radiator running hot

[sincro]

I just installed an after market AC/heater unit in my 65 coupe as part of my partial restoration. The engine is a small block with something a little over the stock 300 hp. It has a 4 speed transmission and 3.70 rear gears.

I am having problems with my cooling system running hot both with the AC on and with it off . I washed out my radiator (found a bunch of mud in it) until clear water came out, blew out the fins, installed all new hoses and 160 degree thermostat and washed out the engine block. I installed the two electric fans, that came with the kit, in front of the condenser as the instructions suggest and they run in the correct direction. What can / should I do to correct this problem? Should I pull the radiator and have it chemically cleaned? Is it possible for the water pump to be not pumping enough water (original pump but no leaks)? Should I put a six blade fan on the engine with more pitch? (Yes the fan cowl is in place) Could the condenser be blocking too much air from the radiator? I have not installed antifreeze / coolant since the overhaul.

The temperature goes up to 180 degrees and holds there for a while. It then starts creeping up and eventually reaches about 220 to 230. (while driving about 55 mph)

Suggestions to solve this dilemma will be appreciated.

 

[wallyknoch]

...put a 180 stat in it...

 

[sincro]

A 180 degree stat. OK, I will give it a try but I don't understand how a higher temperature thermostat will help it run cooler. Care to enlighten me on how this will work? I don't have a clue.

 

[JohnZ]

What kind of radiator do you have? Original-type Harrison stacked-plate aluminum, or a copper/brass replacement? How old is it? Have you verified the accuracy of your temp gauge with an I.R. gun?

 

[Hib Halverson]

A 180 degree stat. OK, I will give it a try but I don't understand how a higher temperature thermostat will help it run cooler.

It won't.
The post from "wallyknoch" offers no useful information as to solving your problem.

Based on your statement that a lot of "mud" came out of your radiator when you "washed" it indicates you may have trouble with a rusting cooling system and a restricted radiator. In fact, if you've been running no antifreeze and have been running straight water with no corrosion inhibiter, you can bet you've got rust in the cooling system.

If the radiator is original ,I'd leave it in the car while you flush then drain the system dry (ie: not only drain the radiator, but also drain the block and the heater core.

I'd scrap the original radiator and buy a replacement aluminum unit from DeWitt's and when you order from them, tell them about the aftermarket A/C. If the water pump is original, I'd replace it. If you don't care about originality, I'd use a modern aftermarket pump, like an Edelbrock.
If you haven't done so already, install new hoses and belts. You can use either a 160 or a 180 'stat, but with a system in good condition, I'm partial to 180s. Use the stock fan and shroud but make sure your fan clutch is working right. Make sure the pressure cap functions properly. If you have an expansion tank, make sure the seal surface in the filler neck is in good condition such that the cap will seal. You need to test the temperature gauge in the car to make sure it is accurate.

As for coolant, you can run straight water as long as 1) the car is never parked or stored in a place where it freezes overnight and 2) you use two bottles of Red Line Water Wetter which contains the proper corrosion inhibiters to replace those that are lost when you don't run any antifreeze.

If you want to run antifreeze, you can either just go 50/50, or you can run only enough to give you the freeze protection you need and the rest water. If that ends up less than 70/30, you also need one bottle of Red Line Water Wetter.

Good luck.

 

[sincro]

Thanks for the information. The radiator and water pump are original. I have been running about a 10% antifreeze mixture since I put it back together about a month ago and the water is still relatively clear. I did not use any of the radiator flush materials on the market because I didn't know what they would do to the aluminum radiator. Is there one on the market that is safe to use with aluminum? I also blew out/washed the cooling fins with a pressure washer (using low pressure) to clear the air passages. I pressure tested the system dry after reassembly and it held 16 psi for over an hour.

The overflow tank is in excellent condition and holds 16 psi. All hoses and belts are new. While I had the car taken apart, I had the block boiled out with freeze plugs removed and installed all new brass freeze plugs. I feel comfortable the block doesn't have any obstructions or buildups.

I would like to maintain the original water pump and radiator if possible. Does anyone make a rebuild kit for the water pump?

 

[BarryK]

if the system was cooling fine before the AC was added I doubt the waterpump is bad, although it is possible that the cast iron impeller inside of it is corroded from age and simply not as efficient as when it was new.
Water pumps can be rebuilt but you need to get new bearings, seals, and a replacement impeller plus have a press to remove the old bearings and press in the new ones. You are probably better sending it out to be rebuilt by someone like Bill Mock or Arthur Gould who rebuild them every day. I see no reason to have to go with an aftermarket water pump at all. Rebuild yours or replace it with another unit available from Delco and keep your original on the shelf and have it rebuilt at some point and it can always be put back on.

trying to retain your 43yo radiator is a going to be a waste of time, especially since you said it was full of mud and suck. As Hib said, there is probably corrosion and rust throughout the entire unit and it's not cooling anywhere near it's capacity as it was new. A new DeWitts radiator is going to make a big difference.

