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Thread: Exhaust Pipe, with a nice Orange Glow

  1. #1
    Member Bart's Avatar
    Join Date
    Dec 2015
    Valdez, Alaska

    Exhaust Pipe, with a nice Orange Glow

    so a few years back, when I first started up my STOCK new, used motor, with an unknown history.
    after running the throttle, I noticed that the exhaust to the #2 cylinder was starting to glow. With out having any diagnostic tools at the time. I just assumed that this was coming from an leaky intake tube gasket..
    well today, after getting most of my ducks in a row, I was able to finally run the motor, and play around with it at a few different RPM's. and guess what. I looked over at the exhaust, and coming off of #2 was an nice orange glow. just a little bit hot. and not quite normal.
    the IR gun was reading 350+ degrees,
    the other side was at a cool 270 degrees.
    well this is not good.

    from my limited experience, and without taking off the cylinder yet, I am thinking that this might be a weak exhaust valve spring. at least a weak spring would cause the valve to float and allow more than a little heat to enter into the exhaust.
    I am just hoping that where I still had good compression, before today. that I haven't lost the valve seat.
    this is just one of the little nuances, that can keep a person guessing.
    where I am seeing a little orange at the base of #4 pipe also. I don't know it there might be 2 problem children,
    the heat might have been migrating back up the tube...
    but it is nice to have a picture to make one think. but it might be good, time will tell.
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  2. #2
    Member Bart's Avatar
    Join Date
    Dec 2015
    Valdez, Alaska

    Re: Exhaust Pipe, with a nice Orange Glow

    so I found an extra hour, and took off the head to see if I could find an simple answer to the problem, and I am glad that I did. From looking at the exhaust valve, it is totally white. looks like it got just a little hot.
    I am glad that I have a spare 042 motor with 1800 hours on it. it just happened to have an head on it. that looked a lot better than the one with the white exhaust valve.
    another bonus. I didn't have to wait the week for a piece to be shipped....
    so the better looking one was installed. and I found some interesting things to think about

    so I put new plugs when I started this up a few weeks ago. the O2 sensor never really was reading rich. but all 4 plugs turned black and sooty.
    but when I started it up after swapping the head tonight, the O2 was reading 10, and you could tell that the motor was running very rich.
    and the cylinder in question is running at normal temps. well it is running close to the other cylinders at the moment.

    so tomorrow, I will be hooking it back up to the computer, and run it on auto tune. to get the fuel delivery back to where it should be.
    I never thought that having a bad exhaust valve would effect the rest of the motor so negatively.
    I am also glad that this was a very simple fix. just need to get an replacement valve ordered, so there will be an usable spare on hand..
    one more thing with this motor, the guy that I purchased it from, was told that it was recently overhauled and was good to go. a while back I replaced the #1 head, and its cylinder walls looked real good,
    but when looking at the cylinder walls on the #2 cylinder, there is a faint cross hatch pattern, but for the most part it looks kind of tired,
    this is giving me a few thoughts. the motor has great oil pressure, at idle it is at 55 and at 2500 rpm it is at almost 65 psi.
    so that is telling me the bearings are good,
    and there is good compression 120 to 115 over all 4 cylinders.
    down the road I could see, just for my peace of mind, in picking up new pistons and cylinders.
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    Last edited by Bart; 07-24-2019 at 02:54 AM.


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