Mercruiser 2003 5.0L cooling lines connections

[delmarjr]

I have a Mercruiser 2003 5.0L engine with 1990 center riser style water manifolds and would like advice on which thermostat gooseneck would be better to use. The first gooseneck is the one that doesn't have lines that would go to the risers only to the bottom of the water manifolds and therefore I would have to use 3/4 inch plugs in both risers. The other gooseneck I have is one that includes the lines to the risers along with the lines to the water manifolds. What are the pros and cons for each application? Maybe it doesn't matter. I believe both goosenecks were used with the newer style water manifolds but I only have my older ones to use. Please provide any helpful information? Thanks.

 

[Don S]

Re: Mercruiser 2003 5.0L cooling lines connections

Take some pictures of the two "Thermostat housings" and post them here.
Is your engine raw water cooled, or do you have a closed cooling system (with heat exchanger and antifreeze in the engine).

 

[delmarjr]

Re: Mercruiser 2003 5.0L cooling lines connections

my engine is sea water cooled and here are some pictures of the two thermostat housings.

 

[delmarjr]

Re: Mercruiser 2003 5.0L cooling lines connections

Sorry, the pictures I tried to upload are to large of a file and did not send. I'll try again later today. The two thermostat housings are almost the same except the one has in addition a tee on top where you can connect two coolant hoses one each to the risers. Where the other one has no tee and I would have to plug the risers. One has 4 ports and the other has 6 ports. My question is which one do you suggest using and why?

Thank you

 

[delmarjr]

Re: Mercruiser 2003 5.0L cooling lines connections

Here are the pictures of the two thermostat housings. Which one do you recommend for my application. I have an Alpha 1 outdrive.

 

[delmarjr]

Re: Mercruiser 2003 5.0L cooling lines connections

I uploaded the pictures back on August 28 and nobody has responded. Is it better to use the thermostat housing that has no lines to the risers and plug the risers since I'm using the older 1990 center style water cooled manifolds and not the newer style dry joint type?

 

[Don S]

Re: Mercruiser 2003 5.0L cooling lines connections

Depends on how your manifolds and risers are plumbed and gasketed as to which housing you will use. Either way usable, but the pumbing has match the housing.

 

[delmarjr]

Re: Mercruiser 2003 5.0L cooling lines connections

You're right both housings work because I tried them both but I wanted to know if one works better than the other. My manifolds connect to both housings the same but the risers is where the difference comes into play. One housing has hoses that connect to the risers by way of a tee on top of the housing. The other housing has no tee so therefore has no hoses to connect to the risers and the risers then have a 3/4 inch plug in each one for that application. I think my Seloc manual shows the housing with a tee and hoses connected to the risers is used for the newer dry joint manifolds but Seloc manuals are not always accurate or clear. What do you think?