1990 Prelude Si ALB

Greetings to the wealth of Honda knowledge! ;-)

I have the aforementioned car; B21A1 engine, 5spd. It burns oil like a
2-cycle engine. (Seriously, I have to put in a quart every 400 miles or
so) I read on Wikipedia where this particular engine has cylinder
sleeves made with FRM, which tears up piston rings. While it seems like
I should just accept that, I don't believe everything on Wikipedia to be
100% accurate, 100% of the time. My dad suggested that since my car has
plenty of power, both torque and horsepower, it could just need a valve
job to stop the oil burning. Is there a way to tell without tearing the
engine apart and looking? Someone told me that one way to tell is to
start the car, let it idle for 5 minutes, shut it off for 5 minutes,
then start it back up. If it immediately puffs smoke out of the exhaust
pipe, it's the valves. If it doesn't, it's the piston rings. How
accurate is this? Any other ideas? Last of all, how much does the
average piston-ring-replacement cost?

Thanks in advance!

Jonathan

 

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Here's a cheap idea: Check to see if your PCV is stuck open, sucking
your oil vapor out of the engine. Always check the most obvious things
first.

'Curly'

 

given the comment stating "These sleeves are so strong that they often
do not lose their factory cross-hatching marks after 200,000 miles!",
i'd do some more homework before accepting the rest of that commentary.
i don't know what the sleeve composition of your motor is, but i can
tell you that there are /many/ hondas that don't lose their
cross-hatching after somewhat higher mileage than that, and they're only
cast iron.

sure, i can tell you right now - replacing valves won't stop your oil
burning. maybe replacing the valve seals will, but valve stem loss is
relatively minor. on the old days, valve stems never even had seals.

maybe, maybe not. unreliable.

look for the gotchas before you do any serious work - as curly says, a
defective pcv valve will have you drinking oil most impressively. other
factors include incorrect ignition timing [too hot combustion
temperature causes excess evaporation], leaks [obviously], and excess
fuel [dilutes oil film on cylinder walls]. if you address all the
above, and you have low compression, go ahead and do the rings, but make
sure you're dead certain about the ring material. if it is indeed a
composite, you may be forced to stick with the original honing, but as a
general rule, you always have to re-hone otherwise the new rings never
bed in properly and the motor will forever burn oil by the gallon.

 

I definitely agree with that. I regard Wikipedia as the world's largest
repository of completely unvetted information. It can give very good
starting points for research, though.

My dad suggested that since my car has

The smoke indicator has mostly gone by the wayside since the catalytic
converter also burns smoke once it gets going. 5 minutes of running is long
enough to make it likely that the converter will suppress the smoke. A
better indication of bad valve seals is a puff of smoke on startup; same
concept, but with a cold converter. Caveat: a bad PCV valve can cause the
same indication.

As 'jim beam' points out, that is a smoke source rather than a place for oil
to disappear. We've seen several reports of oil consumption in your range,
even in relatively new Hondas. The only ones I know of that were tracked
down by tenacious service departments were from a broken ring in one
cylinder. Repair in an older engine would be essentially an overhaul,
because of the number of wear items that should be replaced if you are going
to have the engine open that much. A replacement "jdm" engine is usually a
cheaper approach.

You don't mention smoke, which is consistent with the converter burning it
off as it should. If your only symptom is that you have to top off the oil
every time you fill the tank, it may be your most reasonable way of dealing
with it - carry oil.

Mike

 

Mike,

Thanks to you [AND EVERYONE ELSE] for your input!

Well, I have been carrying oil in my car, by the case, as a matter of
fact. I have noticed this though: I start the car, back out of my
driveway, and then as soon as I shift to 1st and proceed forward, I can
look in my rearview mirror and see a small cloud of blue smoke. The
weird part is, it's just a cloud, not a trail. I see smoke sometimes
when I get on the gas going down the interstate, but I figure that's
just the build-up from the catalytic converter getting blown out. (The
smoke appears to be brownish, not blue or gray, and typically appears
once the RPMs hit around 5k or more) I've had a friend ride behind me
and asked him to look for blue smoke, and he said he hasn't seen any.
(I even asked him to make sure the smoke I see when I gun the gas isn't
blue, and he said it isn't) Now, time for my ignorance to totally
shine: Where exactly is the PCV valve located on a Prelude? (I would
generally be able find this out myself, because I usually purchase a
Haynes manual for every car I own; but believe it or not, there is no
Haynes manual for my car. I checked with both Advance Auto and
AutoZone, and they said that they can't even order one. It doesn't even
exist) Also, how do you tell if a PCV valve is bad?

Thanx again!

Jonathan

 

do NOT waste your money on a haynes manual - utter utter garbage. go to
helm.com and buy the factory honda workshop manual - the best tool you
could ever buy for that vehicle.

regarding smoke, oil is generally "blue", excess gas when cold is black,
excess gas when gunning it on the freeway is brown.

don't waste time trying to test the pcv valve - just replace it. it's
cheap and the new one is guaranteed to work properly.