Overfilling oil damage?

Hi Jonathan,

Sounds like ~5 quarts of oil were added to your engine during the oil change; the excess definitely needs to be drained out of the crankcase.

How much oil can you see in the intake manifold? A small amount is normal.

See attached TSB.

 

The service manual is absolutely unequivocal. Page 1, paragraph 1 of section LU - 1NZ-FXE Lubrication:

"ON-VEHICLE INSPECTION
1. CHECK ENGINE OIL LEVEL
(a) Warm up the engine, then stop the engine and wait for 5 minutes. Check that the engine oil level is between the low and full marks on the oil level gauge.
If the engine oil is low, check for oil leaks and add engine oil up to the full mark.
NOTICE: Do not add engine oil above the full mark."

Toyota specify capacities as follows:

Drain and refill with oil filter change: 3.7 litres (3.9 US quart)
Drain and refill without oil filter change: 3.4 litres (3.6 US quart)
Dry fill: 4.1 litres (4.3 US quart).

Many people here think these quantities are too high - it should be somewhere between the two marks, not right up to the MAX mark. The MIN mark is hard to see on the dipstick because it's right on the tip.

If they're that slapdash they probably used the wrong grade as well. It should be API grade SL "Energy-Conserving", and viscosity SAE 5W-30. The European Prius scheduled maintenance guide says API grade SM from 2006 onward, but the car is mechanically unchanged so I would expect SL is still acceptable.

A serious overfill can result in excess oil pressure. Normally the first thing to go (reportedly) is the rear bearing seal, causing oil to leak between the flywheel and the transaxle (on a manual, this would lubricate the clutch, but the Prius is pretty much bolted together here so shouldn't do any additional harm). Still, fixing the seal requires taking the entire front end out of the car, splitting the engine and transaxle, and basically rebuilding the engine. Not cheap.

 

When you take it back to the dealer DEMAND to speak to the hybrid teck. Each dealer has at least one and he's WELL aware of the TSB's and the oil overfill problem. If the dealer at all care's about their reputation ( especially in this sluggish enviroment) they will correct the problem and give you a free throttle body cleaning since it's their oil change guys fault. Don't let them push you around let them know YOU know what your talking about and want the problem fixed NOW. PS you should always check the oil yourself before you leave the dealer and it should never be above the full mark.

 

Disclaimer: I don't know if the 2004 is slightly different than the 2006-later in this regard. What I've gathered has more to do with these later model years.

It is hard to say how much was added with 3/8" to 1/2" over full. The Toyota refill recommendation alone will put most about 1/4 over as many here have measured directly. Putting in a full 4.0 qts would nudge it a little higher as well. Throw in the possibility of the dispenser giving an extra few percent and 1/2" overfull would be easy to do.

The one thing that is clear is that the oil level is to be between the marks, not above or below.

Whether or not there is/was enough extra to cause your trouble or if it is the cause of oil in the throttle body is a matter of ongoing debate. There is some tendency for oil vapor to condense there anyway (Atkinson cycle perhaps?) so it doesn't guarrantee oil carryover from the crank case if I understand correctly.

But like folks have said, if the dealer overfilled it, they are responsible for fixing the problems since the event occurred.

 

Hi Jonathan,

A coating of liquid is pretty normal. If you saw a large pool of liquid I would start to be concerned. (Note that I say "liquid", not "oil", since it is possible that what you are seeing is condensed gasoline that came up from the intake valves.)

While you are looking around, I suggest that you make the car IG-OFF, remove the top of the engine air filter housing and look down into the throttle body, using your flashlight to help illuminate that. You can open the throttle valve by turning the spring-loaded shaft with your hand.

What do the throttle body interior and throttle valve look like? Do you see any liquid on either? Do they look like they need to be cleaned? If not, then no worries.

If you have the ability to drain the oil on your own, you might want to take on that little project so that you can determine exactly how overfilled the crankcase is. If you have the dealer do it, they won't want to reveal how big their mistake was. Further I would question this dealer's trustworthiness if they wanted to sell you a water pump (hopefully you have personally inspected this to verify that there was no coolant seepage evident on the pump or the pulley.)

Hopefully your driveability symptoms will go away after the oil level is restored to the correct point. If not please let us know. Good luck.

 

Hi Jonathan,

Yes - while you were looking down into the throttle body to see the bottom of the intake manifold, did you happen to note what the interior of the body and the throttle plate looked like?

A normal appearance would be that those parts are dry and clean. If you have lots of miles on your car, the parts will start to accumulate a black coating, and this coating is removed when you have the throttle body cleaned.

Attached photo from my 2004, air cleaner housing has been removed so that the throttle body opening is clearly visible.

