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how to know if a crank seal is gone

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Hey ThumperTalkers,

I was wondering what is a good way to check and see if an engine is making oil on either side or if a small leak on the shifter is a problem here. I checked the oil before riding and after and the engine side had lost about 6mm of oil on the dipstick. i know hondas burn off a little oil and the seal around the shift lever is leaking a little but i wanted to make sure it wasn't an issue with the crank seal. Also do i need to split the cases if i have to change the crank seal? ive been told yes and no. i checked the oil when it was warm and the trans side was high and the engine side was low. i filled it back up for a ride today and checked afterward and everything seemed find but i checked it cold. Im kinda at a loss for why my oil is moving around. Could it be that the engine side oil was low because it was spread out in the case? and the trans was high because it expanded from the heat? any advice on these matters is greatly appreciated. If i was unclear just ask and ill explain or throw pictures up. 


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You didn't post the year of your bike but...

On my 05.

1- You can use a chop-stick or mybe your fingers and gently push in the seal for the shift lever.

2 - I recently did both left and right side crank seal's and left side balancer seal. Did not have to break the cases. If you end up doing this also order cover casket's for both side's. Impact gun for the clutch bolt is key

3 - I had tranny oil going to the engine oil side. If this is the case, right side crank seal or left side balancer seal. (mine was the balancer seal BUT since you need to remove both cover's anyway I did the crank seals at the same time)

4 - since the tranny doesn't have a dip stick I'm assuming you measured this out to fill, then drained and measured???? If your getting lot's of oil to the tranny side, most likely left side crank seal.

My bike burns' very little or no engine oil. I run an hour meter and change engine oil, tranny oil and filter every 10 to 15 hrs.

I change my oil and check level. then start and let run a few minutes the add oil as required. I check every ride and never have to add oil between changes. Had valves done and new piston and rings approx. 130hrs ago.

There are threads here on this if you search cus I'm sure I'm missing something

A Clymer manual will help for any serious work,

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filterx best response ever thank you so much. My bike is a 2005 So this should work out nicely. When I go to change my crank seals I can just pull both side covers off and obviously clutch and flywheel and are they like right there? How hard is this to do?

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It's not super hard BUT I've been working on bike's and car's for year's so you have to know your mechanical abilities

Here's the OEM micro fiche our bike's.

http://www.rockymountainatvmc.com/oem-schematic/2# NOTE use the VIN of you bike here

#19, #20 are crank seal's and I believe #22 is the seal which was causing my engine oil to migrate to tranny side

Left and right side crank seal's are different part number's and size's.

As I mentioned, having a Clymer manual to do this will pay for it's self although crank seal's and balancer seals are in different chapters.

Do a search in the 250R and 250X forum's for crank seals or oil migration. I think I remember seeing a really good post in the 250x forum for this.

I wish I'd taken some video or pics while I did this cus it's a fairly common issue with our bike's since they are 14 year's old.

One of these tool's really help's removing the seals

If you have any serious questions PM me since I check here daily and I'll see if I can help ya


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This is the oil after a quick ride approximately one mile and i took it through all the gears and shifted normally. 

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Yeah my tranny oil usually looks kinda of like that although if a inner water pump seal goes, it can effect the tranny fluid.

For the engine oil side - use the dip stick on the left side to check level's.

For the tranny - The bolt in your pic should only be used to check that you actually have any tranny oil. You need to get a plastic bottle or plastic measuring cup that has milliliters markings up to 1000ML. The 700 in you pic is the recommended amount of tranny oil. I measure out and use 800ML of Maxima 80wt and change every second oil change.

To drain or check tranny fluid level - The drain bolt is under the shift lever. Drain what's in there and discrard (unless your sure how new it is). Measure out new amount and fill. Run for a bit, then drain out and re-measure what come's out. If much more than you but in, there's a seal issue. Otherwise, put the tranny oil back in.

The only issues I've had with losing engine oil are..

-Leaking out of shifter seal. Make sure seal is fitted as above. This seal can get pushed out if you blast a pressure washer into this area.

-Dropped the bike where the handle bar's are below the wheel's - Oil will migrate out the crankcase vent tube into the arir filter box.

Otherwise crank seal.

see your pm's for my email address

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