heat riser

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Oct 11, 2012 | 08:28 PM

abe

Thread Starter

Fleet Owner

Joined: Dec 2000

Posts: 25,376

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From: Central PA

heat riser

Question about the heat riser on my 1970 F350 with a 360. It should be closed when the engine is cold so it gets warm air and then it should open up after the engine is warm, right?

Looking at it today after I ran the truck and the engine was warm, the flapper was up meaning it is not getting air from the outside but from the engine.

How does this work. (is it a bi-metal valve?) How do I correct it?

Oct 12, 2012 | 05:31 AM

NumberDummy

Ford Parts Specialist

Joined: Nov 2006

Posts: 88,826

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From: Simi Valley, CA

Quote:

Originally Posted by abe

Question about the heat riser on my 1970

F350 with a 360.

It should be closed when the engine is cold so the engine warms up faster. Then it should open up after the engine is warm, right?

Correct, except there's no such thing as original, your trucks left exhaust manifold has been changed.

C5TZ-9431-A .. Left Exhaust Manifold-Use with Heat Riser Valve: 1965/67 F100/350 352 & 1973 F100 360.

D3TZ-9A427-A (replaced C5TZ-9A427-D) .. Heat Riser Valve: 1965/67 F100/350 352 & 1973 F100 360.

C8TZ-9431-B .. Left Exhaust Manifold-Use without Heat Riser Valve / 1968/76 F100/350 360/390 except 1973 F100 360.

The flapper is notorious for rusting solid in the open position. People removed the flapper, welded the holes.

Oct 12, 2012 | 08:40 AM

abe

Thread Starter

Fleet Owner

Joined: Dec 2000

Posts: 25,376

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From: Central PA

Thanks, Bill but I think we are talking about 2 different things. The heat riser, or flapper, I am talking about is in the breather neck of the air filter. Yes on the older trucks like my '54 the riser is on the right manifold.

Are the springs shot does it need some WD40 to loosen it up????

Oct 12, 2012 | 12:05 PM

orich

Lead Driver

Joined: Aug 2003

Posts: 7,592

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From: **** hole San Jose ca.

That is the Hot air pick up off the exh manifold. those do go bad. Maybe the little spring is broken or a good cleaning and a shot of wd40 get it working again ..orich