Coolant concern: Head gasket?

[JimNNN]

Hi. I have concerns about the color/nature of my recently changed coolant in my '54 Y- Block 239. I put new coolant in recently - Prestone concentrate with distilled water. What I'd drained out before putting it in had me a little concerned because it was a milky whitish color. After minimal driving with the new Prestone coolant (maybe five miles) the coolant was a grayish milky kind of color. (See picture.)



I'm worried that a head gasket is going. The car runs good and smooth - just like it had before - with no coolant vapor out of the exhaust, and little loss of either coolant or oil that I can tell. I have NOT done a compression reading lately, though.



Just to make sure I hadn't neglected to flush all the previous stuff out completely, I flushed it out again and put distilled water in the cooling system a couple of days ago. The next day the water was the same grayish milky color the coolant was after minimal running.



The oil, however, gives no indication of having coolant or water in it. I changed it recently also and the old oil I took out looked fine. I took a picture of the new oil on the dipstick after running the engine a bit and you can see it looks pretty clear.



I'm wondering if the head gasket is compromised so that combustion gasses are getting in the coolant, but not so bad that coolant is getting in the oil. Like I said, though, no vapor out the exhaust. What do you think?

 

[Dobie Gillis]

From your description I'd say you're probably right, a head gasket is on it's last legs. You say you haven't done a compression test lately. How long has it been since the last one? There is a test kit you can get to check for exhaust byproducts in the coolant. I haven't had to use one for a long time but IIRC you run the engine to operating temperature, then draw some coolant from the radiator with a syringe like device that contains a chemical that changes color in the presence of exhaust gas. The kit is not particularly cheap, but may cost less than replacing the gaskets for maybe nothing.

https://www.amazon.com/UView-560000-Combustion-Leak-Tester/dp/B000NPDL76?tag=atomicindus08-20

 

[JimNNN]

Dobie, it was about 5000 + miles ago that I did a compression test. Pretty decent results for a 50 year old engine that had never been rebuilt: all cylinders over 100 PSI and within 10% of each other. But that was well over a dozen years ago.


Thanks a lot for the link to the tester. I'd heard about those, and that's probably the logical next step. Glad we aren't in the dead of winter or the height of mid-summer.