02 PT Cruiser woes

I did (for a short time) subscribe to and start a thread on
alt.autos.toyota.camry several months ago to see if I could gain some
insight and determine if there are some common root causes between the
sludge problems on those engines and the one that seems to be on the
Chrysler 2.7L engine. My suspicion is that it has something to do with
some ill advised design tricks that restricted oil drainback paths im
order to make some miniscule emissions gains in the PCV area, but that
is pure speculation on my part with nothing to back it up other than the
(apparently) unsuccessful fixes that Toyota tried with the oil drainback
system.

Undoubtedly both Chrysler and Toyota have some new "lessons learned"
about certain things not to do in their future engine designs from their
little experiments, but I'm sure the public will never hear about them.

I was shocked to learn on the 300M ezBoard forums that the 2.7L will be
used in some of the new vehicles coming out. Who knows if design
changes have been made to fix the sludging and failure problems it had.

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

And those full throttle sessions should be in a high gear with the car at
speed, rather than at high engine speeds (RPM).

 

|
|
| "James C. Reeves" wrote:
| >
| > The Chrysler/Dodge owners manual recommends occasional "short" full
throttle
| > sessions every few miles for the 1st few hundred miles. (But not full
| > throttle "starts"!!)
|
| And those full throttle sessions should be in a high gear with the car at
| speed, rather than at high engine speeds (RPM).
|

Not sure that is true. Unless you have the auto stick option locked into
3rd or 4th gear, the auto transmission kicks down at open throttle and revs
the engine quite high even when driving "at speed". The owners manual
doesn't say anything about locking the tranny into a high gear (and you
can't anyway without auto-stick) or anything at all about engine RPM. It
says only something to the effect to do an " occasional short full throttle
burst" when driving to "contribute to a good break-in routine". Some of
those "bursts" are bound to typically kick up some high RPMs for a short
period of time.

 

Yes, this is like the telephone company when they say that "the minimum
threshold
that it is OK for a phone line to support is 2400 baud modems" while behind
the scenes they are spending millions of dollars on new switching equipment
that
can support 56k dialup.

In short, the quart/1000 is a pure sales and marketing figure, that has no
relation
to the actual oil consumption figure that the engine designers aim for. It
exists
because statistically your occasionally going to have an engine right off
the assembly
line where all the piston rings in it are at the absolute minimum diameter
allowable in the
tolerance and pressure and the cylinder walls of all cylinders are at the
manimum in tolerance, ditto
for the valves, etc. plus throw in a small oil leak that only drips when the
oil
is under pressure - and the automakers don't want to have to spend the money
replacing it, because from their view it's cheaper to throw an extra 20
gallons
of oil through the engine during it's lifetime than replace the engine.

If the engine designers actually used this as a real baseline, then due to
manufacturing variances, the automakers would be paying out thousands in
oil leak warranty claims because you would see quart/250 or quart/500
mile burners rolling off the line.

While it is of course not going to be possible to verify this (since these
figures
are held in secret by the automakers) clearly the engineering baseline is
about 20% less than the amount of oil held between the MAX and MIN oil fill
lines on the dipstick over the recommended oil change interval.

In short, if the dipstick MAX and MIN is a quart, and the oil change
interval is
5000 miles, then the engine designers shoot for a baseline of 1 quart per
6000
miles oil consumption, right off the assembly line. This will most likely
put
95% of engines produced OVER the quart/5000 mile consumption line
during the initial 30,000 miles of warranty coverage. (or whatever the
complete, not extended, warranty coverage period is) The unspoken
assumption
here is that the ordinary vehicle owner does not check oil level between
changes, of course.

The reason for this is obvious if you think about it. It is because once
the
oil level drops below MIN then the engine is sucking air, and
self-destructing.
The automakers have to have as a goal the maintaining of that oil level
ABOVE
the MIN line during the warranty period, as long as the manufacturer's
recommended oil change interval is followed.

Now you can point to all the exceptions in the warranties you want that
supposedly let the automakers off the hook if engine damage that happens
during warranty is attributable to low oil level. However, these exceptions
only help prevent the automaker from paying out on the 1-2% of claims
that would result on those odd-man-out engines that just happen to be
heavy consumers of oil - because there aren't enough of these for the
customers
to be any trouble.

