I have a 95 F150 with a 302 and automatic. I've heard that disconnecting the pcv valve and connecting it to the vacuum tree on the plenum will increase the life of the engine and could make the truck run better. Anyone else heard this too?? If so, does it actually do any good or will it cause harm??
I had heard the same thing a while back so I tried it. I blocked off the stock pcv nipple at the back of the intake plenum (in line with # 8 cylinder) and hooked up to the vacuum tree in the center of the manifold and it cured a nagging miss that i had when climbing hills. It seems that the excess oil and air can foul the #8 plug or something like that and cause the truck to run bad, also hear that it can screw up the rings and piston but I am not sure of that. But it was a cheap and cheerfull fix for a persistant problem. Give it a try, it cannot hurt anything as far as I know, in fact I would think that the center vacuum tree would be the logical place to pull pcv vapours from.
If I remember correctly the hose is 3/8 in.i.d. This fits the pcv valve all right but the vacuum tree connection is a bit smaller so I used a small hose clamp to secure it. My tree had a spare connection that had a cap on it but the cap is too small for the connection on the back of the manifold so I just used a small piece of 3/8 in. hose with a bolt in it to block it off ( I know it's mickey mouse but it worked and you cannot see it anyway) This simple mod made all the word of difference in tha way my truck runs now especially on hills. Give it a try.
Seems logical to distribute the crankcase vapours in the middle of the intake rather than aim them at one cylinder. I wonder if this will draw more vacuum as well (stronger volume) and cure a nagging problem I have with my truck when the emissions filter in the air box gets polluted with oil and falls off after a few weeks due to lack of positive flow of fresh air into the engine. It doesn't hurt to spray a can of throttle body cleaner into the vacuum tee once and a while to clean out the carbon build up in the upper cylinders. You guys should get a commission from Ford for making their products run the way thay were supposed to from the factory.
Since I have changed the hose location I have had no oil backfeeding into the airfilter box and my filter for the pcv system remains clean. Prior to the change the filter would fall apart in a short period of time most likely from the oil dissolving the glue that holds the filter element to the rubber base. I also have not experienced any miss since this change.I am now a happy Ford owner again.
Okay, Okay, Okay. . . You guys are too fast for me. Sounds like this is something I want to try, as I too am tired of having to replace the emissions filter every oil change because it's so gunky. Remember though that I'm uneducated about anything much past defibrillators, transcutaneous pacemakers and paralytics (medical stuff which don't do much for my Ford Truck) WHAT are you disconnecting again, and where are you reconnecting it to?
The pcv valve has a hose that attaches to the back of the intake plenum just above the #8 clyinder runner.Just follow the hose from the pcv vavle to the manifold and pull the hose off the nipple and remove the pcv valve and hose. You will need a length of 3/8 in hose to reach from the pcv location around the back of the plenum and up to the center of the plenum where the vacuum tree is. If you are lucky enough to have a 3/8 in nipple cap you can cap off the stock nipple at the back of the plenum,if not take a short piece of 3/8 hose and install a suitable sized bolt in it and use it as a cap, crude but effective and cannot be seen anyway. Now hook the pcv valve to the length of hose and install the valve in the valve cover hole and route the hose around to the manifold tree. I have a 5 spd trans and have a spare hook up on the tree but I am not sure if this is used for the auto transmittions. If you have the spare unused connection just put the hose on with a small hose clamp to secure it as the size of this connection is a bit smaller than 3/8 in. If you do not have a spare connection you will need to go to your parts store for a "tee" to fit into one of the larger lines leading from the tree, perhaps the one that goes to the vacuum booster and hook in the pcv line there. I hope that this will help you achieve your quest for better running. SR.
As the engine runs, some of the gasoline goes by the rings (gasoline molecules are smaller than oil molecules). Since gas is just a light oil, it dissolves into the oil. And since it's lighter, it lowers the viscosity of your oil, which is bad. But it also boils at a lower temperature than the oil, so it evaporates out over time. The EPA doesn't want it in the air, so the PCV emissions system was invented, and it simply allows a small amount of air to be pulled thru the crankcase under certain conditions, thereby purging the volatiles and burning them safely in the engine. It's such a small flow that the "vacuum leak" doesn't affect the engine, but it does its job, assuming the valve isn't clogged. That happens invariably, so the valve has to be replaced as a normal maintenance item, like oil & spark plugs.
The normal operation is for air to flow into the filter box, into the breather filter, thru the hose to the L valve cover, down into the engine and back up the other side, to the rear of the R valve cover, thru the PCV valve, thru its hose, into the intake manifold, and into the engine to be burned. But the hole in the fitting screwed into the back of an EFI plenum is small, and often fouls closed, stopping the flow. Later ones (like my '96 5.8L) go to the vacuum tree like stevieray described, but it's sufficient to just clean the fitting out and reconnect the hose.
I will probably just keep mine clean then and make sure the hole is not plugged. In Volvos (old ones anyway) they have a deal called a flame trap. It plugs up about yearly, and if left untreated, your rear main seal blows, and you lose all your oil.
SO, I'm use to keeping it in check I guess.. And the part is under 4 dollars, so no biggie.