2001 efi cooling issue

[sleeper bird]

Iv got a 2001 efi ser number ot467866 just had the water pump changed by a merc dealer due to an alarm going off at idle,after taking the boat out again now with a smart craft guage this is what i observed ,still creeping up at idle until it hits 185 and alarm goes off,idle it up and temp goes down alarm cuts off,if i idle it at 1200rpm it stays around 135-140 aprox 9 or 10 psi on the guage.at idle the gauge reads from 9-7 psi it jumps up and down.on a plane and pushing it psi around 12 i believe and temp is from say 125-135 degrees runs great idling and pushing it.what iv done new wp kit done by merc dealer,thermostats and gaskets oem(last year) rebuilt poppet valve,new upper temperature sensors oem,new plugs and wires.I ordered everything to rebuild the pump again which includes the housings top and bottom,i am just bewildered how two pumps with very low or in one case maybe three hrs use cant keep the thing cool at idle.motors got 185 hrs

[mvpsteve]

Blockage somewhere in the cooling
system, have you ever had to track down missing impeller pieces?

[leonreno]

Sounds like a blockage, really sounds like stuck shut thermostats. Maybe test the ones you have in a pot with a thermometer. If it’s not the thermostats it sounds like a blockage somewhere else.

[aussiejake]

Replied to your other thread.

,two upper temp sensors(the plastic ones that screw into the head)

I may be wrong but the plastic ones are only for atmosphere air temperature for the smartcraft gauge, not for the motor.

You need the brass temperature senders that screw into the head. The 2 head sensors and the intake plenum air temp sensor are all the same and are brass.

[sleeper bird]

is there anyway to back-flush the system?i have never had any pieces from impeller missing,but i am the second owner of this motor.i am going to pull thermostats and test them thanks for the repys also there is always a strong stream out of telltale

[sleeper bird]

also on my engine there are two other sensors that are in the middle of both heads and look to be held in by a bolt and a fork looking keeper(not sure what to call it)

[aussiejake]

They are the analogue temperature senders.
The screw in ones are the Smartcraft ones.

[aussiejake]

I tried one of the plastic sensors as an air temperature sender in the top of the intake, it would not run properly. A brass one was put back in and had no problems.

[JOE54]

10 psi for that mtr sounds high at idle ,might wanna check see if your getting compression in cooling system [ oring leaking on cyl head]

[sleeper bird]

10 psi for that mtr sounds high at idle ,might wanna check see if your getting compression in cooling system [ oring leaking on cyl head]

How would i check that Joe compression test?

[sleeper bird]

the more i have thought about it,im thinking the best option to confirm no blockage and be sure orings are sealed is pull the heads.Thoughts?

[JOE54]

leak down will show oring if its bad , air psi will escape into water jacket with piston at TDC, or you could pull heads

[sleeper bird]

leak down will show oring if its bad , air psi will escape into water jacket with piston at TDC, or you could pull heads

well i decided to pull the heads this is what i saw.Honestly im not sure what i see other than water jackets look sort of milky .I took pictures but bbc says file is to large

[JOE54]

means fuel oil getting in cooling system

[sleeper bird]

So i would take that as a compression leak correct?

[JOE54]

yes sir /would also look at divider plate gasket

[sleeper bird]

Thank you very much,i will order that gasket

[sleeper bird]

pulled the exhaust diverter and didn't see any signs of water getting past gasket,although half stuck to the block and half to the diverter.One thing i noticed was a pretty good amount of carbon build up in the exhaust tract,also as with the heads the water jackets are yellow looking.Cylinders and pistons look good,cylinders still have cross hatch on all six

[90 5.0]

Take the divider plate and rap on it with a dead blow, shake it around after, sand can get in there and harden up like concrete and block cooling passages.

But it does sound like you had a leaking o ring on head also

[sleeper bird]

good idea i will do that,i guess its hard for me to wrap my head around a leaking head oring when it runs awesome at wot and idles really good except for temp climbing.But looking at the water jackets and the head cooling ports it sure does look yellow-milky and wipes off with carb cleaner,guess theres an upside the cooling passages are not going to corrode anytime soon.