I have a problem with suction through my valve covers.

The PO installed an Edelbrock intake and carb.

The engine runs great, but one of the things he told me was he would get a 'squeal' once the engine came up to temperature.

Well, I finally put the car on the road today and test drove it and, sure enough, when the temp came up the engine squealed.

The PO had changed the water pump and the alternator thinking that's where the problem was, but it still squealed.

I started chasing it down by first removing the serpentine belt, but it still squealed.

Then I pulled the oil cap and viola, the squeal stopped.

Put the cap back and went to the drivers side and pulled the PCV. Same result. Squeal stopped. Looked at the PCV plumbing and realized the PO had hooked the line up to the air cleaner and not a vacuum source.

Went to the autoparts store and bought a 'T' to connect it to the line going to the booster figuring that would solve the problem.

Nope. Still squealed with the PCV hooked up.

Put my had over the hole in the cover and it has a lot of suction which pulls the PCV shut and the squealing starts.

The only thing I can think of that may be wrong is that the PO either didn't seal the intake well when he installed it, or maybe put on the wrong gaskets.

Hopefully it's nothing worse.


Any thoughts?

I really don't want to have to pull it apart, but If I have to, I will.

Thanks


Edit: I should mention that the car does not overheat or blow any oil out.

Engine only idles slightly higher without the PCV.

 

If the previous owner had the PVC plumbing hooked up to the wrong source, then he/she probably also had the vent plumbing hooked up wrong - probably had them switched, which means the vent hose is going straight to a vacuum source. And this is the only explanation I can come up with as to why you have a vacuum in the crankcase...

 

Not sure which line would be the 'vent'.

You can see where the PCV is going to the air cleaner. (not there now)

Is the 'vent' line the one on passenger side valve cover in the rear(just ahead of distributor)?

 

Yes. What is the other end of that connected to?

 

PCV is supposed to suck excess oil out of the crankcase. Sounds like a vacuum leak. Replace the gaskets properly and go from there. Assuming you have the pcv system working properly of course.

 

Wrong. It vents crankcase pressure to the manifold. The PCV valve is simply a meter that controls the amount of air that can pass through.

 

Well, while I was waiting for an answer, I decide to check the line in the other valve cover.

Sure enough, it was hooked up to the vacuum line at the front of the carb.

Reconnected it to the breather and hooked the PCV back up.

Seems to be ok but if you hold your thumb over the vent line it will start to pull vacuum.

Runs with no problem tho.


Thanks for the help Danno

 

Solution edited.

Sounds like you have the problem solved.

 

Meant oil vapors but apparently that's not correct. Keeps combustion byproducts and unburned fuel vapors, from mixing with oil and sludging up (obviously). Oh, and you called it a PVC. It's positive crankcase ventilation not PVC = polyvinyl chloride. Anyways, Glad you solved the problem!

 

Yeah..

And now that I see that these lines were hooked up wrong, I'm beginning to suspect the same problem with the heat controls not switching between floor,vent,defrost and heat.

Matter of fact. I could almost bet money on it.

 

 

Actually, it keeps crankcase vapors from being vented to the atmosphere by routing them back through the intake system where they can be burned...

 

Actually the crankcase is sealed so the vapors don't go into the atmosphere. But yes, the excess is routed to be burned up.

"The blowby vapors that end up in an engine's crankcase contain moisture as well as combustion byproducts and unburned fuel vapors. The crankcase is sealed to prevent the escape of these gases into the atmosphere, but the vapors must be removed to prevent oil contamination that leads to sludge formation. The positive crankcase ventilation (PCV) system siphons these vapors from the crankcase and routes them into the intake manifold so they can be reburned in the engine. "

I knew this but believed that it purged excess pressure in oil as well which was what I was originally trying to type. Left a word out and you came across like a rude @sshole. No worries.

 

Maybe hook the PCV line to direct manifold vacuum. A tee in the booster line for the PCV will hinder the power assist.

No vaccum to the HVAC should put the system in default mode = defrost no matter what is selected.

 

I'm going to change it later tomorrow.

And the thing is, I bought a new 'T' and then discovered, with the help of Danno, that the vent line was connected through a 'T' on the front of the carb.

Could have just disconnected the vent and plugged the PCV in it's place.

Oh well...

And as far as the HVAC. I'm thinking the line that's connected on the 'back' of the carb isn't pulling enough, if any, vacuum.

The PO of this car has so many things wrong, that I had to straighten out, nothing would surprise my anymore.

There's still no cruise (half of it is missing) and no AC. Condenser and the 'high' line is missing. AND the PO cut the wires off..

Right now, it's running good and driving great.

I'll fix the other things as time goes by..

 

All Fixed!

And the HVAC vacuum is now connected to a full on vacuum source and works great.
The PO had it connected to a metered port.

 

Excellent.

 

Thanks Danno!

I think the next thing is to replace the 'home made' throttle and TV cable bracket.

Everything is working ok, but the cables really aren't in there tight and the alignment is a little too far off for my liking.

I may just buy the Edelbrock bracket and do it right.

And that throttle return spring is just a little to stiff for me.

Foot gets sore after about 5 miles of pressing so hard.

 

The PCV is not supposed to suck excess oil out of the crankcase. It's job is to keep air pressure from building up in the crancase (which would push oil out of the engine through seals etc. and also cause air pullution as the gasses escaped) and is routed to the intake (vacuum source) so that any fumes are burned in the engine.

 

you obviously didn't read the follow up posts. yes. i know it's purpose. i've actually had to replace the entire system on another car that sludged up and was pushing oil through the gaskets. READ the follow up post where i explained it was a typo!!!!!!!!!!