Had my truck in for service today, as the muffler was rusted through and
the rest of the system didn't look too good either. Since I had it in
to an exhaust expert, I had them look for the cause of the P0455 code
(Evaporative Emission Control System Leak Detected (no purge flow or
large leak). I've had codes for this system for years, it started with
the P0422 code, then changed to P0455 6 months or more ago. I've been
ignoring it as there's been no driveability issues.
Turns out Twig (the mechanic) doesn't have a smoke machine, but he did a
physical inspection of the system, and didn't find anything untoward.
The only thing that was done to the truck was replacement of the muffler
(and the shocks, but that's not important here) - he said the rest of
the system is solid, despite the rust.
Odd thing was, after resetting the code, it didn't come back! In the
past, when I've "rebooted" the truck to clear the code, it came back
very quickly. Now, I'm not counting chickens yet, but will see what
happens tomorrow when I drive it to work.
If the code comes back, the mechanic does have a line on a smoke machine
he can borrow, so I'll take it back for a smoke test.
Just wondering if it's possible that it was actually the muffler that
was causing the codes, and if someone could explain why. Twig said he
thought it was unlikely that the system could "sense that far down the
system" to throw this code because of a muffler problem.
He didn't know the proper way of resetting the code on my Dak (they
don't have them here). You should have seen the look of surprise on his
face when this lady pulled a truck manual from under the front seat :)
The exhaust system will not cause that code. The check engine light will, I
fear, return. Your truck is equipped with an OBD II diagnostic system that
performs periodic self tests. After three good self tests, the check engine
light will turn itself off. Thus, if the problem was no longer there, the
light would have self extinguished by now. Sorry to be the bearer of bad
Suddenly, without warning, Mike Simmons exclaimed (7/31/2007 7:50 PM):
Waaaaah! Now look you've gone and made me cry! :)
I was hoping though, but I know that I've had the code for a lot longer
than the seriously rusty muffler.
How often does it run these self-tests? So you're saying I shouldn't
"reboot" my truck after it's fixed, I should wait and see if the code
goes away on its own?
I had the same problem. I had reset the code as well but it kept coming
back after a 2 or 3 days. I had one split hose end and later a plastic
manifold where hoses all connected together was cracked. These were
located along the frame rail.
A bad gas cap can also cause the code.
Suddenly, without warning, miles exclaimed (7/31/2007 11:02 PM):
Yea, the gas cap was the first thing I replaced, so I know it's not
that. The mechanic did a visual inspection of all of the system he
could see, and he didn't *see* any damage. I know that this doesn't
necessarily mean there's no damage.
Either way. If the tech clears the code after the repair and the light
doesn't come back on, voila! If the repair is made and the light goes off
after several days of driving, voila again! The self=test isn't performed
at each start up. An OBDII drive cyle must be completed before the
self-test runs... usually a couple or three days of normal driving will do
Suddenly, without warning, Mike Simmons exclaimed (8/1/2007 10:00 AM):
Thanks. The light hasn't come back yet, I've driven about 40 miles
today, it's been started three times. I'll keep an eye on it.
Worse news though: I think my engine started knocking! Noise is in the
right side of the engine block as I face the truck, a tickticktick noise
at about two ticks per second.
I noticed it as I arrived home today. Can only hear it at idle. Shut
the truck off, went back out just now (about an hour or so after turning
the truck off). Turned it on, no tick. As soon as I revved the engine
a little though, the tick started again. I suspect it starts when the
truck gets warm. It's not really loud, but can be heard inside the cab
when the window's rolled down.
Knock is serious, isn't it? I just had the sparks replaced, not two
months ago. I don't understand why it started up right after an
unrelated repair (dammit!).
How hard is this going to be to fix, and is it going to cost a lot? Is
it ok to drive it for short distances until repaired?
