Surprise...egr valves can leak (to atmosphere)

[ThikStik]

Learn somethin new everyday. Ive always had rich o2's and K at wot. Also have surging low speed cruise, miss at cold cruise, and hunting idle. Well, had been suspecting disturbed mixture from a loose throttle body seal. No ones ever suggested it that Ive seen, but an egr valve can leak. Mine does. It leaks boost upon boost/vacuum. The leak is a straight shot past the pintle as visible from outside of valve, to the intake side . I could blow air threw it with lips. Probably like taking a 1/8 hose to atmosphere on intake side. Car drove better with less throttle to cruise. Idle doesnt hunt, tip in is perfect now. I cant believe this was never suggested as a tuning strategy. (btw, the pintle seals perfect against seat, thats been checked). Thats what I get for running egr !
WOT tuning is only alittle better.

 

[turbodave231]

I made a tool to pressurize my intake thru the TB with regulated shop air. I loosen up the rocker shafts to close all the intake valves. I was suprised to see how many leaks there were.

The two biggest offenders were the PCV valve and the EGR valve. I got an inline PCV check valve to solve the PCV leak. I took the EGR valve and cut the diaphram can and pintle off the base. I filled the base with JB weld and reinstalled it. Leak solved.

You'll find lots of smaller leaks this way too. Add them all up and they equal lots of pressure loss.

What does this all mean? It means your turbo has to work harder to maintain an effective level of boost. The turbo will add more heat to the air, the harder it works. More heat equals less usable air for combustion and more detonation.

 

[Jerryl]

.........I made a tool to pressurize my intake thru the TB with regulated shop air.......

Just made one 3 months ago for my Hot Air. I use my leak down tester and some soapy water to find leaks.

 

[ThikStik]

Yes, I too was using a pressure jig with a psi gauge and soap. It was unbelievable how much egr valve was loosing. The check valve going to egr solenoid also allowed air to go to solenoid, egr diaphrgm and then out past the diaphragm. Im sure it was disturbing mixture badly under non boost. Ill be JB welding mine also. I even checked a new one , a Borg/Warner, and it did allow some air past as well (human blow test) ....this seems un-acceptable and I never would have supected. It wasnt as bad as my OE of course. I imagine all the carbed/egr'd cars Ive worked on have had it compensated for by idle adjustments, but under load, it would take jets/needles to compensate for this leaning. And all o2 feedback cars can compensate including ours, but wow, it has made a difference in mine. I mean im up 102 hp and 156 on tork! :tongue: HA HA, I know , boring topic...but drivability is better for real.

 

[turbodave231]

Its not always about the big gains in performance. Small leaks add up, small weight losses make a difference, decreasing friction and rotating mass even a little bit increases performance.

You may not notice any one small change, but if you find enough small things, they equal alot. Using a pressure tool to find leaks is one small way to be sure you're not giving away performance.

Dave

 

[83ttypecooled]

egr leakage

Hi,
How about cleaning the valve? Remove it, pour a small amount of top engine cleaner into both ports, and let it sit an hour or so.I would stuff a rag in the diaphragm area to absorb the stuff that runs down the shaft, as this stuff is pretty caustic.A little work with a dental pick woudn't hurt. The valve is admittedly not designed to control positive pressure on the intake side, but the Buick boys must have overlooked that possibility, or thought it was irrelevant. Remember, the stock Garrett T3 was a huge turbo in it's day, at least for use on gas motors. I guess they thought the extra capacity was adequate for the needs of the engine at 1 atmosphere pressures.
Barring such weird **** as pintle or seat erosion, or diaphragm spring fatigue, what could be wrong here? By the way, steer clear of those generic EGR valve replacements. With all those inserts they come with, I doubt that calibration can be very accurate. Dump too much, instant bog, dump too little, ping, ping ,ping!
Finally, I know you are not a big fan of emission regulations, but consider this. Without these regs, we would probably be living in an atmospheric sewer right now. The new rules are designed to keep up with what technology has come on line in the past 20 years, and despite what the domestic automakers always complain about, are usually easily meetable. You never see the Japs in Washington lobbying against these laws. It is all economics, and they have an edge up on us with the cash they can spend on r&d, due to a lot of other factors, so they don't care. It makes them look good ,too.They LIKE to spend that extra cash, makes them saints, in the public's eye.
Personally, I like to be able to pass an emissions test with my 22 year old car, feel like I'm helping out with an important issue. Fast, Economical and Clean, that's a good turbo Buick! Thanks....

 

[ThikStik]

Roger that on the cumulative effects....the last leak point is now around the edge of turbo where compressor housing mates together. I wonder if o-ring is missing. If anything, I would imagine this will help consistancy also, especially in hotter seasons.
RE -emissions, Yea man. I was for the clean air act of 1970 even though it caught Detroit of guard, and then allowed the Japanese to totally win with their new ground up offerings. It would be horrible to still have draft pipes (no pcv). And the computer/cylinder head tech, etc has made emission controls not near the performance/mpg killer as it was during the spaghetti vacuum hose/valves days. But the ever tightening regs are onerous. The rage about ground level ozone IMO is about keeping the EPA alive. It is a fact that the conifer forest (basically pine trees) around here contribute 40% to the ozone on "bad" days. The heat triggers them to emit VOC's...thats where turpentine comes from ya know. This ozone has not even been proven to cause all the health problems they say it does. Asthma is more prevalent due to sedentary kids, artificial foods, molds in neglected public schools. Not ground levle ozone. These are very "little known " morsels of info that the media likes to hide. The epa admits-radon gas is the most dangerous carcinogen. But they cant extract money from the public by actually protecting the public by helping out with this . The demonizing of cars and industry are paramount...yet urban sprawl, open borders that just add more cars, decaying "minority" neighborhoods due to illegetimate births are a few things i wish the epa would address. That would improve the environment around here! Rant off.

 

[ThikStik]

I Forgot to mention 83 TTcooled, I doubt theres anything to do on the egr valve to fix it. The leak is from the cool side thru the pintle/bore. Id like someone to see if they can blow thru one that is supposed to be in good condition. The new one i avoided buying, borg/warner did allow air past also, but not as bad. It also had a different taste... :biggrin: I agree to avoid them due to calibrations.

 

[83ttypecooled]

taste

Hi,
What did it taste like? Metallic? All kidding aside, thanks for your input.

 

[ThikStik]

Why soyntly. Yours too.

 

[turbo2nr]

I've often wondered why there is no seal in most turbo compressor housings. I usually put an almost invisible coat of silicone sealer on the mating surface of turbo, after I clocked it and marked the proper position on my car. Ever tried smoothing the inside of turbo housings? Some garrett housings have huge rough spots from sand casting. I also grind off the bottom of any screws that enter the housings, and grind the boost refernce port flush with the housing (looking from the inside). If you get really board, you can spent a full day grinding on a turbo. Fill any holes with JB weld (the holes that were tapped for the six screws to hold cover on, usually two or three poke thru to the inside of turbo.)

 

[ThikStik]

Silicone seems like a good idea . I need to do all that someday. I wonder what real world effects a leaking turbo causes. Obviously our ecm will trim out mixture variences. But i bet a o-ringless turbo will leak alot when cold. And as stated by TDave, will work harder for nothing. At least this leak is not as much of a nuisance as this egr valve which was like a straight shot to the intake. Like vac hose off all the time.