53 merc v8 overheating

[Lhead]

I have a 53 merc 255 v8.Ive been driving it since mid 80s . Offenhauser heads , isky max 1 cam , holley 4 barrel, mallory duel point dizzy. Started now to overheat excessively on passenger side bank. Had rad pressure checked , flushed block, 160 thermostats.When engine idling pas bank temp starts climbing after a while idling .I pressure check system holds at 7psi. Where do I start start trouble shooting .
I
Just a thought has anyone ever tried the cooling trick Barney Navarro used. Placing a length of copper pipe behind the water pump cavity through the water jackets to the back of the block to increase circulation.Apparently this has allowed the engine to run cooler.Anyone try this . Let me know if its worthwhile to try.
Thanks

[Merc Cruzer]

Are you still using the original sending units and gauge? If you don't have one, go to Harbor Freight and get a laser temperature gun. Worth their wight in gold for temp issues.

If you have the stock set up with the temperature sensors, you are actually only measuring the temperature on the passenger side. The sensor on the drivers side is nothing more than a thermal on and off switch. The sensors tend to go bad and are a bit expensive.

You might think about going with mechanical sensors and gauges on each side. I got mine at O'Reilly' Auto Parts.

I also find that the passenger side runs 5 - 10 degrees hotter, than then drovers side.

The old rule is, if it is not "throwing water" (over flowing), you are fine.

[oldbugger]

check your thermostats by putting them in a pan on the stove with a thermometer, see if they start to open at 160 and where they are fully open. label them left and right, fun to watch.

[jimvette59]

Head Gasket ? I had the same trouble with my 255. Could be corrosion on the heads. JMO

[Lhead]

I used a laser temp to verify head temps. Mechanical gauges on both sides . Passenger temp starts risinf after idling for a while .Keeps climbing to over 200 F , then starts puking out of rad .

[Lhead]

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Originally Posted by oldbugger

check your thermostats by putting them in a pan on the stove with a thermometer, see if they start to open at 160 and where they are fully open. label them left and right, fun to watch.

I dunked them in water to test them after having two brand new thermostats that didnt open till + 200F.Iam questioning the quality. I have tested the 160F stat seems to open okay . Drilled 2 bypass holes will try that on the passenger side head. Hope that works.

[paul2748]

Instead of running two gauges, get a toggle switch and with just one gauge, toggle between the two heads. I used this system and it worked good.

[Lhead]

Originally Posted by jimvette59

Head Gasket ? I had the same trouble with my 255. Could be corrosion on the heads. JMO

I previously flushed the engine , lots of rusty crap coming out. Hope the head gasket on the passenger side isnt blown but there is a possibility.

[oldbugger]

[QUOTE=Lhead;2280269]I dunked them in water to test them after having two brand new thermostats that didnt open till + 200F.Iam questioning the quality. I have tested the 160F stat seems to open okay . Drilled 2 bypass holes will try that on the passenger side head. Hope that works.[

at least your eliminating possibilities.

[Joe B.]

Take the rad. cap off and check for bubbles in the coolant before it boils over. Doesn't that indicate a head gasket problem?

[ms fowler]

I feel like I am reading the backstory to " Hotrod Lincoln"...."the Ford got hot and wouldn't run no more...."
Also--" They all do that"

[ms fowler]

I feel like I am reading the backstory to " Hotrod Lincoln"...."the Ford got hot and wouldn't run no more...."
Also--" They all do that"

[OhioRick]

Use 100% vinegar and run the engine on the road with it. Drain, flush and refill as many times as needed until you’re clear. Finally flush with baking soda as a neutralizer.
See link.
https://www.fordbarn.com/forum/showthread.php?t=206756

[38 coupe]

The facts as I understand them are:
1 - both thermostats are verified good, and have air bleed holes drilled in them
2 - temperature gauge for each head and gauges match the behavior of the engine
3 - driver's (left) side does not show overheating on its gauge
4 - passenger side (right) temperature slowly keeps climbing until the radiator overflows


Given the driver's side doesn't overheat it isn't a radiator problem. Either the passenger side needs a lot more flushing, or the passenger head needs to come off for a good visual inspection.

[Merc Cruzer]

Cranked block on the passenger side? Just a thought.

[Lhead]

Thanks guys for the input . Ive removed all the hoses and checked the thermostats . Still trases of rust inside the head and rad hoses. Drilled two bleed holes in the thermostats . Next step will test run see what happens. Trying to get the simple more accessible things first before removing the head. Since the 80s when I bult the the engine Ive had the heads off so many times think they should manufacture the with zippers. Thanks again for the advise .

[flatford8]

In post #2 you have the heat gun pointed at the exhaust cross-over that goes thru the intake manifold. I don’t think that’s an accurate measure of your coolant temperature. Try it again aimed at the head near the thermostat housing. Be sure to hold the gun the same distance for each measurement. I hope you’re able to find the problem........Mark

[Ken/Alabama]

Remove the thermostats and reinstall the thermostat housings. Then leave off the upper radiator hoses. Then remove the belt that runs the water pumps. Fill the block with water through the water necks until you can see water inside the neck . Start the engine and look for bubbles.

[Merc Cruzer]

Mark,

I chose that reading, as it represented the temperature of air coming up through the heat riser into the carburetor, since tube goes directly into the heat riser. My logic was that the temperature of that air, directly effected the temperature of the body of the carburetor and therefor, if I could reduce that temperature, I would be able to reduce the temperature of the carburetor body and the air going into the carburetor.

You are correct, the head temperature is allot cooler.

When the original engine in my 53' Merc started overheating. I tore it down, and found a crack through the valve seat into the cylinder.

[petehoovie]

Originally Posted by Merc Cruzer

Mark,

I chose that reading, as it represented the temperature of air coming up through the heat riser into the carburetor, since tube goes directly into the heat riser. My logic was that the temperature of that air, directly effected the temperature of the body of the carburetor and therefor, if I could reduce that temperature, I would be able to reduce the temperature of the carburetor body and the air going into the carburetor.

You are correct, the head temperature is allot cooler.

When the original engine in my 53' Merc started overheating. I tore it down, and found a crack through the valve seat into the cylinder.