Why Does My Suzuki GSXR750 Keep Losing Coolant?

If you have to keep topping off the coolant on your Suzuki motorcycle every few weeks but there isn’t a visible coolant leak, where inside the bike could that coolant be disappearing to?

Partzilla’s Suzuki motorcycle expert John Talley hosts live Q&A sessions on our YouTube channel every Friday at 3pm Eastern. In this session, John was asked what could be causing a 2007 Suzuki GSX-R750 to be losing coolant when there are no signs of leaks.

Suzuki GSXR coolant loss

Suzuki GSXR 750 Coolant Loss Q&A

Thanks for the great videos. They’ve helped me a lot with my 07 GSXR750. The problem I’m having is that every 4-5 weeks I have to top off the coolant. I’ve checked all the pipes and tightened all the hoses, but I don’t see any visible leaks. I’ve changed the radiator cap as well. Could it be the thermostat or the radiator?

John Talley: Well, the disappearing coolant, if it’s not leaking anywhere, it has to be going somewhere, so it’s probably one of two places. Neither one of them is really good, but one is much worse than the other. Alright, to really hone in on this, I would suggest to go ahead pressurize the system, roughly 10-12 psi should do it. And you’re looking for leaks in one of two places. One, it could be going past the water pump seal and into the crankcase. Or — and hopefully this isn’t the case — you could have a failing head gasket, especially in between the water passages and the oil passage. If I remember correctly, there are a couple that are really close together. And more than likely, it’s not pumping it into the combustion chamber. Otherwise, you would be feeling a dramatic difference, especially the amount that you’re talking about. And this could be the beginning of a major problem, but it’s better to get ahold of it now, especially if you’re pumping coolant into the oil system. It’s going to do a fair amount of damage very quickly, especially with the tight tolerances on a performance machine like the GSXR. That’s what I would focus in on, and hopefully it’ll just be one of those seals. I think there are two seals on the water pump, and I would suggest replacing them both.