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Help with strange cooling system issue

A

andyt

New member
I have a '97 4.3LX Gen+ which had the original one-piece exhaust manifolds. I wasn't getting any water flow from the starboard side, so I went ahead and converted to all brand new Merc two piece manifolds, elbows, etc. So I've replaced everything from the block to the Y-pipe including the flappers. And I still have a low flow of water on the SB side only. I pulled off the thermostate housing and inspected it. It's a bit rusty, but otherwise all the ports are open and free from clogs. If I disconnect the water hose for the SB side and run a garden hose the manifolds flow just fine. It's almost like the water in the thermostate housing is somehow diverting to the port side, and starving the SB side. Since I have good flow on the port side, I haven't (yet) inspected the water pump.

Anyone have ideas????

andy t.
 
I still have a low flow of water on the SB side only.
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Water flow variance between sides is normal. If you can place the palm of your hand on the manifold while it is runing w/o a burn then all is normal.
 
guyjg said:
Water flow variance between sides is normal. If you can place the palm of your hand on the manifold while it is runing w/o a burn then all is normal.
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That much I know.... Just using my hand, the port side is cool to the touch (even the tube) when running at idle w/ the muffs on. The starboard side is warm, and the exhaust tube is HOT! I even disconnect the water inlet tube at the bottom of the manifold; started it; and ran it for a minute or two. The water just gurgles out, while the port side flows evenly.
 
The starboard side is warm, and the exhaust tube is HOT!
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Since you have replaced the exhaust the problem lies in the thermostat housing. There is a diverterport hole inside of it that can become narrowed w/rust and crud. See a factory service manual for accessing the port. Make sure it is open. It is on the bottom of the hsg. and may be hard to see. You may need to remove the hsg. assy. and have it cleaned at a radiator shop.
 
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I had the housing off for a visual inspection, and checked flow w/ the garden hose, but I will take a better look at it. BTW; how does one remove the thermostat? I didn't really try, but it looks like it is held in place by a block; almost like it is integrated into the housing.
 
You may have to pry it out if it's rusted in place. Use a Dremel to grind out the rust buildup on the hbsg. Walls.
 
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