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Title: exaust manifold heat riser thermostat bi metal coil Post by: roachy on September 22, 2012, 12:38:36 PM hi everyone noticed metal coil on back of exaust manifold in pretty bad shape read it is a heat riser thermostat coil is the correct function of this thermostat valve important thanks heaps for feedback Roachy
Title: Re: exaust manifold heat riser thermostat bi metal coil Post by: roachy on September 22, 2012, 01:25:35 PM Can anyone explain the function/purpose of this coil for me please thanks heaps again Roach do I need to worry about it
Title: Re: exaust manifold heat riser thermostat bi metal coil Post by: mcl1959 on September 22, 2012, 08:12:44 PM There is a flap inside the manifold which is normally held open by that spring when the engine is cold. Heat from the engine is then directed up onto the base of the inlet when the engine is started to warm it for better cold running performance. Once the engine heats up the coil spring closes the flap as the heat from the engine is not needed on the base of the inlet anymore. From my experience the effect is marginal and not many of these work properly now anyway.
Ken Title: Re: exaust manifold heat riser thermostat bi metal coil Post by: roachy on September 23, 2012, 08:20:47 AM thanks Ken guessing my exaust manifold valve is probably siezed so could it be permanently directing hot exaust to intake manifold,
is there a better position for this valve if siezed . could I possibly free up valve and put in preferred best position closed directing hot exaust upward into the intake manifold or open. thanks again . roachy. great to here this valve does not have huge effect on operation. Title: Re: exaust manifold heat riser thermostat bi metal coil Post by: MalFE on September 24, 2012, 09:03:49 PM The valve usually seizes in the open position.
To free the valve I spray each end of shaft with WD40 and tap the end of the shaft. It will move a small amount and then tap the other end, might take a few minutes and easier with a hammer in each hand. The valve is in the open position when positioned towards the engine. |