How can I test to see if My head gaskets are leaking on my 1995 FOrd F-150 4x4, 5.0L. I never have any coolant drip out of it, I dont see any leaks, and I dont have any steam coming from the tailpipe, but my coolant keeps dissapearing. I havent been checking it regularly, but i know i changed my thermostat a few weeks ago and flushed and filled the system, and now the resivoir is bone dry, and the radiator is low enough that I cant see the level of the coolant when i look down into it. Its been like this since I have owned it, THe coolant in the resivoir is usually brown and when i fill the resivoir up, it dissapears very quickly, but there is nothing leaking out onto the ground, and no smell of coolant burning off the block. When i changed the thermostat, i flushed out the system because all the coolant was brown, is that a sign of exhaust gasses seeping through the head gasket and contaminating the coolant? How can I be sure if the head gaskets are the problem, and could this be the reason the truck seems to have almost no horsepower in hot or humid weather? Any help is appreciated. Thank you.
-John

 

[updated:LAST EDITED ON 27-Jun-02 AT 07:14 PM (EST)]If you are losing it into a cylinder, you will typically see steam coming from the exhaust. My philosophy is that if you're not leaking it and it's not ending up in the oil pan, you must be burning it. IT also could be such a thing as that you just didn't have all the air out of it yet from the flush and it pulled all the coolant out of the recovery tank to compensate. Try filling the radiator and the tank again. Refill again after driving a good distance. And then keep an eye on it. If it sucks the tank dry again, you've got a problem.

 

I would pressurize the cooling system with a radiator pressure tester. Remove the spark plugs and see if you get signs of coolant leakage in the combustion chamber. Sometimes just examiing the sparkplugs will give you a clue. Antifreeze sometimes leaves a greenish residue on the plug insulator or cleans the plugs compared to non leaking cylinders. (Assuming you are using green colored antifreeze). You can probably rent the pressure tool. Autozone loans tools for a deposit. Are their any other clues at all? Engine running hotter? Sweet exhaust odor? Oil residue in the coolant? I know the 302 engine is buried bad and you can not easily see some potential leak areas.

fatfenders

 

Further to Fatfender;

I recently had a leaky lower intake manifold that allowed coolant to drip into the oil pan via the valley. I hear that the bolting and gasket used on the 351w is not all that good a design. The bolts go through the casting at 45 degrees relative to the gasket plane. So when you torque the bolts they feel elastic and getting to the torque spec. is difficult as it keeps slipping/stretching.

Anyway, after i fixed the leaky lower i wanted to make sure i didn't have a bad head gasket. I found a easy way to test this. I went to my friend who works at a carb rebuild shop who has a 4 or 5 gas sniffer that has a very sensitive CO2 sniffer. He had me let it cool down, took off the radiator cap, put a plastic collector bag over the radiator spout and inserted the sniffer probe into the bag. He said that his unit could detect down to as little as 0.2 ppm and that if any leakage was coming from a head gasket it would be able to detect it right away before it got up to temperature. Good news for me, nada on the CO2. It's a driving good now, 20" of vacuum at the tree at idle.

Ron
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