coolant psi and engine temperature are running higher


formula280ss

formula280ss

New member
Took boat out this weekend and notice the starboard coolant pressure and temperature were running higher the normal, I have twin 2006 mercruiser 6.2 mpi
It didn’t overheat but running higher than normal
I’m thinking because both the coolant psi and engine temperature are running higher it’s the thermostat?
 
Don't see it being the thermostat

Assuming you have closed cooling with heat exchanger's (HE), I would pull the end caps off the HE and have a look. May need to get a bore brush to clean out the tubes. Can also be exhaust components. If your running a tad low on power look down the Y-pipe for the shutters.

You could verify your water pressure with a mechanical gauge in one of the drain ports.
 
yes I do have closed cooling
not running low on power, power and rpms all running perfect
all flow on drain ports seem normal but will look again
 
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just ran engines (on freshwater hookup) for 30 mins temperatures stayed even at 160, 25 mins at idle and 5 mins at 2000 rpm about 15 mins in then back to idle,
just the coolant psi ran about 10 at idle and 15 or bit more at 2000 rpm
I used my Digital Temperature Meter on fallowing
flow on drain all running around 105
heat exchanger at 100
all lines to heat exchanger about 105
Exhaust Manifold & Exhaust Elbow all running even with each other
Y-pipe at 100
I’m stumped
 
Comment: running the motor much above 1200 rpm on a hose can starve the impeller for water and can ruin it.

Running the motor even at higher rpms on a hose or in the water in neutral will not produce the same amount of heat as moving.

coolant psi ran about 10 at idle and 15 or bit more at 2000 rpm
Click to expand...

Your saying coolant but assuming this is raw water pressure correct?
If so, when in the water your pump will move even more water. Think of it like have a pressure gauge on a 5/8 ID hose end. Have another 5/8 hose attached to the other side of the gauge and turn the water on half way. There should be little pressure show up. Open the valve full, and there will be a bit more pressure show up but still not that much more.

Now, remove the second 5/8 hose and install a 1/2 ID hose. Turn the water on 1/2 way and there might be a tad more then the 5/8 but still not much. Open the water up full and pressure will increase due to the reduction in water flow.

So if your HE is just a tad clogged, running idle and such there should not be much change. Open it up on plane and WOT pressure will increase and since there will be less water flow temps will go up also

Edit: my motor runs 2 to 4 psi at idle, and 20+ psi cruising with raw water cooling
 
Thank you AllDodge
OK next step is to check HE see if clogged, I’ve never done it before, I’m assuming taking the ends of the HE off, will I need new gaskets? Or other parts? Any suggestions or warnings?
BTW my impellers are in good condition, I don’t normally run motors at high rpm on hose just idle just this one time, but thank you
 
My serial numbers are OW368820 and OW368819
Also, I’ve never changed my thermostats on either engines do I have to change both thermostat and housing or just the thermostats? Housings are not cheep
 
Don't mess with the thermostat's or housings, I don't see this as your problem.

Your HE are in the link below and the seal parts are items 25 and 27 which match the numbers I listed above.
https://www.mercruiserparts.com/bam/subassembly/31957/11681/290

Just remove the end caps, then get some bore brushes at a hardware store. If there is a lot a scale build up you may need some chemicals. Can find you tube vids of how others have cleaned them
 
Added photos of old HE seals starboard side were in bad shape as you can see in photos port side are in good shape,
There was no scale buildup on ether HE we did take a bore brushes to all tubes all were ingood shape with no buildup in any tubes
Starboard side the seals were blocking several tubes
I am replacing all seals on starboard and port sides even though port side are in good shape,
Just waiting on new seals and O-rings
001.jpg002.jpg003.jpg
 
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