99 GMC Suburban - EGR Issues

dan.DeleteThis@somewhere.com wrote:
> OK, I put the new EGR valve in. Of course the truck runs correctly
> now. No stumble/surge at any RPM. Idle is very smooth. Most likely,
> by June 19 the new EGR valve will be fouled.
>
> I believe that my engine is making lots and lots of carbon. This is
> obviously what is fouling the EGR valve. I also believe the top
> engine cleaning and the Klean Screen are most likely irrelevant. It's
> not chunks of carbon fouling the valve. If this were the case, I
> should have been able to clean my old valve (i.e., wash the chunks of
> carbon out) and the valve would have worked again … but it didn't.
>
> So my theory is that the gasses flowing though the EGR passages simply
> foul the EGR valve … within two months. Whether the passages are
> clean or not, those "toxic" gasses are going to flow through the valve
> causing it to foul. I'm guessing that either i) the engine is
> basically worn out or ii) there is something wrong with the way the
> intake manifold is installed.
>
> Anyway, once I got the injectors changed the engine finally ran OK and
> life was good (for a few months). But then it started leaking coolant.
> Of course it was not the water pump … again … this time it was leaking
> coolant from the block, at the intake manifold. So the local mechanic
> changed the intake manifold gasket and the leak was fixed. But its
> been EGR hell ever since. I took it back a few times … again too much
> to detail here.
>
> So I wonder if it is possible to screw up the installation of an
> intake manifold and cause all kinds of horrible fumes to flow into the
> EGR passages. If this is possible, perhaps I need the have the intake
> manifold done again (only correctly this time). In the alternative I
> could try to make some sort of bulk purchase of EGR valves (since I
> will need 6 of them every year).
>
>
> Thanks,
> Dan
>

Yes it is possible to screw up the intake gaskets. Do you notice and
white or blue smoke from the exhaust? If your not using coolant or oil
at a rapid rate I would guess the gaskets are OK.

It is also possible that the valve you purchased just failed.

The gasket is mainly to keep chunks of carbon from sticking the pintle
open. The top end cleaner dissolves the carbon and allows it to blow
through the system. It also cleans the valve heads, rings, and passages
where the carbon likes to build up.

--
Steve W.

On Sun, 20 Apr 2008 09:27:02 -0400, "Steve W." <csr684NOT DeleteThis @yahoo.com>
wrote:

>dan@somewhere.com wrote:
>> OK, I put the new EGR valve in. Of course the truck runs correctly
>> now. No stumble/surge at any RPM. Idle is very smooth. Most likely,
>> by June 19 the new EGR valve will be fouled.
>>
>> I believe that my engine is making lots and lots of carbon. This is
>> obviously what is fouling the EGR valve. I also believe the top
>> engine cleaning and the Klean Screen are most likely irrelevant. It's
>> not chunks of carbon fouling the valve. If this were the case, I
>> should have been able to clean my old valve (i.e., wash the chunks of
>> carbon out) and the valve would have worked again … but it didn't.
>>
>> So my theory is that the gasses flowing though the EGR passages simply
>> foul the EGR valve … within two months. Whether the passages are
>> clean or not, those "toxic" gasses are going to flow through the valve
>> causing it to foul. I'm guessing that either i) the engine is
>> basically worn out or ii) there is something wrong with the way the
>> intake manifold is installed.
>>
>> Anyway, once I got the injectors changed the engine finally ran OK and
>> life was good (for a few months). But then it started leaking coolant.
>> Of course it was not the water pump … again … this time it was leaking
>> coolant from the block, at the intake manifold. So the local mechanic
>> changed the intake manifold gasket and the leak was fixed. But its
>> been EGR hell ever since. I took it back a few times … again too much
>> to detail here.
>>
>> So I wonder if it is possible to screw up the installation of an
>> intake manifold and cause all kinds of horrible fumes to flow into the
>> EGR passages. If this is possible, perhaps I need the have the intake
>> manifold done again (only correctly this time). In the alternative I
>> could try to make some sort of bulk purchase of EGR valves (since I
>> will need 6 of them every year).
>>
>>
>> Thanks,
>> Dan
>>
>
>Yes it is possible to screw up the intake gaskets. Do you notice and
>white or blue smoke from the exhaust? If your not using coolant or oil
>at a rapid rate I would guess the gaskets are OK.
>
>It is also possible that the valve you purchased just failed.
>
>The gasket is mainly to keep chunks of carbon from sticking the pintle
>open. The top end cleaner dissolves the carbon and allows it to blow
>through the system. It also cleans the valve heads, rings, and passages
>where the carbon likes to build up.

Yep, I'm sure the TEC cleaned the combustion chambers. This is
certainly not bad. I'll bet there was carbon in there. But it does
not really make a noticeable difference when you are driving. The TEC
did not clean the previously fouled EGR valve and I was unable to
manually clean an earlier fouled EGR valve with carb cleaner (i.e., an
entire can of carb cleaner).

I installed a brand new EGR valve and of course the engine runs
"perfectly" … or at least as good as you could expect from a 1999
5.7l Vortec. The truck does not seem to be using fluids or blowing oil
smoke from the exhaust. It seems to run perfectly fine (with a new
EGR valve) … so I am a bit puzzled as to where all this carbon is
coming from. I should probably talk to the local mechanic. He spent a
lot of time on this truck (as did I). I mean, I bought a darn code
reader six years ago just so I could figure out why the service engine
soon light was always on. And I used that code reader a lot over the
years. The local mechanic fixed lots of problems over the years at
very reasonable prices. But this EGR thing has just sucked. He lost
a lot of money trying to fix this truck (cause I kept bringing it
back)… I'll be lucky if he agrees to work on it again (I wouldn't if I
were him).

I took a drive this morning and I actually enjoyed driving the truck.
If you press the gas pedal (even just a tiny bit) you feel some
acceleration. That is, the truck actually responds. Once the EGR
valve starts to go, you just don't feel the responsiveness and often
it is opposite of what you want (i.e., you depress the gas pedal and
the truck actually decelerates or hesitates or surges …). With the
new valve, the truck feels 500lbs lighter … it's like a whole
different vehicle. It can even go up hills without dropping out of
overdrive.

The drivability issues I have with this truck are kinda my fault. The
5.7liter engine was never really adequate for a vehicle this size. I
really knew this when I was buying the truck. I should have bit the
bullet and sprung for the 2500 with the 454 engine. Of course the
2500 is super major overkill for my needs (and gas mileage would
probably be worse than the 5.7l … if one could actually imagine that)
but at least I would have been happy with the power output.

So for now the truck is technically "not broken." Since it is garage
kept, it looks almost brand new. It took it to the car wash, cleaned
up the wheels and tires, cleaned all the glass and vacuumed the
interior. So if I left it in the garage for the next six months and
didn't drive it … it would be pretty and "not broken" for six whole
months. But alas, we are going to drive the thing. I will post an
update when I have something new to report.

Thanks,
Dan