Overfilling an oil tank?

[ATVer14]

Does anyone know if there are any problems associated with overfilling the stock 400ex oil tank? I just checked my oil level after I changed it and ran a night of racing on it, and noticed the oil level was about 1/4 to 1/2 of an inch above the fill line on the dipstick. Are there any problems with running it this way? Thanks
Kenny

[300exjuggalo]

you could blow your oil rings if you keep doing it

[Dune Surfer]

Originally posted by 300exjuggalo
you could blow your oil rings if you keep doing it
How? why?

[ATVer14]

On the piston? Why would that happen, oil level shouldn't have anything to do with the piston rings, right?

[Honda Jay]

I agree with ATVer14 about the oil + compression rings, the only thing i have ever heard about oil level is when it is too high the crank will spin in the oil and churn up bubbles in the oil and that air being in the oil will heat up a lot. that leads to a seased motor. i just run mine at full, which is a after i warm the motor up, let set and start again with NO throttle so the oil pump doesn't foward more oil through the system and keeps a study balance within the entire assembly:D

[Honda Jay]

sorry, SEIZED, brain fart

[TORO1968]

I, too, have overfilled my oil tank at times, however, I don't belive that this is a problem. The reason: the 400ex engine is a partially dry sump engine, meaning it cycles oil from the tank, only drawing how much it needs from the base of the tank and returning it at the top. The flow rate of entering and leaving oil has to be exactly the same as well. So, if the tank was "overfilled", how could the engine draw more oil than if it was at the full line?

In addition, I believe the oil tank has more than enough room to hold at least another quarter of a quart.

So, when and if I install a Pingry or CFM oil tank that allows me to add more oil then stock, am I gonna screw up my engine? :rolleyes:

Hey ATVer14, I wouldn't worry about it... :)

[flyin#5]

if you overfill it it will most likely blow your rings. the four stroke motor is not made to burn oil with gas and if you overfill the oil it will get into your crank and reach the piston and burn with the gas. idk it is hard to explain.

[Mr_Bub400ex]

if u were just racing the motor would be hot and the oil expanded

[ATVer14]

Thank you for all the replys, and after reading all of them, I think that I agree with TORO1968 the most. Since the 400ex is a dry sump engine, it would make sense that overfilling the oil tank wouldn't cause any problems with blow-by near the piston or bubbles caused by the crank. So now the only other problem I might see is that when the oil expands after riding it for a while, would that build up too much pressure in the oil tank, causing it to crack, or won't that happen?
One last thing, are you supposed to check oil level when the engine is warm or cold?
Thanks
Kenny

[QuadTrix6]

Originally posted by ATVer14
One last thing, are you supposed to check oil level when the engine is warm or cold?
Thanks
Kenny

let it idle for 5 minutes when is cold then check the dipstick without screwing it in

[RIDER11X]

Originally posted by TORO1968
I, too, have overfilled my oil tank at times, however, I don't belive that this is a problem. The reason: the 400ex engine is a partially dry sump engine, meaning it cycles oil from the tank, only drawing how much it needs from the base of the tank and returning it at the top. The flow rate of entering and leaving oil has to be exactly the same as well. So, if the tank was "overfilled", how could the engine draw more oil than if it was at the full line?

In addition, I believe the oil tank has more than enough room to hold at least another quarter of a quart.

So, when and if I install a Pingry or CFM oil tank that allows me to add more oil then stock, am I gonna screw up my engine? :rolleyes:

Hey ATVer14, I wouldn't worry about it... :)

I agree TORO1968, That extra room in the tank is to hold extra oil after running at higher rpm going backto idle, more oil is coming in than going out, (Need MORE room.)JMO:rolleyes:

[lilpoppy]

There are a lot of oppinions in here but the fact is that the owners manual says overfilling will cause damage. Don't do it.