 

The Prius engine won't rev like a "normal" car when not moving if the throttle pedal is depressed. You would have to manually turn the throttle plate to do that. The oil in the intake stream is caused by the "Atkinson" valve timing and is normal as is the discoloration of the intake plumbing. Pools of oil indicate a problem.

The amount of overfill you got would be unlikely to cause a problem, other than the rough running. That is caused by the added friction making the start-stop of the hybrid control a little rough. Higher weight oil also causes this roughness. A combination of the two would be really noticeable.

Remove some oil and you will be fine. It could even be removed from the dipstick hole with an oil suction tube. The dealer should make it right, but personally, I would -NEVER- go back there after how they treated you -TWICE-. I'd go back to the first non-dealer mechanic and have him remove oil until the level is just below the full mark. It sounds like he is honest and knows his stuff, even if it isn't hybrids.

 

I thought that your other mechanic decided that the water pump is fine.

I'm interested to know the part number of whatever pump is replaced, since there are two electric pumps (one for the cabin heater and one for the coolant heat recovery system) as well as the mechanical one mounted on the engine.

 

Unless the dealer recovered a computer code that indicates a water pump problem I'd bet there's nothing wrong with it. I wouldn't let them touch the water pump until after you've had the oil level corrected, the throttle cleaned and you've driven it for a while.

 

I was under the impression the "puddle" visible in the intake manifold - with the TB blade manually held open - was residual gasoline due to the Atkinson Cycle. I dipped a long swab into the puddle, it seemed to be gummed up gasoline. When I burned the swab, it also smelled of gasoline

You can get the same effect by putting a bit of gasoline in a small glass jar, and putting a couple of holes in the cap before screwing the cap on. Give it a couple of weeks, you will have a brown sludgy mess in the glass jar as the volatiles evaporate off

I used to think oil overfill was responsible for the Prius Puddle. The dealer did the first two changes, I have done all the rest, putting in no more than 3.3 litrres of oil. Still have the Prius Puddle

Like most garages, the dealership uses an automated central oil filling system. They have bulk, no-name Mystery Oil delivered to a tote bin, a pump sends it to the fill system. THe tech dials in how much oil he wants, and the system then pumps it in, almost like how you pump gas into a car with the nozzle

I have no idea how often these bulk oil fill systems are calibrated, if they even ever are calibrated. So you dial in 3.9 quarts, you might get 4.4 US quarts, who knows

Another issue is fill speed. I've seen the industrial systems in action, and they can do 5 quarts in under 10 secs!

So you pump the oil in so fast, the oil drainback holes can't let it drain into the block fast enough. You flood the cylinder head, and the excess oil gets into the PCV vent system. The vent tube might hold 1/3 of a quart. You start the motor, that oil gets gulped into the intake manifold

 

Does that go in before or after the intake air filters? If before, the filters will tell you.

 

I had something similar on my '05. I had an oil change done at a Jiffy Lube in another state while on vacation. 4 qts were put in. One month later, during some nasty cold weather, the oil got sucked up into the intake manifold and caused the engine to not start. After towing it down I was advised by the hybrid tech that the oil level should be right in the middle, between the fill and full marks. ** approx 3.5 qrts ** Especially in cold weather climates. Luckily mine was fixed with a fresh oil change and the tow bill. Not too expensive.

 

The PCV on both my Prius and my FJ are after the air filter. I also had deposits on my FJ throttle body and MAF, which I easily cleaned out last fall

I think the climate you live in has a lot to do with how quickly you have deposits on your MAF and TB. I know quite a few folks in Utah and Nevada, who have never touched their MAF or TB, and they're almost squeaky clean.

This climate, which can dip to -40 in winter, is pretty hard on a vehicle. The cold temps, more idle time, introduces a lot of vapor into the intake system from the PCV

It's not just Toyota that has this issue. That hunk of s*** 2000 GMC Sierra I used to have, with a Vortec 5.3, I needed to clean out the Idle Air Control poppet valve and IAC passages in the TB twice a year, or it would sometimes be cranky to start and idle badly

Cleaning out the IAC is a royal PITA. YOu have to be careful not to fiddle with the IAC motor or valve, or you could bugger it up. Then after you had everything squeaky clean, and reassembled, you had to go through the Idle Learn Procedure.

The year Vortec the MAF was up against the air filter, near the passenger side fender. I did check the MAF after 3 years, it had some fine deposits on the wires. They didn't have MAF cleaner then, but I used an alcohol-based electronics cleaner. I didn't notice any difference in performance

 

Could be oil was already in the PCV hose. With bitter cold temps, the oil suddenly flowed into the TB area

Again, I have the Prius Puddle even though I carefully do my own oil changes, never more than 3/4 up on the dipstick two dots