Valve covers with vent on my bt5 - lots of leakage

[Geoff Ver]

Hi all,

Hope you can give some advise. After an engine rebuild I've been driving my 356 about 500 miles. The last 3 trips the vents in my valve covers start to leak after parking the car (mainly on the left side). They keep leaking for many days (see picture). Any idea if this will stop eventually or is it better to close the vents?
Thanks for your help!

[Ron LaDow]

Make sure the covers aren't twisted and replace the gaskets with Vic's: http://356enterprises.com/engine-rebuil ... rsche-356/
Probably the last rocker box gaskets you'll ever need.

[Geoff Ver]

Make sure the covers aren't twisted and replace the gaskets with Vic's: http://356enterprises.com/engine-rebuil ... rsche-356/
Probably the last rocker box gaskets you'll ever need.

Thanks but it is not a gasket problem...the leakage comes from the vents.

[Heidi Frances]

What does your oil level look like? Not super overfilled I hope?

Franny

[Geoff Ver]

What does your oil level look like? Not super overfilled I hope?

Franny

The oil level is between the lines..

[Heidi Frances]

Hmmm... If you remove the valve covers are they completely full of oil? I'm wondering if the oil isn't returning somehow... Is the crankcase breather breathing? This is on both sides?

[Geoff Ver]

Hmmm... If you remove the valve covers are they completely full of oil? I'm wondering if the oil isn't returning somehow... Is the crankcase breather breathing? This is on both sides?

No, not full of oil. It seems to be more like an oil vamper on the floor than only engine oil.
It is breathing, problem is on both sides but most of te leakage is on the left side.

[David Jones]

Franny may be close in her estimation of a restricted oil breather tube. Make sure that nothing is nesting in there. Blowing it back with a water hose will clear it out then leave it for a day to dry or rinse it out with alcohol or even 10% ethanol gas. I believe that what may also be happening is that after only 500 miles the rings are still bedding in and if you are getting some blowby as a result you are also getting somewhat higher levels of water in the oil as byproducts of combustion. These vapors will condense out when they reach the relatively cool surface of the valve cover. Just keep an eye on the state and level of the oil and whether or no the oil leakage slows down with increase in mileage. If the oil level is not dropping then it is just a cosmetic issue.

[C J Murray]

The VC vents would only leak while the engine is running and then only if blow-by was excessive and during higher rpm. The vents would not leak with the car parked for 5 days but significant oil leaks could distribute oil that could drip for a while.

I would wash everything with Gunk and run the engine, car stationary, at elevated rpm while observing the area where the oil forms. Pay special attention to the cheesehead screws to the front and back of each intake manifold. When they vibrate out there can be a major oil leak that will stream down the valve cover.

[Jim Liberty]

CJ could have found the problem. Be sure you use the correct sealant on them as well. The communicate with the oil.

...................Jim.

[Geoff Ver]

Thanks David, CJ...will test this next week. Maybe it is a bigger oil leak, it is till coming out after days without running the engine.
Lots of work to get a smooth running engine after a rebuild!

[Al Zim]

Start the engine and let it warm up. Remove the cap or open the top of the oil filler. If smoke is coming out then let the engine cool. Borrow a compression tester usually a Snap On tester will attach to an air hose. bring each cylinder to top dead center lock the car in 2nd gear with the parking brake on and put air in the cylinders. If you hear it coming out the oil filler hole it usually goes past the rings. I would also listen at the carburetor and the exhaust pipe for air noise, this would indicate there is a leak through the valves. The engine builder man not have rotated the rings so the openings were staggered. Your specification sheet should reveal the cylinder to piston clearance. Many times the Non German sets are near the wear limit because they are cheaply made. Be sure you ask your builder if the depth on the heads where the cylinder seals is 9.5 mm. Over 10 mm and the heads will not seal to the cylinders. I would contact your engine builder and look at his specification sheet al zim

[Vic Skirmants]

How does air get to the valve guides with the valves closed???

[Al Zim]

Vic: that will teach me not to write after I have been her for 12 hours. I will remove that statement from my post. al

[Jules Dielen]

check the screws on the engine sheet metal where it attaches to the heads. I had a loose one on mine and it made a BF mess.