Mercruiser 170 back pressure thru valve cover vent ??

tinydog

Cadet
Joined
Mar 18, 2012
Messages
25
Just purchased a Wellcraft American 190 thats been sitting for a while and this is my 1st inboard. Motor starts and runs good on the muffs but there is a fair amount of constant pressure at the vent from the valve cover to the flame arrestor and Im just wondering if its normal to have some pressure there. thanks.
 

Technorunner

Petty Officer 3rd Class
Joined
Oct 1, 2010
Messages
95
Re: Mercruiser 170 back pressure thru valve cover vent ??

it should be coming some vapors when the engine is warm. But you shoudent have any pressure there. if it has benn sitting it can be compression rings that have been stuck. Try and do a compression test and se if you get some bad readings there
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Mercruiser 170 back pressure thru valve cover vent ??

The 470 seem to always have a lot more pressure out that vent than most engines. Without seeing it, it's hard to tell if it's too much or about normal.
 

riptorn

Chief Petty Officer
Joined
Mar 8, 2012
Messages
433
Re: Mercruiser 170 back pressure thru valve cover vent ??

Any pictures?
 
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