Losing transmission oil

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90SDKDX
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Losing transmission oil

Post by 90SDKDX »

I took the bike (1990 E series) out for the first time yesterday for around a half an hour to try and tune in the idle adjustments (big elevations changes from my house to riding area) and to make sure everything was operating smoothly after I rebuilt my KIPS valves.

When I got home I checked a few things over to make sure everything was in working order. Topped off the coolant, pulled the plug (looked okay as far as I could tell), and checked tranny oil. Well there was hardly any tranny oil in the case. The drain plug was a little wet, but not soaked. Pulled the magneto cover and noticed a small amount of oil in the cover (which I knew of before) but nothing major. I then drained what oil I did have left and very little came out (nothing close to the .8Liters it takes).

Now I know from some research that the E series have a supposedly known problem with casing materials on the magneto side allowing small amounts of oil to seep through into the cover. It has something to do with the aluminum on one side and the casing materials being different, so one swells and creates a small oil leak (something like that). So I don't think this is the issue or the magneto side oil seal for that matter.

As far as the tranny side seal I'm not exactly sure how to tell if that would be bad, other than doing a leakdown test. But, correct me if I'm wrong, if that side seal was leaking, and I lost almost a quart of oil through it, wouldn't something have alerted me to this situation (I.e. motor issues, huge plums of smoke, etc...)?

If my memory serves me correctly the last time I checked the oil was at the end of last riding season. I know it hasn't been filled since the summer before that when I first purchased the bike. I'm going to fill it tonight and maybe ride it back and forth to work a couple times to see if I lose any more oil. I put a fresh drain plug gasket on when I put the fill plug back in last night.

Any help or insight is appreciated. Thanks
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Re: Losing transmission oil

Post by osobad »

Tranny side will run rich. Flywheel side will cause lean conditions
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Julien D
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Re: Losing transmission oil

Post by Julien D »

Time for a bottom end. Mix behind the flywheel cover is indeed a sign of leaking crank seals, as is losing transmission oil, obviously. On the other hand, it really doesn't matter if the flywheel side is bad or not, you will want to change it when you change the RH seal. No reason to do just one side.
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Re: Losing transmission oil

Post by KDXohio »

+1 likely the crank seal if there's no visible external leak. I had an issue with me 90 leaking around the sprocket after I changed the sprocket size changed the seal problem solved but with nor external leak its gotta be crank seal
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Re: Losing transmission oil

Post by KarlP »

I think your plan is good. It has been a while since you looked at the tranny oil level, true?
If my memory serves me correctly the last time I checked the oil was at the end of last riding season. I know it hasn't been filled since the summer before that when I first purchased the bike.
I wouldn't start splitting cases yet.
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90SDKDX
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Losing transmission oil

Post by 90SDKDX »

Rode it back and forth to work today (roughly a mile each way). Not far of a ride but it doesn't appear that my tranny oil has gone down. Will ride a couple more days to see if anything shows up.
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Re: Losing transmission oil

Post by KDXGarage »

Are you 100% certain you had the correct oil level before riding?

Transmission oil will not leak out of the flywheel side seal unless it leaked into the crankcase, then went all the way over to the left side.

I am familiar with your comments on the left side swelling/seeping problem. My 1994 had it. I did the Team Green roughening and J-B Weld technique on it.
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90SDKDX
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Re: Losing transmission oil

Post by 90SDKDX »

Jason wrote:Are you 100% certain you had the correct oil level before riding?
You mean before I rode to work or when I took it out to test?

When I took it out to test ride I did not check my oil before hand (silly I know). After I realized I had none I drained and filled. Checked it again this morning before riding to work and it's right around the same level (haven't invested in a stand so got it as parallel with the ground as I could guess). Also pulled the magneto cover off and didn't have any oil in the cover.

I know none of this is definitive proof that my seals aren't leaking but I'm hoping for the best since the season is about to begin. I know when I first got the bike and did the drain and fill on the trans fluid that I used a yamaha crush washer on the drain bolt. The drain bolt hasn't gotten wet since I put the correct washer on there. No signs of external leakage ATM.
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Re: Losing transmission oil

Post by Julien D »

Well that's good news. I hope your problem is not a problem. :)
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Re: Losing transmission oil

Post by KDXGarage »

from when you took it out to test


I hope it is OK
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Re: Losing transmission oil

Post by 90SDKDX »

Jason wrote:from when you took it out to test


I hope it is OK
I did not remember to check it before the test ride. I didn't notice until I got home that my trans oil level was extremely low.
But in an unfortunate turn of events when I got home yesterday from work I saw coolant on my swing arm and sure enough my coolant tank has cracked towards the top so I'll be ordering a new one. :sad:
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Re: Losing transmission oil

Post by KDXGarage »

Weird on the collant catch tank. I know mine leaked a bit when I managed to put the lid on without the gasket.

I would just keep an eye on the transmission level compared to when you first filled it up and verified it was full.
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