I did flush the block recently and nothing crazy came out. Some fine particles, but nothing significant.

The exhaust has fresh free flowing flowmasters on it, so I doubt back pressure is an issue.

I have inspected both pumps that were in use and they are funstioning properly.

 

That is exactly the thermostat that i had that failed after less than 500 miles, and it never did work right, the car always ran too hot, and it finally stopped opening at all.. If the wax leaks out of the wax motor, it can't fail open, it fails closed. The fail open feature seems to nothing more than a lock mechanism that catches the valve in the maximum open position if it ever gets there.

NAPA replacement cured the problem.


.060" over shouldn't cause overheating, but maybe it was bored .125" over? .090'? Can't know until a head is pulled. Crap in the block would cause oil temps to rise, it wouldn't make the cooling system run too hot.

You are really OK at anything less than 235*F. Though carb perc would be really obnoxious after shut down.

 

http://www.flowkoolerwaterpumps.com/cooling_faq.html

This gives a decent question/answer on water pump issues

 

I went thru the same process[new DeWitt's, new pump, thermostat, fan clutch, check timing, etc] as you a few years ago. The new radiator was the last item for me, and like you, it wasn't the answer either. On my way to the Golden Gate bridge to jump off, I remembered one item that was easy to back track and check again. I removed my NEW Robt Shaw 180 deg. "never stick closed" thermo and put it in a pot of water on the stove. I turned on the heat and watched the water heat to a boil, but the thermo never opened! I exchanged it at my FLAPS for a new one and brought it home. I put it to the "stove test" before I installed it and it opened before my eyes. I then installed it and problem solved. I hope you get as "lucky" as I did, you deserve it-lib

 

Glad to hear of the improvement. I wouldn't pull the motor yet. You can remove both of the rear freeze plugs from under the car. Done it. Large screw driver and hammer. Can't remember if you power flushed it...suggest pulling the plugs then flushing again. After that, pull one head while its still in the car and check gaskets and passages. After that, The intake manifold. After that, pull it. Don't recall if you said which heads you have? Aluminum or original iron?

 

I have read through most of this thread and if temp climb going down the road.....it is insuffcient water flow.

I run a Weiand aluminum pump with a Mr. gasket stat...but as stated...these ARE NOT failsafe open....one trick I have been doing for years is I drill two holes along the "cup" of the stat at 6 and 12 o'clock.....this ensures flow no matter what and is not detrimental to the stats function.

I also run a New 6 blade original fan and clutch.....in South Texas...on a 100 degree day it might see 195 if it sits idling for 20 minutes or better in traffic.

Let me ask a stupid question: What is the diameter of your WP pulley?

Jebby

 

I rembemer doing this in in 1964 on my 57 chevy

 

I was also having over heating problems. It came down to my solid lifter adjustment was to tight. Backed it off and it solved the problem.
Might be of interest to someone . Regards

 

 

My contribution to overheating problems: My 1966 327 developed a sudden overheating problem. It could sit in the driveway idling and not overheat. Take a short trip around the neighborhood and it would overheat. The culprit was the vacuum advance controller. As rpm increased above idle speed, the lack of vacuum advance created a timing problem resulting in overheating. The vacuum advance is ACDelco part number 19110657 and is easy to replace. Available from numerous vendors but I bought from auto_parts_for_you_florida on ebay for $26.24.

 

Sorry to hear of your problems. I just spent all morning reading through the entire thread.
When I bought my 65 coupe last year, it overheated only when running the AC on a hot day. When the AC was off, no overheating. It had the overheating problems at idle and at highway speeds. I never let it get too close to being pegged, but it did get awfully close sometimes. For me, the immediate solution was to simply turn off the AC and the temperature went back to 180 in a few minutes. However, in Florida, this just is not an option in the coupe!
Just like you, I did not want to try the expensive option (new DeWitts radiator) first. Everyone told me this would fix everything, but I wanted to try the easy, cheap things first. I put in a 10 inch pusher fan first. It made no difference. I replaced the fan clutch with a spacer. It made no difference. I then tried a 12 inch puller fan (it would not fit as a pusher). It made no difference. I then tried a 14 inch puller fan. It made no difference. I then bought a 16 inch fan from a local auto parts place. When I got it home, I saw an "expensive" 16 inch fan on sale on eBay (an overstock). It had several hundred cfm's more than the fan I bought locally. I was about to put it on the radiator when, on a whim, I decided to test the actual cfm's of both fans. The expensive one turned out to be putting much less CFMs than the rating of the cheap fan and the cheap fan was putting out much more cfm's that the expensive one was rated. So I sent the expensive one back (they actually took the return without any hassle!) and put on the cheap 16 inch fan. Now, the cooling system never goes above the three quarter mark (I think that is the 240 temperature). That is the OK temperature for these AC coupes. Back when they were new, they were running that "hot". The TSB had the dealer install a new gauge to that put the 240 temp at the middle of the temp gauge. Nothing else was changed. People were happy as long at the needle pointed straight up and not towards the right.
Anyway, I solved my problem without a lot of expense. it sounds like your problem is still there. Keep us posted!

 

210 is straight up on the later gauges, not 240. If your car is running 240 with the A/C on, that is not good.

 

I had the same issues as you describe. Our summer heat here in Florida is brutal. I have a new Vintage Air system When the A/C was off, the car's temp ran at 210 (gauge accuracy verified with 2 IR guns). But when I turned on the A/C, the temp headed over to the 3/4 mark before too long, especially in traffic, so I'd have to shut down the A/C.

I replaced my radiator with the Dewitts model with the built-in SPAL fan. The SPAL fan cuts on at 210 and that's as high as it goes until I park and shut the engine off at which point it climbs to the 3/4 mark.

It seems like many of these older cars with A/C (either factory or add-on units) have trouble keeping their cool in the hot southern climates without a little extra help. For me, the solution was a Dewitts.

-- Steve

 

I couldn't remember the three quarter and end numbers on the gauge but I remember the gauge positions and that straight up is 180 degrees. Without the fan, the needle went past the three quarter mark, so I would turn off the AC to prevent "pegging" the needle. Fortunately, I have never had a boil over because I watched the needle and turned off the AC prior to allowing it to get way past the three quarter mark. Now, with the 16 inch fan, the needle never makes it to the three quarter mark. It is a hair prior to the three quarter mark, but rock solid at that position. I drove across Florida the other day, on the way back (more than 50 miles on the interstate highway), the radio said the outside temp was 94 degrees. Previously, that would have easily pushed the temp gauge needle past the three quarter mark.

 

My small block had the same problem a lot of people overlook this .
This is usually with original 63 to 67 small blocks

 

Thanks for the suggestion. I've replaced the vacuum advance before, but not with this exact part number. For less than $20 on Amazon Prime, I figure why not!?!

 

Tebok,

You've resurrected this thread after almost two years. Are you still having the overheating issues? If not, what finally solved your problem?

 

The radiator made it manageable around town so I've been able to enjoy the car.

Issues have continued on long highway drives.

 

I read through that whole, long thread while ago.

At one point, you said your total timing (minus vacuum advance) was 32 degrees. Did you ever dial any more than that into the engine? It needs it. You said the initial was 14 which is good for idle. 32* not so good on the highway.


Another point. Did you ever confirm the thermostat was opening all the way? I never saw any reference to that.

Both of the above could give you heating problems at speed.

 

Thanks for putting in the time MikeM.

I'll have to go back and check the timing to give you a quality answer. I'd hate to take a guess from my cubicle. I will receive that new vacuum advance in a couple days and will come back with a full report on timing and results when I do.

I did confirm the t-stat was opening all the way and allowing good flow.