But imagine if an autmaker produced an engine that BRAND NEW off the
assembly line, 80-90% of the engines ran at quart/1000 miles consumption,
the MAX/MIN difference on the dipstick was a quart, and the oil change
recommendation was every 5000 miles. You would have a class-action
lawsuit certified within a few years due to all the angry owners of engines
that
wore out at the 50K mark, to say nothing of the terrible publicity that
would ensue.

And imagine also the damage it would due to fleet sales. Rental car
companies
today almost all of them are doing "unlimited" mileage and scenarios where
people fly in to an airport then rent a car and drive 300-500 miles a day
are not uncommon, and you can assume that no car renter is going to give
a damn about oil. At a quart/1000 miles, you would have rental cars being
sawn to pieces on dry bearings right and left.

And this may actually be conservative anyway because the automakers are
responsible for _emissions_ components up to 80K miles, and extra oil in
the combustion chamber clogs cats and 02 sensors, they may actually be
shooting for a far lower oil consumption figure to get out of paying for
those components under warranty.

Cute. I personally see nothing wrong with a quart/3000 miles, but that
is because I change my own oil at 3000 miles and use dino oil. (OK, now I'm
going
to get lecture from the Amsoil folks) I believe that 3000 miles/dino oil
is the current "conservative" recommended oil change interval.

Ted

 

Ford? Talking about oil consumption? Thats a hoot, after their disaster
letting the 5.4L Modular get on the market with inadequate oil control
rings and poor piston design! They've got it down to manageable levels
now, but the 5.4 was an oil hog its first several years on the market,
and it WASN'T the PCV system.

And my Chrysler engines (both the '73 and the '93) use no more oil than
any Toyota engine I've ever seen.

 

The published ring clearances and bearing clearances on my '93 3.5L v6
are IDENTICAL to the ones on my '73 318 and my '69 440.

And none of them burn oil, either. The older ones *leaked* oil until I
replaced the cork/rubber gaskets with modern neoprene ones, but they
don't burn oil.


The only "big old v8s" that have "sloppy tolerances" are a) the ones
built in the early 50s or prior, and b) the ones people see today that
have been run to the ground on substandard or never-changed oil.

 

I add one quart (or less) per 7000 mile oil change interval on my '73,
69, and 93 engines. I think that's pretty acceptable, especially since
all of them have >200,000 miles on them.

 

That's another topic of debate among armchair mechanics. The
counter-argument is that you SHOULD take it to redline during breakin,
but never hold it at high RPM for any extended period. The theory being
that because connecting rods stretch slightly and crankshafts bend
slightly, the only way to break in the last few thousandths of piston
travel up the cylinder wall is to take it to full RPM.

 

Sales and marketing? I've never heard oil consumption advertised. It
is a warranty-based parameter.

I never said it was a design target.

That's not clear at all. The design target might be no oil consumption
at all or it might be something different. I don't know and you don't
know either unless you are an automobile engine designer or know one
well ... and that assumes they would tell you even then and risk their job.

Except that many engine makers no allow oil changes of 7,500 miles...

I don't think many engines suck air at 1 quart low. I'm not sure what
the minimum is before serious damage occurs but I've seen a few cars
that were run with the level completely off the bottom of the dipstick
with no obvious signs of distress.

I know more about airplane engines than car engines and I don't know
that you can make any extrapolations from one to the other, but my last
airplane had a Continental O-470 that held 12 quarts when full, but
would run down to 2 quarts, yes, TWO quarts before failure occurred.

Matt

 

Geez, Matt, imagine what you could do if you only had a clue.

doc

 

Jiffylube wants you to change your oil every 3,000 miles. They make a _lot_
of money that way. If you burn a quart every thousand miles, then you'll
get into their bays with only a quart or so left in your engine. That's not
very smart for a company that depends on repeat customers,is it?

Burning a quart per thousand miles is definitely an indicator that
something big is wrong with your engine. You should be able to go at least
5,000 miles with today's synthetics, even 12,000 miles, though I wouldn't
reccomend it. Even so, you won't have to change oil because of low levels;
that's totally ridiculous. If you're losing your oil before 4,000, then you
have big, big problems.

Yeah, you can go 50,000 miles without a change, in a decent engine. Not a
good idea, but attainable, if you're not losing a quart per K like you are.

