PCV system on an old astro van

[4D-56]

Hey folks!

Im brand new on this forum, have been reading many posts for months now but decided it was time to dive in!

I have a 1989 V6 astro with 277,000 miles. 2WD. Had it for about 18 months now, was neglected somewhat before that. very dirty, slugy engine, was amazed at the blackness of oil that i have had out of it...was running it on Amsoil for a long time but gave up cause it was burning too much!!

Have had a qt of kreen thru both engine oil and gas....thats stuff is awesome, pulled my mpg up from 13 to 16...now running shell formula 10/40 with MMO.just learning (thanks to you guys!) the importance of the PCV system being fully operational. have bought an AC Delco valve, replacing grommets and PCV intake hose....as for PCV hose, im gonna do an oil catch can.

I have a LOT of blow-by....with the engine running, when i pull the PCV valve out, the idle speed goes up....plug it back in, it bogs down again..??...lots of blow-by at the oil filler cap...less since kreen but still a lot....whats is this idle speed change with PCV valve plugged in or not telling me?

thanks guys...

 

[justinf89]

Maybe the computer is compensating for the large vacuum leak?

 

[pcoxe]

There probably should be a vent hose on the opposite valve cover going to a breather filter in the air filter housing. The PCV valve pulls a metered amount of air through the engine at all times to ventilate it. It sounds like you are pulling a closed vacuum on your crankcase. Maybe instead of a solid oil fill cap you need to add a breather type cap?

 

[MrHorspwer]

Check the PCV port in the throttle body. The old 4.3L TBI engines used to always coke up the port, especially as mileage was accumulated, and block off PCV flow.

Also, it may be worth a look under the valve cover. I have worked on more that one 4.3 that was a jello mold of sludge under the valve cover, preventing any PCV flow. These all also had a coked up port in the throttle body.

 

[4D-56]

Thanks guys!...
so, I do have the typical set up of 2 hoses, one pulling air from the TBI and one from the PCV valve itself going back to the TBI. On the inside of the TBI, where the hose form the PCV valve is, there is black gunk, hence my thinking that i need a catch can.

pcoxe: when you say "It sounds like you are pulling a closed vacuum on your crankcase" do you mean that the PCV intake hose is plugged and not pulling fresh air thru? I dont like the idea of a vented oil cap cause its gonna stink and that blow-by is gonna cover everything in an oil film?....better to use the catch can?

MrHorsepwer: I had thought about pulling the valve covers a while back but i guess im avoiding having to do it?! Actually,, im looking at a print-out from my chevy dealer from when i ordered new grommets and PCV intake hose, I think my hoses might have been swapped and are going to the wrong ports on the TBI and throttle body?!!

does anyone know where i can find some of those long small diameter wire bushes for cleaning inside diameters?

I will get this old girl running good!!