air intake

[cwilson jr]

when you put on a performance air filter assembly or whatever they're called, you put a breather in the valve cover to eliminate the hose and then you have that vent that goes into the exhaust manifold, i assume that has something to do with the egr?  what can i use to eliminate/block it off?

[cwilson jr]

i guess this is called the exhaust manifold shroud?

[77c15]

I beleive the part you are refering to is the exhaust preheater that on a cold start will direct warm exhaust air into the air cleaner assembly to help the engine warm up quicker. The best way, I found, to rid this item is with a nice pair of Summit brand long tube headers. For less than $100-$150 you can have the headers short pieces of tube, and some glasspacks to have a decent sound and rid of the preheater.

[VileZambonie]

That pipe that goes to the exhaust maifold is called the stove pipe. It works with a thermostatic aircleaner. When the engine is cold it draws air that is heated from the surface of the exhaust manifold and routes it into the air intake. This helps better atomize the fuel when the engine and intake air cold. If you remove it you will have longer warm up times and waste more fuel when cold but you do not have to plug anything. It just simply sits on top of the exhaust manifold.  

[cwilson jr]

thanks, that's what i wanted to know.  wasn't sure if there was a small opening venting exhaust maybe for the egr.

[shpark2]

So on my 1980 C15, it's like 15 mins to warm up - running without a stovepipe, new thermostat, 50/50 coolant.  I don't believe the stovepipe is the real problem, I'll put it on anyways because Canadian winters can suck at times.  Temp gauge barely pulls itself off the first line on the gauge, and the heater core lines are both screaming hot and eventually the top rad hose heats up.  The fan seems to pull a lot of air right from the get go, is there a test procedure to check the fan clutch?  I already suspect my gauge/sender because the block is hot to the touch after only maybe 5 mins, does anyone know the electrical details on the sender and what the ohmage should be at operating temp, cold temp, etc?

[VileZambonie]

The fan clutch should slow down within about 2 minutes in cooler temps. When it sits for a long period of time the viscous fluid has to be re-distributed before it will disengage. That's normal. Make sure you can turn the fan by hand, make sure there is no axial play. Pull the wire off of the coolant temp sending unit then ground it and observe the gauge. If the gauge appears to function correctly put in a new sending unit.

[shpark2]

So sitting cold or hot and not running, the fan should turn freely with minimal play.  It does and doesn't have a shred of wobble to it.  When grounded the gauge should sweep past high temp to the far right side?  That's what mine did anyways.  The coolant switch is right below a bolt in the valve cover(IE leak) and the contact and sender is not the cleanest, it's got the T top and slide on connector so every bit of crap can get into it.    I cleaned it up and will run it later today and see if it made a diff.  I think the Olds 455 I have, has the same switch - the switch Summit called out is the spade connector with 3/8NPT - mine is way bigger.  It didn't appear to me that GM used many different sizes for this switch.

I appreciate the help I get here for sure, I'm a newbie there's no doubt.  I always try to search for previous posts in case someone has already gone over it, so pardon me if I dig up old stuff and attack it from a different angle.

Thanks again,
Patrick