And SIXFOOTER is right you should have a relay kit installed.

 

I saw a graph once produced by Ford research that was illustrating engine wear vs engine temperature. The take-away was anything less than 180 and the engine wear levels went way up. I wouldn't run a 160 stat. Have you replaced your radiator ...or had yours boiled out.

Mark G

 

You need to understand that the Thermostat has NOTHING to do with how HIGH the water temperature goes (that's the radiator and fan's job), it only regulates how LOW the water temperature is allowed to go.

You didn't say if you ADDED the fan (i.e. still have the stock belt driven fan). If you have both, then this can actually cause overheating!

 

I think that's what he meant here, but I agree. Both sets of fans are probably antagonistic. I'd also rewire like earlier suggested with an independent harness and relay. My 2c anyway.

 

I know that the car came with 195 stat but when it gets to that temp the values ping at acceleration, and at red lights it goes to about 205 degrees. I have set my timing to specs, but still had the ping at acceleration.

 

There is nothing wrong with running at 205°. Are you running high octane fuel? You might have carbon build-up that is causing the ping.

 

I run high octane and I've put octane bosst in as well. The spark plugs are very clean.

 

I have both fan pulling air to the engine through the radiator, how can that make the car run hotter.

 

I think you need to diagnose why your engine is pinging. I don't think it's your radiator or fan. Assuming your gauge is accurate, it's not running too hot. Is your EGR operating properly? Do you have carbon build up on the pistons or valves? Did you set your timing using total timing at 36°, or did you just plug the vacuum advance and time it at idle?

 

I have a 1980 that used to get hot on the expressway. My car is a four speed so it is running about 3500-4000 rpm at expressway speeds. It would slowly climb to 205. I actually swapped the motor with a mild 350 build 325-350 hp) and had the same problem with that motor even though I put a hi flow water pump on the car. I then went to NAPA and bought a new radiator it is not factory correct but it worked great. I can run as far as I want on expressway with no problems. Summer temps get well into the 90's here and I have no change on hot days. I run a 180 degree thermostat. It stays pegged on 180.

 

My 1982 came with both the Engine fan and a Auxiliary fan. The Auxiliary fan does not come on until the engine Temp. reaches 238 and shuts off at 201. The book says it was added to keep temp. under control in slow traffic. Have a great one Gene.

 

Thanks for you advise on the tach. It worked!!!

 

Install a Mr Gasket high flow 180 thermostat. First of all like mentioned. The thermostat has nothing to do with controlling the temperature when car is running. The thermostat heats the cylinders walls so that the car runs much better. If the cylinder walls are not hot enough when the car is running it will shorten the life of your motor. You have to up your thermostat, this will be a simple explanation. When you start the car and run it, as your temp reaches 180, your thermostat opens dumping cool water in the engine. You should see your gage go down quite a bit, as your thermostat closes, you begin the radiator water cooling process again.

I have heard something that I am not sure is true but I will share it with you anyways. An old man that used to be a chief mechanic for GM told me this and it does make sense. Back in the days it was said that running a motor with out the thermostat will never let your motor get hot. He told me that that was false. He said the water begins to leave the radiator passes through the motor back to the radiator back to the radiator getting the water warm comes back throught the radiator getting hot and cycles back and the temp of the water starts getting really hot to the over heating stage. The reason is that there is no resistance to cool the water down. A higher temp thermostat when it closes give the fans some time to cool down the water. It really does make sense, but again not sure if it is true. Spin you clutch fan by hand, if it free spins, replace it. Go to spalusa.com and look into purchasing a relay for the fan. You need one. Your temp switch may have become damaged as well. Your tack resistor may have become damaged with the heat of the motor. My tack did the same thing and when I replaced the resistor all was okay.