2008 Prius - burning oil at 135,000 miles

Recently had engine rebuilt including the replacement of the entire engine short block. Kept the old block in the garage. Enclosed are some photos of the old engine piston.

 

I would love to see pictures of the cylinder bore walls. I would be looking for the factory crosshatch finish and/or lack of it in spots.
Thanks!

 

Thanks John, interesting pics. It looks like there's definitely enough crude build up around the ring area for stuck oil control rings to have potentially been the problem.

 

Thats exactly what my observation was as well.

johnjohn - care to share how many miles your engine was at, and what kind of engine oil (brand/grade) you used?

Also, did oil consumption prompt your engine rebuild or was it something else?

 

Hi PriusGuy, I asked that question a bit earlier in this thread. Those pictures make me realize just how much a good quality oil in the prius is money well spent.

 

The crosshatch markings (honing) would have gone by that mileage on the area that the rings are in contact with, as they are only microns deep. These would normally be polished away leaving a glass like finish to the bores. Ware would show as a step at the top of the bore in the piston land area. My observations are the same as Uart of a build up of carbon and lacquer especially in the oil control ring area.

John (Britrius)

 

John,
When was the last time you saw a modern engine apart? In my former career as an independent mechanical inspector, up until 3 years ago, I averaged seeing several in a month. With today's oils and ring construction, cylinder bore wear is not what it used to be. Many engines maintain much of their crosshatch over 100k miles. In fact, Toyota had a bulletin on the 1.8L Corolla engines for lack of crosshatch under which they were replacing engines and I wanted to compare the wear patterns I have seen in those engines to the Prius 1.5.
Besides that, why would you presume to know the reason I was asking for the pics? I never criticized or commented one way or the other about your theory. At worst, those pics could contribute something to this knowledge base.

 

Joe 26, My post was not meant as a criticism of your comments about pictures and I do appreciate the difference in construction of modern engines and the qualities of modern oils.
It is a fact however that many people do not take advantage of the latest lubricants sticking with what they have always used and changing oils at intervals at the same frequency they did 40 years ago.
This again is there choice.
In the UK some vehicle manufacturers stipulate engine oils costing £70 ($110) for one oil change (5 Ltrs) when it is possible to buy 5 Ltrs of "dino oil "a term not used in the UK" for £9 ($14) so guess what oil they buy. Many people buy oil based on price not quality or specification, or go to a cheap oil change outlet not knowing what oil is being put in there engines, or even what grade, they consider oil is oil.
Again I am not saying this is what the OP has done and it could be that the vehicle was bought second hand and has no clue as to the previous owners oil choice.
From reading these forums it seems to be generally considered that UK/EU are of a higher specification or are ahead of those found in the US, but not having access to US oils I have no way of confirming this one either way.
I would be alarmed if in my car "now very close to 100,000 miles" the pistons and rings looked like those in the pictures.
I have dismantled "modern engines" with less than 50,000 miles on them with no signs "apart from the very top of the bore" of cross hatch markings and this on it's own is not an indicator of a bore with excessive ware.

John (Britprius)

 

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what my dipstick looks like after 12,000 km so in 75% hwy/25% city driving. Odometer sits at 312,000 km. I haven't topped the oil once, I believe I'm used some form of synthetic 5w-30 whatever was on sale at Canadiantire. Seems my time is running out...

oh yes the car was on a flat road sitting for at least 24 hours! And yes oil was at the FULL mark after an oil change

 

Looks like your engine is consuming ~1 US quart after 7,200 miles (12K km) which is quite good considering your odometer reading. The distance from top to bottom dimple amounts to ~1.6 US quarts.

At 157K miles, my 2004 is consuming around 1 US quart (5W-30 synthetic) after 5K miles.

 

Just start topping off between oil changes. It's not rocket science.

 

i might cheat and just start changing oil at the minimum mark lol

 

Enclosed are some photos of the cylinder walls per your request.

 

My Prius has round 185,000 miles at the time of repair. I have used whatever oil is on sale at any given time, mostly name brands, but sometimes store brands. The repair is mainly due to significant oil consumption (at least 1 quart per gas fill up), and distant second reason is the poor gas mileage (around 43 mpg and slowly decreasing).

 

Thanks for the pics! If I am correct, I don't see any polished areas or scuffing on the cylinder walls or the pistons. Do the oil rings (the smaller 2 rings that are together) move back and forth in the ringland (not up and down but side to side) or are they stuck?
Thanks again,
Joe

 

Could this be related to the Atkinson cycle or the offset crankshaft?

 

See my update on oil consumption
One for the Experts - Only (Oil usage) | Page 2 | PriusChat

 

Here are some additional photos of the cylinder walls. I do see some darker polished areas going straight down the cylinder walls in all four cylinders.
Inspected all four oil rings. They were free to move in the groove, albeit not very smoothly, and with some frictional resistance.
Also, my mechanic told me that he tested the old disassembled engine by filling the cylinders full of transmission fluid. All of the fluid leaked out within 2 to 4 hours for each of the cylinders.

 

Awhile back someone was contemplating just changing out the valve stem seals and giving the engine a good cleaning rather than purchasing a salvaged engine. I was wondering if anyone has done this and what the results were and cost? Is it feasible to do it or does it make more sense just to buy a salvaged engine with as low as miles as possible and replace the whole thing?

Ema is at 354K now and will probably need something done around 400K if not sooner.

Chris