Disabled EGR causes burnt valve 5th cyl? - Page 3 - PeachParts Mercedes-Benz Forum

Old300D · #31 12-15-2004, 01:49 PM

Quote:

Originally Posted by duxthe1

As mentioned before EGR lowers the combustion temerature in the engine.

Though often maligned for gumming up intakes the EGR is not the true source of the gumming. The crankcase vents into the intake before the EGR. There's all kinds of nasty vapors that are getting vented. As these vapors mix with the hotter EGR flow it cooks off the volatile parts and deposits what's left into the intake. If the EGR was responsible for intake deposits, the intake would look like the exhaust, dry and sooty, not gummy like tar. Ever notice that the smaller tube that feeds the EGR valve doesn't gum up, (unless the engine has oil consumption issues) but the intake pipe after the EGR does? Just b/c something is on a car for emissions reasons doesn't mean you have to disable it for the car to perform. In fact having EGR allows more fuel for the same exhaust gas temperature.

My 617.952 is running hot these days, and I'm pretty sure I have a substandard radiator, however it seems like it's running hotter than when the EGR was originally hooked up. I live up at altitude too, and I have to watch the temperature accelerating and going up long grades. I'm thinking of recoring my old all metal 300D radiator to see if that helps.

I don't think I'll ever re-connect the EGR. My intake was really nasty, and it took quite some time to clean it out. I hear that burning bio-diesel will keep the intake insides nice and shiny, so I will check the intake in a few months to see how it's doing.

boneheaddoctor · #32 12-15-2004, 01:53 PM

Quote:

Originally Posted by Old300D

My 617.952 is running hot these days, and I'm pretty sure I have a substandard radiator, however it seems like it's running hotter than when the EGR was originally hooked up. I live up at altitude too, and I have to watch the temperature accelerating and going up long grades. I'm thinking of recoring my old all metal 300D radiator to see if that helps.

I don't think I'll ever re-connect the EGR. My intake was really nasty, and it took quite some time to clean it out. I hear that burning bio-diesel will keep the intake insides nice and shiny, so I will check the intake in a few months to see how it's doing.

I will lay odds you have solder bloom in your radiator that a citric acid flush will cure.....it fixed mine....

I have about 8 lbs of this I am going to package in 2.2 pound ( one kilo) containers...and offer to a couple members here soon.

Its food grade Citric acid..... I bought 10 lbs of it in a bulk purchase, the rest is surplus to me.....it does work...

Before you recore you may want to try this first.

Old300D · #33 12-15-2004, 01:59 PM

Quote:

Originally Posted by boneheaddoctor

I will lay odds you have solder bloom in your radiator that a citric acid flush will cure.....it fixed mine....

I have about 8 lbs of this I am going to package in 2.2 pound ( one kilo) containers...and offer to a couple members here soon.

Its food grade Citric acid..... I bought 10 lbs of it in a bulk purchase, the rest is surplus to me.....it does work...

Before you recore you may want to try this first.

Thanks for the suggestion, it sounds like a good idea.

boneheaddoctor · #34 12-15-2004, 02:03 PM

Quote:

Originally Posted by Old300D

Thanks for the suggestion, it sounds like a good idea.

Mine was doing that ONLY on long mountain grades....never in stop and go traffic........after the Citric acid flush the temps stayed well within limits...

Pete Burton · #35 12-15-2004, 02:20 PM

After the acid, what did you use to neutralize? Years ago, before the EPA banned it, Du Pont had a 2 part heavy duty coolant flush that REALLY worked, not like anything today. You could clean out a large chunk of Detroit iron in no time. Basically, the first part was oxalic acid, and the second was borax to neutralize it. You can still get these items seperately at a good paint store, but I NEVER specifically SAID you could use them for an automotive purpose. Citric acid is safe and I've heard good things about it - worth a shot

Rick Miley · #36 12-15-2004, 03:13 PM

Quote:

Originally Posted by Old300D

I don't think I'll ever re-connect the EGR. My intake was really nasty, and it took quite some time to clean it out. I hear that burning bio-diesel will keep the intake insides nice and shiny, so I will check the intake in a few months to see how it's doing.

The biodiesel can't actually clean anything or help keep it clean if your EGR is disconnected. You're only getting fresh air flowing through there, so the fuel never gets to it.

If the EGR was still connected then biodiesel wouldl help because it does not produce as much soot, thereby lessening additional deposits in the intake manifold.

boneheaddoctor · #37 12-15-2004, 03:27 PM

Quote:

Originally Posted by Pete Burton

After the acid, what did you use to neutralize? Years ago, before the EPA banned it, Du Pont had a 2 part heavy duty coolant flush that REALLY worked, not like anything today. You could clean out a large chunk of Detroit iron in no time. Basically, the first part was oxalic acid, and the second was borax to neutralize it. You can still get these items seperately at a good paint store, but I NEVER specifically SAID you could use them for an automotive purpose. Citric acid is safe and I've heard good things about it - worth a shot

I mixxed a half a pound of Baking soda in a gallon of hot water...poured it in and topped off, ran it 20 minutes with heater on...of course this is after 2 flushes with clear water.

and flushed iit twice more after that....opening the block drain plug..and running heater full blast.

Old300D · #38 12-15-2004, 03:51 PM

Quote:

Originally Posted by Rick Miley

The biodiesel can't actually clean anything or help keep it clean if your EGR is disconnected. You're only getting fresh air flowing through there, so the fuel never gets to it.

If the EGR was still connected then biodiesel wouldl help because it does not produce as much soot, thereby lessening additional deposits in the intake manifold.

The blow-by from the valve cover has plenty of exhaust in it.

oldnavy · #39 12-15-2004, 04:02 PM

Here's an EGR from VW TDI with crud build up at 60,000 miles.

Here's intake manafold from same car.

boneheaddoctor · #40 12-15-2004, 04:03 PM

owww thats one ugly picture.

Pete Burton · #41 12-15-2004, 04:16 PM

If you drink enough red wine, will the positive effects rub off on your VW?

#42 12-15-2004, 05:47 PM

To begin with, valve burning in a diesel engine is EXTREMELY rare. Since in a diesel you are only drawing fresh air, not a fuel/air mixture.

In a gasoline engine, a vacuum leak near an intake valve can lean out that cylinder only causing valve burning. In the described case, we are talking about BLOCKING the EGR, thus not introducing such a leak.

What is the difference between fresh air through the air filter vs. fresh air through a vacuum leak? The only difference is that one will possibly have dirt introduced into the engine.

I think that this tech that is saying this is a gas engine guy and like many people who don't understand the diesel engine, incorrectly tries to transpose gas engine theory into the diesel world.

Just remember almost all the theories involved with diesels are backwards as compared to a gas engine.

Merry Christmas,

oldnavy · #43 12-15-2004, 07:03 PM

Quote:

Originally Posted by LarryBible

To begin with, valve burning in a diesel engine is EXTREMELY rare. Since in a diesel you are only drawing fresh air, not a fuel/air mixture.

In a gasoline engine, a vacuum leak near an intake valve can lean out that cylinder only causing valve burning. In the described case, we are talking about BLOCKING the EGR, thus not introducing such a leak.

What is the difference between fresh air through the air filter vs. fresh air through a vacuum leak? The only difference is that one will possibly have dirt introduced into the engine.

I think that this tech that is saying this is a gas engine guy and like many people who don't understand the diesel engine, incorrectly tries to transpose gas engine theory into the diesel world.

Just remember almost all the theories involved with diesels are backwards as compared to a gas engine.

Merry Christmas,

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