though i found problem

Johnnydidd

Johnnydidd

Well-known member
My 56 Merc still shows hotter on gauge than should be, its showing 210 after driving for 10 miles, I removed the thermostat, it runs at 180 to 190 on gauge if I slow down the temp goes up it will goes as high as 210. I used my hand held device at the thermostat it shows 190, top of radiator shows 190 , bottom of radiator shows 147, head where temp sending unit is shows 210, why the difference?
 
The back of the head is kind of a dead spot in cooling. It has to find its way forward to get out. Not so much at the front where the crossover is and the tsat. Your readings sound pretty good to me, assuming it's a hot day. With a good pressure cap, 6 lbs or so (whatever stock is) and a 50/50 mix of antifreeze, you're some distance from boiling. Some of the replacement stats don't have that big an opening. Using a Robert Shaw, among others, for the Chryslers have a larger opening when open. Someone will have the part number. I like to drill a small hole in the edge of the stat to let the air out when I fill the radiator from empty. Some guys like to partially restrict the bypass hose from the manifold to the water pump. Opinions, as always, will vary.

In broad general terms, if it's hot on the highway, it's a radiator problem (or water flow). Hot in traffic, it's air flow, as in fan and shroud. You'll get a lot of opinions on this, and the solutions, and more specific areas to look. But if everything is up to snuff in the cooling system, I think you're ok.
 
Removing the 'stat is a good diagnostic tool. I do it sometimes to see if it improves or worsens the condition.

How old is the radiator and water pump? I'd think your radiator should be more heat-balanced than what you are seeing.
 
Radiator is 3 row core and is new, water pump is new also, have 4 blade fan which is standed for the car, I do also have 6 blade fan which I planed to install when I put in AC. I failed to mention the motor only has 128 miles since a complete bore and rebuild, I hope it will cool down after 500 miles or so. What do you think?
 
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Recheck your timing, if it is off it can cause the eng. to run hotter than normal. remember that y-blocks like a bit more advance that what most manuals call for. use a dial back timing light if you can get access to one that way you can check it at different rpm ranges, although it won't be under load it will give a good idea of what is going on. balancers do " slip".
 
I just looked up Overland Park, KS on the weather channel. Said it was 90 something today. So, you've got a new, tight motor, high ambient temperature, and you're running 190 at the stat and 147 out the lower radiator. I've got a good friend in Tucson with a 56 bird. He's a hell of a heavy equipment engineer and long time car guy. He runs a restricter in the bypass hose, a big 6 or 7 blade A/C fan (trimmed to fit), and a Hayden Clutch on the fan. The only thing he hasn't done is remove the water pump spacer from the 'bird and space the pulley and fan back out. This isn't a concern on a passenger car, they didn't use the spacer. Thunderbirds have a problem getting airflow, the engine compartment is tight. Popping the hood (it opens at the rear) is a common solution stuck in traffic or a parade.

At 90 degrees ambient, he can hold 190 on an accurate gauge. At 126 on the freeway up in Phoenix, he was 230. Well under boiling with a good cooling system and 50/50 mix. My bird holds 180 pretty well moving, but on a 90 degree day, slowed down, the electric fan comes on. It runs a 90-120 second cycle and turns off for 60-90 seconds. Even with the a/c on. I run a really good BeCool radiator, and very efficient electric fan, and a tight, sealed custom shroud. If I was starting over, I'd go with the big clutch fan. When I did this the motor had a supercharger on it, and I couldn't clear a regular fan.

So, I don't think you have a problem. Fitting the 6 blade fan will help at low speeds, but will take horsepower and make more noise on the highway. I can find his posting giving the Hayden clutch number on another site and forward it if you want, just PM me.

As I'm fond of saying, opinions will vary, but that's mine.
 
Since the left head is running hot at the rear, check to see if the head gasket is on backwards. There should be a square corner of the gasket sticking out from under the head at the front, upper corner of the head. If the square corner is at the back of the head, the gasket is backwards. That cuts off most of the water flow to the rear of the head, where the temperature sensor is. John
 
I checked both head gaskets the are installed correctly, the man that rebuilt the engine said he drilled out some holes in the head gasket to make it run cooler?????????????

Mike I called Hayden Clutch they would need 2 3/4 inch space between radiator and water pump I only have 2 1/2.

Thanks guys
 
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I always say if the coolant is staying in the system you really don't have a problem. If it never gets over 210 in summer heat, I wouldn't be too worried. Due to inaccuracies and core shift in the casting process, some engines just run a little hotter than others. It could be a passage that has some casting flash or restriction.
 
I would check the timing and take a close look at the lower radiator hose, make sure that's not collapsing.

On my '59, the radiator (Champion 3 row) is uniform top and bottom, using ribbed hoses, Dayco brand. My timing was initially retarded upon 1st fire-up, has been corrected.

I have about 300 miles on a total rebuild. I had a shop do the short block and cam installation (degreed it), I did the assembly. Using a 180* 'stat and it runs 180* unless I get stuck in traffic, then it creeps up slow to 220*, comes down fast when I move. And I'm driving in 95* to 102" temps. A shroud should fix me up.

But look at the timing and lower hose. Do this test, with the car running, hold a shop rag in front of the radiator, it should pull the rag onto the radiator. How far are the fan blades from the radiator?
 
If you have a six blade fan, put it on. It will cool much better in traffic. A 1/4 inch spacer should not affect it much.
 
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