Author Topic: Motor overheating problem  (Read 213 times)

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Offline cv-19

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Motor overheating problem
« on: December 03, 2017, 08:36:40 PM »
 
  Took the boat out yesterday and developed a heating problem thats strange .CV-19 JET BOAT.
   It runs 140-150 degrees normaly but on my return trip noticed 220 and thought I lost the belt.
   Belt was on so I  checked exhaust manifolds and hoses for temp. and they were normal to the touch .
   NO weeds in the jet pump intake so I checked to see if it would get on plane . As soon as I took off
   the temp gauge dropped like a rock to 100 for only10-15 seconds then right back up to 220 all within
   30 seconds.Thought t-stat so I removed it ,still have the same problem. Took off supply water hose flushed
    it out with garden hose and also flushed out to motor with good flow,still same problem.This motor has a water pump
     but I wouldn't think a problem there would cause the huge temp. swing. Pump is not lose  or leaking .Tomorrow will check it out more. Looking for
    thoughts and imput. Never seen this problem before.
   

Offline cv-19

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Re: Motor overheating problem
« Reply #1 on: December 03, 2017, 08:55:52 PM »

 Just checked the oil and it looks a little cloudy may have a little water in it. Problem maybe head gasket or cracked head . Wouldn't think it would run that hot being lake water cooled?

Offline carlsoncvx18

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Re: Motor overheating problem
« Reply #2 on: December 03, 2017, 09:11:05 PM »
We'll certainly could be a head gasket for water in the the oil.

As for the overheating I would maybe suspect a gauge of temp sensor.

I also had a similar problem one time chased it for quite awhile ended up that the risors on the exhaust manifolds were plugged up, removal and a soaking in mutation acid cured the problem.

« Last Edit: December 03, 2017, 09:18:58 PM by carlsoncvx18 »
1987 CVX18
1977 GT150 110hp Johnson
1986 CV23
1988 CVX18

Offline cv-19

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Re: Motor overheating problem
« Reply #3 on: December 03, 2017, 09:19:20 PM »
 
 Its that hot I can hear water boiling  when I turn it off.

Offline carlsoncvx18

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Re: Motor overheating problem
« Reply #4 on: December 03, 2017, 09:33:09 PM »
Ok thought you said they were normal to the touch.
1987 CVX18
1977 GT150 110hp Johnson
1986 CV23
1988 CVX18

Offline cv-19

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Re: Motor overheating problem
« Reply #5 on: December 04, 2017, 03:11:33 PM »

 That's what odd the manifolds are not hot. Tested it again today, has to have a bad gasket or head leakage. Bypassed the oil cooler just to see if it was the problem. Used a temp. gun and its 105 + - 2 degrees on both manifolds risers. The intake manifold
is 195 on one side by the temp. sensor and the other side is about 100. Got to be exhaust  getting in causing problem.

Offline GIL_CV21

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Re: Motor overheating problem
« Reply #6 on: December 04, 2017, 04:52:50 PM »
water pump shot ? thats the only thing moving water through the motor with the take up system ?

Offline cv-19

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Re: Motor overheating problem
« Reply #7 on: December 04, 2017, 06:41:15 PM »
 

 That' was on my check list GIL but the water in the oil and it now has a miss in it makes me think head or gasket leaking.
 Water can get into the oil pan from the water pump, had that happen before . Going to pressure test it tomorrow.I am an AC tech
 and plan to use Freon to pressure test the motor.  15-20 PSI then remove spark plugs and use electronic leak detector to check .I think this will
 will let me know.

Offline cv-19

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Re: Motor overheating problem
« Reply #8 on: December 04, 2017, 08:27:43 PM »

  Also strange is that the tstat housing is 100 degrees and 2 in. away is the temp sender  that is in the intake manifold and its 195 and the hand touch proves the temps are correct.

Offline carlsoncvx18

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Re: Motor overheating problem
« Reply #9 on: December 04, 2017, 08:38:57 PM »
Did you boil the t stat check it is working correctly?
1987 CVX18
1977 GT150 110hp Johnson
1986 CV23
1988 CVX18

Offline cv-19

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Re: Motor overheating problem
« Reply #10 on: December 04, 2017, 09:12:01 PM »

 Yes  its a 140 and opens full at 150 .Took it out for now and it makes no difference.

Offline Plugcheck

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Re: Motor overheating problem
« Reply #11 on: December 04, 2017, 10:54:17 PM »
100 degrees at one point, and 190 2-3" away can only be two things, obstruction or no water flow.  Another remote possibility is the temp sensor is bad.  Only time I've heard water boiling in an exhaust was when the impeller got destroyed, but that was an I/O.  Not a jet guru, but the block has to receive water from some pressure source.
Michael
1979 CVZ-18 388 CI Vortec Mouse
1980 CVX-16SS 140 Mercruiser
1979 CVX-16 Johnson 175
2002 Bennington 2275CC 90 Mercury
1985 Intimidator project, gps 85 mph (on trailer)
1989 Lowe 200 Redneck fishin Toon

Offline cv-19

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Re: Motor overheating problem
« Reply #12 on: December 05, 2017, 06:45:02 AM »

 Temp sensor good and its accurate. Tested it.

Offline cv-19

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Re: Motor overheating problem
« Reply #13 on: December 05, 2017, 04:13:42 PM »

 Water supply is from the jet pump .

Offline cv-19

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Re: Motor overheating problem
« Reply #14 on: December 05, 2017, 06:28:39 PM »

 Failed the pressure test. #1 cylinder is the problem all other cylinders OK.  That's very close to the temp sending unit
 and I think thats why it was only hot in that area.