Overfilling Oil

[marshaks]

Several people have mentioned problems with overfilling the oil. What type of problems will this cause with the Prius hybrid system?

[aaf709]

General feeling seems to be a decrease in mpg, at the very least.

[tochatihu]

The notion that the cranshaft and connecting rods might be splashing in high oil has been discounted. In some peoples' minds at least.

When oil is installed to the Prius engine too rapidly, some of it certainly seems to find its way into the intake manifold. I believe this can occur whether or not the final fill is "over". When Prius has oil there it expresses displeasure in a few different ways, probably including reduced fuel efficiency.

[dandeman]

<div class='quotetop'>QUOTE(newtoprius @ May 24 2006, 10:45 PM) [snapback]260733[/snapback]</div>

Several people have mentioned problems with overfilling the oil. What type of problems will this cause with the Prius hybrid system?
[/b]

Well, the same as with any engine.. if overfilled to the point the crankshaft is in the oil, it will foam the oil to the point that air can get sucked into the pressurized oil system..

Bearings don't like air circulating through them...

Also the "windage" loss in the crankcase would go up dramatically. i.e. the source of the loss of mpg.. While the website below is a discussion of helical gear loss, conceptually many of the same things occurs in the crankcase and the definitions of the terms is still correct.
http://www.geartechnology.com/issues/0905/mba.htm

btw I've read here http://www.ornl.gov/~webworks/cppr/y2001/rpt/121813.pdf the oil misting (for cooling reasons) in the MGs is a one of the larger sources of energy loss. Also some good pics of the internals in this document..

[marshaks]

btw I've read here http://www.ornl.gov/~webworks/cppr/y2001/rpt/121813.pdf the oil misting (for cooling reasons) in the MGs is a one of the larger sources of energy loss. Also some good pics of the internals in this document..
[/quote]


Thanks for the info. I was asking becquse I'm wondering if it could be the cause of my 9mo old 2005 Prius needing a new transmission.

[paprius4030]

My Prius teck told me when I first got my Prius that it screws up the various sensors and something else in the intake and causes a no start condition.

[Frank Hudon]

<div class='quotetop'>QUOTE(newtoprius @ May 27 2006, 07:51 AM) [snapback]261761[/snapback]</div>

btw I've read here http://www.ornl.gov/~webworks/cppr/y2001/rpt/121813.pdf the oil misting (for cooling reasons) in the MGs is a one of the larger sources of energy loss. Also some good pics of the internals in this document..
Thanks for the info. I was asking becquse I'm wondering if it could be the cause of my 9mo old 2005 Prius needing a new transmission.
[/b]

ok tell us what the H happened to lose the PSD unit

[galaxee]

<div class='quotetop'>QUOTE(dandeman @ May 27 2006, 09:13 AM) [snapback]261736[/snapback]</div>

Well, the same as with any engine.. if overfilled to the point the crankshaft is in the oil, it will foam the oil to the point that air can get sucked into the pressurized oil system..

btw I've read here http://www.ornl.gov/~webworks/cppr/y2001/rpt/121813.pdf the oil misting (for cooling reasons) in the MGs is a one of the larger sources of energy loss. Also some good pics of the internals in this document.. [/b]

this depends on exactly how much oil you're talking about. if someone managed to shove 6 qts of oil in there, and the computer did not stop the engine (which would normally throw the P3191 no start code) sure, you could have damage. the prius is a slightly different case than the average car. the computer will not start the engine if it doesn't like the oil level.

in the case of a slight overfill, it blows most of the excess out of the PCV valve and you can see it in the throttle body.

the oil you're talking about in the last paragraph is WS ATF, not motor oil. there are no consequences of a motor oil overfill on transmission function.

[jayman]

I think adding the fresh oil too quickly has caused more grief than adding a bit too much. If you carefully follow the PCV plumbing it should be apparent if you flood the cylinder head with oil, the excess will flow into the intake.

I would still like to check my intake, but does anybody know a safe way to move the electric throttle positioner? I don't want to jam a screwdriver in there, what if it's a stepper motor with plastic gears? Would be pricey to fix.

This is a concern to me as I used to regularly clean the IAS/TB assembly of my 2000 GMC Sierra. That involved removing the IAS stepper motor and pintle valve. The shop manual clearly warned you not to try to move the pintle valve by hand or you would break the plastic gears inside the stepper motor. Afterwards you still had to do the Idle Learn Procedure.