Getting toasty

[daniel.drives]

My 220k road course beater Marauder was sitting for about 2 weeks while I rigged up a trans cooler that didn't block airflow to the radiator, and installed a Corbeau drivers seat. On a test drive, i hit 210F, 220, 230, all the way up to 240 as I pulled off the freeway and let it idle. Feeling around, the coolant bottle was cold, as was the top of the radiator, so I assumed the thermostat had failed. Waited for the car to cool down, swapped it, burped it 96% of the way, and same issue, only this time it lived in the 220s instead of the 230s. Important note: temp climbs rapidly when above idle, and drops slowly at idle, moving or not. The radiator is two years old Rockauto, the thermostat I thought was bad was less than a year old, water pump is 3 month old oreillys house brand, hoses are original but in good condition. I run no antifreeze, but RO water with water wetter per track regulations (not a problem in AZ/Socal).

My questions are: Could something about my coolant cause a blockage in the radiator within 2 years? Again, the top drivers side was hot, the top passenger side (by the bottle) was cool to the touch, the air coming out of the fan was warmer than ambient but certainly not as hot as it should be with indicated water temps in the 230s. Worst case scenario, does the rapidly increasing temp with throttle indicate a blown head gasket? There's no other signs of excessive water out the exhaust, the coolant isn't disappearing, and oil analysis shows no anomalies.

Two other general questions: I know there's a temp sensor on each side of the crossover tube, which side reports to the gauge and which to the ECU? (assuming that's how it works). Second, I'd like to verify my understanding of coolant flow: when the thermostat is cold/closed, coolant flows down the hose coming from the crossover tube and back into the engine, whereas when hot/open, coolant finds an easier path through the radiator, past the expansion tank, and back into the engine via the lower rad hose, correct? With a malfunctioning thermostat and no real cold weather operation, could one pinch/cap that down hose and delete the thermostat? That would be emergency trackside fix, but I just want to make sure I know my options.

I signed up for a few track days this month, not being able to run because of cooling is a huge bummer. Tempted to parts cannon a radiator and a head gasket test kit to get things moving again.

Thanks in advance for any insight/info

[daniel.drives]

Found my problem: I conflated distilled water, which is what you want, with deionized water, which is chemically active and will cause problems. To avoid that, I used Reverse Osmosis treated water, which should be fine, except that RO water that I found in the store all has minerals added for taste, which build up everywhere. So even though I kept the liquid in the system fresh, I was just adding more and more minerals. Big facepalm.

So I did a chemical flush, I'm going to go ahead and replace the radiator out of caution, and refill with distilled water and water wetter. Will report back after a track day this weekend.

[Peace2Peep]

There is a pretty elaborate flushing/filling sequence to make sure there is no air in the system. That is a problem that any deal with when doing this process.

[sailsmen]

This procedure is based on a collaboration of information from the forums, the Ford TSB and personal experience. I’ve only included what I feel is relevant in order to refill the system properly as quickly as possible. The general concept here is that air will accumulate at the highest point in the system which is the crossover tube.

1) Car must be parked level or on a slight incline with the front higher is even better.

2) Remove the radiator reservoir cap and crossover plug.

3) Fill the reservoir just past the full line. It is best to add antifreeze (3/4 gal is about 20% concentration) or any additives at this time. Cap the reservoir and you should not need to open the reservoir again. In fact ALWAYS CHECK AND FILL THE SYSTEM AT THE CROSSOVER PLUG after verifying the reservoir is full. (Warning: Do not rely on the reservoir bottle to degas the system or indicate coolant level. The reservoir may show normal level even when there is a large amount of air in the system. There have been those who have lost engines due to not adding coolant at the crossover plug.)

4) Get a funnel and wrap some tape around the tip in order to make a seal with the crossover tube opening. Screw the funnel down into the crossover threads until the funnel seats in firmly.

5) With the reservoir capped, continue adding coolant at the funnel until the funnel fills up an inch or two. Squeeze the upper radiator hose a few times to force air pockets out of the piping.

6) Turn the heater temp control to hot. Start the engine and let it idle but occasionally rev the engine a bit to dislodge any trapped air. Add coolant to keep the funnel full if necessary. You will notice many large air pockets escaping at first but eventually the level will rise in the funnel as temperature goes up expanding the coolant. Keep the engine running just until the thermostat starts to open a bit. (About 170-172° with our thermostat) When this happens the upper radiator inlet will be warm to the touch. (It is normal for tiny air bubbles to still be escaping out of the funnel- this happens because the system is open and unpressurized.)

7) Shut off the engine but be ready to add coolant because the level in the funnel may drop as soon as you do so. Quickly unscrew and remove the funnel, top off the coolant and reinstall the crossover plug only snug. (This is done to keep coolant from being expelled because stagnant coolant in the engine becomes heated and starts expanding again) A common mistake is to run the engine too long which creates excessive heat and, instead of dropping, the coolant level rises in the funnel when the engine is shut off. If this happens just reinstall the plug quickly to minimize coolant loss.

8) After 40 min to an hour the engine will still be warm. Slowly remove the crossover plug but use caution because there may still be a little pressure in the system. Top off the coolant again but this time do not reinstall the plug.

9) After 3 to 5 more hours the engine will be completely cooled down and you will need to top off the crossover once more. Reinstall the crossover plug then verify that the reservoir is full. DO NOT OPEN THE RESERVOIR CAP WITH THE CROSSOVER PLUG REMOVED.

10) You may drive the vehicle normally. Make sure the engine reaches full operating temperature. Best to do some highway cruising and/or the engine should see some mid-rpm speeds at minimum.

11) Later or the next day when the vehicle is completely cold again: Do not start the car and do not open the reservoir. Just top off the coolant at the crossover again. If you have to add more than an ounce or two of coolant then repeat this step again after another heat cycle. (For those who want to get every bit of air out you can repeat this step a few times until you can add only a capful of coolant.)

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