GT750 Leaks

[simmons1]

Over the winter my GT750 has developed both an anti-freeze and oil leak.

Before I start taking things apart I have never taken apart before I thought I would get some opinions here first.

Anti-freeze

When I pulled the bike out of the shed to service it there was antifreeze under the engine. Looking closer it appears to be dripping off the center expansion chamber that runs directly under the water pump cover with the bike sitting on the side stand. It was not dripping when I parked the bike last fall. It looks like I need to pull the center chamber to get access to the water pump cover. Wayne Meuir that built the engine potentially had some trouble in the past with the cover. I can see a gasket and lots of orange RTV where the cover mates to the engine. Is it possible that just the gasket has failed since it started leaking while parked? If I drain the antifreeze and remove the water pump cover, what exactly I am looking for other than a gasket leak? Do I also need to remove the water pump? How difficult is removing the water pump and what do I look for on the water pump? I do have a NOS water pump that came with the bike.

I rode the bike yesterday and other than the leaks it runs perfect and comes up normally operating temperature just like it should.

Oil leak

Same deal, it seems to have started leaking while parked. Looking at bike from the right side while parked on the side stand the oil appears to be dripping off the side stand bracket. What I can't tell is if the oil is coming out the drain hole on the bottom of the sprocket cover, or is also coming out near the water pump cover like the anti freeze is.

Any thoughts suggestions would be much appreciated!

Thanks!

Rich

[karl pa]

How difficult is removing the water pump and what do I look for on the water pump?

If the pump has been in for awhile, it may be very difficult to remove. I seen somewhere someone drilled a hole in upper case above pump shaft, using a punch drove pump out the bottom, then tapped the hole and put a bolt in case to seal hole.
It could be leaking coolant past the mechanical seal in the pump, but the only way to see the seal is to remove the pump.
It could just be the cover gasket, it could be the mechanical seal has a rough spot, these seals need a mirror surface to work proper.
How much does it leak? maybe the seal will wear in and stop leaking.
Oil leak could be from gear/neutral switch under sprocket cover, there is a case bolt on the bottom left near water pump cover that needs a gasket washer. sometimes oil leaks can take awhile to find.
It could be the water pump bearing has play causing oil seal and coolant mechanical seal to leak. If you remove pump cover you may detect play if you wiggle pump shaft.

[simmons1]

Thanks for your thoughts.

When I pulled it out of the shed there was a fair amount of antifreeze soaked into the wood floor. No clue how long it been dripping. Moving it around and riding it a little it doesn't appear to be leaking real bad oil or AF. I rode it 15 miles the other day on test ride, and there were a couple oil drops after sitting for a few hours and no AF drops on the ground. I am thinking maybe the AF just hit the center expansion chamber and evaporated or once it got up to temperature it stopped leaking.

The next day I rode 3 or 4 miles to the chiropractor and back and within a few minutes or getting home there was an AF spot about the size of a half dollar and no oil on the ground.

It has never leaked a drop before so I am wondering how the bearing could go bead just sitting parked. Stranger things have happened I suppose.

I don't know for sure but I think Wayne put NOS water pump in it when he put the engine back together about 10 years ago when he restored the bike. I am not a super duper wrench and a little worried about messing with the water pump.

I didn't ride the bike much at all in the last year. I may ride it a some more and see if heals itself before doing any disassembly.

I'll put some more miles on it and report back here.

[karl pa]

Another thought is to put some stop leak in coolant, my understanding is that Suzuki used stop leak when these were new. I put some stop leak in my 74 a few years ago.

[simmons1]

Is this what you used?

https://barsleaks.com/product/radiator- ... rate-1196/

Thanks!

[karl pa]

Bars stop leak should be good. I would go a little on the light side of the amount added, maybe 1/4 to 1/3 of the bottle.

[simmons1]

Update.

I added some BARS stop leak and went for a 45 minute ride. Looks I am still leaking AF. Also, still leaking oil.

Lets start with oil first. I pulled the sprocket cover and looks like the oil is coming for Gear Position Switch. I looked in my manual and a parts diagram but didn't see any kind of o-ring or gasket for the switch.

Before I remove the Gear Position Switch:

1. Do I need to drain the transmission oil to not have a big mess?

2. After it is out what parts do I need to replace since I didn't see anything in my manual?

Thanks!

[tz375]

Pretty sure it uses O ring 09280-28002 under either the gear indicator switch or the neutral light (early models).

Water leaks from that cover are typically from a failed O ring or seal. If the mechanical seal has started to leak, that's harder to fix but O rings and seals are easy and cheap. The biggest PIA is getting the pump out. There are youtube videos out there, but it can usually be levered out carefully with teh bike lying in its side.

Remove pipe, tank and side covers and lay the bike down carefully onto some thick blankets after you drain the antifreeze of course. then remove the bottom cover to get to the pump. Order new gasket O rings and seal first of course. Then some the fun part.

If you have access to a machine shop it would be a good idea to machine up a split clamp to go around the pump shaft and lock into the circlip groove. For the rest of us, judicious use of levers and screwdrivers are needed AFTER the impeller and it's tiny circlip and removed to get to the main circlip that holds the pump into the crankcase.

[simmons1]

Thanks for the o-ring part number.

I snugged up the bolts holding the gear position switch bolts and put a piece of paper towel in the valley under the switch. My test ride confirmed that's the oil leak, as no oil dripped after my test ride.

I also confirmed the AF is coming out the weep hole on the pump cover. After a 10 or15 minute ride it leaves a few drops on the ground. Sounds like getting the pump out is a real project that I am nervous about taking on. It went from not leaking a drop to what it is doing now sitting over the winter. I am hoping the means it just o-rings.

That said I have an unused NOS water pump that came with the boxes of parts that came with the bike. My mind is telling me that even if I use that pump I should change the 0-rings on it?

Thanks again for all of your suggestions and help.