You have major engine problems, my friend, and oil consumption is the the
least of them.

doc

 

Total bullshit, of course. Still, it's the owners' car and this dickhead
will never pay you for doing what he suggests if he's goes wrong.

Always the problem with interenet experts: ask a question, you'll get an
answer. You're money, their time. They'll always have more than you will.

doc

 

I can say with some certainty that it is NOT "zero oil consumption," at
least not if the designer intends for the compression rings to be oil
lubricated

Frankly, I'm amazed at how little oil a nice tight piston engine will
burn (and the fact that the current level was pretty much achieved 40
years ago), given that every few milliseconds the cylinder wall goes
from being bathed in oil to being exposed to combustion.

 

According to you? Not according to some engine manufacturers.

You're one of them.

 

Really? My Grand Voyager just rolled over 140,000 miles last evening
and has consumed a quart of Mobil 1 about every 2,000 miles since I
bought it 6 years ago with 33,000 miles on it. Engine runs just fine as
it has since I got it. When do you think this "big, big" problem will
surface, Mr. Einstein?

And my Chevy truck has 82,000 miles and is 10 years old and uses a quart
every 3,000 miles or so. Likewise, when will the "big bang" event occur
with this engine?

Never said I was losing a quart per K. Are you able to read?

Maybe you are the major problem?


Matt

 

It's already there. You've polluted the atmosphere with over 13 gallons of
burned motor oil in the last six years. Not that you care, apparently.

Add another 7 gallons of burned oil to our mutual environment. Good going;
you're up to 20 gallons, so far. I bet you don't bitch about gas prices,
either. Why should you? You're a major contributor to them. At least your
Chevy truck helps offset the damage by delivering crops to the market. I'm
assuming you're not an urban truck-owner, of course, with the cutesey
tonneau cover over the bed. Talk about conspicuous consumerism! Those
posers really take the cake.

I drive about 8,000 miles a year and change my oil twice in that time. I
might burn 1/4 quart between changes, which comes out to about 1 quart
every 16,000 miles. I'm not helping our mutual environment, but I'm having
a significantly smaller effect on it than you are. And I care about that.
You obviously don't.

If I'm the major problem, then the world's in pretty damn good shape,
wouldn't you say?

doc

 

Ummm - excuse me - but where did that oil come from in the first place?
How many gallons of gasoline do you burn into our mutual environment in
a year's time? A lot more than 20 gallons I'd venture to say.

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

Nice attempt at dodging the issue. I've also polluted the atmosphere
with ~4,864 gallons of gasoline during that time, so I don't think the
13 gallons of oil is exactly significant.

Again, inconsequential compared to the ~5,125 gallons of gas burned
during that same time. I don't complain about gas prices, at least not
much, as I lived for 4 months in England back in the 80s and learned
what a real bargain our gasoline is. It costs less than bottled water
for crying out loud.

Nope, don't deliver crops in my truck, but it is used as a truck. It
hauls firewood, all manner of building supplies, carries a snowplow in
the winter and has 4.56 r&ps for better low-speed work. I hardly drive
a truck to show off at the mall. If I did, I wouldn't still be driving
a 1994 with plans to drive it another 10 years if possible.

Then where'd you get the above statement from?

You haven't a clue about my environmental position. I change my oil at
5,000 mile intervals, which means I use 4.5 quarts for the change and
another quart or slightly more in between for 5.5 or maybe 6 quarts per
5,000 miles, so I'm using in total ~1 quart per 834 miles. You change
every 4,000 miles and assuming you also use 4.5 quarts for a change (I
have no idea what engine you have) plus another 0.25 quart to give 4.75
quarts per 4,000 miles. This is a total oil consumption of ~1 quart per
842 miles. Yep, the extra 8 miles per quart that you get compared to
me makes you an environmental saint to be sure. An you are using oil
filters at a faster rate than me assuming a new filter at each change.
So, I'd now say you need to rethink the detrimental affect your too
frequent oil changes are having on the environment.

Hardly. We have way too many self-righteous blow-hards already.


Matt

 

Thanks, Bill, you and I were thinking the same thing. I just posted a
more thorough analysis on this exact subject for doc the wonder boy.


Matt

 

You can't be serious, can you?

Of course, but the car's designed for that. You knew that, didn't you?

Maybe not, based on your previous ridiculous question. You don't have many
of your preconceptions based in reality, do you?

doc