4.3l Risers - Maxum Boat Owners Club

CasCaed · 07-09-2018, 08:40 PM

Hi All,
Have aftermarket thermostat housing and Custom made risers. The housing does not accomodate a hose from the top of the riser. I am considering crossing over directly from one riser to the other. I have seen this done before, is it a good idea? Please could i have the Pro’s & Con’s of this?
Thanks in Advance
Carl

jrsick · 07-09-2018, 10:10 PM

Carl,
Important to understand that the hose is for water going from the thermostat housing to the riser. This water keeps the riser cool. The water then goes out an exhaust port. You really need to have a separate hose going from the thermostat housing to each riser.
Can you send a picture of your current setup? I'm thinking you have a thermostat housing that is for a 3.0L engine and has only one outlet.

mmwjr · 07-09-2018, 11:21 PM

What is the year of the engine? Newer 1995 and up do not run a hose to the riser just the the exhaust manifolds which then flow into the riser.

What problem are you trying to solve?

CasCaed · 07-10-2018, 02:47 PM

Quote:

Originally Posted by jrsick

Carl,
Important to understand that the hose is for water going from the thermostat housing to the riser. This water keeps the riser cool. The water then goes out an exhaust port. You really need to have a separate hose going from the thermostat housing to each riser.
Can you send a picture of your current setup? I'm thinking you have a thermostat housing that is for a 3.0L engine and has only one outlet.

Hi Jrsick,
Thanks for your reply. There are four connections on the aftermarket housing (I believe it is for the 4.3l). 1 for sea water in take, 1 for connection to water pump, 2 for connections to the manifold. The original had 6, the 2 additional were going directly to each riser. So the problem is that when I had the risers manufactured they allowed for a connection to the riser. So I now have outlets on the risers with nowhere to go

I did a bit of research and some people have just crossed over between the two risers - this is what I am considering doing - hence the question.

CasCaed · 07-10-2018, 02:59 PM

Hi Mike,
Thanks for your reply. My boat is a 1996 model. Engine is 4.3LX. Judging by what you are saying, the new housing is correct.
The problem I am trying to solve is that now I have inlet hose connections on my risers which serve no purpose, so I was wandering if there will be any harm in crossing over directly from one riser to the other riser with a hose. Effectively creating a loop.

CasCaed · 07-10-2018, 03:37 PM

Hi Guys, A photo of my issue.

[IMG]file:///C:/Users/Carl/Documents/6_BOAT/Custom%204.3%20Risers.mht[/IMG]

mmwjr · 07-10-2018, 05:01 PM

Quote:

Originally Posted by CasCaed

Hi Mike,
Thanks for your reply. My boat is a 1996 model. Engine is 4.3LX. Judging by what you are saying, the new housing is correct.
The problem I am trying to solve is that now I have inlet hose connections on my risers which serve no purpose, so I was wandering if there will be any harm in crossing over directly from one riser to the other riser with a hose. Effectively creating a loop.

You should be able to remove the hose fitting in the riser and install a plug, this is how they are installed with the four fitting t-stat

CasCaed · 07-10-2018, 05:05 PM

Thank you Mike. Do you think that is better than crossing over, I thought that would maybe assist in keeping the risers at an equal temp. I am by no means an expert, so appreciate the advice.

jrsick · 07-10-2018, 05:14 PM

Plugging the riser water inlets as Mike suggested would be a better option. Running a hose from one to the other would serve no purpose.
My recommendation: Plug the riser water inlets and see if water from the manifolds is enough to keep them cool. You should do the test in a body of water, vice using muffs, and have an IR gun to monitor riser temp.
If riser temp gets above 130 F then I would consider the risers too hot and get a thermostat housing that has the additional outlets for the risers.
I have seen several 4.3 manifolds and risers that are cooled by a single hose going to the manifold, so I think you will be fine.

mmwjr · 07-10-2018, 10:55 PM

Quote:

Originally Posted by CasCaed

Thank you Mike. Do you think that is better than crossing over, I thought that would maybe assist in keeping the risers at an equal temp. I am by no means an expert, so appreciate the advice.

Adding a cross over hose would do nothing as the lower pressure is on the output side of the risers and water will flow that way. The hose may fill with water and just sit there.