Merc 165 I6 Crankcase vent question

[sextondm]

Hello all;
I just bought my boat ('74 Starcraft Chieftain with Merc 165 inline 6 (just finished rebuilding it
My valve cover has one vent, which is pointing directly at the carb. which also has one vent, pointing directly at the valve cover vent. Just want to make sure it's that simple, and things are hooked up correctly. I'll attach a picture of the carb/valve cover.
Thanks!!

Dave

 

[ziggy]

Re: Merc 165 I6 Crankcase vent question

yep, it's that simple.
my '72 165hp L6 was set up the exact same way.

not sure, but ya might look into the fuel line from the fuel pump though. if that hose isn't a1 rated, i believe it would be in violation of uscg rules... from the fuel pump to the carb should be solid tubing fuel line or, uscg approved a1 rated fuel line.

 

[sextondm]

Re: Merc 165 I6 Crankcase vent question

Thanks! I was reading another thread discussing this and it had some great pictures from yours, and others 165's! Seems to differ sometime in the '72 to '75 timeframe though. Think later ones had hose from valve cover to the flame arrestor, and the fuel pump vent line went to the barb on the carb... Little worried about that vent line now...

 

[cr2k]

Re: Merc 165 I6 Crankcase vent question

The vent line is typically plastic tubing. Clear so you can see if fuel is venting from the pump (ruptured diaphragm). The A1 hose is the fuel line.

 

[oldsub86]

Re: Merc 165 I6 Crankcase vent question

This is not my boat, but my boat has a setup like this one with the vent hose attached to the flame arrester.

Randy

 

[ziggy]

Re: Merc 165 I6 Crankcase vent question

Think later ones had hose from valve cover to the flame arrestor,

this appears to be true. my '75 is set up like oldsub's pic. my '72 is set up like your pic.

and the fuel pump vent line went to the barb on the carb... Little worried about that vent line now...

imho. this didn't show up till '78 in my guesstimate. the reason i say that is that mercruiser service manuals 1 and 2 don't refer to a clear vent line from the fuel pump back to the carb. i believe up to '77 they had (for all practical purpose) auto fuel pumps. w/o the vent line back to the carb. i don't believe it was a safety feature (the third vent line back to the carb. in case the diaphragm ruptures so fuel dumps back to the carb instead of the bilge) until '78, which is covered in mercruiser service manual #3.
that's my take. i'd love to hear alt. thoughts on this though.

 

[starsnstripers]

Re: Merc 165 I6 Crankcase vent question

I think you nailed it Zig, how are you BTW? If i were you sex i would update it to a safer setup, get a flame arrestor that accepts that vent from the valve cover. Geat the proper fuel pump with the fuel barb to send the fuel back to the carb upon pump failure and hook a clear line from it to that barb on the carb. What do you think Zig? that would work right. I'm assuming the clear line can hook in that spot on the carb. Been awhile since i messed with the L-6 but i'll look tomorrow. I have a couple setups from around 1972 out here.

 

[starsnstripers]

Re: Merc 165 I6 Crankcase vent question

Here ya go, looks like the clear tube does go to that barb.

 

[sextondm]

Re: Merc 165 I6 Crankcase vent question

Thanks everybody for the pics. and info.! Shouldn't be hard to fashion the little bracket for the arrestor. And I'll look into the clear line to run from the fuel pump to the carb. Wish I could find the Merc stickers for my valve cover...

 

[alexr254]

Re: Merc 165 I6 Crankcase vent question

From your pic i also see a custom copper gas tube from pump to carb, thats a very dangerous setup.

 

[ziggy]

Re: Merc 165 I6 Crankcase vent question

custom copper gas tube from pump to carb

that's the stove pipe i believe it's called, for the auto choke. it rests down inside the manifold and heat build ups in it and rises up to the auto choke. the heat passed through the copper tube warms up the bi metal spring inside the auto choke and pulls the choke off when warm.

edit. a pic of the pipe still in the manifold. manifold removed..

can't remember which manifold that is. either '72 or '75. not much diff. between the two i don't think though...

 

[achris]

Re: Merc 165 I6 Crankcase vent question

From your pic i also see a custom copper gas tube from pump to carb, thats a very dangerous setup.

As ziggy said, that's not a fuel tube, the only thing that is in it is hot air.... Usually they have a bit of lagging around them... (part # 32-57831)

 

[glastronomic]

Re: Merc 165 I6 Crankcase vent question

1978 engine and setup.

 

[Fishermark]

Re: Merc 165 I6 Crankcase vent question

Yep - I went through the same thing a few years ago. Here's the post with more info and pics. I ended up making my own fitting that I attached to the flame arrester. If memory serves, I used an old stainless steel door striker plate and cut and bended it - then soldered a copper tube to it. Found a scrap piece of molded hose that fit - works well! Here's the pic:

 

[starsnstripers]

Re: Merc 165 I6 Crankcase vent question

From your pic i also see a custom copper gas tube from pump to carb, thats a very dangerous setup.

Yeah disregaurd that part, it's not my boat. lol