And I agree with everyone else that you are better off with a 180º t-stat. That isn't going to make the slightest different to your cooling issue but once you get everything worked out and the cooling system is back up to par a 160º t-stat is too low of a temp.

Also, since to say the temps creep up while at highway driving, that usually indicates either a radiator of insufficient capacity (very likely in your case from what you have already said), restricted coolant flow, and/or restricted airflow.
Having the fans in front of the radiator can somewhat restrict the airflow since the frame of the fans block a certain percentage of the radiator but once they kick on the added airflow from the fans should overcome that. At what temp are the fans wired to switch on at?

 

[sincro]

They kick on about 160 degrees. By the way, I have verified the temperature with an IR digital hand set. I guess if I am going to replace the radiator, I might as well try some flushing solution in it first to see what it can get out. I will replace the water pump with a new Delco unit. I have a full machine shop so pressing bearings and the impeller isn't a problem.

 

[BarryK]

if you have a full machine shop and a press why not rebuild your original? The new units available from Delco are NOT made by GM, they are outsourced out. I just found this out myself since the WP on my '78 just went bad and needs a new bearing.
I also recently read an article about rebuilding the waterpumps and it doesn't look difficult, especially since you have the press to do the bearings.
Mostly it involves the new bearing, a new seal, and depending on the condition of the old one maybe a new impeller. Your '65 WP has a cast iron impeller and later units went to a stamped steel one. I think most places that rebuild them are going to use the stamped steel impeller but you might be able to dig up an original cast one if you want or just put in the stamped steel newer style one.

right now I'm deciding on whether to rebuild the original for my '78 or keep it for now and rebuild it later and just put on a replacement pump. I don't have a press so for me rebuilding the pump would require sending it out but since you have the equipment rebuilding yours shouldn't be a big deal.

EDIT: I found the link on the Water Pump Rebuild article for you
http://www.corvettemagazine.com/content/view/63/

 

[wallyknoch]

It won't.
The post from "wallyknoch" offers no useful information as to solving your problem.

Based on your statement that a lot of "mud" came out of your radiator when you "washed" it indicates you may have trouble with a rusting cooling system and a restricted radiator. In fact, if you've been running no antifreeze and have been running straight water with no corrosion inhibiter, you can bet you've got rust in the cooling system.

If the radiator is original ,I'd leave it in the car while you flush then drain the system dry (ie: not only drain the radiator, but also drain the block and the heater core.

I'd scrap the original radiator and buy a replacement aluminum unit from DeWitt's and when you order from them, tell them about the aftermarket A/C. If the water pump is original, I'd replace it. If you don't care about originality, I'd use a modern aftermarket pump, like an Edelbrock.
If you haven't done so already, install new hoses and belts. You can use either a 160 or a 180 'stat, but with a system in good condition, I'm partial to 180s. Use the stock fan and shroud but make sure your fan clutch is working right. Make sure the pressure cap functions properly. If you have an expansion tank, make sure the seal surface in the filler neck is in good condition such that the cap will seal. You need to test the temperature gauge in the car to make sure it is accurate.

As for coolant, you can run straight water as long as 1) the car is never parked or stored in a place where it freezes overnight and 2) you use two bottles of Red Line Water Wetter which contains the proper corrosion inhibiters to replace those that are lost when you don't run any antifreeze.

If you want to run antifreeze, you can either just go 50/50, or you can run only enough to give you the freeze protection you need and the rest water. If that ends up less than 70/30, you also need one bottle of Red Line Water Wetter.

Good luck.

Ya, listen to this guy. Sounds like a Democrat good at spending other peoples money. The thread starter did everything he knew how to but obviously didn`t know a 180 stat is the recommended stat. The water pump proposal would be a waste of money, The only way it wouldn`t work is if the impeller fell off. This guy must lecture auto shop 101. ...

 

[Bwmurph]

DEMOCRATS are spending other peoples money ??? Who is spending US$ 10 BILLION a MONTH in Iraq in a war we didn't need.

Just my $0.02; (which is all I'll have left when we finish paying off W's debts)

 

[Hib Halverson]

Ya, listen to this guy. Sounds like a Democrat good at spending other peoples money. The thread starter did everything he knew how to but obviously didn`t know a 180 stat is the recommended stat. The water pump proposal would be a waste of money, The only way it wouldn`t work is if the impeller fell off. This guy must lecture auto shop 101. ...

