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BlizzND

Proper 351C Thermostat

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Thermostat Replacement

"Beating the Heat"

 
text and photos Garth Rodericks a Pantera enthusiast

His site is down, I retrieved these using the "way back machine"

 

 

Symptoms of a Problem Over the last few days I noticed a boiling/percolating sound coming from my 

coolant tanks (pressure and swirl tanks). The tanks sat there vibrating as the 

contents sounded like they were boiling, but I hadn't detected any fluids being discharged from the overflow hose. And, the temp gauge still showed consistent temperature readings, albeit with a few erratic swings of the needle (but no alarming temperatures reported).

Notes on my Cooling System Last year I installed...

1. Brand new radiator - stock style copper/brass, no leaks

2. Weiand aluminum water pump

3. Rebuilt the stock cooling fans (with Cortina blades) - they work beautifully

4. A Tefba coolant filter - filter is clean, with no obstruction to flow

Additional notes...

1. Temperature sender was mounted in the water pump

2. Cooling system had been bled twice since the symptoms appeared - very little air

3. And, it didn't appear to be losing coolant - fluid level appeared constant

Anyway, I posted my dilemma to the DeTomaso E-Mail Forum and received a lot of questions and suggestions which helped me determine the best course of action to resolve the problem.

I picked up an infra-red temperature gun on my way home from work and checked temperatures at various points along the cooling system to determine if coolant temps were consistent throughout. They were not. It appeared the most likely culprit was a stuck thermostat due to the large temperature difference between the coolant bottle and the radiator, and the fact that once I removed the cap from the pressure tank it immediately boiled over. This led me to believe the coolant was merely circulating through the engine instead of through the radiator.

Correct 351 Cleveland Thermostats The thermostat for a 351-Cleveland is different from the thermostat for a 351-Windsor. Either will fit in each engine, but the 351C thermostat has a copper "hat" that seals against a bypass restrictor plate inside the block, closing the bypass circuit when the thermostat opens, so that all coolant has to go through the radiator. 

 

351W style, missing "hat" New Thermostat

windsor%20wm.jpg

 

Correct 351C style, with "hat Thermostat Comparison

Stant%202.jpg

 

351C%20Thermostats%20Chart.jpg

 

 

New vs. Old Thermostat Restrictor Plate

 

Old

old%20restrictor.jpg

 

 

New

restrictor%20in%20block.jpg

nd Temp Part No. Notes

 

Those thermostats in the chart marked as "Cleveland specific" have been verified to be correct 351C thermostats with the hat to seal the bypass circuit in the block. I used a Stant #29468 thermostat because that's what was available from my local Kragens Auto Parts store. I also used a thin coat of Permatex #2 gasket sealer on the gasket surface to ensure a water-tight seal.

 
NOTE: It has been brought up that some of these may not be Cleveland specific, Verify the copper "top hat" prior to purchase.

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