I hate to say this but that IS NOT knocking. Engines don't normally knock
at idle. That sounds like something more serious. It could be something
fairly simple like a failing lifter or something much more serious like a
blown head gasket or a cracked head. If it is coming from inside the block,
then it could be the initial signs of a failed bearing. It is impossible to
say exactly what is going on without actually hearing it but I would get
that looked at ASAP. A light tick, tick, tick sounds more like a lifter
then anything else so the news is not horrible and that can be left alone if
you choose but I would have someone confirm that is actually the problem.
If at first you don't succeed, you're not cut out for skydiving
Thats true but it is a possibility especially with 2000 and earlier 5.2L
and 5.9L's. My 2000 pinged at idle unless I ran midgrade or above. Did
so since new and was told it was 'normal'.
On some GM vehicles its common to hear the injectors tick. Don't think
I've heard that on any Dodge though.
Suddenly, without warning, Nosey exclaimed (8/2/2007 1:15 AM):
Can you elaborate? All he did was replace the muffler, and do a
physical check of the rest of the system. But I'm taking it back
anyway, since he's close and was recommended to me as a good mechanic.
I'm with Nosey on this. Put your hand down where the engine pipe bolts to
the exhaust manifold. You may be able to feel the exhaust blowing out, don't
get burned. It may have been disturbed when the muffler was replaced.
OK, before everybody jumps off the deep end, lets look (listen?) to the
noise. Is the ticking variable with the engine RPM or does the ticking
remain at a constant frequency regardless of the engine RPM? If it is
constant regardless of the engine rpm, it is likely an evap purge solenoid
doing its job. It will make a ticking noise as it recycles fuel vapors back
into the engine.
If the ticking noise is variable with the engine, is it possibly a fuel
injector. These little guys are like the water valve in your automatic
washer and make a (normal) ticking sound as they operate. Take a long
screwdriver and put it against a fuel injector (you have eight of them) and
place your ear on the other end of the screwdriver... is this the noise you
are hearing. BTW, do the screwdriver thing while no body is looking or
they'll think you've gone nuts.
Does the ticking only occur on cold start up and then goes away after the
engine is warmed up? This could be a small crack in the exhaust manifold
that seals itself as the manifold expands with heat. Another possibility is
that when you last changed the oil a poor quality filter was used that
doesn't have an anti drain back valve and what you are hearing are the
lifters until they refill with oil.
The bottom line is that there are many, many things that can make the noise
you are talking about... most of 'em not very serious. An engine that is
failing usually does so gradually and has other warning signs so I would not
panic just yet.
Let me know if any of this helps.
Suddenly, without warning, Mike Simmons exclaimed (8/2/2007 11:08 AM):
Well, I feel better eddicated, anyway :)
Took the truck back to Twig today. He used a piece of rubber hose,
listened here, listened there, listened while revving the engine a bit.
Here's what I heard while he was doing that:
When the truck was cold, I heard no ticking, but then I didn't pop the
hood. When the engine is revved, I could sometimes hear it have what I
can only call an arrhythmia (my heart does that sometimes) before I
stopped hearing it. It's really hard to say, I'm not sure but it didn't
seem to get more rapid, it's more like it got... erratic, but maybe
faster too. But not fast as in keeping pace with the rpms. Does that
make sense? Not sure if it stops at that point or if it can't be heard
over the engine. With all this careful listening, it seemed to me that
it wasn't a metal-on-metal noise, sounded more... airy.
The ticking gets worse as the engine warms up, so it might have been
ticking at cold, but it definitely gets more pronounced as the engine
warms up. To me, when standing on the driver's side, it sounds like the
tick is coming from just back of center of the main engine body, down
low below the sparks. This would sort of jive with what luck Twig
wasn't having, he seems to agreed with that as he wasn't getting an
exact location with his bit of rubber hose, from above.
There's a good quality oil filter on, I can't remember if it's a K&N or
I haven't tried the screwdriver thing. Should I still, based on the above.
Ok, so before you read the next line, what do you think it is?
Twig's take: Manifold gasket (that'd mean Nosey wins, right?). You guys
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