6.2L Diesel Mystery

4320diesel · Feb 14, 2009

i have a mystery to solve with my 85' 6.2L diesel theres a thing under the aircleaner that looks like a diaphram mounted to the intake manifold with a hose coming off of it and it goes though the airfilter cover and then has a bolt shoved in it what does this diaphram do and where is this hose supposed to go? can someone answer this for me? and can you tell me why its capped off?

Bob · Feb 14, 2009

It's an EGR valve. (Emissions CRAP.)

The rubber hose would have gone to a cluster of vacuum solenoids mounted at the left rear of the intake manifold.

You DON'T need it, be GLAD it's disconnected.

4320diesel · Feb 14, 2009

so wad it do and why was it unhooked?

bradk · Feb 14, 2009

EGR valve.Almost all I see have been disconnected and hoses plugged off.I think they caused bogging and low power issues on higher mileage engines.

Bob · Feb 14, 2009

The EGR valve pukes exhaust back into the engine's intake at certain speeds/loads to control nitrogen oxide emissions to keep the enviro nazis happy.

It also serves to clog up the passages in the intake with diesel exhaust products.

It serves NO good purpose as far as the engine is concerned.

Disconnecting the rubber hose insures that the EGR it will remain closed and not blow the crappy exhaust back into the engine.

The HD versions of the engine had better-flowing intake manifolds sans the EGR passages and valve... the thing you are seeing below the aircleaner.

4320diesel · Feb 14, 2009

ok that explains why theres a inch layer of black soot in the intake so ill leave it as it it so the engine runs fine

Bob · Feb 14, 2009

Part of the crap in the intake is dirty diesel oil, as well, from the crankcase ventilation system.

When combined with the exhaust soot, it REALLY makes a mess.

4320diesel · Feb 14, 2009

i was wondering where would that line hook onto i wanted to see if it made a difference in fuel milage having it hooked on i get around 22 MPG on the highway normally and i was gonna try with it hooked up think it would make a difference?

Bob · Feb 14, 2009

Activating the EGR valve WILL NOT increase fuel mileage.

4320diesel · Feb 14, 2009

k then so the only point of it is emmissions and thats it well ill leave it unhooked

Anonymous-0 · Feb 14, 2009

The EGR valve from my 6.2 intake. Bought a freeze plug for the hole under the valve and pressed it in with a bfh, the EGR valve then went in the trash.

Clefus · Feb 14, 2009

not to get OT but get a Duramax if you ever upgrade.....WOW...Chevy is my preference but I was kinda impressed with a Cummins at first...then found out how the Duramax's were...just couldnt afford a new one right away...
ran those old ones and YUK....

JDemaris · Feb 15, 2009

If you're really getting 22 MPG, you're getting about as good mileage as any 6.2.

If anthing, if you totally unhook the EGR system, you might get a slight improvement - but NOT just by unhooking the hose from the EGR valve in the intake. There is an EPR valve (exhaust pressure regulator) that controls a shutter valve in the driver's side exhaust manifold. It restricts the exhaust on that side to divert it up to the EGR in the intake. If all you do is unhook the EGR on top, you still have that shutter retricting the exhaust. Unhook the line to it and tie it open with a piece of wire.

4320diesel · Feb 15, 2009

ok ill look into that and i wanted to get a banks turbo kit for it someday how much is one of these kits worth?

JDemaris · Feb 15, 2009

Here's what the valve looks like in your exhaust manifold. The photo with two manifolds shows a J-code 6.2 manifold alongside a C-code 1/2 ton manifold.

In regard to your question about the Banks turbo kit? They tend to sell in the $500 price range used. Banks has discontinued it new, but it was around $2000. Why do you want it? 6.2 can't handle more then 8-10 PSI boost and it's not going to give you better fuel mileaage. More power - yes. A turbo on a 6.2 results in making power about equal to a gas 350.

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6.2L Diesel Mystery

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