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Question on Temp rise on a 2000 5.0

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rick3452

Regular Contributor
Hi guys, Serial # 0M012817 Half closed system with heat exchanger.
The other day I was cruising the intercostal with my family... I've had this boat 5.5 years and have put 1600 hours on it (now has 1800 hrs.) When I went to open it up within maybe three minutes the gauge went from the "constant " 160 to 180. I throttled it right back and within a few min, the temp returned to 160. This never happens... It had been 5 years and 1500 jrs since I replaced the Manifolds and Elbows so Yesterday I replaced both sides and took it for a ride. This time while running high RPM's it stayed pretty much at 165 but a few min later it rose to 170. So I brought it back and changed the Impeller including the new housing. There was 600 hrs on the impeller and it was completely in-tact I sort of thought that there may have been missing fins, but no. so when I take it out tomorrow and if it does rise.... What else should I look for? I have noticed on the Heat Exchanger hoses I have seen slight amount of green seepage.

Thanks as always for any help..
Rick
 
Remove the covers on the Heat exchanger, no worries only sea water will come out. Make sure the tubes are clear. I use a brazing rod to clear the tubes.

Now if the tubes are clear, you need to pull the boat from the water (onto a trailer or a work rack) and check the water fitting on the transom assembly. Behind the engine on the transom assembly you will see where the water hose connects.

Here is what you need to look for, Under the water fitting the coolant hose comes through that supplies the raw water, they are known to swell shut or clog with minerals and salt from the water, especially on a trailer, rack or lift stored boat.

When you remove the screws that hold that fitting on and pull the fitting away it will look like a balloon knot.
 
Chris, Thanks again! I will check Heat Exchanger this afternoon. Also my boat is on a lift here on the New River..
Rick
 
rick3452 said:
Chris, Thanks again! I will check Heat Exchanger this afternoon. Also my boat is on a lift here on the New River..
Rick
Click to expand...

If the exchanger check out to be clear, Pull the boat onto a trailer, don't pull that water fitting apart while it is on the lift because if it is bad it will not be going back together..


Here is an example. This is from a lift kept boat.

balloon knot.jpg
 
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You did say it was a half cooling system. Take the valve out of the bottom of the exhaust manifold and make sure this is clear. You will hear the check ball rattle around in it when shaken. Make sure the manifold is also clear.

The manifolds and elbows may just be plugged up also.
 
Hey Chris!
Ok I just took it out for a ride.... Runs 160 perfectly when I get to the section of the intercoastal that I can accelerate after a few minutes it went to 172 on the gauge. We did check it with a digital thermo meter and that said more like 160. After a couple of min. right back to 160 although the thermo tool said 150 at the T stat. By the way I did replace manifolds and elbows two days ago.
ThankS Rick

Oh!! Heat Exvchanger was nice and clear!!
 
Hi Chis,
Can this be repaired from inside the boat? Does the drive have to come off? And there is an aftermarket "kit" that has a stainless steel fitting from a company called Aftermarket Marine, would this be a good option? I would like to keep it original rather than through hull if I can.
Thanks again
Rick
 
Chris, I think I would like to go with the through hull brass strainer pick up.
the one I saw today was a 1 1/4 with the strainer. I'm assuming that the ID is 1 inch. Is this sufficient for supplying the sea water pump? I'm going to do this myself. I'd like to mount it on the other side of the engine because I have much more room there. So drill the hole, 5200 the brass fitting, also should I put a piece of 1/2 inch plywood in the inside for strength and to attach the fittings 4 screw holes up though the plywood. Then 90 degree to a hose connector end and run the new 1 1/4 hose around the back of the engine to the impeller. Thanks!
rick
 
Make sure there's no air leaks before the raw water pump or it will do some nutty overheating regardless of what's been changed downstream.

Jeff
 
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