Engine blow by |
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Jbradford
Groupie Joined: June-09-2015 Location: Edna,Tx Status: Offline Points: 49 |
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Posted: June-29-2015 at 10:40pm |
My 1975 350 OMC has a lot of blowby, I have ordered a new DUI to replace the GM delco HEI which whoever installed did a horrible job, it leaks oil all around the intake. It is coming out the dipstick in small amounts as well. Performed a compression check today and had 180-190 degrees on all cylinders and the engine runs well. I bought it set up with 1 line from each valve cover joined together with a chrome item with a vent, it emits small amounts of smoke when idling. I do not know if it is a PCV valve or not. I have no where to connect to my flame arrestor unless I modify it. How should I vent the crankcase on this old little darling? That has to be the problem with compression that good. Previous owner (they are always good to blame) did not do anything right that I have seen yet so I know he probably ran these vent lines together from the valve covers. Bilge is full of oily water after an 2 to 3 hours of running now.
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Riley
Grand Poobah Joined: January-19-2004 Location: Portland, ME Status: Offline Points: 7953 |
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You should have a PCV valve on one valve cover hosed to a vacuum, and a vented oil cap or hose gong to the flame arrestor on the other valve cover . We had a problem with blow by and I removed the PCV valve and stuck the hose right in the valve cover and the blow by went away. Replaced the PCV vale and it was fine. PO had installed the wrong PCV valve.
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Jbradford
Groupie Joined: June-09-2015 Location: Edna,Tx Status: Offline Points: 49 |
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Where do you get vacuum on this old motor?
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Jbradford
Groupie Joined: June-09-2015 Location: Edna,Tx Status: Offline Points: 49 |
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By the way I have a new to me Rochester Marine Quadrajet Carb, the boat did not have a marine carb before.
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baitkiller
Platinum Member Joined: October-11-2011 Location: SW Florida Status: Offline Points: 1693 |
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Interesting. if you are running a quadraflush i assume you have an adapter (and) wedge. Many times these (spacers) are fitted with ports. Not so? Thats OK, we can get around it. Pretty sure there is a vac plug in the plenum if needed. Just for giggles do me a favor. Next time your aboard, fire it up and at idle, pull the oil cap and rest a dollar bill or other paper over the hole and see if the bill pumps. I expect not but hate to overrule a broken ring none the less. > Dumb questions:> oil weight? How much oil is in it? Gotta start there. |
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Jesus was a bare-footer.............
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Jbradford
Groupie Joined: June-09-2015 Location: Edna,Tx Status: Offline Points: 49 |
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I will try that with dollar bill. Running 5 qts valvoline vr1 20w50, originally put 6 qts but after research think it is 5 qts. Oil dipstick is not correct.
Thank you for the help |
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Jbradford
Groupie Joined: June-09-2015 Location: Edna,Tx Status: Offline Points: 49 |
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Tried with a dollar bill and it just basically lays there at idle. I took a pic of my carb and I know it is not the best but could not get a good angle. Where fuel comes In there is a barb that has rubber piece on it to seal off that below fuel entrance, the one above is going to hook to my new marine fuel pump I think is correct.
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Jbradford
Groupie Joined: June-09-2015 Location: Edna,Tx Status: Offline Points: 49 |
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Is the lower port that has the black rubber seal vacuum to go to one of the valve covers with a PCV valve, I made a nipple for my flame arrestor for one of the valve cover now I need to run the other valve cover breather to somewhere. I do not know have a port on my adapter plate, Or should I just put both valve covers up the flame arrestor?
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Jonny Quest
Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2958 |
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On the picture above, that port with the black rubber cap on it (just below the fuel inlet) is a good port for your PCV hose. Make sure to use a PCV valve -- don't just hook-up a straight hose from the valve cover port or you'll have a monster vacuum leak.
If you choose to not use a PCV valve, then you can run hoses from each valve cover up to the flame arrestor. Also, don't over-fill the crankcase with oil. I've seen situations where an over-filled crankcase has pumped oil out from various locations. JQ |
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Current
2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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Jbradford
Groupie Joined: June-09-2015 Location: Edna,Tx Status: Offline Points: 49 |
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That will work Thank you. The barb above fuel inlet is where I ran my new marine fuel pump overflow to, I assume that is correct?
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Jonny Quest
Grand Poobah Joined: August-20-2013 Location: Utah--via Texas Status: Offline Points: 2958 |
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Some marine carbs have a barb/port for the fuel pump diaphram rupture safety tube. Did the carb have the safety tube hooked up originally? If there is any doubt, put a rubber cap on the barb/port and run the fuel pump tube up to the flame arrestor. JQ |
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Current
2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
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Jbradford
Groupie Joined: June-09-2015 Location: Edna,Tx Status: Offline Points: 49 |
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When I bought the boat it had a auto carb,pump,starter and alternator and delco hei distributor so I had buy everything new. The barb above the fuel inlet in the above pic is what I connected pump to. When the carb came in it did not have a cover on it.
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