Unless you're primarily interested in adding a room, or perhaps
replacing a toilet, this doesn't belong in a.h.r., even if you live in
the car. Try rec.autos.tech.
If the mechanic is competant, he can find out if the problem is major
without doing any dissassembly at all. There's probably no way he can damage
it worse than has already occured and the problem might just be the
bearings of an accessory. If the mechanic is unwilling to start the
car then find another.
It is insane to write off the car without even starting it again and
listening for where the noise is coming from.
On Tue, 08 Dec 2009 11:28:52 -0600, Red Green wrote:
Mmmm, engine devastation... :-)
Fond memories here of an old friend buying a vehicle once where it was
obvious that the engine was about to go (it was dirt-cheap, and he had an
engine already lined up for us to drop in). Sounded like a clothes dryer
full of bricks when it ran. It was about 5 miles to the house, so the
decision to risk driving it back was made. He kept the revs low, tried not
to stress it too much, and amazingly it got to about 50ft from the house
when the engine went bang - a *loud* bang, too. Managed to coast it right
up into the driveway... and then we had to go back along the road and
clean up the trail of engine parts.
Near as we could tell from the wreckage it was an oilway to a main bearing
that had originally blocked; the loud knocking sound it was making (which
was the point when the previous owners parked it up on their driveway) was
the crank bouncing around after the bearing shells had started to
disintegrate due to lack of oil. When it let go completely, the (alloy)
sump was demolished when one of the big ends exited the bottom of the
engine, whilst the corresponding piston went upwards and high speed and
completely trashed the head.
A picture's worth a thousand words, and I really wish I'd taken photos at
the time :-(
Yeah - that's why when my son had two web pages full of plugs in front of
him, trying to decide which ones were the prettiest, I said "Go to the
Toyota dealer. Go to the Toyota dealer. Go to the Toyota dealer. Go to the
Toyota dealer." He did. He's happy.
OK - so now that we've established that there's a broken spark plug
(assuming the mechanic's telling the truth), what are the various levels of
horror which could result from further diagnosis?
Valve seat(s) wrecked?
Piston damaged? Top? Sides? Don't ask, it's too scary?
Worst case is something like:
The timing belt/chain is worn and skipped a tooth (just fixing this
could be a few hundred).
This caused the pistons to hit the valves, damaging the valves, a
spark plug, head, pistons and possibly even rods.
Broken bits of valve and/or spark plug gouged the cylinder walls.
Or, you could just have a bit of broken spark plug bounding around in
there and running it for a few seconds with that plug out will clear
Somewhere in between those two...
Just consider basic mechanical engine timing. If the engine is an
interference design (common on many higher performance and import
vehicles) the pistons can definitely collide with the valves if basic
mechanical timing is lost (eg, timing belt stretches and jumps a tooth).
Pretty high percentage of any current production engine will be same.
Need the tolerances to meet emission and mileage requirements any more...
And you definitely don't want to break a timing belt in anything these
days--pretty much guarantees new/rebuilt time...the one-cylinder thingie
may be a "get-by" or top-end job, the other is they're all toast.
My wife had the timing belt let go on her 1998 Toyota Rav4 while
powering up a steep hill. The engine simply stopped. No big bang, or
anything. The entire repair consisted of installation of a new belt
and idler assembly. No collateral damage.
Most higher performance engines are "interference" designs and do not
suffer failures so gracefully. A high compression ratio and the ability
to break a timing belt without crashing valves are mutually exclusive.
replace "roosters" with "cox" to reply.
My point is that many cars that you would EXPECT to have issues, do
not. I also had the fiber timing gear on my 1969 Pontiac Firebird 400
HO convertible fail under hard acceleration. It quietly coasted to a
stop. No damage other than the gear. That was a a high compression,
high performance engine from prehistoric times that seems to also defy
Depends entirely on what you're using to create the expectations
from...compression and a specific definition of "high performance" that
epitomized the muscle-car era aren't the appropriate ones. Those were
not "interference" engine designs; in fact virtually all were very
conventional old pushrod designs w/ simply beefed up compression and
high cfm carb's that sucked gasoline at a prodigious rate to generate
those hp. (Since had '69 Charger, know the symptoms well... :) )
Yeah, realized I typed before engaging there...the symptoms can end up
similar, just the mechanism of "how" is different. Fortunately, the old
timing chains gave more warning than the belts do by being noisy when
they stretched if one paid attention...
The dang CRX was told it had had a new timing belt before I bought
it--turned out they lied... :(
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