Inliners International Forums General Discussion Engines Vapors from the breather

Vapors are coming out of the breather on the valve cover. Mechanics that see this instantly say I've got significant blowby despite a lack of smoke from the tail pipe.

Three different sources all said worn rings, worn valve seals, worn guides or combination of these.

One says valve seals are no big deal to do.

Two others say pull the head, send it off to get rebuilt and do the rings with the block still in the car.

All three have been or are full time mechanics. All three are trusted friends. Two offered to do it for me free if I supply the parts and help out.

What do you people think?

The degree of blowby is not significantly affected by valve seal or valve guide wear.

There is always SOME blowby in an engine caused by a less than perfect ring seal. If it is not enough to cause blue smoke at the tailpipe why not consider installing a PCV valve vented into your intake. That would be a lot cheaper than valve guide or head work.

Before you decide to tear into the engine do a cylinder LEAKDOWN test. Also Moroso makes an inexpensive ($80) blowby meter. Those two tests will tell you a lot. Good luck.

I agree with Frenchtown,a PCV valve vented into the intake may help.

Are you seeing an unusual amount of smoke under the engine from the crank case vent pipe as well? There is always some atomized oil in the crank case and the top of the head. Doing a simple compression test (first dry and then with a little oil in the top of the cyl should tell if the rings or the valve guides are sealing sufficiantly. I agree with the above suggestion that a pcv will probably fix your problem assuming no unusual blow-by. I have an article somewhere on three different methods of installing a pcv. One canibalizes the crank vent tube. I'll try to find the article and forwad it to you.

Thanks, BroDo.

Send it to zekefishburn@hotmail.com as I would like to setup and PCV system anyway.

I like smelling like old car but the wife is sort of ambivolent to it.

I cranked up my old 1947 Oldsmobile Straight Eight today and drove it about thirty miles or so;noticed a lot more fumes than I remembered.I sold this car and bought it back; the person I sold it to had the fuel pump rebuilt and I think that the fuel pump is putting fuel into the crankcase as well as letting oil leak out at the pump; I think I will rempve the pump and use an electric fuel pump installed close to the tank and I would also like to add a Positive Crankcase Ventilation set-up! Any good ideas on which type of valve to use etc. any websites on this? Thanks for helping the old man out! "Leroy"

By law 52 and earler automobiles don't require SMOG, so your are probably going to have to "roll your own". Since you have a flat head the trick might be to finding a spot above the pan, near the head to vent the crank case vapors to the carb or intake manifold. What PCV valve to use is another good question. Are there any flat head 8s made after 52(?) a PCV for one of them would probably be a good choice. btw of all the SMOG equipment a PCV is the only positive one, so a licensed SMOG Tech told me once. As to the electric pump, I'd get a good rebuilt mech. The thump, thump, of the electircal, when I turn the key on disturbs me.
Larry

You can use pretty much any PCV valve, unless you have a really low vac signal. In that case, try one from a 1970 Corvette LT1 350 (last of the solid lifter HP engines). Otherwise, try one for a 250 Chevy six.

When mounting a PCV, try to put it where it doesn't have oil splashing directly on it, or you will be sucking in more than just vapors. Mounting it in place of the road draft tube is usually a safe bet as it is usually baffled.

One last thing, when running a PCV valve, you can't have a sealed engine. You need to have either a breather located somewhere on the engine, or a vent tube running from somewhere on the engine to the air cleaner. If you don't do one of these things, you will be pulling a hard vac on the motor which could cause the gaskets to leak or possibly worse.

Try a PCV valve from a late model engine of about the same displacement as your engine. An EV-98 from a Ford 289 / 302 is probably a good choice. Remember to include a filtered breather vent to allow fresh air circulation throughout your crankcase. This will greatly increase the life of your oil as it will purge the corrosive compounds formed as a byproduct of combustion. Put the PCV at one end of your valve cover and the breather at the other end. Or use the existing crankcase breather location. Good luck.

First PCV that I remember was on my 1964 Pontiac GTO It was "Black-Magic" in those days. I remember having an old 1956 Chevrolet 4 door hardtop with a worn out 265 and I tried to put on a PCV and ended up it drew out all the oil in a short period of time. I dont like the electric pump either but it will push fuel to the carb. without grinding the starter to get it there.
The previous owner spent big money on having this pump rebuilt and it "SUCKS" except when it is supposed to. We used to rebuild our own pumps. All this NOS stuff is so old that it is rotted also. I had rather find something else that will fit off a later model that is available fresh. I will look around;this deal gave me severe headache after yesterdays drive.

Frenctownflyer,Its a flathead but I can tap into the road draft tube or remove it and place an freeze plug etc, in its place and pull the air back thru the oil-filler-breather-dipstick; (which is a combination on this engine).Wonder where to get the vacum? Possibly the intake manifold itself? I think this engine is only about 228 cubic inches or so. Very small displacement for such a huge chunk of castiron.Worst thing is there was nothing wrong with the fuel pump as far as I know till he decided that it needed to be rebuilt?

The PCV valve needs to get its vac below the trottle plate of the carb. Either the intake manifold itself, or make a plate with a fitting on it between the carb and manifold. Do NOT try to tie it into the same source as vacuum wipers if you have them, the wipers won't work if you do.

oops - forgot about the flathead - try a pcv valve from a 3.0L engine. Too small is better than too big.

gearhead,
i put a pcv on a 216 in a 49 chevy & ran the line to the same place as the vacum wipers & it didn't affect them a bit. the pcv also worked as it should.
robert

I tried combining mine and it didn't work...

Thanks for all the hints and helps This car does have an dual diaphram fuel pump and I have now rebuilt it and reinstalled. Found that the big oil leak was caused by the fact that there is a flat steel plate between the block and the pump; and the block doesnt have a full surface for the fuel pump to mount on and I had to make a gasket that would work and seal off. Stock gaskets would not work here and left a gap a full inch long allowing oil to pour out.Probably can put PCV valve in the side cover where valves are adjusted,but will wait till later.Will be easier to do with manifold removed.Good excuse to put on duals or triple exhaust system? Anybody ever put duals on a straight eight?