Not again!!!

Well here I go again. About 6 months ago I had a one time deal with oil flowing out of the oil check hole. :thinking:Today took the beast for a ride and on the end of the trip checked the oil and their we go again. Oil was flowing out the hole, but this time it was mixed with coolant ( kinda dark creamy green)why! I thought I took it very easy on this bike. Im guessing its a leak in the head gasket and im just wondering if any one else had the problem and what should I pay to have this fixed?( I would love to do it but I think this over my head)I did change the oil 2 times and it did look a little creamy. I just dont understand why the coolant stays the same leave. If any one cane help I would be very greatful :)

If your coolant is staying at the same level it isn't coolant in your oil. The radiators and the capture bottle needs to be checked to see if they are both at the same level all the time. If the system is compromised it may not allow transfer of fluid between the capture bottle and radiators. If both these are at the same level then you are getting water in from somewhere else.

Do you do any water crossings? Leaving it sit for awhile would allow some mostiure to get into the engine but as soon as your run it for a bit it should evaporate out of the engine.

If you are talking about the weep hole on the bottom of the right side of the engine. You need to replace the water pump impellar shaft, oil seal, and water seal. $50.00 for the Yamaha parts. :)

No Indy, the oil was comming from the dip stick hole. I took a short ride, shut it off and decided to check level and it just pored out ( about 2 cups full of dark creamy green oil). So I changed the oil, 2 times, not as light, very light cream shade. Took to the dealer so your prayers are very much welcome. :)

when you changed the oil, did you pull out the strainer on the frame down tube? almost sounds like it's clogged. good luck.

Green creamy oil eh?

It doesn't take much coolant to do that to your oil especially if you only have 1200cc of oil to begin with!

I would guess that couple oz of coolant would do that. Especially if gets circulated for a little while.

Also if the engine is hot the coolant /oil mixture will it will want to percolate out of her!( trying to boil)

My bike did the puke thing last time I changed my oil as I was too Drunk to remember to drain the frame.

All I drained was the cases , added another 1200cc and checked the oil level after warming the engine for 2min and it poured out of the dipstick hole.

Apparently bikes and booze don't mix for me , even when I'm not riding her.

Anyways sounds like a base gasket or inner seal of impeller is passing coolant into the oil.

If it was the head gasket you'd be burning coolant -and would know it from all the white exhuast and stench.

Fix it right away , and at least drain the oil right away if you can't fix it like "now" cause the coolant will bugger your clutch fibers if they bathe in coolant for long.

If it were my bike I would dissassemble the clutch, wash the plates in varsol, soak them in engine oil and reinstall.

Also flush the engine with a couple of oil changes after the problem is corrected.

Even a minute amount of coolant will glase, then swell the fibers, eventually needing replacement.

I know first hand as I learned it the hard way when My last cr500 blew the inner impeller seal and the coolant got into my tranny oil.

Good Luck :)

When I bought my bike and changed the oil for the first time, I checked the strainer it was extremely dirty, cleaned it, then replaced the filter which was less clogged but still dirty. In your situation, a clogged strainer/filter could cause a differential pressure situation across the filtration system, leaving the downstream side at, you guessed it- the dipstick. This might help with the oil coming out of the fill problem, but as far as the coolant IN the oil, I would take the bike to a radiator shop. They can put a test cap on one of the radiators and pressure test the coolant system. If the system dosent hold might be in a wee bit of trouble since the leak is obviously internal.

Just my thoughts, but I think the radiator shop would do the test for you at no charge, then if it was a leaker, you could take it in to the dealer and tell them what the problem is. That might reduce your bill a tad. :)

out- DD

Well I got it back from the dealer and Rod told me they couldn't find a thing. I asked them to flush coolant, bill was $35 bucks. Just sucks big time. He said coolant level was fine alone with oil level( I told him I had changed it two times the night it overflowed with the dark creamy green oil) Maybe I have a small leak at the impeller or base gasket like dubious said. I might change, check the oil level more often,until the leak becomes worse. Thanks everyone :)

I had kind of the same problem. The only difference was my oil was creamy red. I changed the oil once and warmed the bike up, drained the oil and it came out the same.

