engine temp gauge reads high

Discussion in 'Sport Cruisers' started by JohnV56, Jul 6, 2018.

  1. JohnV56

    JohnV56 New Member

    8
    Jul 6, 2018
    2003 280 sundancer twin 4.3
    twin 4.3 raw water cooled/ alpha one gen 2
    Hi, I just got a 2003 280 sundancer. I had 2 smaller sea rays before. I try and do all the work myself but I need help.

    My engine temps on my gauges read about 170 with 160 degree thermostats. raw water cooled. When on plane port goes to about 190-200. starboard about the same. I checked with IR gun and get 158-162 around the temp sender and hoses and thermostat housing. I changed the temp sender and temp sensor and get the same reading and even a little higher on my gauges.

    Do you think its a bad gauge? I really would like to have same temp on gauge as I do on engine. My manifolds riser elbow will be changed in fall they are on their last season. would clogging elbow raise engine temp at the gauge but not at the thermostat housing?

    thank you
    John
     
  2. CaptRonn

    CaptRonn Active Member

    252
    May 25, 2016
    Houston
    1999 Sea Ray 400 Sedan Bridge
    Mercruiser Horizon 8.1 MPI
    Sea Ray gauges are notoriously inaccurate especially once they age. Since you have verified temp and replaced the sender, this pretty well isolates the gauge as the culprit.

    Did you check the temps while running on plane to verify?
     
    JohnV56 likes this.
  3. JohnV56

    JohnV56 New Member

    8
    Jul 6, 2018
    2003 280 sundancer twin 4.3
    twin 4.3 raw water cooled/ alpha one gen 2
    Hi Capt Ron,

    Thank you for the response.

    The only way I was able to test the temps was when I was driving her back ( by Myself) from Greenwich I drove about 20 minutes on plane dropped her back down to neutral and hit it with my IR gun. I did this about 3-4 times till I got it back home which was about an hour drive. I never got a temp higher than 162 on the senders, hoses, thermostat housing, block. only my gauges would show 190
     
  4. northern

    northern Well-Known Member

    Jan 17, 2007
    West coast Vancouver to Alaska
    380 Aft Cabin 1989 GPS and Charts by Nobeltec
    Twin 454 strait shaft
    I have the same thing one gauge reads 10 higher than the other but IR gun gets the same reading. Been that way for 2500 hours. I also changed sending unit. Did not change anything.
     
    JohnV56 likes this.
  5. JohnV56

    JohnV56 New Member

    8
    Jul 6, 2018
    2003 280 sundancer twin 4.3
    twin 4.3 raw water cooled/ alpha one gen 2
    Thank you!!
     
  6. Jimmy Buoy

    Jimmy Buoy Active Member

    Dec 3, 2008
    Sarnia, Ontario, Canada
    340 Amberjack
    twin 8.1S 370 Hp + 4.5 Westerbeke Genset
    I sounds like your gauge is a bit wonky. Here's an idea for you. I find that carefully placing your hand on the top of each riser and comparing how "hot" they feel gives you a good idea if there are any major blockages in the exhaust system. You can even do this right after starting the engines. On mine, I feel the temps increase as the exhaust gases pass the top of the risers then it cools down with the introduction of cooling water flowing within. Even after a run, I can place my hand on top of the risers, although one side is always a bit warmer than the other on each engine. The side that gets its cooling water last is obviously hotter.
     
  7. JohnV56

    JohnV56 New Member

    8
    Jul 6, 2018
    2003 280 sundancer twin 4.3
    twin 4.3 raw water cooled/ alpha one gen 2
    great thanks ill try that,
     
  8. Loyd Dinneen

    Loyd Dinneen Member

    240
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    I have the same issue on my pair of 1977 470's. starboard side reads over 3/4s up the gauge(doesnt show degrees)and starts to get near red when rpms are applied and the port goes up to 3/4s when run up. Went thru and changed thermostat acid boiled the housing,took off the heat exchanger and did the same to it(only a slight bit of crud in it)and replaced all the antifresse with 50/50. I then ran the engine and took a temp reading with a radiator temp probe at the reservior and it only got up to about 150 - 160 and this time the gauge only went up half way on the stbd side. Havent started on the port side yet. Mind you this was on muffs not running as before still have to take it back out to the lake. I'm going to get one of those temp guns to check the whole engine. Both gauges when turned off set at the halfway point and go to part up cold when switched on before starting engine. Have yet to ground the wires at the sender to check gauges, I'm out of town at the moment. Will try the riser trick to see it's temp.
     
  9. JVM225

    JVM225 Well-Known Member

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    Solid info on being able to keep your hands on the risers.
    Also:
    Sounds like the temp goes up when on plane and then comes back down again when you slow down.
    Does that sound like what’s happening?
    If the boat is new to you and you don’t know for absolutely certain when they were last done then it might be a good idea to change the raw water impellers too.
    A bad impeller will do what it sounds like you’re describing.
     
  10. Loyd Dinneen

    Loyd Dinneen Member

    240
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    I went completely through both outdrives and replaced the waterpumps and impellers on both sides. When I had it out to the lake the first time I got both engines up to about 3500 rpm and the gauges started climbing, I didn't let the starboard side get into the red as I didn't want to blow a head gasket or hurt the engine so I backed off and it stayed at 3/4 at about 2000 rpm as did the port side then started to climb so I shut it down. The port side stayed 3/4 even when I took it up to 3500 and it stayed there. Needless to say I never had a chance to get it up on plane. What I hear about other boats running at Lake Mead is they all run a little warm because of the lake being warm on the surface sometimes 80 degrees plus. The temps only go down a slight amount when I slowed down the starboard not enough to be able to run it without worrying about it. I will check the risers when I get home. Right now I'm hoping to get out deep sea fishing out of Seward Alaska this Sunday as long as the weather holds it should be a go.
     
  11. JohnV56

    JohnV56 New Member

    8
    Jul 6, 2018
    2003 280 sundancer twin 4.3
    twin 4.3 raw water cooled/ alpha one gen 2
    Hey. So I went to sea ray dealer got some new gauges. My engine temps are back to 160-170 degrees. I just started boat let it get to temp. Haven’t taken her out yet. Old gauges were over 200 degrees now. Glad that worked out.

    Also my manifolds are wet joint and are 6 years old. The elbow is very hot to touch so I’m thinking it’s the last year the entire exhaust system will be on. Impellers are 2 years old and will also be changed at end of season.

    Thank you all for the tips. I’m just glad to see my gauges and my IR temps are finally in synced.
     

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