Overheating (65 Riviera)

joeinbcs · July 5th, 2009

I bought my car in San Antonio about a month ago and drove it back to my home in College Station (about a 3-hour drive), followed by a buddy in case of problems. The car overheated twice on the way. Each time I stopped immediately and checked the radiator (carefully). Plenty of antifreeze, but I let it cool off and topped it. I had the thermostat changed when I had a tune-up, oil change, etc. I was told by the PO that the car had a sticky thermostat. Seemed to run cool enough after that.
Today I took it to a car show about a 15 minute drive away. No problems on the way over, but as I dropped of a buddy on the way home who lives near me, the hot light came on.
I tried to find some direction on where to look next, and found the following from a discussion of Riviera's:

ENGINE: Overheating is the most frequently reported problem with early Riviera engines. Reasons include partially-blocked radiators and drag from or failure of the clutch-activated engine fan. The fan itself should have seven blades and when spun by hand should only revolve once or twice. If it spins freely, the clutch unit in the fan boss needs replacement. Oil pump wear will produce oil aeration and low pressure in early cars.

My fan does not spin freely, so I guess the clutch is not the problem.
Maybe a "partially blocked radiator" ? Any advice on how to tell if this is the culprit?
Any other tips on where to look to solve this?
Its over 100 here today. Is this too much to ask for a 45-year old car?
Thanks for any thoughts! Joe

tim63riv · July 5th, 2009

Joe,
One area of the cooling system that gets over looked a lot is the radiator itself. You must have excellent contact between the radiator tubes and the fins. If the radiator fins are loose they cannot conduct heat away from the tubes and the engine will overheat.
A good friend of mine lived in Phoenix and all the car guys he knew used a radiator called the Desert Cooler. The had very high fin count per inch which equates to higher area for thermal transfer than other radiators.
Most radiator shops have a infra red thermometer that will tell them the difference between the temperature of the radiator inlet and outlet and by knowing that temperature they can give a pretty good idea about the efficiency of your radiator.
As far as a 45 year old car having overheating issues, with the new technology available now they shouldn't have any more issues than a modern car. Just make sure that the cooling system is up to the task!
HTH,
Tim McCluskey

gungeey · July 5th, 2009

How old's the antifreeze? Pretty easy to see if rad is clogged, just leave cap off and get up to operating temp, should look like a quiet river flowing in there...not white water rapids and not a stagnant stream. The clutch fan should be harder to turn when engine at op temp than at cold...A/C blasting? Poor tune up/low idle?
There is also a new hi-po antifreeze out that has a higher boiling point, check your auto enthusiast mags. Steve

joeinbcs · July 5th, 2009

Thanks, Tim...I guess I need to pay a visit to a Radiator shop. Joe

msht9o · July 6th, 2009

Another help might be if your car is a non a/c car it more and likely does not have a fan shroud. That is a good investment if you do not have one. That and a four core radiator seems to have helped me quite a bit.

Jim_Cannon · July 6th, 2009

Your radiator is probably clogged. In Texas, if you re-core it, put a 4-row core in the radiator.

Regarding fan clutch, when engine is hot (driven 20 minutes or more) and you rev the engine (not in gear) the fan should ROAR. If it does not, your clutch is bad and needs to be replaced. They don't cost that much and are fairly easy to replace, so when in doubt (as in you don't know how old it is) replace it.

Even at highway speeds I hear my fan clutch engage sometimes when the A/C is on.

simplyconnected · July 6th, 2009

Save your money and buy an electric fan. They pay for themselves in no time because they only run when they need to. eBay has 16" fan and controls kits for about $50. They can either mount as a push or pull fan. I just bought two, one for my '59 Galaxie and the other for my '55 Ford Customline.

Resd-up about extra rows of cores. They sometimes get in the way of airflow. If air can't flow, heat won't transfer.

Be sure your radiator cap holds the proper pressure. More pressure raises the boiling point of your coolant about three degrees for each pound of pressure. Ex: 7# X 3 = 21* At sea level, 212* + 21* = 232* boiling point (no longer 212*). My wife's Intrepid has a 16# cap...

jrbartlett · July 6th, 2009

As current owner of two 66 Rivieras, plus a new '66 back in the day, I can assure you that overheating was never an issue with these cars when they were new, or today when they have good, clean radiators, operating fan clutches, etc. Even during the current Texas heat wave. I drove one last week in 100 degree weather, in stop and go traffic in Houston, with the AC on, and the temp guage never got beyond half-way. Normally, it's less than half-way. I think you need to look at your radiator and have it rodded out, or re-cored. You don't need an electric fan. But first, you might get one of the infrared heat sensing guns and take an actual temparature reading to ensure that your temp sending unit and guage aren't malfunctioning.

whalerman03 · July 6th, 2009

My car sat for almost 14 years.... once running again it started randomly over heating... changed thermostat and continued randomly over heating... took it to a shop which tested it using a infrared gun... temperature throughout the engine block was 'normal' and not over heating... it turned out to be the overheat sensor was corroded from sitting so long... $12 part solved the issue
Good luck!

joeinbcs · July 6th, 2009

Ok....thanks for all of the great advice.
My local O'Reilly's had a fan clutch and it looked to be a job even a guy of my modest mechanical skills could handle. I decided to start here because it is the cheapest fix...if it works!
For some who have contributed advice, here are a few details. My car does have A/C, and you'd better believe I was using it yesterday. I just had all of the fluids changed and a tune-up, new plug wires, etc. I did check and the antifreeze seems to "run like a river" when the cap is off and car running. Not sure if this means I don't have a partially blocked core or not, but, as I said, I thought I'd start with the easiest thing first.
Which brings me to a question. When I removed my fan, I noticed that it had only 5 blades. From my searching around, I thought the fan was supposed to have 6 blades? Could this be part of my problem?
And, as for the new fan clutch, it came with locknuts, which do not fit on the studs..only room for the nuts. Is this a problem? Do I need to torque the nuts, or is tight good enought?
Thanks again for all the help, Joe