Burnt Valve??
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Senior User
Joined: Sep 2007
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From: Indio,California
well got the miss fire in cylinder#1 new plugs wires cap and rotor. what would a compression test tell me? how would i know its not the rings? its a 1996 4.9 with almost 200k on it. if the compression is low should i replace the head?
Postmaster
Joined: Jan 2009
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Take a compression test on all the cylinders , if the # 1 is low put a little oil in that cylinder , then test it again if the comp comes up its the rings , other wise its time to pull the head & see whats going on ... Lew
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Senior User
Joined: Sep 2007
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From: Indio,California
ok heres the verdict....code p0301 cylinder 1 misfire. compresion test shows #1 30psi #2 35psi # 3 140psi #4 150psi # 5 155psi # 6 150psi.
where do i go from here? burnt valve? or bad rings? could it also be an intake gasket?
thanks
where do i go from here? burnt valve? or bad rings? could it also be an intake gasket?
thanks
Post Fiend
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From: Lakewood, Ohio
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Senior User
Joined: Sep 2007
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From: Indio,California
ok the truck did have what i believe was an exhaust manifold leak. when you hit the gas it would have a ticking sound. sounded manifold to me. so i sould pull the head then? should i replace the head? could the block be warped?
Post Fiend
Joined: May 2004
Posts: 11,289
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From: Lakewood, Ohio
HEAD GASKET!!!!!!!
have the head checked but these are big heads and usually do not warp.
it is probably just the head gasket.
you have to understand, we are on the web, not there in your garage.
very hard to say EXACTLY what is wrong or what to do.
have the head checked but these are big heads and usually do not warp.
it is probably just the head gasket.
you have to understand, we are on the web, not there in your garage.
very hard to say EXACTLY what is wrong or what to do.
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 13
From: Sand Lake, MI
#1 30psi #2 35psi # 3 140psi #4 150psi # 5 155psi # 6 150psi.
A equally low reading in two adjacent cylinders would indicate a blown head gasket, blown between the two cylinders.
Burnt valve tends to produce a POP POP POP out either the intake or exhaust depending on the valve burnt.
light poping all the time with heavy loud popping under hard acceleration when valve is severely burnt Ie: large hole.
"Pops" when under load only, damage more on the minor side to the valve Ie; smaller hole.
So no doesn't sound like you have a burnt valve, as stated sounds like you have a blown head gasket, solely based on what you have stated here so far that is.
Time to pull the head and examine the gasket for damage, the cause should be fairly clear if it is the cause of the low readings on those two cylinders. Gasket material burnt and or discolored, or completely blown away in between those cylinders.
A equally low reading in two adjacent cylinders would indicate a blown head gasket, blown between the two cylinders.
Burnt valve tends to produce a POP POP POP out either the intake or exhaust depending on the valve burnt.
light poping all the time with heavy loud popping under hard acceleration when valve is severely burnt Ie: large hole.
"Pops" when under load only, damage more on the minor side to the valve Ie; smaller hole.
So no doesn't sound like you have a burnt valve, as stated sounds like you have a blown head gasket, solely based on what you have stated here so far that is.
Time to pull the head and examine the gasket for damage, the cause should be fairly clear if it is the cause of the low readings on those two cylinders. Gasket material burnt and or discolored, or completely blown away in between those cylinders.
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Senior User
Joined: Sep 2007
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From: Indio,California
ok ya the truck doesnt pop at all. it runs like 1 plug wire is misssing. ill start pulling the head in the morning. what could cause the gasket to pop in between cylinders like that?
Lead Driver
Joined: Aug 2006
Posts: 5,670
Likes: 13
From: Sand Lake, MI
what could cause the gasket to pop in between cylinders like that
Might have been a flawed gasket from the get go, been working on it little at a time ever since. Might have overheated at one point and weakened it there, then under load, you gave it gas to take off or pass a car or something had all it could take and she blew.
It not a uncommon thing, it just couldn't take the pressures anymore and failed, but if it helps, you ain't the first......won't be the last! LOL
Might have been a flawed gasket from the get go, been working on it little at a time ever since. Might have overheated at one point and weakened it there, then under load, you gave it gas to take off or pass a car or something had all it could take and she blew.
It not a uncommon thing, it just couldn't take the pressures anymore and failed, but if it helps, you ain't the first......won't be the last! LOL
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Senior User
Joined: Sep 2007
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From: Indio,California
lol....thanks well i live in southern california in the palm springs area so 125 in the summer is common. its about 100 now and it happened the other day in 105 heat. its all original with 200,000 on it so maybe its time. any special brand gasket i should get????