Hey guys, I have a '76 250 S6. Most of the vacuum lines are hooked up right, except the one that plugs into the egr valve from the air cleaner. The car runs fine with that line deadheaded on a bolt, but once I plug it into the egr the car sputters out and dies. Does this mean I have a bad egr valve? What does this mean? I'd just like to make sure before I spend $50 on a new one! Any help is appreciated! Also, ill attach the clearest diagram so you can see what Im talking about.
I would think that the EGR valve is not malfunctioning. It sounds like it is being commanded opened at idle. I would suspect the EGR vacuum control valve is not working correctly. Maybe someone with more experience with older EGR systems can chime in, but my understanding is that EGR is commanded very little (or not at all) at idle.
If you don't have emissions inspections, get rid of it! You can get a plate to block it off or just leave it on with no vacuum line attached.
Well I don't have to pass emissions right now, but I was under the impression that having a working egr would not only tie up that loose end (the vacuum line), but would also improve the running quality and smell of exhaust?
A properly working EGR system improves fuel economy and lowers combustion temps. I don't think it will improve your running quality or exhaust smell.
Yes, it is. That is what it was designed for. I would see if you can find diagnostic info about the two temperature valves that control the EGR and Thermactor system. It is also possible that there is supposed to be vacuum on the EGR line at idle, but it should not open the EGR valve far enough to stall your engine. Also, double check your vacuum line connections. If one is plugged into the wrong vacuum source, it could be operating your EGR valve at the wrong time.
The EGR should remain closed at idle, likely the connections are incorrect and it has full vacuum routed to it instead of ported... As far as improving mileage, if it does I've never seen it, been tossing or blocking vacuum to them since the late 70s...
I removed mine and used an aftermarket blockoff plate for a 5.0L. I figured it was just one more thing to go bad at some point. I like simple.
It made my fuel mileage worse! I removed that valve probably 10yrs ago and it was working "properly" then. After I removed it the fuel mileage was better, the engine ran smoother, and it started much better when cold! I didn't touch anything else just to see what difference it would make. I'm sure in different areas of the country it could possibly help. (higher altitudes) An easy test is to just unplug the vacuum hose, plug the hose, leave the port on the valve open, and see what result you get.
The EGR valve should only get vacuum when the throttle is above idle. If there is vacuum at the valve at idle someone has switched the source to manifold vacuum. Just trace the vacuum line back from the valve to see where the source is. Correct that and your dieing problem should go away. Ron
Like in the diagram I attached, the line goes from the egr valve up to the t-split that goes into the top port of the rubber splitter that plugs into the air cleaner, so I'm not sure where there could be a problem in that
Like I said in the original post, that's basically the way it is now (vacuum line plugged, egr left open), and it runs pretty good! I'm basically only asking cuz I want to tie up any loose ends that may make it run a little better
I said if once already and Krazy Comet said the same thing. If there is vacuum on the hose that connects to the EGR valve when at idle then it is connected wrong somewhere. You may have traced the hose routing but somewhere they crossed or you don't understand the functions of all the devices. If in doubt run a hose directly form the 'ported vacuum' port on the carb to the EGR valve. That should confirm that no vacuum is present on that connection and the engine should idle normally without dieing. If that verifies it then figure out where it is going wrong when everything is connected as 'you' think. Get a correct hose diagram and/or have someone else verify the connections. The drawing posted earlier is not thorough or detailed enough to know for sure. It's really not that complex. Ron
