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Mug 12v183 overheating saga cents more interesting

Discussion in 'Technical Discussion' started by CTdave, Jul 23, 2018.

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  1. CTdave

    CTdave Senior Member

    Joined:
    Mar 21, 2004
    Messages:
    776
    Location:
    Greenwich CT/ Stuart FL
    So I have two problems, both motors overheat, haven’t been out once this season. Port side slowly heats up but starboard is the stranger one.

    Done so far:

    Completely cleaned out reruns hulls/strainers. They were completely clean. Replaced fresh water circ impellers, they were in good shape. +Replaced thermostats, belts etc.

    The strange thing is my my mug guy got back and checked it out. He thinks it’s raw water pumps. He took a hose off of the gear case and it spit out winterizing fluids and exhaust gasses. I removed the water hose that runs to the raw water pump from the strainer and it was full of winterizing fluid. It’s not pulling water through the system.

    I don’t think mature makes the raw water pumps, prob Jabsco but I doubt a bronze impeller suddenly wears out. The only thing I can think of is a shaft breaking. The mechanic is taking the pumps apart but from what I’m reading on the web, the parts and labor to rebuild a pump is around $3k and a new one is around $5k.

    Is there anything else that you think it could be? With the hose off of the strainer, water gushes in when I open the thru Hull. Could there be a clog somewhere else that’s not letting the raw water pump push water through the system like heat exchangers?

    It was running fine when winterized and sat in the water for the winter. The starboard gauge read a little high before but the mechanical gauge on the engine would sat 175 or so. Nothing else was changed or done till the first ride down the river where the port got hot very slowly and the stud jumped right up and blew steam/water from the relief valve on the resivoir.

    I’ve had to cancel two cocktail Cruses that I donated for charity and I have two more for VA families coming up%

    Starting to hate boating
  2. Capt J

    Capt J Senior Member

    Joined:
    Jul 11, 2005
    Messages:
    10,199
    Location:
    Fort Lauderdale
    You do not want your mechanic rebuilding one of those pumps, order a rebuilt one from MTU. It can suck air from the pump O-rings and the pump could have a bad bearing, or not be turning at all. You need a real mechic to diagnose......should be easy with a photo temp gun and your cold water......should be able to see metal parts lose temperature pretty quick after starting the motor. Could also be sucking air from sea strainer, even a cracked hose.....You need someone knowledgable to find the issue, NOT throw parts at it. Could be a blockage in a heat exchanger as well. I had a tough one to find once and it ended up being a blocked fuel cooler on a 12v92 TI......
  3. chesapeake46

    chesapeake46 Senior Member

    Joined:
    Jul 26, 2009
    Messages:
    1,063
    Location:
    Chesapeake Bay, Delaware Bay & S.Jersey
    is it possible that the raw water pump is sucking enough to collapse the inside of the raw water hose ? longshot, i know but stranger things.......
  4. CTdave

    CTdave Senior Member

    Joined:
    Mar 21, 2004
    Messages:
    776
    Location:
    Greenwich CT/ Stuart FL
    Geese, I need to spell check more often. Most importantly, my “mug” guy is supposed to read MTU guy. It’s AMTfrom both FL and up here in Ct in the summers. They are all very well seasoned with all mtu engines and I’ve never had a problem with them as well as four other MTU boats on our dock
  5. motoryachtlover

    motoryachtlover Member

    Joined:
    Jan 29, 2007
    Messages:
    72
    Location:
    smithfield, VA
    Don’t know what year the boat is but my 1995 Viking needed new exhaust risers. They had some life left in them but we had everything apart changing out transmissions and decided to replace. Some people call them shower heads and the holes slowly corrode closed.
  6. CTdave

    CTdave Senior Member

    Joined:
    Mar 21, 2004
    Messages:
    776
    Location:
    Greenwich CT/ Stuart FL
    Risers, didn’t think of that.
    Here’s the latest
    Port side all good, running at 175 on mechanical gauge on engine and laser temp gun. Gauge at helm is bad so I’m trying to find a sender and one of the square VDO gauges.
    Starboard side still too hot at 225 degrees on mechanical and gauge and heat sensor gun.
    We’ve done thermostats, raw and circulating pump, flushed a lot of crap out of the heat exchanger with some kind of salt/barnacle dissolver. The yard hooked up this concoction and circulated it for the day and loads of junk came out.
    So, blockage somewhere else? Heat exchanger still blocked with something? Risers?
    We went out with the kids and their friends for the first boat ride of the summer YESTERDAY just a short slow run to a local island and had a great day but I can’t believe we have only three weeks left before they go back to school. I can’t take everyone on our usual Block Island/Montauk trip with one engine running at 225 deg. I need help and nobody can seem to figure it out and aside of the thousands I’ve spent trying, I’ll pay more if someone can fix this. HELP!
  7. johnjen50

    johnjen50 New Member

    Joined:
    Mar 23, 2013
    Messages:
    5
    Location:
    Portsmouth RI
    There are zincs in the heat exchangers that break off if not changed frequently enough. Those pieces can get jammed up in the shower heads and cause quite a restriction. The barnacle cleaner will not take care of that issue. Have you taken the hose off at the shower head to take a look? They will be pretty apparent if that is the restriction. Also you didn’t mention what the raw water flow out the back looked like. Must have been pretty minimal if there was still pink stuff in the engine. Also stuff can be jamming up your inter cooler or after cooler as well. Not as familiar with those engines but had some of that in my Detroit 871ti’s.
  8. Pascal

    Pascal Senior Member

    Joined:
    Feb 29, 2008
    Messages:
    3,747
    Location:
    Miami, FL
    I had a warm running 3412 a few years ago which took me a while to figure out... turned out to an air link on the intake side of the raw water pump. On the sea engines cat had placed the fuel cooler between the strainer and the pump and it had developed a pin hole. No leak as it was on the intake side and the only reason I found it was because one time I shut down the engines from the ER and I heard a sucking sound which was air coming in as the water drained down

    Sometimes these things can be a pain to figure out

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