oil in coolant GL1000

Information and questions on GL1000 Goldwings (1975-1979)
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Motorcycle: 1979 GL1000

oil in coolant GL1000

Postby randallkc » Sun May 06, 2012 3:16 pm

I just purchased a used GL1000 goldwing from a customer of mine. He didn't know much about it but had it for almost 7 years. Well I just checked the coolant and noticed the overflow tank was empty and appeared dirty. When I opened the radiator cap there was black oil on top.

Now what?
What is the likley cause?

The bike has 30k miles on it. Seems to run good. Did not over heat. Radiator is full.

This is my first real bike. I am pretty good with a wrench. I am not afraid to tear it down but have never done this engine before. I am pretty clueless.

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Re: oil in coolant GL1000

Postby D2D » Sun May 06, 2012 4:52 pm

Could be as simple as a bad gasket. I'd pull my valve covers and look for signs of water to see if I had a leaking head gasket. You could also pull the plugs and see if there is signs of water in any of your cylinders. It could also be any number of internal gaskets that have failed .. just a process of elimination.

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Re: oil in coolant GL1000

Postby Fred Camper » Sun May 06, 2012 9:21 pm

Sounds like it needs a head gasket. A compression test is one way to get an indication.

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Re: oil in coolant GL1000

Postby seabee_ » Sun May 06, 2012 9:54 pm

The oil could also leak through the seals in the water pump and mix with the coolant. How is the oil? Any water in the oil? Any coolant/oil leaking from the water pump weep hole? See the pic for possible leak problems.
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Re: oil in coolant GL1000

Postby randallkc » Mon May 07, 2012 5:20 am

The oil in the crank case is clean and no water. No signs of smoke of any kind when running the bike. I am gathering the first thing I should check is pulling the water pump and changing the gasket?

Should the water pump just be changed?
How is the water pump driven?

I need a schematic of this thing..

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Re: oil in coolant GL1000

Postby virgilmobile » Mon May 07, 2012 7:25 am

Easiest thing to test is to remove the lower radiator hose and the 3 bolts for the pump cover.Grab the impeller and wiggle it about.It will NOT turn as it is shaft driven.If there is any lateral movement in the bearing....Replace it.
There are O rings in the front cover that could leak oil into the coolant lines too.

Usually if oil is leaking past the water pump seals,it will drain out the weep hole.It should not be able to enter the coolant system from there.The oil on that side is not pressurized but the coolant is.If the water pump seals are bad,the most common result it oil or coolant leaking from the weep hole or if it's plugged,coolant in the oil.
To get oil in the coolant,the oil has to be under more pressure than the coolant pressure,about 7 psi.
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Re: oil in coolant GL1000

Postby thrasherg » Mon May 07, 2012 11:49 am

Before removing/attacking the water pump, I would visit your local Honda dealership and see if they will pressure test the coolant system. As mentioned, if the water pump fails, the water or oil (Depending which seal fails) will normally come out of the drain hole on the bottom of the water pump housing. You need to run a pressure test on the cylinders to see if a head gasket has failed and run a pressure test on the coolant system to see if you have a leak somewhere in the coolant system. The oil you are seeing in there may just be because the previous owner used an oily container to fill the coolant system and not due to a failed gasket. Start with the easy stuff first. Check the cylinder pressure and get the coolant system pressure tested. Depending on your results we should be able to help identify possible causes for your issue. If you just jump in and start changing things willy nilly, it can get very expensive very quickly!! :)


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Re: oil in coolant GL1000

Postby randallkc » Mon May 07, 2012 8:57 pm

Well I toped off the collant and had a good ride tonight. Didn't see any weaping. I think I am gong to flush it clean it all out and see what I got.

When I got the bike it ran so bad I could barley get it home. One of the plugs that goes onto the spark pugs was broken all apart and the spring was laying in the cylinder. I performed some magic with some super glue and it runs great. I was wondering if I can just get a new end piece or if I have to buy the whole coil assy to fix it.

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Re: oil in coolant GL1000

Postby dingdong » Tue May 08, 2012 9:28 am

It will be to your advantage to replace the timing belts asap. This is an interference type engine and if a belt breaks you will at a minimum have valve damage. At most valve and piston damage. Easy to do and the belts are cheap a NAPA.

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Re: oil in coolant GL1000

Postby JellyBelly » Tue May 08, 2012 1:16 pm

randallkc wrote: I performed some magic with some super glue and it runs great.

You gave me a giggle with this line...glad to see another classic running right (with super glue) :-)
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Re: oil in coolant GL1000

Postby randallkc » Tue May 08, 2012 2:28 pm

Lol. Superglue. So far I have spent about $0.50 in parts and materials. I am going to change the timing belts next after a radiator flush.

I have done the timing belt on my VW TDI diesel but not on this engine. I had lockdown tools to set ting on my VW. I am not a big fan of paint and prey. What is the timing belt procedure

What about lining the wheel bearings and other things. I want to go thru this bike to make sure it won't leave me sitting along side of the road.

I would like to get a new ignition wire cap

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Re: oil in coolant GL1000

Postby dbmcd » Thu Sep 18, 2014 6:35 pm

Well I would paint and pray on the timing belts. I did just like was suggested and removed my belts when I first got my wing. I knew it would be simple because the timing marks are right there. Only thing is they are not perfect. It's hard to tell if the arrow is on this side of the tooth or the other...paralax. Therefore if you paint and match the paint mark to the new belt by counting teeth and marking, if will be exactly as it came off. You won't be a tooth off from the way the factory set it. I messed around several times taking the belt on and off because I couldn't get it to run the way it was before. If you paint and mark you don't have to worry about where the gears are relative to TDC, but just don't move them. You are only matching the paint mark on the old belt by counting teeth and marking the new belt, then matching that mark to the arrow on the camshaft gear. BTW I also changed my timing belt on my VW 1.8 Turbo and I marked, it came out perfect---no praying involved except on Sunday.

IF YOU DO discover you have a oil leaking into coolant problem, there's a good chance it's happening under the front cover where coolant and oil are seperated by o-rings and a gasket. I had oil leaking out of the waterpump weep hole. It wasn't the waterpump leaking, it was the three bolts that hold the waterpump in, that allowed oil to slip by. I used gasket sealer and wet installed those stinking bolts!!! It worked.


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