67 273 Commando Cooling issues

[67commando]

I recently had Grandma's 67 fastback restored (it's mine now :icon_smi. It has a 273 Commando with auto tranny. It overheats frequently in summer, mostly while at a stop. I was looking for a 67 fan shroud to fit the 22 inch radiator, but just discovered the radiator is a 22 inch for a 68 with 318. Since the 68/69 shrouds are much easier to come by, can I just order and mount one of those, or do I need to verify fan size first? It has four evenly spaced threaded holes on the radiator, apparently for mounting a shroud...I have been considering replacing the radiator with an aluminum three row, adding fans, adding a shroud, changing the thermostat or even adding electric fans. I am looking for the least visual change with the most cooling effect...

 

[Oldschoolcuda]

Welcome to this fine site 67commando. Did you have your radiator replaced or re-cored during restoration? If not that could be your issue. What type of fan do you currently have? Is it a six blade unit and does it have a clutch setup or not? Another issue could be your timing. If set incorrectly she will run hot. Shroud be able to use later shroud but not positive. Sure others will chime in. A stock radiator & fan setup should be cooling your 273 fine as long as everything is in good working order.

Oldschoolcuda

 

[Commando66]

I agree with what Oldschoolcuda said. Also some things to consider are a properly functioning thermostat, the radiator hoses are not collapsing, good radiator cap and if it's an automatic, is the trans cooler in the rad causing it to overheat?

 

[smlveightis]

Welcome aboard from the mitten state! x2 what Oldschoolcuda and Commando 66 stated above. Good luck and post your results.

 

[65dartcharger]

In would start with the thermostat, continue with opening up the lower radiator hose and check the coolant. If it's full of dirt replace the cooland in the engine. Next would be to have the engine block opened up by the freeze plugs and check for dirt. If so clean and new plugs.

The last thing would be to restore the radiator. The 273 HP just had fan shroud with A/C. Good luck with your car. If you like, shoot some pictures.

 

[67commando]

Wow! I should have signed up a long time ago! Thanks for all the responses and suggestions. I believe it is a six blade fan and know for certain it does not have a clutch. The restoration included a full tear down on the engine and tranny - no dirt and new hoses that don't collapse. Cap is new too. I plan to pull and check the thermostat - not sure of the temp so I thought if it is high, I would replace it with a cooler running thermo. As for the current 68 radiator, it was completely gone through and found to have no issues. I was a bit disappointed to find out someone had replaced the oem 67 radiator, as everything else is original - except I went with dark blue instead of the bright blue on the paint. Thanks again for the responses! Should I go back to the 67 radiator?

 

[Commando66]

Is it a stock 6 blade fan? Does it have the aluminum spacer between the pulley and fan to get the fan closer to the radiator? What water pump? If you can, post some pictures of the engine compartment...pictures are worth a thousand words.

 

[67commando]

Okay, I will get some pics after the game and post them by tomorrow. Thanks!

 

[67commando]

Commando66,
Okay, had a break between games so here are some pictures as requested. Tell me what you think, or tell me if I need to retake. The silver color is painted onto the shaft to the fan from the restoration...is it a spacer? It looks to be attached to the rest of the pulley perhaps? I think the water pump is stock or a stock level replacement - is there something I should look for in particular? Oh yeah, the fan is only a four blade..what was standard? Could that be the problem?

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[cudamark]

Yeah, ditch that 4 blade and get a 7 blade rigid fan. If you still have overheating problems, update us. How are you determining that the engine is actually overheating? I wouldn't rely on the factory gauge unless it's been verified accurate. Stick a known good thermometer in the coolant and see what it actually reads.

 

[smlveightis]

Although on the expensive side, a pressure tester can be just the ticket. If not in the cards, take it to a radiator shop and have them pressurize the cooling system. Might be worth your while, less headache.

 

[Commando66]

Great looking car! Does it boil the water out of the over flow hose and cause a mess? Check out the thermostat and a seven blade fan could help.

