Announcement

Collapse
No announcement yet.

5.0L Merc port side exhaust hotter

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • 88fourwinns
    replied
    Also look at the outlet ports on the hot side elbow, (inside of where the exhaust hose slides over the elbow exit), flakes of rust can clog them.

    Leave a comment:


  • 2850Bounty
    replied
    ................
    Originally posted by raspeitia View Post
    I removed both manifolds this winter to replace the exhaust gaskets where they mount to the block and it looked nice and clean.
    The areas of concern will be the seawater transfer ports that are between the manifold and elbow.

    Leave a comment:


  • raspeitia
    replied
    Thanks everyone. I appreciate all the extra knowledge and for all the detailed responses.

    When I last checked it while under power, the intake and return hoses from the manifolds seemed about the same temperature. I'll make sure to temp gun those though.

    I removed both manifolds this winter to replace the exhaust gaskets where they mount to the block and it looked nice and clean.

    I did see little bits in the drain port when I winterized it last fall though, so there definitely is something there but not a lot from what came out.

    I'll pull the hoses and see if there is anything in the channels on that side before I go out next time.

    Leave a comment:


  • 2850Bounty
    replied
    Originally posted by raspeitia View Post
    .................All the info from the mercruiser service center says its supposed to be 160 .
    Just to clarify......
    raw water cooled engine:

    .... lake or river water...... 160 is OK
    .... ocean water....... 160 is too high, and will accelerate Salt Water Crystallization.


    .


    Leave a comment:


  • 2850Bounty
    replied
    ......................
    Originally posted by raspeitia View Post
    I replaced the thermostat on my 5.0 Mercruiser carbureted engine (165 degree) and I have noticed that the port side exhaust runs hotter than the starboard side. Its not burning my hand, I can hold my hand on the down elbow a for like 10 seconds, but the other side feels almost ice cold in comparison.
    The engine's thermostat is upstream of any division of "spent" seawater, therefor it cannot be responsible for incorrect division of "spent" seawater.
    (spent seawater = seawater that has cooled the engine and is now on it's way to the exhaust system)


    I read somewhere, this is somewhat normal but I wanted to see if there is anything I should check out, just in case?
    A slight deviation in temperature between Port and Starboard exhaust elbows is acceptable.
    Anything beyond that is NOT acceptable, and will indicate a spent seawater restriction.


    For example, the ball valves in the T pipe looked ok, but I did not replace those. Should I?
    I hate those silly things. No other company uses them.
    Merc says to leave them and/or replace them.


    This is a fresh water boat with, raw water cooling.

    Anyone seen this before?
    Oh yes..... this is quite common!
    find the restriction, and things should return to normal.


    Remove both exhaust Elbows. Look closely at the seawater transfer ports.
    Clean/clear them from any rust scale.
    Also look closely at the port(s) that supply seawater into the mixing chamber.


    You may also want to remove the T-stat housing and look for a rust scale caused restriction.

    Leave a comment:


  • Chief_Alen
    replied
    Fresh water boat ...

    Last time elbows were took off and the ports looked at ?

    Start with the hotter one first.

    Last time impeller changed in the drive ? I use a complete kit housing and all.

    Leave a comment:


  • builderdude
    commented on 's reply
    If used in lake/river water only the 160 would be ok for a raw water cooled engine.

  • raspeitia
    replied
    The TStat I removed was the original and was stamped build year 2002 and 160 deg from the factory. All the info from the mercruiser service center says its supposed to be 160 too.

    I also just replaced the impeller, seals, housing, etc this winter. Its carbureted and not EFI, if that helps.

    I'll temp gun it this weekend and see the difference in different spots, and report back the info.

    Leave a comment:


  • builderdude
    replied
    Agree with Don 140 if raw water cooled 160 if closed cooled. Change your t stat then check your temps again. Often at idle rpm one side can run a touch warmer than the other, bump your rpm up somewhere around 1000 then check it again. You’ll likely feel a decrease in temp on that side. May be time for a new impeller.

    Leave a comment:


  • Nauti_Mike
    replied
    Common for one side to be hotter, get an IR temp sensor and get real readings to know if an issue exits.

    Leave a comment:


  • Don77
    replied
    If raw water cooled I think you have the wrong tstat, it should be 140*.
    Don

    Leave a comment:


  • raspeitia
    started a topic 5.0L Merc port side exhaust hotter

    5.0L Merc port side exhaust hotter

    I replaced the thermostat on my 5.0 Mercruiser carbureted engine (165 degree) and I have noticed that the port side exhaust runs hotter than the starboard side. Its not burning my hand, I can hold my hand on the down elbow a for like 10 seconds, but the other side feels almost ice cold in comparison.

    I read somewhere, this is somewhat normal but I wanted to see if there is anything I should check out, just in case?

    For example, the ball valves in the T pipe looked ok, but I did not replace those. Should I?

    This is a fresh water boat with, raw water cooling.

    Anyone seen this before?
Working...
X