Honda Car Forum

"Peter H" <haneburyp@rogers.com> wrote in
news:1148556544.075960.244760@j33g2000cwa.googlegr oups.com:

> I had the car in for an oil change and the guy recommended that he add
> this compound to the engine to clean it out. He propped the hood open
> and hooked up this bottle of goop. When I fired up the engine some
> smoke came out from under the hood and the guy doing the work made the
> diagnosis. This was one of those rapid oil change places and I realize
> that the workers there have limited knowledge of the vehicles that they
> work on, but this guy was in charge of the shop and I have some
> confidence in his knowledge.



Are they sure they didn't just spill some oil on the exhaust or something?

Sounds like pretty flimsy evidence on which to spend money replacing an
exhaust manifold. If the crack is big enough to emit smoke, it will be big
enough to emit noise.



>
> I've also noticed it is noisy when first started and then settles down
> once it's warmed up.
>
>


That sounds like piston slap, not a manifold leak.

If I were you, I'd get a second opinion on that "cracked manifold" thing.

--
TeGGeR®

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

"Peter H" <haneburyp@rogers.com> wrote in message
news:1148556544.075960.244760@j33g2000cwa.googlegr oups.com...
>I had the car in for an oil change and the guy recommended that he add
> this compound to the engine to clean it out. He propped the hood open
> and hooked up this bottle of goop. When I fired up the engine some
> smoke came out from under the hood and the guy doing the work made the
> diagnosis. This was one of those rapid oil change places and I realize
> that the workers there have limited knowledge of the vehicles that they
> work on, but this guy was in charge of the shop and I have some
> confidence in his knowledge.
>
> I've also noticed it is noisy when first started and then settles down
> once it's warmed up.
>
Smoke isn't a common indication of exhaust leaks. Although start-up smoke
can be in the exhaust from leaky valve seals, getting enough of that exhaust
out into the air would require a leak large enough to produce a terrible
roar. Small leaks normally suck air in rather than blow exhaust out.

Typical exhaust leaks from the manifold area have a distinctive sound. The
sound is a distinct tapping sound that we'd never think was an exhaust leak
unless we knew it already; it sounds exactly like a small metal part tapping
against a larger metal part. The sound is like a noisy lifter but a bit
sharper, and unlike lifters, wrist pins and rod bearings it gets noticeably
louder when accelerating. Piston slap sounds similar (including the loudness
when accelerating and quieting down as the engine warms up) but isn't as
sharp. Note that the quieting with warm-up doesn't usually apply to cracks,
just to leaks where the manifold is bolted to the head.

The only certain diagnosis is to locate the leak.

Mike

Thanks to all who replied. It sounds like the guy at the lube shop
spilled a bit of oil on the motor and when it smoked he blamed it on an
exhaust manifold leak, or perhaps he noticed the sound, believed it to
be a leak and mentioned it to me at the same time as a bit of oil was
spilled, which caused the smoke. I assumed that the smoke and leak were
connected.

I do hear a tapping when the engine is cold and it does sound like a
smaller piece of metal hitting a larger one.

I'll take it into a shop for a diagnosis. It's time for an oil change
anyway.

Thanks again for the great advice.

Peter H