A good thing and a bad thing about the CAC is we have many and varied people here. Some really know their stuff, others need help and are receptive to the suggestions of CAC members and others are pretty damn ignorant know-it-alls.

The point of my 'stat comment was that going from a 160 to a 180 isn't going to fix this problem. I agree that the recommended value is a 180.

Also, the comment by "wallyknoch" that the only way the water pump wouldn't work unless the impeller fell off is just about as stupid as the first comment. Inside a 40 year old pump, the impeller could be eroded due to cavitation or, in a system which had lacked corrosion inhibiter, rusted or corroded. Either way, pump flow would decrease. In addition, some of the aftermarket pumps, ie: Howard Stewart, Edelbrock, etc, are noticeable improvements in flow, volume and side-to-side flow consistency.

Actually, we have two problems with this engine 1) failure to cool properly and 2) increased load on the cooling system and reduced airflow through the radiator due to the aftermarket A/C.

The first problem may be a combination of original parts which might not be doing the job they once could do 40 years ago and problems brought on by rust and scale in the system. The second problem may be one of not enough cooling capacity under certain conditions. My comments were general suggestions offered in the process of DvI (diagnosis by Internet) which might fix the problems.

The one issue I forgot to mention, if the engine happens to be running lean at part throttle cruise can also cause problems with cooling.

As for the politics crap, I can only laugh at the two knee-jerk posts both of which show strong opinion but little grasp of the issues. Politicians, Democrat, Republican or otherwise spend our money unwisely.

Reality is that be it President Obama or President McCain, there will be little change in how money is spent but there may be some big changes in how money is collected. If we want a big change in how our elected officials spend our money, the change needs to come in the halls of Congress not the Oval Office and the needed change in Congress is unlikely to happen.
Now...about that radiator...

 

[wallyknoch]

Apparently there was no cooling problem until the AC was installed with a 160 stat so therefore going back to a OEM recommended temperature that the above guy finally admitted is correct is not out of the question. Even a 40 year old pump that we dont know if its that old ran correctly before the AC install and stat change. Merely throwing a bunch of new aftermarket parts into the engine is not the correct way to fix any car. But I guess thats how the so called experts do it...otfl

 

[sincro]

I really don't have any data from before the AC was installed. The car sat in a barn for 21 years before I bought it and started restoring it. I installed the AC as part of the restoration. I didn't drive it until post restro.

Update; I flushed the radiator with Prestone super flush today. It seems to have helped a little but it still runs at better than 220 degrees. I advanced the timing at the same time as the flushing. I set it originally at 8 degrees (which is what is recommended for 300HP) I bumped it up to 12 degrees and the engine seems to run smoother and I had to idle it down. A little more test driving will tell.

The next action on the list is to change the water pump. Not sure how to determine if it is pumping enough or not. The radiator starts getting warm quickly after start up and it builds pressure at operating temperature. I guess it could be thermal siphoning.

More info as I progress through this problem.

 

[BarryK]

before starting to change out parts needlessly such as the waterpump may I suggest starting with the basics:

first of all look at WHEN the overheating occurs:
if it's at idle or slow speed driving it's usually a timing, vacuum advance, or fan clutch issue.
If it's when driving at high speeds than it's usually an airflow restriction, coolant restriction, or not enough radiator capacity.

Based on the above can you check and confirm:
1. what your total timing is with the vacuum advance line disconnected and plugged. I know you said you bumped the initial timing up to 12º but what's the total timing?
2. Is the vacuum advance system connected to full manifold vacuum (not ported) AND operating correctly? When you disconnect the vac adv hose off the distributor vac adv can does the idle speed change?
3. Is the fan clutch operating correctly? Get the motor up to operating temp and turn it off. Watch the fan, it should stop within 1-3 revolutions. If it takes much longer or simply freespins it needs to be replaced.
4. is the cap on the expansion tank sealing correctly?


I would suggest checking these things first than we can look into air or coolant flow restrictions afterwards if needed. If all else fails than chances are it's time for a new radiator but why throw money at the problem until you see IF it's needed and where.

 

[sincro]

Thanks for the information Barry K and everyone else. I find talking through problems like this to be very helpful and enlightening.

I checked the timing with the vacuum advance disconnected and plugged. I didn't check it with it reconnected, but I will. It is hooked to the standard port on the carb. but I will check the vacuum to see if it is full manifold pressure or not. I converted the distributor to a solid state ignition system. The module is from Crane Cams.

The overheating happens two ways. If I let it idle for 15 - 20 minutes, it will overheat regardless of what RPM it is running (700 @ idle up to 1500). When driving at 40 to 60 MPH, it will gradually get hot after about 15 miles with our without the AC on.

