AQ130 Oil out the breather

"Guys, firstly thanks for all

"Guys, firstly thanks for all your advice to date, this is the finest resource on the web.
I have a question. When I rev my AQ130 to about 4500rpm a little smoke comes out of the oil filler cap, which I know is a breather. After prolonged running, you can clearly see a film of oil in the recesses around the outside of the rocker cover, therefore im assuming the 'smoke' is infact oil. A local mechanic has told me this is perfectly normal, but i'm just checking with you guys.
Thanks in advance,"

"It si perfectly normal if you

"It si perfectly normal if your engine is having blow-by, which happens to all engines when they are getting "tired". A bit of blow-by gas is not to be worried about, but when it becomes excessive it is time to pull the engine to rebuild or re-ring it."

"On my AQ130C, which is a fact

"On my AQ130C, which is a factory rebuild with about 150 hours on it, I have to be sure the oil filler cap is on tight and the gasket seated properly against the valve cover, otherwise I get oil leaking out and onto the valve cover. I always thought that the "breather" is on the port side of the engine with a rubber hose leading up to the rear carb's flame arrestor. The only blow by I get is out my engine oil dip stick...a little oil leaks out of it, so I use a rubber cork in place of the dip stick and keep the dip stick elsewhere. I figure any excess blow by will come out of the breather and into my carb...and I get very little.

breather

"Bob, some oil caps are tight,

"Bob, some oil caps are tight, others have a gauze and work as breathers as well, indepedently of the engine having vent hoses coming from elsewhere attached to the carb suction. My old AQ240 (351 Ford) is an example of an oil cap that works as vent. I don't have one at hand from an AQ130, so I'll take your word and I will stand corrected.

By the way, you have a nice looking engine installed on your boat, without any visible traces of corrosion. Way to go!"

"El, thanks...my boat never ev

"El, thanks...my boat never even comes close to saltwater...the closest it gets is in the Sacramento River Delta near Rio Vista...70 miles up river from the ocean."

"Guys, thanks for the replies

"Guys, thanks for the replies they have been most helpful.
El Pescador, should I start saving for a rebuild?
My Filler Cap has a gauze inside which im presuming acts like a filter. The blow-by only happens when the engine is revving at full-tilt and even then, it's not like the engine is bellowing gas, just a slight haze"

"If you don't have a signi

"If you don't have a significant loss of power or don't see a lot of blow-by gas coming out of the breather or the oil cap, then it's probably a bit early to be concerned. One thing I would do, though, is to disconnect the breather hose from the carb when the engine is running and check how much gas is coming out of there (check at a wide range of RPM, from idle to full speed); if the amount of gas is excessive, that's a bad indication. Also, to verify that there is no significant loss of compression, you should consider doing a compression test followed by a leakdown test. The compression test will give you an idea of how balanced is the engine, and the leakdown test will indicate if compression is being lost (and how much) between piston rings and cylinder walls."