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Re: New valve seals or rebuilt cylinder head? Corolla
"Munchman" <einsteinford@yahoo.com> wrote in message
news:1145154060.768818.303720@j33g2000cwa.googlegroups.com...[color=blue]
> ***1986 Toyota Corolla FWD Sedan, carb, single cam, 173,000 miles,
> 3-speed transaxle
>
> We've had HEAVY white/blue smoke and MAJOR oil consumption for some
> time without changing the valve seals, but the car ran fine with no
> major problems. For less than a week, we have been experiencing a
> major problem that we attribute to a complete failure of one or more of
> the valve seals.
>
> The car now makes a constant valve chatter or clicking sound ONLY when
> in gear and accelerating. When the transaxle is in PARK or NEUTRAL, no
> valve chatter or clicking is heard, even when the gas pedal is pressed.
>
> The valve chatter and clicking is accompanied by a MAJOR loss in power.
> The car usually stalls when coming to a stop. When coming to a stop
> light, the transaxle must be shifted to neutral, and the gas predal
> pressed, to keep the engine from shutting off. To move the car again,
> we shift the transaxle to first gear, then FLOOR the gas pedal. If the
> gas pedal is not floored immediately after the transaxle is shifted
> into gear, the car will stall. Then the car moves at a snails pace,
> especially when going uphill, until some momentum builds up.
>
> If valve seals completely burn away, what parts are slamming together
> to make the valve chatter or clicking sound while accelerating? Is the
> valve chatter and clicking caused by the fact that keepers, spring
> retainers, springs, and spring seats are loose without the oil seal, so
> when accelerating they vibrate against each other? Are the valve
> guides affected by a valve seal that has been completely burned away?
> Can replacing just the valve seals alone solve this problem? Do
> additional parts need to be replaced?
>
> Or, is a rebuilt head the best option? If so, where is the best place
> to buy a rebuilt cylinder head and how much does it cost?
>[/color]
I don't think you are hearing valve train noise because valve train noise
would be evident whether it is in gear or in neutral and whether or not the
engine was under load.
Clattering noise under load and loss of power sound more like pinging than
valve train noise. Check the base ignition timing and see if ignition
timing advances as RPM increases. If the timing doesn't advance, check the
vacuum and centrifugal advance mechanisms. Make sure that the distributor
doesn't have any engine oil under the cap. If there is engine oil there,
the O-ring on the shaft is leaking and can be replaced.
Check for vacuum leaks - they can keep the ignition timing from advancing
and cause a loss of power and poor idle.
The oil leaking into the engine may be due to leaking valve stem seals (not
valve seals) or a problem with the piston rings. It is possible that
deposits have built up in the combustion chamber due to the leaking oil, and
these deposits can cause problems with the air/fuel mixture igniting at the
incorrect time, causing the noises you're hearing. Higher octane fuel can
reduce this effect somewhat but I doubt if it would cure the amount of
pinging that you're describing. If higher octane fuel does not eliminate
the pinging due to combustion chamber deposits, then the only cure is to
remove the deposits. A service called "Motor Vac" may work, or a walnut
shell blasting, or engine disassembly are the only ways to remove deposits.
--
Ray O
(correct punctuation to reply)
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