Vacuum Hose

[Anonymous]

I inspected the vacuum hose from the valve cover to the orig single barrel carb of my I6 200. I found out that the inside of the hose is clogged by what seemed to be the melted rubber. A mechanic told me that this hose is not needed and I can plug the carb inlet. I told him that Ford designed it that way, and I should keep it.

What's the effect of this plugged hose on my carb? Thanks.

 

[BIGREDRASA]

What car? What year? What tranny?
PM me with your e-mail addy, I'll send pics, you tell me which hose.

 

[Anonymous]

Sorry for not being so clear. It's a 67 Mustang with I6 200 and C4 trans. The hose runs from the carb to the top of the valve cover. It's around 3/4" in diameter. Thanks.

 

[simon]

The hose you´re dealing with isn´t referred to as a vacuum hose; though it can be a reason for vacuum leaks sometimes.

However, your mechanic is not wrong at all.
This connection routes blowby exhaust gasses from the crankcase from the PCV valve in your valve cover to the spacer of your carburetor; basically all environmental geegaw.


Concerning the "molten inner surfaces" you describe, I think some former restorers used the wrong rubber material hose for this task on your car, as "perbunan rubber" or any other kind of oil-and solvent-resistant rubber is needed.

 

[Anonymous]

Yes, the hose is badly worn. Cracks everywhere. So if I decide to do away without this hose, I have to plug the inlet on the carb spacer? Thanks.

 

[Anonymous]

Um... I may be wrong here... but I would not do away with that system.
You should have a good breather cap, and a clear PCV system to get the best performance out of the car.

On mine I carry an extra valve in the trunk because those things clog up easily and reduce the performance of the car. When mine clogs I notice a big difference in Idle and top speed.

It is such a simple and cheap fix, why kill it... get some hose and a new PCV valve at the Auto store... less than $10.00 to fix.... just pull yours and take it with you to the store so you can get the right size...

 

[simon]

When mine clogs I notice a big difference in Idle and top speed.
...

everything ok with that, jimbo, just some little refinements:

"stuck" would describe it better, because even a clogged PCV valve isn´t that clogged that it´d be airtight. Ususally, oil-and carbon buildup stuck the system so it stays half open (or half closed, whatever you like).

Of course you´re experiencing bad idle, transition and WOT differences or even problems, because the PCV system´s operation varies according to intake manifold vacuum and blowby pressure (which changes during acceleration, part throttle and full throttle)

In technical aspects, the only practical reasons for a PCV system are better running at low temperatures (even smallest amounts of hot blowby gasses routed in by the PCV valve heat up the intake manifold enough to help prevent icing), and less exhaust gasses.
Arguments against the PCV are a possible vacuum leak, and oil sludge buildup inside the manifold.

Very often, PCV valves can be cleaned in hot, soapy water (dishwasher detergent) an used again. I have a couple of spares nevertheless

 

[Anonymous]

That mechanic has been sniffing exhaust fumes for to many years!

Go to the auto parts store and pick up a new pcv valve and a couple of feet of gas line hose to replace that old hose....It'll be as good as new!!

Later,

Doug

 

[MustangSix]

Do not eliminate that hose. Of all emissions systems, this one is the least complex and has little effect on performance.

A good PCV system can help extend the life of the engine by eliminating water vapor, acidic combustion byproducts, and excess comubustion fumes that would turn to sludge. It also helps reduce crankcase pressure and thereby helps prevent oil leaks.

Your mechanic needs to retake that section of the ASE test.

 

[BIGREDRASA]

Jack, I tried to PM Webscorpion at 12:05 PM, with essentially the same thing you just said. The message is still in my "Outbox." What am I not doing right?

 

[Anonymous]

Red:

You are not doing anything wrong... the message stays in the outbox.. till the member logs in the next time... then it goes into their inbox.. and your sentbox... it's a neat way to see who has gotten your messages.

I still have a few PM's in there from a few people who have not logged in for some time... you can also edit the message and change something if it has not been received.


J.

 

[Anonymous]

Thanks for all your replies. I think I should really buy a new valve and replace that hose. It should be there for a purpose

Will this clogged PCV valve and hose explain why my engine stops when I try to go WOT? I had my carb serviced by the same mechanic but hadn't installed it yet.

Thanks for taking time to send me a PM. Will read it now

 

[BIGREDRASA]

I think you need a new mechanic. Better still, get yourself a good manual, and trust in the wisdom of all these sages.
Seriously, I used a 90 degree elbow on the PCV valve, so that I can use a straight hose, rather than the preshaped factory hose.

 

[Anonymous]

No they are probably not related...

A "Stuck" valve might reduce your power slightly... but it would not shut the engine down...

That sounds like another carb problem altogether...

 

[Lazy JW]

Every internal combustion piston engine develops blowby gases in the crankcase. These blowby gases are mostly unburned fuel. These gases need to be vented out of the crankcase or they will condense in the oil, which dilutes the oil and leads to the developement of sludge. This is very bad for your engine In the old days, cars had a vent tube that extended down from the crankase, and the air moving past helped to pull the fumes out. This kept the underside of your car well lubed. A good PCV (Positive Crankase Ventilation) system does a much better job of ventilaing the fumes, doesn't pollute as much, and doesn't make a mess on your engine. You definitely need a better mechanic if he doesn't understand this.
Lazy JW

 

[Anonymous]

So if my pcv is working properly do I still need a vented oil cap?

tks
don

 

[BIGREDRASA]

Yes, unless you draw fresh air in through the air cleaner.

 

[Anonymous]

This brings up an interesting question....

on my 69 log head that I was running the Oil Cap was in the back and the PCV was i n the front... I have seen them hooked up this way and the reverse?

Now on this 250 2v should it be the same?
Would it even matter?

 

[MustangSix]

Doesn't matter, front or rear.

 

[Anonymous]

Yes, unless you draw fresh air in through the air cleaner.

Please remember I am dense, I don't get it? I am an Oxymoron. I have a little oil coming out of this vented cap onto the valve cover and dripping down the engine. It's not so bad now that I have the pcv working a little but I know it is not supposed to do it.

don