How often does a valve job make rings go bad? (123)
Don Stauffer
Nick Halloway wrote:
>
> ... on an older engine with 127K miles on it?
>
> Half the time? 10% of the time?
>
> A shop did a valve job on my engine with that many miles on it. A
> leakdown test was OK at the time, but the rings went out 1000 miles
> later. They didn't warn me the valve job might do this.
>
> If this happens half the time, it's something to complain about, if
> it's rare, no.
>
> Thanks ...
Very rare. But what I don't understand is why, if the leakdown test was
okay, you had the valves done?
--
Don Stauffer in Minneapolis
home web site- http://home1.gte.net/stauffer/
home email- stau...@gte.net
work email- stau...@htc.honeywell.com
??????????
I have a 1985 Reliant with the Mitsu 2.6, and I asked about a valve
job.. (188K)...my mechanic told me to drive the car until the wheels
fell off, because a valve job would cause the rings to go bad due to
increased pressures. He wouldn't volunteer any time, but the statement
was Definitely... like 100% of the time. So, I'll keep oil in the
engine and drive it...appreciated the honesty...wish all mechanics
could be that honest.
Dennis
On 2 Feb 1998 15:58:43 GMT, sn...@rain.org (Nick Halloway) wrote:
>... on an older engine with 127K miles on it?
>
>Half the time? 10% of the time?
>
>A shop did a valve job on my engine with that many miles on it. A
>leakdown test was OK at the time, but the rings went out 1000 miles
>later. They didn't warn me the valve job might do this.
>
>If this happens half the time, it's something to complain about, if
>it's rare, no.
>
>Thanks ...
Not correct e-mail address...tired of 'spam' please respond to the group,
as your advice could also help others..thanks!
L. Smith
I don't have a statistical analysis of this, but let's face it. At
125,000 + miles, your engine is getting toward its twilight years.
I wouldn't normally recommend a valve job on such an aging engine.
(Especially when you consider the fact that - by the time you get the
heads and all the brackets off - you would not have had to do so very
much more to completely overhaul the engine. At least, I see it that
way.)
If it had been 60,000-80,000 miles on the engine, then fine - you could
expect quite a bit more engine life.
We rebuilt a 350 Chevy in November for my son, and we had about $475 in
engine parts, machine work, etc. The cost of the machine work for the
heads was $75.00. We put in a new cam, lifters, etc.
(We had to replace the crankshaft, but managed to use most of the
pistons, recondition the rods, etc.)
All told, we add it up to $550 and change, and some hours work.
If you paid a dealership to do this,the cost would most likely exceed
$2000.
The labor you paid for the valve job was likely substantial, I would
guess.
You should have been made aware of the possibilities and the options.
--
- Larry Smith Sr
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NLW TFW NM
I just went through your entire, precise scenario (the long version you posted
on the legal forum). EVERY mechanic I asked after the fact said they would
never do a top end job on a high-mileage engine.
And mine was on a van, multiplying labor costs considerably.
Next time ....
Mike
Ken Schottler
Nick Halloway wrote:
> ... on an older engine with 127K miles on it?
>
> Half the time? 10% of the time?
>
> A shop did a valve job on my engine with that many miles on it. A
> leakdown test was OK at the time, but the rings went out 1000 miles
> later. They didn't warn me the valve job might do this.
>
> If this happens half the time, it's something to complain about, if
> it's rare, no.
>
> Thanks ...
A valve job does not make rings go out, but if there have been burned
valves for a period of time, then the fuel entering the cylinders with
the burned valves does not burn completely, and washes the oil off the
cylinder walls, causing the rings in those cylinders to ride against
the cylinder walls without benefit of lubrication and consequently they
wear excessively, and theough it does not consume excessive quantities
of oil in that state, when the valves are ground and the engine
reassembled, the compression and vacuum on the affected cylinders is
now increased and the rings have already worn out, hence the increased
oil consumption. When doing a valve job on a high mileage engine
that has valves that have been burned for a period of time, as
witnessed by a large section of the valve being burned away, the
cylinders with the badly burned valves should have the piston rings
replaced, at the time the valves are done, eliminating the problem you
have encountered. Mechanics that say doing a valve job on a high
mileage engine will blow the rings out, are just not thinking what
caused the rings to fail. It is possible in your case that the
problem rests with the valve stem seals not being installed properly on
the head when the work was done, or the valve springs were compressed
too far when installing the keepers and the retainer was crushed into
the seals causing damage to them. Before throwing the vehicle on
the trash heap, it would be wise to check the valve stem seals first,
as you stated that it was 1000 miles before the oil consumption problem
manifested itself.
Ken