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This is getting a bit ridiculous. I've gone through all the necessary steps to get the EGR "system" to work as it should, only the net result so far has been needing replacement air filters on a regular basis.

My '89s 307 was burping oil into the air cleaner housing--you can hear tell of this in my earlier posts--looking for all the world like a Starbucks coffee machine what with the hot cream-and-brown fluid that was collecting in there.

Replacing the EGR valve and crankcase filter (and hoses & fittings) stemmed the tide--for the most part--but enough oil vapor is still making its way into the housing that an air filter gets saturated enough to need replacing fairly regularly.

SO, can't I just "cap off" the EGR "tube" ahead of the valve--in effect disabling the EGR function and thereby stopping oil vapor from getting sucked into the air cleaner housing--with no ill-effects (apart from destroying the environment, as I'm sure that reasoning got the EGR put there in the first place)?

It's a really fine sheen of oil vapor that swirls around in there, and it makes the air cleaner housing look like you lightly sprayed it with Pam (rather than the cappuccino slurry that was there before). I would almost leave it to its own devices if it wasn't for the whole overwhelming-the-air-filter thing.

I don't live in California any more, so I couldn't care less if this "fix" would fail inspection/emissions-testing/whatever. And so far as I can tell, despite her advanced production date (she's an '89), her engine is still strictly old-school, with a carb and without a computer.

So, can I somehow bypass or whatever the EGR in such a way that it causes no ill-effects whilst it ends the ill-effect I have now? And if so, how do I do it?

There has to be a way....

Lady72nRob71

Did you replace the PCV valve and make sure the hose going from it to the carb is clear? I would not think the EGR valve would have anything to do with burped oil...

MDchanic

As Rob says, are you talking about EGR or PCV?

It sounds like your PCV isn't sucking air, and instead is blowing it out.
Either that or you've holed a piston.

Oh, and No, you don't really need EGR, but without it your carb might run a bit lean.

- Eric

oldsy

you dont need "EGR".

Lady72nRob71

Yep. The carb is tuned for EGR, so it will need to be retuned for without it.
The 307 will knock when the EGR is disabled or plugged.

Have you done a compression check on all cylinders?

Redog

It sounds more like you are talking about a PCV valve (Postive Crankcase Ventlation) The EGR (exhaust gas recirclation) brings exhuast back into the manifold to be reburnt in an early 80's attemp to reduce emissions (at laest the way that EGR was designed for the 307)

As for the engine knocking without the EGR. I never heard of that. My A.I.R. tubes are not hooked up. I found that out when I was changing my oil and looked up to see the air tube just hanging there instead of being hooked into the cat

rustyroger

The EGR system introduces a little exhaust gas into the intake to reduce formation of oxides of nitrogen. It works by reducing the oxygen content in the combustion mix thereby reducing peak combustion temperatures.
That is why your carb will need to be retuned, and preignition (knock) can result from removing it from an engine designed to run with it under extreme conditions. The advance curve might want adjusting as well.

I believe it was pioneered by Volkswagen in their air cooled engines, more to protect the engine from damage than any emissions concerns.

However it seems your problems are more to do with excessive breathing than EGR problems.
Could be a plugged PCV valve, or even worn/broken piston rings and bores. How many miles has it done?, does the thermostat work properly, allowing the engine to run at its designed operating temperature?.
I think you should be looking in these areas rather than focusing on the EGR system.

Roger.

MDchanic

AIR is not EGR either.

AIR pumps fresh air into the exhaust manifolds to add oxygen after the exhaust comes out of the cylinders, to get just a bit more of the hydrocarbons burned.

EGR pumps exhaust (inert gas with essentially no oxygen) back into the cylinders to, as Roger says, cool down the combustion mixture a little bit.
Because the exhaust gasses are inert, all they do is take up space, and if you disconnect the EGR, then you are replacing the inert gas in that space with a certain amount of oxygen. While it is true that the new oxygen has passed through the carburetor, while the former EGR gasses did not, it is none the less the case that the new mixture is a bit leaner than the old mixture, and so the engine will run lean, and may knock when it otherwise wouldn't have, unless the stock carb. is richened up slightly.

- Eric

RonzBoyz4

68 350 in a 80 Cutlass-
I am rebuilding and want the most for my efforts.

So, I do not need, have to have, the EGR valve.
If not installed (capped), adjust the carb accordingly.

Correct?

MDchanic

Right.

Unless your local jurisdiction requires it.

It's easier to build an engine without having to calibrate it for EGR, which is just an added complication.

- Eric

DFitz

Caution for states the require a smog test. EGR is required, and required to work. CA, with all the great weather, is really screwed up when it comes to smog tests. Any car newer than 1974 will require smog tests forever.

M-14

If your breather is pushing oil into the air filter housing, you either have a non functioning pcv system or your engine is tired (excessive blow-by). Oops, I was responding to the OP, a little late I guess.

nsnarsk65cutlass

1976 and newer.

DFitz

Come to think of it, I believe you are correct, 1975 also does not need smog tests. CA Starts with 1976. Thanks, It's changed a few times.

joe_padavano

First, EGR has nothing to do with oil in the air cleaner housing. Changing, plugging, or otherwise screwing with the EGR will not change the oil blowby. Second, on a 307 (which is the subject of this thread), the carb and timing is tuned to take advantage of the EGR. The valve only opens at part throttle cruise, so it has no effect on W.O.T. performance. Since the recirculated exhaust gas effectively cools the combustion process, the CCC system is designed to add timing during the conditions when the EGR is open. Eliminating it usually leads to part throttle pinging on 307 motors still using the computer.

MDchanic

Thank you, Joe.

For clarity, the answers from 2013 (as opposed to those from 2011) are regarding a threadjacker who was asking about a '68 350.

- Eric

joe_padavano

DOH!