97 Honda CX 40 mpg but burning oil?

Hi, I have a 97 Civic with 165k miles that seems to run strong and get
good gas mileage. I do courier type work and have been getting 38 to
40 mpg. I do use a fair amount of oil, about a quart every 700-1000
miles, although I don't notice any smoke. Passed emissions three
months ago.

I haven't done wet/dry compression test yet but will soon.

I guess my question is whether burning oil usually corresponds with
lower performance or gas mileage? Do bad rings or seals just let oil
in and then "seal" under the power stroke/pressure?

Thanks for any ideas... Tim

 

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Check your PCV. It's probably sucking out your oil (vapor) invisibly and
burning it. Most folks recommend a Honda valve, but they are expensive.

'Curly'

 

wrote in @r35g2000prh.googlegroups.com:

Excellent chance your rings are shot. Rebuild/replacement time.

No smoke because the cat eats it up.

Mileage unaffected because engine burns it as though it were gasoline.

Power has been lost, but it happens so slowly you don't notice.

Emissions unaffected because modern engine oils combust very cleanly, to
protect the cat.

 

Thanks for the info, I guess the compression test would tell for
sure?

I plan to put about 500 to 800 miles a week on it for the rest of the
spring, summer, and into the fall. Unless something fails completely,
I will probably run it up to timing belt replacement and then change
out everything.

Is rebuilding or replacing the block and head generally recommended??

 

rebuilding is simply uneconomic on a readily available commodity motor
like this. buy a used low mileage japanese import engine and replace
the whole assembly. much cheaper and more reliable.

 

Thanks again, where do I shop for a motor? Online, at a junkyard, or
a local engine remanufacturer? I think I called a "engine" place once
and they wanted $3,000 which seems way to much. I generally like to
shop local, online purchases this big always seem to go wrong, I am
near Philly, PA.

 

search online for "jdm import motor". should be in the $300 to $500
range for your engine. i wouldn't bother with a domestic junkyard motor
- it'll be much higher mileage and made here so maybe subject to the
same quality issue you have.

 

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Did you check the PCV ? ? It's only worth about $20 and might cut your
oil usage by 75%

'Curly'

 

agreed - check that first.

 

I was thinking along the same lines that it is often a ventilation issue
that causes a gradual increase in oil consumption particularly since
160K is not real high mileage for a Honda. OTOH, if there is a lot of
stop 'n go, an engine will "age" faster.

JT

(Who wishes it was that simple on the $200 Civic turdbox...)

 

Thanks for all the help, I looked for the PCV valve but couldn't find
it offhand, even under the intake manifold. There just seemed to be
standard hose connections. the manual I have is pretty unclear,
nothing specific to my exact car. The PCV valve pics I have seen for
this car are 90 degrees, I haven't seen anything on my car that
corresponds with the pics.


What I did find was a hose directly from the top of the valve cover
into the throttle body, directly under the air filter. There is a
oily trail from that connection down into the throttle. I didn't see
any valve, there are two 90 degree hose connections( which were
flexible, couldn't feel an internal vavle) and a metal tube. It
looked stock but should there be a valve in between?

 

I did find the PCV valve way up above the oil filter and cleaned it
with carb cleaner, the "rattle" seemed to be smoother and louder so
maybe it was clogged. I will check out the oil mileage this week....
thanks again.

 

===================================

You have to check it by blowing through it. It's supposed to allow a
certain amount through one way, but none the other. If the spring is
fatigued or broken (rusted to nothing), sure it will 'rattle', but not
work. Walk into the dealer and ask them if you can compare a new one.

'Curly'

 

Right, it allowed the carb cleaner one way only, I will give it a week
or so and see what happens. Thanks...

 

Keep us posted.