99 1500 coolant issue

[JD Diesel]

I'm Pretty sure it's a bad head gasket. bought this bike that sat for 12 years. And I have been working on it for 3 months going thru everything from carbs to brakes. Got her all fixed up nice and runs great. checked the coolant after my first long for testing. The next morning the coolant was down to the bottom of the fill neck. Toped her off and a couple days later took for another long ride and checked next morning. Coolant down to bottom of filler neck. So I start bike with cap off before long coolant is rising and overflowing. start seeing bubbles coming every now and then. Now I shut it off a big pile of air comes up and coolant goes down. This is why I think its head gasket. So today I do a compression test just to check cylinders. All cylinders read at 120 psi, strange I have never done a compression test and got the same reading on all cylinders. Book says 185 to 242 psi. So all cylinders are low BUT starts and runs great. Any other ideas for me to check ? I'm doing a leak down test later.
JD

[PMC777]

I just saw a video on youtube about that. Check your reservoir and see if it's filling up. If so, check the hose going from the radiator to the reservoir for cracks. as the coolant heats and expands, it flows into the reservoir, then vacuum pulls it back into the radiator as it cools.... You get the picture! .. If you're not showing leaks or burning white smoke, you might only have to replace that hose.

[JD Diesel]

Yep it is pushing coolant to the reservoir. Going to check that too.
JD

[Crusty1]

In addition to the over flow hose and tank tube a failed radiator cap can cause coolant being added to the Tank but not returned. The radiator cap serves 2 function both pressure control and vacuum vacuum to pull the coolant back from the tank. There are 3 seals in the cap. The main pressure seal controlled by main spring, the vacuum valve and small spring in the center and the upper gasket. It’s common for the upper gasket to fail after time. If the rubber is still pliable sometimes you can fix the cap by evening the ears to tighten it.

[JD Diesel]

Yep I replaced the radiator cap last week. Also ordered all the reservoir lines today.
JD

[Crusty1]

A ph based combustion gas detector is a good tool for head gasket diagnosis. No too expensive and widely available able. Also coolant and water are excellent at removing carbon in the combustion chamber so if you see one white spark plug or a clean piston (with endoscope) that would be a good indication.

[WingAdmin]

You can get an inexpensive tester on Amazon that will test your coolant for byproducts of combustion, which would indicate a failed head gasket.

Find This Item on Amazon:

https://www.amazon.com/dp/B07RS3N98V?tag=goldwingdocs-20