Dead cylinder issue
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Dead cylinder issue
Here is an interesting article helping explain why sustained moderate heating of the intake manifold is beneficial. See the attached link:
Why you need to heat your intake manifold Langdon's Stovebolt
Why you need to heat your intake manifold Langdon's Stovebolt
Excuse my total ignorance. I hope my question doesn't sound stupid but could this be the reason that my new 300 engine seems to have stopped firing on 1st 2 cylinders? Truck runs really cool. Much cooler than old engine did. Compression is good 105Lbs. spark is good.
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Joined: Sep 2017
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From: Union County, NC
105lbs of compression seems a bit low to me. Is that consistent across all 6 cylinders? The last time I checked my compression I had between 170 and 175 lbs on all cylinders (except for the one with broken ring landings, which had 80 lbs).
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Joined: Dec 2007
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From: Boise, Idaho
Hi Evan,
I moved your thread. In the future, please don't hijack other threads with troubleshooting questions, especially not in a technical sticky. Just start a new thread.
In regard to not having intake manifold heat, no, that wouldn't cause the issue you're having. That only helps with overall fuel mixture.
If you have two cylinders that aren't firing (but have compression), you need to look elsewhere, such as damaged spark plugs or plug wires, damaged distributor cap, etc. Something that would keep the spark from firing for the cylinders.
If you have spark, then you don't have air/fuel, which would mean that you possibly have valves that aren't opening/closing. Check your valve springs to see if one or two possibly broke, or if you have bent push rods.
I moved your thread. In the future, please don't hijack other threads with troubleshooting questions, especially not in a technical sticky. Just start a new thread.
In regard to not having intake manifold heat, no, that wouldn't cause the issue you're having. That only helps with overall fuel mixture.
If you have two cylinders that aren't firing (but have compression), you need to look elsewhere, such as damaged spark plugs or plug wires, damaged distributor cap, etc. Something that would keep the spark from firing for the cylinders.
If you have spark, then you don't have air/fuel, which would mean that you possibly have valves that aren't opening/closing. Check your valve springs to see if one or two possibly broke, or if you have bent push rods.
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sorry about hijacking, I'm kinda new to this forum and didn't know what I was doing. I'm afraid I might have a lifter or valve problem. We have all good spark etc. My guy is changing the intake gasket right now as a last stitch effort to see if that could be the problem before trying to pry a new engine from the company that sold me the new engine.
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Joined: Dec 2007
Posts: 7,987
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From: Boise, Idaho
Did you break in the camshaft or was that done by the company that sold you the engine? If it was done wrong, worst case scenario is that a lobe or two may have flattened.
Something that you can do right now is to remove the valve cover and then rotate the engine over by hand. Watch the valves and rocker arms. This should tell you a lot.
A bad gasket is not going to keep a cylinder from firing. That's just going to give you a vacuum leak.
If you have spark, then something's most likely up with the valve train.
Lastly, was the 105 psi on ALL cylinders? Or just those two? If not, what were the other cylinders? As 81Franken said, a tight, new engine should be around 170 or so.
Something that you can do right now is to remove the valve cover and then rotate the engine over by hand. Watch the valves and rocker arms. This should tell you a lot.
A bad gasket is not going to keep a cylinder from firing. That's just going to give you a vacuum leak.
If you have spark, then something's most likely up with the valve train.
Lastly, was the 105 psi on ALL cylinders? Or just those two? If not, what were the other cylinders? As 81Franken said, a tight, new engine should be around 170 or so.
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New User
Joined: Sep 2017
Posts: 19
Likes: 0
Did you break in the camshaft or was that done by the company that sold you the engine? If it was done wrong, worst case scenario is that a lobe or two may have flattened.
Something that you can do right now is to remove the valve cover and then rotate the engine over by hand. Watch the valves and rocker arms. This should tell you a lot.
A bad gasket is not going to keep a cylinder from firing. That's just going to give you a vacuum leak.
If you have spark, then something's most likely up with the valve train.
Lastly, was the 105 psi on ALL cylinders? Or just those two? If not, what were the other cylinders? As 81Franken said, a tight, new engine should be around 170 or so.
Something that you can do right now is to remove the valve cover and then rotate the engine over by hand. Watch the valves and rocker arms. This should tell you a lot.
A bad gasket is not going to keep a cylinder from firing. That's just going to give you a vacuum leak.
If you have spark, then something's most likely up with the valve train.
Lastly, was the 105 psi on ALL cylinders? Or just those two? If not, what were the other cylinders? As 81Franken said, a tight, new engine should be around 170 or so.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
This is really a problem between the shop that did the work, and the supplier.
It has some kind of warranty, and the labor should be warrantied as well by the installer. There are some things that the rebuilders insist on (new water pump for example) but you shouldn't have to get involved whatsoever.
Them: !!! ??? !!!
Me: "Yeah well that's nice ... let me know when it's ready to go."
Whatever you do, don't pay the balance (1/2 down, 1/2 at completion right?) till it's right.
It has some kind of warranty, and the labor should be warrantied as well by the installer. There are some things that the rebuilders insist on (new water pump for example) but you shouldn't have to get involved whatsoever.
Them: !!! ??? !!!
Me: "Yeah well that's nice ... let me know when it's ready to go."
Whatever you do, don't pay the balance (1/2 down, 1/2 at completion right?) till it's right.
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