General Question About Crankcase Overfill

[Cristobal]

If the crankcase is over-filled, will this get more oil past the rings and expose the CAT to more oil?

I am not talking about gross over-fills, just about a half liter or so.

 

[OneEyeJack]

Could depend on crankcase volume but for most car a half liter might not make any noticeable difference. I'd bet that many commercial operations that change oil and use bulk oil might over/under fill a half liter on a routine basis.

 

[BrocLuno]

It increases crankshaft windage pick-up of oil off the top of the sump. The problem goes up with engine speed. So until it gets back to the normal range, just don't spin the motor very hard

 

[The_Nuke]

Overfilling by 30% or so could be enough to kick off some adverse effects, but not without other extenuating circumstances also being present, e.g. severe duty or extended high RPM operation.

In that scenario, if the oil level in the pan were high enough that the rotating crankshaft is making contact with the liquid oil at each rotation, the oil will lose its ability to effectively lubricate the parts most in need of lubrication due to the air bubbles being introduced by the continuous crankshaft-liquid oil contact going on.

Nothing good follows after that...

 

[Merkava_4]

You have a crankshaft above a pool of oil. As long as the pool of oil stays clear of the crankshaft counterweights, there is NO ISSUE.

 

[Lyman]

It all depends on the design of the engine. I have seen racers pull the pan and test capacity to see how much more oil they could safely run.

 

[alreadyinuse]

Yes, it is all in the design, as to the threshold before whip occurs.

Ford overfilled my now ex's car during a routine change, and I brought this to their attention (I always check work). The guy that came out seemed to know his stuff, and said that generally it's not a huge deal, but her engine certainly needed to be drained, since there was not much "tolerance" for overfill. I'm guessing the crank could start whipping it, under certain circumstances.

Thankfully he was truthful, and they fixed this. Also, check your oil level ANY time someone else does the work for you.

 

[Ratchetgrinder]

Originally Posted By: alreadyinuse
Yes, it is all in the design, as to the threshold before whip occurs.

Ford overfilled my now ex's car during a routine change, and I brought this to their attention (I always check work). The guy that came out seemed to know his stuff, and said that generally it's not a huge deal, but her engine certainly needed to be drained, since there was not much "tolerance" for overfill. I'm guessing the crank could start whipping it, under certain circumstances.

Thankfully he was truthful, and they fixed this. Also, check your oil level ANY time someone else does the work for you.


And check it either with engine full cold first thing in the morning or before use, or if your engine has a different procedure to check it, then use that. Most engines get an accurate oil level check full cold, on a level surface.

 

[Lightninrod]

Mine was overfilled on the previous change by a local oil change shop but it was not their fault. Chrysler/Jeep put a too-short dipstick in the 5.7L engines beginning in 2011. I read about the incorrect dipstick in a Jeep board that I read daily. I bought the new, correct length dipstick and sure enough, my crankcase was overfilled by 1 quart(8 qts instead of 7 qts). Not knowing about this at the time, I drove my 2013 Jeep Grand Cherokee Overland V8 for a few thousand miles before finding about this.

There was no outward signs of this; no oil smoke coming from the exhaust tips, etc. After finding out about the dipstick mistake, I had the same shop change the oil recently with 7 qts of Pennzoil Premium 5W-20 and a Fram Ultra filter.

Dan

 

[lubricatosaurus]

You can check the dipstick right after driving hot to see if you see bubbles on it. Tell-tale sign.

 

[mjoekingz28]

Originally Posted By: BrocLuno
It increases crankshaft windage pick-up of oil off the top of the sump. The problem goes up with engine speed. So until it gets back to the normal range, just don't spin the motor very hard

Seems like a great answer.

 

[4wheeldog]

In my experience, the first problem with an overfilled crankcase is usually oil going through the PCV into the intake. This not good, from several perspectives.

 

[Greasymechtech]

Depends on the engine.

Year, make, model, engine?