1990 Yamaha Big Bear 350 - Oil Change/Diff Change

[steelcity]

Hello all looking to do some first time maintenance on my 1990 big bear 350 4x4 just bought it 2 weeks ago: The oil change seems pretty straight forward with only 1 drain plug and oil filter but the other diif drain and fill seem a little confusing , the front diff drain and fill seems straight forward but then is there 2 more in the rear ? 1 in the rear and 1 in the middle ? Thanks for the help in advance.

Also it mentions in the service manual about once you change oil and start it up to loosen some oil plug up top on the side of the engine to see if oil is coming out it sounds like some oil bleed valve ? Does anyone do this ?

[oxidized_black]

the plug at the bottom of diff is to drain, and the middle plug is inspection and fill hole. just fill gear oil to the top of the threads, as far as opening a bleeder valve, i have never done that, but i just saw that in my manual too.

[oxidized_black]

when we both read about the oil change and the bleeder screw, it was for an oil change without changing the filter. if you change the filter too, you shouldn't have to do this.

[steelcity]

Thanks for the reply ,now there is a front diff and a rear diff(final drive) and how about a middle gear box ? The manual makes note of 3 ?

[oxidized_black]

do you have the service manual? it is here : http://www.quadcrazy.com/atvforum/yamaha-atv-forum/11122-1987-yamaha-big-bear-running-rough.html

the tranfer gear is supplied by the motor oil ... check in manual 2-10, 2-11 and 2-12

[steelcity]

What has me confused is on page 2-29 they make mention of 3 drain plugs 1 final gear case 2 front diff case 3 rear diff case , The front and rear are easy to figure out but the final gear case has me scratching ? Just wondering if anyone has experience with this ? I guess all 3 have filler holes which I just fill up to the threads ?

[oxidized_black]

you have the front and rear diffs with gear oil, (1 & 2)

and you have the engine oil/transfer gear oil (3)

[steelcity]

To help other members in the future here is what I did : drain and filled front and rear differential with gear oil (I used bel-ray 80w-90 hypoid gear oil) and then I did an oil change using yamalube 10w-40 now this is where I got confused : there is the motor oil change with filter ~ 3 quarts and then there is the transfer gear oil drain and fill which also uses yamalube 10w-40 ~ less than a 1/2 qt . Hope this helps .

Edited April 15, 2012 by steelcity
what else spelling

[chopperhed]

Hi, I'm new here, but not new to powertoys. I have a 95 Big Bear here now, for a front end re build again. From what I can see the transfer case has a separate reservoir that has its own drain. I'll soon be draining everything and will have more info as I find it