RCR

Since this was a hot topic a few weeks back, I thought I'd mention that since blocking the holes off on the heads, I've noticed a significant decrease in blue smoke when I start up in the morning. My guesstimate is that the open EGR ports were pressurizing the block causing some oil blow-by. Can anyone back this up?

tpi_roc

Well did you previously notice the blue smoke under driving? Load? Idle?

At Idle the EGR shouldn't have been open unless it was stuck so thats some direction...


But I can't see there being any/enough pressure to cause blow by....

Done a leak down?

(If it was pressurizing the block that would only make it harder for oil to make it up into the combustion chamber due to the positive force)

RCR

There was a lot of blue smoke on start up. Nearly nothing now. The way I've always understood it, the PCV puts a vacuum on the crankcase to pull fumes out and to help with oil control. By pressurizing the block, you'll push oil out all the seams. Namely the rings and valve guides. I did recently do a work over of the engine, but I left the heads alone.

tpi_roc

I believe what happens is while running your engine oil gets super heated and creates its own vapor, this vapor builds up pressure within the engine and the pcv doesn't necissarily create a "vacuum" but more or less an escape route for this pressure, and naturally instead of dumping it into the atmosphere its routed into the intake to burn this combustable vapor, Granted vacuum now plays a roll just because of being hooked to the intake, but either way the vapor makes its own positive pressure.

And Its not "pressure" pushing oil out the seems, but gravity as far as the valve guides/seals go, and there's oil on cylinder walls from the crank splashing around in the pan, when your piston pulls down at say 40 times a second naturally its not going to be able to scrape EVERY bit of oil off the walls and some gets burned.

"start up" smoke is usually due to valve seals since looking from a gravity perspective it has the opertunity to leak down open intake/exhaust valves.

theres not really any route for oil to come UP passed the rings. Without a running engine.


Hope this helps (and hope I'm right)

Dont quote me

junkcltr

iTrader: (1)

Oil was probably leaking down into the EGR port of the head sitting on the exhaust valve.
J

tpi_roc

what route would oil have into the EGR?

Gruvin84SS

leaking intake gasket

tpi_roc

You're talking about a pretty substantial leak...

At least .5" of missing/seperated gasket.


not impossible, but still it'd be noticable during the intake swap.

John Millican

iTrader: (1)

I was lucky enough when I did my prototype even though I didn't notice the gap in the intake flange. I have Trick flow G2 heads and the EGR port in the head is a very small 1/2" round hole, the LT1 intake more then covers that small hole so I never paid it much attention.
Still, be assured I am working on a simple way to fix the problem on future intakes.

FstBrd6point3

what do I need to do on my 87 heads to get the EGR ports blocked off on the heads?? is it hard? or just another piece of sheet metal?

junkcltr

iTrader: (1)

I welded a small piece of alum. angle plates to each side. I am running GM heads so this is the only reliable solution. You just have to use a square to make sure they are perpendicular with the rest of the flange.

I bought a roll of alum. wire and a 2' bottle of argon for my welder (approx. $40). You have to keep the wire very straight to keep the wire flowing correctly. It is just a generic mig shop welder. Or just make the pieces and have a local show weld it.

I also added weld to the top part up by the valve covers for that port and the water ports to make sure there was a good seal there. Without doing this, the gasket is just barely covered. This is just added insurance.
J