Posted by Willy-N on Thursday, June 19, 2003:

In Reply to: why don't you test your thermostat posted by mike stone on Thursday, June 19, 2003:

Original article by G.T. Koldjeski can be found at http://www.p15-d24.com/

Mike; I have checked all the other parts already, haven't tested it in water with a thermometer. Just found this site with a good check list and gives me a lot of things to check. It also states most 218/230 had the 160 stat and I got the number "Gates #30026" here is a copy of what I found; "Cooling System Check List Most 218/230 flatheads use a stock 160 degree thermostat and will run all day long in the 160 –170 degree range. I have driven a P15 across the California desert in 100 degree weather at 60 mph and the water temperature climbed to the 200 degree range. These vehicles have large radiators with sizeable coolant capacity so overheating is not a common experience. In fact, I have found them to be a bit on the cold hearted side. So if you are seeing temperatures above the 170 degree without extenuating circumstances such as towing or climbing hills, your engine is telling you something is wrong. Ignoring the warning signs will almost always lead to engine damage ranging from burned exhaust valves to a cracked block or head.

Cooling Check List
Phase 1 are quick checks for common problems with easy fixes. Break out the tools and plan on a Saturday for Phase 2. Phase 3 are those really tough problems that unfortunately are usually expensive to fix. Good news is they don’t occur that often

Phase 1

• Low coolant
• Check the engine oil to see if any coolant is leaking into the oil. It will appear white on the oil. Check all hose clamp and hoses for leaks.
• Loose, worn or incorrect fan belt
• Ignition timing too far advanced
• Radiator cap missing or defective
• P15 and D24s use a non-pressure cooling system. If you use a pressurized cap you will probably damage the radiator as it is not built to handle the higher pressure and it may push the water temperatures up.
• Coolant mix
• Just use the amount of antifreeze required to protect your engine from freezing in your area. Additional antifreeze actually reduces the water’s ability to transfer heat. Remember water is more efficient that antifreeze for heat transfer.

Phase 2

• Faulty reading temperature gauge, check against another gauge
• Defective water pump, leaking seals or impeller rusted, impeller shaft broken. Wiggle the fan, check for leaks around the front shaft.
• Clogged or inoperative thermostat, installed incorrectly, wrong thermostat
• Clogged radiator
• Clogged block
• Clogged, missing or rusted out water distribution tube
• The water distribution tube plays a critical role in cooling the upper block and valve system. Cool water from the water pump is directly pumped into the water distribution tube, reducing the temperature in the valve area. The tube carries the water to the #6 cylinder area. It then travels on down the block water jacket.
• Soft radiator hoses
• Hoses which collapse under suction when hot, especially the lower return side hose from the radiator.
• Missing or bent fan blades
• Carb heat riser valve stuck in open position

Phase 3

• Wrong water pump installed (Bypass Pump Info)
• Carbon buildup on the head causing high compression
• Cracked water jacket in the head or block
• Leaking head gasket, coolant level is always low.
• Leaking freeze plugs, coolant is always low." I hate to say this but I might have the stat upside down but I am sure I put the sensor to the engine side. Mark H.