[TORO1968]

So it sounds like the engine won't draw more oil than it needs, but what you guys are saying is that there still needs to be enough room in the tank for excess oil to return after being run at high RPMs. However, the crankcase is always going to have a certain amount of oil in it, and if the oil tank has only so much oil in it at idle, how can the amount of oil in the tank after high RPM running exceed this level? If it did, this means that the oil level in the crankcase would have to decrease.

In addition, the amount of expansion for motor oil once it heats up is negligible...Viscosity change is the main thing that happens to oil as its operating temperature varies.

[SUPERFLY 400]

I woundn't worry about 1/4" or 1/2" over the full mark. The oil pump will only pump what is was designed for. It does not care about how full the resivor is (unless its empty). As for the oil rings on the piston blowing...Not gonna happen, if anything goes bad it will be your seals because of too much pressure, thats why there is a vent or breather if you perfer to let pressure escape. As for the piston rings a dirty airfilter or dirt falling down in the spark plug hole when changing it will damage rings before overfilled oil and besides your not overfilling the sump. just the aux. oil resivoir but lets be reasonable about overfilling and not going hog wild and fill the thing to the top, because oil expands when it gets hot......or a unopened soda can left out in the sun to long:D

[TORO1968]

Finally...someone that I agree with! :D

[SUPERFLY 400]

Toro, mechanical engineering...nice choice. I'm a tech for Freightliner. Sometimes you have to set the young pups straight on mechanic's. LOL:D

[TORO1968]

Thanks...I hear ya on that one! :D

[ATVer14]

I'm studying to be a mechanical engineer? Does that count? I'm an intern at Caterpillar tractors now, so I'm picking a lot of stuff up on cooling, lubrication, and hydraulic systems :D
Kenny

[DirtDiggler]

I don't know the answer but Toro does make sense especially if you put in the perspective of a bigger oil tank. If you have a stock tank or a tank that holds an extra quart it's not like the oil pump can tell how much oil is in the tank it just pumps what it was designed to pump. If you found a way to put a larger amount of oil in under pressure that would force it's way through the pump that might be another story. I would think you could do some redneck engineering with a little duct tape and put a gas tank in there to hold oil and the pump wouldn't know the difference.
Diggler

But then again it's not like I have a clue anyways;)

[Doibugu2]

On the 400 your supposed to check the oil when the quad is warm.

Now for my 2cents. Honda says 1.95 quarts for a reason. I may not know what that is, but the is my opinion. Doesn't matter if you have a 1 qt oil tank or a 5 gallon, its the pressure in the engine that matters. If you don't have room for the oil to expand, then your going to blow something. Your response is that is why they installed the vent or breather. Well what happens if the vent s cloged or blocked? I will bet that the vent was installed as a prevention device. So if you had to much oil and the pressure builds as the quad gets hot, instead of the pressure being released from the vent it gets released through one of several other things, like rings or seals.

But again that is just my uneducated accounting degree talking. And oh yea a little extra I don't think is going to hurt.

[TORO1968]

Hey ATVer14,

Which location are you working at? Somewhere in Peoria? Just wondering, cause some of my friends work over there.

-Jordan

[toby400ex]

If the engine is always gonna have the same amount of oil in it then why would it hurt anything. I would think as long as their is a little room in that oil tank there will be enough room for the oil to expand in it. But I seriously dont know. Will that extra .05 liters of oil make a dif if i just poor both of the bottles in completely. I dont wanna have to little and im to lazy to find out how to convert whatnots.:rolleyes:

[ATVer14]

TORO-
No, I'm in the Aurora plant. Do you know anyone there?
-Kenny

[PHIL_B54]

the vent is to vent blow-by that makes it past the rings, ever seen a tractor thats in need of a overhaul, more exahaust will come out the breather than the exahaust

they then just vent it back into the engine via the air boot for emissions

i will say this, the oil res has a 3 functions(if i remember back to college) 1) cooling 2)storage 3)settle out the air bubbles which is kinda part of storage i would guess that you would have to have a little room for the air to settle to, like someone else said just dont go crazy and i wouldnt worry about it