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Butterfly valve in driver side exhaust manifold? 6.2 diesel w/ banks kit. Pic inside

rwright07

rwright07

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I am lifting the engine to get the pan out to do a new seal and rear main, and motor mounts while its up in the air. This thing

is keeping the motor from lifting any higher.

wtf is it. why is there a butterfly valve in my exhaust. is this some 1980's exhaust brake?

It doesnt look like it works, so i was just going to cut it off and continue, but figured i would ask the CK5 gurus before i made a mistake.

thanks!
Rick

also tips on resizing that picture... haha
 
yea a google search helped me figure out that it needed to be cut off.
Im thinking about cuting out the valve for better flow too, unsure if the exhaust would leak after though...
 
Its called an "EPR valve"--(Exhaust Pressure Regulator)....Rene is right,its part of the EGR system--I read on a diesel the EGR valve stays open when at idle and closes at throttle,just the opposite of a gas engine...that valve regulates exhaust flow,from what I read I think it sends exhaust from the drivers side bank thru passages in the intake to the EGR,and eventually out the passenger side manifold..

I have a "J" code intake on a '87 6.2 I got from a friends ramp truck when it snapped the crank,I was going to put that on it and ditch the EGR setup completely--haven't done it yet though,not sure I will get too either...lately just keeping diesel in it is keeping me broke...:(
 
Yeah get that EPR out if you can. The diverter on mine never closed so it would choke the engine under anything past mild throttle. You can just pull the vacuum line and it will keep the exhaust open (diverter shut) all the time.

It's a terrible system - I can't wait to swap in the j-code and get rid of the EGR crap.
 
It looks just like the heat riser they put in carb trucks. During warmup it captures exhaust heat in the DS manifold so the intake snorkel can suck warm air. What is the physical difference between these two valves?
 
The "heat riser" or EFE valve used on gas engines is similar but serves a different purpose--its usually on the passenger side manifold,when it closes it diverts all the exhaust from the passenger side head from going out the exhaust ,instead it sends it into heat riser passages built into the intake manifold that run under the carb base,which pre-heats the fuel air mixture to aid in proper vaporization when the engine is cold--after it warms up ,a ported vacuum switch denies vacuum to the EFE valve's canister and a spring inside it opens the butterfly,allowing the exhaust to exit normally out the exhaust pipe...some older vehicles had a simply bi-metallic spring on the heat riser instead of the vacuum type,I think around 1973 when EGR started being introduced is when they went to vacuum style ones..

My previous post explained what the EPR valve does...
 
You may have a non -egr intake on it then...or maybe GM deleted them after a while,my 2 diesels ,an '82 & '85 both have them ,(motor in the 82 was an unknown vintage one from salvage yard )..the intake I got was originally from an '87 C-30 ramp truck that had a SM465,no egr,no vacuum pump either (bummer,because it would be nice to have a spare one,they are getting costly and scarce now!)..
 
Well the one I had didn't route anything to the intake manifold. There was just a tin jacket around the exhaust manifold with a fitting for a hose. This hose went to the intake snorkel. A thermal vacuum switch and vacuum actuated flapper built into the snorkel would suck hot air until the intake air warmed up.

My point was just that it seems weird to build two different but similar valves. Both that mate to the exhaust manifold, both with vacuum actuation, etc. I was supposing that perhaps they were the same valve, but controlled differently in the gas and diesel applications.

No matter how long you hang out here you keep learning something new about stock trucks.
 
I put a J code intake on mine and eliminating the EGR but there was nothing like this on mine.
 
The tin "stove" around the exhaust manifold,the foil pipe and the vacuum flapper on the air cleaner intake was part of the "CCS" system (Controlled Combustion System") GM started using it in 1968 to reduce emissions and improve fuel economy--it was a combination of leaner air fuel ratios,advanced ignition timing and the switch to a 195 degree thremostat--some engines used an A.I.R. pump also,starting in 1967....the EFE valve or heat riser wasn't used on all applications ,many higher GVW pickups had none,some even had no EGR valve up until 1978 or so--I saw quite a few Canadian built GM trucks that had only a PCV valve,as far as emission controls, well into the late 70's,some even still had points as late as 1978 or so!..

It may be that Canadian built diesel trucks also had a different emission contorol system (or lack thereof!)..I dont know that for sure,but wouldn't be surprised if they did...
 
The Blazer was born in Flint, MI. Has the UAW sticker on the door.
 
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