5.7 liter in 2000 mariah
 

I am planning on updating the engine to a 4bbl intake and carb. I've run into a slight issue. Does anyone know what the small approx 1/2" x 8" copper pipe in the attached pictures (from the intake to the exhaust manifold covered in a sock material) is used for? Can I eliminate it when I change to a 4bbl carb abd intake? any issues to be aware of when upgrading to the larger carb? Any thoughts on what carb to use? what did they come with? I'm a good car guy and a little skidish with boats. Don't want to screw it up. Any advice would certainly be appreciated. Thank you

Re: 5.7 liter in 2000 mariah
 

It almost looks like some sort of heat riser for a choke setup , but I don't think that is it. Does the carb have a electric choke on it?
I'll try and search into it further tomorrow.

Re: 5.7 liter in 2000 mariah
 

It does have an elctrical choke. I thought it may be a heater but I think there is an exhaust passage that runs under the carb (similar to automotive) for that. Might it be for cooling the underneath of the carb so there is no vapor lock due to heat?

Re: 5.7 liter in 2000 mariah
 

sami , can you get me the ID number from the drive or engine?
That might help pinpoint things a bit. :)
You got me interested in this too , never seen it before.:confused:

It doesn't have a closed cooling system does it?

Re: 5.7 liter in 2000 mariah
 

It looks like it goes into the intake water passage. Maybe some sort of quick warm up or over heating protection delio... :confused:

Re: 5.7 liter in 2000 mariah
 

Vin# is 1ZJB25257M049673. I don't have the engine number handy. I'm on a field trip with my son riding in a bus to Chicago..I'll look if I have the drive number from some pictures..

Re: 5.7 liter in 2000 mariah
 

Prop numbers of that helps

Re: 5.7 liter in 2000 mariah
 

I've never seen on of those before. It looks like someone made an air bleed or a thermostat bypass by connecting the water passage of the intake manifold to the water jacket in the exhaust manifold. Since it is not standard Merc running gear...you will probably be OK if you omit it when you change your intake to the 4bbl. Just put a pipe plug in the exhaust manifold when you remove the mystery pipe.

Re: 5.7 liter in 2000 mariah
 

Definitely not OEM as Steve stated.
I can't find anything on it in any of the Mercruiser manuals.

Re: 5.7 liter in 2000 mariah
 

Might you know where I get a mercuiser service manual for a this 2000 5.7l? thx