Oh No another valve?
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Senior User
Joined: Jan 2005
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Oh No another valve?
Alright just a refresher because no one probably remembers but I replaced a valve in my head because i had 3 low compression cylinders. I found out 3 head bolts worked themselves loose and caused one cylinder to be low and the other had a bad valve.
Now recently i have a loudish ticking noise every revolution and sounds like it comes from #5 which pulled a 60# compression. I put oil down the cylinder and pulled #63 and put alot down it and got up to 70# so it doesnt look like the rings. Do all these signs point towards valve to yall?
PS I have to drive to the folks home tomorrow and its 80 miles away so I am debating on whether or not it will be alright. I will probably take it for a test spin since I have to bring stuff back with me and have no other vehicle to do that with.
Now recently i have a loudish ticking noise every revolution and sounds like it comes from #5 which pulled a 60# compression. I put oil down the cylinder and pulled #63 and put alot down it and got up to 70# so it doesnt look like the rings. Do all these signs point towards valve to yall?
PS I have to drive to the folks home tomorrow and its 80 miles away so I am debating on whether or not it will be alright. I will probably take it for a test spin since I have to bring stuff back with me and have no other vehicle to do that with.
Logistics Pro
Joined: Jan 2002
Posts: 4,907
Likes: 39
From: suburban atlanta
Pull the rocker cover and check for loose rocker arm. The self-locking nut may not be functional. That would explain the noise, and the low compression. Least expensive fix, if that is the problem.
tom
tom
Logistics Pro
Joined: Jan 2002
Posts: 4,907
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From: suburban atlanta
Bd, doncha think that if the rocker is loose, it can decide that it doesn't want to open very much... and thus lead to lowered compression because there's nothing (or little) to compress? Seems if you had a cam with a bad lobe, it would do the same thing, but without all the added noise, and that for sure could lead to lowered compression.
tom
tom
Fleet Owner
Joined: Sep 2005
Posts: 28,609
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From: Lake Tahoe, Nevada
Well Tom, that would be a pretty extreme case. The valve is designed to seal on compression, but on the intake stroke, at cranking speed, if the valve opens at all it would allow the cylinder to fill with air. And that is all assuming that we are talking about an intake valve. What's needed is a leak-down test to isolate the cause of the compression loss.
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Yeah ok well I ended up driving it home anyway and I did pull the valve cover off and make sure all the rockers were tight. There were some loose but nothing big and that didnt help it any. I am almost certain it is a valve. I had a problem on the way home thinking that it overheated and replaced the thermostat but in the process cracked the damn thermo housing so since it was sunday I couldnt get a replacement and had to leave it with the parents this weekend.
When i get it back I am going to pull the head off and replace the valve. I may do them all since this is the 2nd one in a month.
And it seems like the exhaust valve because on slow down she would cackle pretty good. I could hear the gas getting through the cylinder unburned and burning in the manifold and pipe. The last one was an exhaust was well but not this prominent as a problem. It got sucked into the head from the valve spring and looked like a clover shape.
When i get it back I am going to pull the head off and replace the valve. I may do them all since this is the 2nd one in a month.
And it seems like the exhaust valve because on slow down she would cackle pretty good. I could hear the gas getting through the cylinder unburned and burning in the manifold and pipe. The last one was an exhaust was well but not this prominent as a problem. It got sucked into the head from the valve spring and looked like a clover shape.
Elder User
Joined: Apr 2004
Posts: 970
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Sounds to me like you may have some late timing in that engine and is the head fitted
with stellite seats? Valve springs shouldn't have exhaust valves that hot that they can pull them into the port. They do pund the soft seats away since there is no lead in the gas. What year head are we talking about?
with stellite seats? Valve springs shouldn't have exhaust valves that hot that they can pull them into the port. They do pund the soft seats away since there is no lead in the gas. What year head are we talking about?
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Senior User
Joined: Jan 2005
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Yeah I was surprised that the valve got pulled into the port but the valve seat looked good when I pulled the valve out and replaced it (The first one).
This is off a 78 F150. This is a pretty much a no frills truck. It was my grandpas and he didnt care as long as it ran well.
This is off a 78 F150. This is a pretty much a no frills truck. It was my grandpas and he didnt care as long as it ran well.
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