The fan clutch seems to be working properly. I compared it to the fan clutch on one of my other cars and it seemed to be the same. With the engine running, the fan blows a good stream of air out of the cowl, but I can't attest to what it does when driving.

The cap on the expansion / overflow tank is the original cap but it is on correctly and it holds full system pressure.

I am trying to eliminate each component at a time, starting with the easiest and working up the list. I don't want to spend money I don't need to spend plus I would like to keep it as original as possible.

I will report back with the next episode as more data is collected.:confused

 

[sincro]

Thanks for the information Barry K and everyone else. I find talking through problems like this to be very helpful and enlightening.

I checked the timing with the vacuum advance disconnected and plugged. I didn't check it with it reconnected, but I will. It is hooked to the standard port on the carb. but I will check the vacuum to see if it is full manifold pressure or not. I converted the distributor to a solid state ignition system. The module is from Crane Cams.

The overheating happens two ways. If I let it idle for 15 - 20 minutes, it will overheat regardless of what RPM it is running (700 @ idle up to 1500). When driving at 40 to 60 MPH, it will gradually get hot after about 15 miles with our without the AC on.

The fan clutch seems to be working properly. I compared it to the fan clutch on one of my other cars and it seemed to be the same. With the engine running, the fan blows a good stream of air out of the cowl, but I can't attest to what it does when driving.

The cap on the expansion / overflow tank is the original cap but it is on correctly and it holds full system pressure.

I am trying to eliminate each component at a time, starting with the easiest and working up the list. I don't want to spend money I don't need to spend plus I would like to keep it as original as possible.

I will report back with the next episode as more data is collected.:confused

 

[sincro]

overheating

Thanks for the information Barry K and everyone else. I find talking through problems like this to be very helpful and enlightening.

I checked the timing with the vacuum advance disconnected and plugged. I didn't check it with it reconnected, but I will. It is hooked to the standard port on the carb. but I will check the vacuum to see if it is full manifold pressure or not. I converted the distributor to a solid state ignition system. The module is from Crane Cams.

The overheating happens two ways. If I let it idle for 15 - 20 minutes, it will overheat regardless of what RPM it is running (700 @ idle up to 1500). When driving at 40 to 60 MPH, it will gradually get hot after about 15 miles with our without the AC on.


The fan clutch seems to be working properly. I compared it to the fan clutch on one of my other cars and it seemed to be the same. With the engine running, the fan blows a good stream of air out of the cowl, but I can't attest to what it does when driving.

The cap on the expansion / overflow tank is the original cap but it is on correctly and it holds full system pressure.

I am trying to eliminate each component at a time, starting with the easiest and working up the list. I don't want to spend money I don't need to spend plus I would like to keep it as original as possible.

I will report back with the next episode as more data is collected.

 

[BarryK]

I checked the timing with the vacuum advance disconnected and plugged. I didn't check it with it reconnected, but I will. It is hooked to the standard port on the carb. but I will check the vacuum to see if it is full manifold pressure or not.

checking the timing is usually done with the vacuum advance disconnected but checking it connected can also be helpful by seeing if the idle drops when you disconnect it (shows it's connected to full manifold vacuum although still best to also check the connection nipple also to see if it is showing full manifold vacuum) and also by checking timing with and without the vac adv connected it will let you see how much vac adv you are actually getting.
At idle you should be getting full amount of vacuum advance, about 15º-16º of additional advance over your initial timing setting, so if initial is now set at 12º when you reconnect the vac adv you should be getting about 27º-28º of timing at idle.

As mentioned, also check your total timing with the vac adv disconnected to see where that is at. The factory manual calls for setting timing by setting the initial timing because when the car was new they knew how the distributor was set up and knew that by setting initial timing at "x" degrees that total timing was also correct but after 40 some odd years later who knows who has been inside the distributor making changes so it's safer to actually set timing by setting the total timing, not the initial timing. Even though you bumped up the initial timing to 12º for all we know the total timing may be only around 30-32º or whatever and if it's too retarded of a setting it can easily raise your operating temps.

also, another thought is how does the car feel when driving? plenty of power or weak?, any hesitation when you step on the gas, etc? If the jetting in the carb is too lean it can run hot.
Lean=hotter temps
rich = lower temps

Besides the temp rating on the t-stat, which at the moment is irrelevant, have you tested it to make sure it's actually opening up all the way? You can test it in a pot of hot water on the stove and a thermometer to see when it opens and to make sure it's opening fully. If it's not, that is a restriction in coolant flow.

One last thought......... is your lower radiator hose the correct type with the internal spring in it? If there is no internal spring the hose can collapse from the pressure of the water pump causing a restriction in coolant flow.