Hope you can help us out. Have a 1989 27' Baja Mercury 454. We changed to Kodiak exhaust manifolds. The manifolds are looped to the risers. So our question is, what changes need to be made to the thermostat housing (have 2 hoses that are extra). Pics attached.
Last edited by jazorlando; 04-18-2012 at 10:30 AM.
Your thermostat system utilizes 4 hoses feeding the exhaust. Two of the hoses are connected to the bottom of the exhaust manifolds. The other two are connected to the risers. Inside the thermostat housing assembly where the upper hoses connect, there are a set of nylon balls that are spring loaded on a shaft. The purpose of the check balls is to direct the water flow to the bottom hoses when the thermostat is opene to ensure the manifolds are being cooled. When the thermostat is cosed, the balls are unseated and water flows to the riser which prevents the exhaust hoses from being burnt as a result of low water flow.
On a stock set up, water passes from the manifold water jackets to the riser water jackets internally. Your after-market exhaust system does not have this feature. In order to install this exhaust system on your engine, a custom fitting will need to be fabricated that allows your existing upper hoses to be connected and also provides for flow from the manifold to the riser. GIL Exhaust uses a similer fitting when their exhaust is installed using the type of thermostat assembly that you have.
You will need a stainless steel tee that is 3/4" NPT on one side (on the run), and allows for 1 inch hose (push-on) to be connected on the other two sides. Screw the tee into the manifold and connect the hose from the thermostat to the other side of the run. Using a molded hose, connect the remaining outlet on the tee to a fitting in the riser.