Backfires when turned off.
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- G-Sergeant First Class
- Posts: 78
- Joined: Sun Mar 24, 2019 4:20 am
- Location: New Hampshire
Backfires when turned off.
Hello all. Recently after taking my 151 out of it's winter slumber there seems to be a back fire that has developed. Over the winter the only maintenance done to it is a new wiring harness and alt conversion. I have read a couple different threads on here about other back fire situations but it appears mine only occurs once the engine is turned off. It has a slight sputter back fire if I down shift and allow the transmission to slow the vehicle down but a small tap of the gas and that one goes away. The one that concerns me is when I turn the engine off. Ran fine all last year with the exception of a small vacuum leak. Have not moved the distributor any and made sure all intake and exhaust bolts were tight from the beginning.
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- G-Lieutenant General
- Posts: 5911
- Joined: Sun Mar 19, 2006 10:04 am
- Location: Pemberton, New Jersey
Re: Backfires when turned off.
A backfire at shutdown is 99% of the time raw gas igniting in the hot exhaust due to a leak in the exhaust, most often at the donut between the manifold and pipe.
1964 M151A1
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
1984 M1008
1967 M416
04/1952 M100
12/1952 M100- Departed
AN/TSQ-114A Trailblazer- Gone
- W. Winget
- LTC, U.S. Army
- Posts: 4448
- Joined: Mon Dec 16, 2002 10:37 am
- Location: USA, Virginia, Carrollton
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Re: Backfires when turned off.
I was going to offer that there may be some sticking in the valves allowing gas mix to cross flow out into the exhaust, and perhaps some Marvel Mystery Oil added to the gas tank to add a little valve lube since she's likely running some older gasoline as well.
Just a thought.
V/R W Winget
PS hand with rag over the exhaust tailpipe while idling held by a friend would help you hear an exhaust leak if you had.
Just a thought.
V/R W Winget
PS hand with rag over the exhaust tailpipe while idling held by a friend would help you hear an exhaust leak if you had.
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