It runs like a top and does not smoke a bit. I checked the water level and it appears to be ok. I just picked the bike up used and I did check the oil before I went out for the first ride and it was fine.

I did do some water crossing where the water was above the bottom frame rail and the head vent tube. I figured this was the problem and draining the oil twice would cure it but it was just as bad the second time as the first.

I already have the 2000 water pump shaft, seals and bearing ordered. Since the bike is used I figured it was better to know this upgrade was done and when.

My question is, why is my oil red and not green like my coolant? :)

P.S. The bike is a 1998 WR400F and I can not find a screen in the down tube. Where should it be?

There's a big (24 mm?) nut at the bottom of the front of the frame downtube. A hose connects there that goes to the bottom right side of the engine case, just under the oil filter. It should be checked for debris once an hour, so man, you're screwed. :)

Obvously, I'm just kidding. I check the screen about every 10 oil changes. I used to do it every 3 oil changes but that was a big waste of time.

Your oil is red because red looks like light brown. If it gets aerated because it's overfilled (or if the screen is so clogged it fills up in the frame) it will look pink or red. If that is happening I have a feeling the engine will suffer oil starvation damage.

If you don't have coolant or oil coming out of the water pump weep hole then it's not leaking. Wait until it starts to leak before you change it because you're wasting good seals otherwise. And don't forget to get a new right side engine cover gasket when you do change the water pump seals and impeller.

I may very well be wrong, but I see no way that coolant can get into the oil at the water pump unless there is a catastrophic seal failure and then you'd have oil and coolant all over the place. There is an air gap open to the atmosphere between the two seals and therefore can't pressurize so there seems to be no motive force to drive the coolant into the oil or vice versa.

:) Well I ripped the whole think apart and I see what you mean about the air gap. I did figured out where the screen is and it was spotless.

There was definitely moisture in the oil because there is a milky foam on the cover and I can see drops of water on the clutch. I don't think it is coolant because it is not the slightest bit green and there was no sign of water coming out of the weep hole. I think I must have sucked some water up the valve cover vent tube, I did stall a couple of times in a flooded section of trail where the vent tube was under water. :D

Since I have the cover off and all I think I am going to install the new seals, shaft and bearing anyway. The old shaft looks like it is starting to get grooves where the seal rides.

Thanks for the info!


If you run the bike through water deep enough that the crankcase breather tube is under water, you are OK, it doesn't suck water into the engine. If it stalls and you try to start it with the vent tube under water, then it can suck water up into the engine.

I have gotten water into the engine a few times because I dumped it in a large puddle. If you change the oil a few times and clean the screen and filter between each oil change you should be fine. Run the engine for a few minutes between each oil change and check for signs of water in the oil after you drain it. When it comes out clean you should be good to go. I always use cheap oil for those clean-out oil changes.

Rich, Thanks for the help! It makes me feel a lot better. :) I thought I would have to rip the whole motor apart and replace all the bearings and the clutch.

I will change the oil a few more times and change the placement of that hose.

Thanks Again!


No one is saying what oil ( brand ) they are using. The oil brand could cause the color of the creamy oil. I am wondering if you check the oil hot after riding, it could possibly be aerated from the tranny and the crank and be in a foamy state the same as if you overfilled the diff or tranny on your truck. If this is the case then it would come pouring out when you pull the stick. I think that your manual will have the oil check procedure. Also put tees in the two carb vent lines and the breather tube to prevent sucking water or starving the carb for fuel in water crossings. My .02---WR Dave. :)

Can you elaborate on these "tees" possibly with pics? Im a little confused but it sounds like a good idea. Thanks :)

In the two carb vent lines I installed "T" fittings below the top of the tubes arc over the carb and I ran hoses up under the tank. If any water gets into the tube from the top it simply runs to the "T" fitting and out to the ground. Or if the lower tubes are in water the carb can vent from the tube running up under the tank. On the breather hose I installed the "T" fitting at about the valve cover split line and ran the new piece of hose up behind the left rad and under the tank, it performs in the same manner as the carb vents. PM me your e-mail address and I will send whatever pics I have. WR Dave. :)

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