LM4 #5 running HOT
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LM4 #5 running HOT I have an LM4 in my C10. I am getting a knock at idle, the knock seems to lessen as RPM’s increase. Also cylinder #5 is running hotter than the other cylinders, around 480-490° at the header tube.
any ideas here?
Thanks in advance.
any ideas here?
Thanks in advance.
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Joined: Dec 2017
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Cyl 5 injector may be different from the others. If not, it's a mechanical problem, such as a burned valve.
What kind of "knock at idle"? Spark knock (pinging), rod, ??? I can't imagine a situation where an engine "knocks" but only at idle, unless it's a broken flex plate or something (which can sound a whole lot like a knock sometimes).
What kind of "knock at idle"? Spark knock (pinging), rod, ??? I can't imagine a situation where an engine "knocks" but only at idle, unless it's a broken flex plate or something (which can sound a whole lot like a knock sometimes).
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Teching In
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Cyl 5 injector may be different from the others. If not, it's a mechanical problem, such as a burned valve.
What kind of "knock at idle"? Spark knock (pinging), rod, ??? I can't imagine a situation where an engine "knocks" but only at idle, unless it's a broken flex plate or something (which can sound a whole lot like a knock sometimes).
What kind of "knock at idle"? Spark knock (pinging), rod, ??? I can't imagine a situation where an engine "knocks" but only at idle, unless it's a broken flex plate or something (which can sound a whole lot like a knock sometimes).
I'm just guessing at this point. I checked the push rods, flex plate and torque converter bolts, all are ok.
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A rod knock will not make a cylinder's exhaust run hot. Nor any other kind of knock either, for that matter. (that is, the things that CAUSE the one, won't CAUSE the other)
You may have 2 problems; while we all like to think that there's only one thing wrong at any given moment, and try to find the one failure most likely to cause all observed symptoms, sometimes it just doesn't work that way.
I find it hard to believe you "checked" the flex plate. They break at the center, where they bolt to the crank, most often, requiring a pretty significant tear-down to spot. Same for push rods; it takes A BUNCH of work to "check" those. For example, did you remove them and roll them on a piece of glass to check for straightness? If one is bent, even if not enough to see by eye just sitting there, it could be deflecting when operating, enough to hit something.
I'd suggest at this point, less posting on the Internet "discussing", and more exchanging #5 and #x injectors, and seeing if the "hot" problem moves to cyl x while #5 temp becomes normal. Then go from there.
You may have 2 problems; while we all like to think that there's only one thing wrong at any given moment, and try to find the one failure most likely to cause all observed symptoms, sometimes it just doesn't work that way.
I find it hard to believe you "checked" the flex plate. They break at the center, where they bolt to the crank, most often, requiring a pretty significant tear-down to spot. Same for push rods; it takes A BUNCH of work to "check" those. For example, did you remove them and roll them on a piece of glass to check for straightness? If one is bent, even if not enough to see by eye just sitting there, it could be deflecting when operating, enough to hit something.
I'd suggest at this point, less posting on the Internet "discussing", and more exchanging #5 and #x injectors, and seeing if the "hot" problem moves to cyl x while #5 temp becomes normal. Then go from there.
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A rod knock will not make a cylinder's exhaust run hot. Nor any other kind of knock either, for that matter. (that is, the things that CAUSE the one, won't CAUSE the other)
You may have 2 problems; while we all like to think that there's only one thing wrong at any given moment, and try to find the one failure most likely to cause all observed symptoms, sometimes it just doesn't work that way.
I find it hard to believe you "checked" the flex plate. They break at the center, where they bolt to the crank, most often, requiring a pretty significant tear-down to spot. Same for push rods; it takes A BUNCH of work to "check" those. For example, did you remove them and roll them on a piece of glass to check for straightness? If one is bent, even if not enough to see by eye just sitting there, it could be deflecting when operating, enough to hit something.
I'd suggest at this point, less posting on the Internet "discussing", and more exchanging #5 and #x injectors, and seeing if the "hot" problem moves to cyl x while #5 temp becomes normal. Then go from there.
You may have 2 problems; while we all like to think that there's only one thing wrong at any given moment, and try to find the one failure most likely to cause all observed symptoms, sometimes it just doesn't work that way.
I find it hard to believe you "checked" the flex plate. They break at the center, where they bolt to the crank, most often, requiring a pretty significant tear-down to spot. Same for push rods; it takes A BUNCH of work to "check" those. For example, did you remove them and roll them on a piece of glass to check for straightness? If one is bent, even if not enough to see by eye just sitting there, it could be deflecting when operating, enough to hit something.
I'd suggest at this point, less posting on the Internet "discussing", and more exchanging #5 and #x injectors, and seeing if the "hot" problem moves to cyl x while #5 temp becomes normal. Then go from there.
I removed al the push rods and rolled em on glass and they were fine.
Thanks, I’ll swap injectors next. Appreciated.
