First Post - Coolant in my GL1500 oil

[MacNuggit]

First off—I am so thankful for this community. I have lurked on Goldwing Docs over the past month learning about my bike and am truly glad so many users here are willing to share all the fun and interesting things they do with these bikes.

I purchased my new-to-me 1997 GL1500 Aspencade 1.5 months ago in Reno, NV and rode it a few hundred miles to my home just outside of Las Vegas.

The bike had just over 56,000 miles on the odometer at the time of purchase and I’ve put about 1,200 miles on it since then. The bike came with a stack of service history receipts from the Honda dealership, including a full coolant flush and oil change in 2020, among other things.

Today, I decided to inspect the coolant. I removed the cap/plastic dipstick from the reservoir and, to my surprise, the coolant inside was black. Appeared to be full almost entirely of oil.

I cracked the coolant drain nut and good, clear/green coolant came seeping out. “Okay, did somebody just put oil in the overflow tank as a mistake? Maybe I just need to flush that out.”

I decided to then drop the oil to make sure it was okay. To my horror, the engine oil is milky and green.

The bike has run flawlessly for the past 1.5 months. I’ve driven it over a thousand miles so far and I’m planning a road trip with my girlfriend in three weeks to the Grand Canyon. This news has truly blindsided me and I’m worried I may have bought a GL1500 with a blown head gasket or a cracked cylinder head.

I’m at a loss. I spent $4,000 on this motorcycle, another $700 to buy tires and have them mounted, and hundreds of dollars on other misc. things for this bike. Beyond the money, I felt I would ride this bike for years to come and make many memories with it. I’m feeling upset a bit helpless. Any guidance as to what steps I should take at this point would be highly appreciated.

Is it possible that this is the water pump? Is there any answer to this issue that isn’t highly invasive and expensive engine work? Where should I start to diagnose this?

Thank you all again for making this forum a place where lurkers like me can get all the info they need. I hope to keep this bike and remain a member of Goldwing Docs for a long time!

[Rambozo]

I take it you didn't check the oil dip stick when you bought the bike?
At this point it doesn't sound good, but the first thing is to change the oil and coolant just in case there really was a mixup. Also pull the spark plugs to look for signs of a blown head gasket. (plugs will be steam cleaned)

[WingAdmin]

Check the water pump. It has both coolant and oil (coolant on one side, oil on the other) with seals in between. The seals wear out and fail. There is a channel in which coolant or oil which leaks past a failing seal will drip out a "weep hole" (also called a "telltale hole" by Honda) at the bottom of the pump.

I have seen bikes where owners saw a leak coming out of this hole, and "fixed" the leak by plugging it up with epoxy, and in one case, by driving a sheet metal screw into the hole!

This defeats the failsafe, and can force the leak to breach the other seal, mixing oil and coolant together.

In the quantity you're seeing, I would suspect a head gasket, however. Do you see air bubbles in the coolant when the engine is running? Can you do a compression test? You could also buy a combustion gas detector to identify if there are traces of combustion in your coolant, which will usually point to a failed head gasket.

[MacNuggit]

Thankful to see some replies.

While I’m fairly handy with bikes, I don’t trust myself diagnosing and repairing this. Thankfully the Kawasaki dealership down the road is willing to do the diagnostic for me and let me know what needs fixing. And they had another GL1500 on the lift! Said they work on them all the time, so hopefully they know their way around the bike well.

I’ll update when I get some more info. Many thanks.