 

[67commando]

Again, thanks for the suggestions. I checked it last time with a laser temp reader at the sending unit...but it was fall and not overheating..read 170ish. What does pressurizing the cooling system do? No boil out yet with the temp pegged on the stock gauge, so it is suspect, but I do think it is running hot still in the summer. If it would ever rise above freezing again, I might be able to run more tests...Guess I will have to wait until at least June.

 

[Oldschoolcuda]

X2 on nice looking car. Thanks for posting pics. Definitely do not go by the reading on your stock gauge.These rascals are unreliable even rebuilt. The one in my cuda stays pegged even when she's running at a normal 180/190 degrees. Get a nice autometer, etc. water temperature gauge and see where you really are temperature wise. A nice oil/water temp combo is discreet & really does not take away from stock appearance. Also like cudamark said that 4 blade fan has to go. She should have at least a 6 blade unit so that might have left with your original radiator. Keep us posted & hopefully your weather will warm up. Looks like all of Washington state is seeing some really bad weather.

Oldschoolcuda

 

[smlveightis]

If your cooling system is truely overheating, then one of two things are happening.
#1 Air is being introduced into the cooling system. Could be anything from a pin hole in a hose, worn or inadequate p.s.i. radiator cap, intake/head gasket leak. A pressure test will confirm if any of these are the problem.
#2 In-adequate system cooling. As Cudamark, Commando66, and Oldschoolcuda stated above, ditch the 4 blade for a 7 blade fan, also look into getting a fan shrould, and quite possible an over flow/catch can. All of these items will greatly decrease your chances of overheating in the future.
FYI, my first FB Barracuda w/273, auto, and non-a/c, had the 4 blade fixed fan, and only once overheated, due to radiator needing to be re-cored.
Good luck and keep us posted with your results!

 

[trapster]

Couple of things to consider.

Check your spark plugs to make sure you are not running too lean. You may need to clean or rebuild your carb.

A thermostat is only there to keep your engine from running too cool. If it is overheating, putting a lower temperature thermostat will not solve the problem. A high flow stat may help.

Your water pump may be rotted away and not circulating like it should. check your flow.

It looks like you have a slant six fan. get a bigger one. A flex fan would work nice but it wont look original.

Keeping your system pressurized and with the correct antifreeze mixture will raise your boiling point. Check for leaks and make sure your cap holds pressure.

 

[RedFish]

The 4 blade fan and no shroud was sufficient when it was new, even without a shroud.
I have to beleive GPM through that radiator is the problem because I had the same problem. It run a little hot in the summer and would detonate/spark knock at times, and it would boil over if I got caught in traffic. After wasting a lot of time and money on all the less expensive fixes, New radiator cured it.

 

[67commando]

Trapster: Carb newly rebuilt as is most everything mechanical. It is the original Carter Carb and was completely gone through and readjusted due to hard starts. Now is starts easily, is hard to kick down from high idle and runs rough at 30 to 40 mph. I will inquire as to what they did with the radiator, but I know they went through it. Tranny cooler should have been covered in that, but I will check. As for water pump, not sure yet but will ask about that too. Even though the stock gauge has been pegged in the summer, it has never produced steam or boiled over, so I suspect as most of you do, it is the gauge. When I ran the temp sending unit test (grounding it) it pegged, which indicated a bad unit I think that is what someone said months ago anyway. I replaced it but after the heat so I will have to wait until this white stuff stops falling and we come out of the ice age to see if that was the problem. I will get a seven blade fan - Commando66 offered one up so I will talk to him about that.

 

[trapster]

If it is hard to kick down from high idle you may be running the choke for longer than you need to.

I don't think this will cause the engine to overheat but it will cause it to run rich which isn't good either.

The easiest way to check flow is to let the car warm up with the radiator cap off and just look in while you rev the engine. You should see flow.

 

[swingingdart]

you might try some purple ice, or other super coolent additives (from auto zone) this will drop the temp for now, untill you figure out your problem. but if it's an automatic your tranny may be giving you your problem.