For the first time I tried one of those combustion gas leak tester kits. I refer to the kit that has a test tube like glass tube that you put about an inch of purple fluid in it and then seal the rubber end on it against the opening of the radiatior (cap off). With the engine running and warm you squeeze a rubber bulb at the other end to draw the air at the top of the radiator up through the purple fluid and if there are any combustion gasses it turns yellow. Is this a reliable test? In other words, if you have even the slightest head crack that is causing a leak will it be detected this way? Thanks, Rebecca
Yes, I have found them to be reliable. I have friends that race turbocharged Fords and they swear by that test. It will tell them if it is lifting gaskets (common on SBFs since they only have 10 head bolts) even if there is no detectable coolant or compression leak.
the instructions said to test for 1 minute with the engine warm. I started with a closed loop condition so I did it for 5 minutes until it was obvious that the thermostat was open. I got no color change. I was only doing this to rule out a cracked head or bad gasket in my continuing search for the cause of a bad overheating problem. I am going to knock out the freeze plugs not that I have ruled out cracked head. (Buick straight 8 263). I think that probably my assessment that the water jacket is plugged up with crap will be proven correct. Thanks for your comments. Rebecca
I have the one from NAPA been using it for years If nothing shows up check your water pump impeller might be gone Back flush the whole system
something to look for in the early blocks is the water distribtion tube that ran down the inside of the water jacket to make sure cooler water got from the wate pump all the way back to rear of the block. Was common on many of the long block engines. I am not certain the Buoick had the tube in there, but if it were me I would find out. The tubes were mild steel and with the less that perfect anti corrosives in the old style antifreezes - if any was used at all - they wer comonly rusted out and no longer doing the job they were designed for. The result is a major over heat issue with no apparent cause. Just another thing to consider.
They are reliable, but ONLY when you have the presence of combustion entering the cooling system. In other words, only if combustion is escaping the cylinder into a water jacket. JM$.02
They are a very accurate detection tool. It will let you know if there are combustion gases in the cooling system.
My buick engine does not have a water distribution tube. However, my plymouth engine does (so I know what you are talking about). I pulled the one in my plymouth engine out and it looked perfect so I stuck it back in. Rebecca
I took the cover off the water pump impeller and the impellers looked perfect so I re-sealed it and re-installed it (and now it leaks a little). I think that I will knock out the rearmost freeze plug and see what I see. Rebecca
I just got one of those kits, the kind with two chambers. I tested my flathead and got nothing. Wondering like you if the tester was any good, I followed the instructions and cupped one hand over the end of the tester and my mouth to breath out as I squeezed the bulb to suck in my breath. The thing detected the CO2 I expelled and turned the blue to green. Doing that test gives you confidence in the thing.
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