Overheating help XL2001 150 Saltwater

[gstuck1956]

I am chasing an overheating issue with my 2001XL Mercury 150 Saltwater 0T554697. Here is what has been done already?replace water pump (complete rebuild), replaced thermostats 2X, replaced poppet valve completely. Mercury suggested that I change my poppet valve to an 884236-split poppet that will open at a lower pressure and allow more cooling water. That part has yet to arrive to me so that has not been accomplished. I have the required PSI within the specs (idle 1-4 psi?8-10 psi at 3000 and 12-15 wot) for the engine (via pressure gauge check). Back it into the water and idle out to the point and temp on the gauge went to 180 real fast. Started to get on plane and the alarm went off. Back it down to idle and the alarm went silent. Gave it the gas and got on plane and no issue. Slowed down to go through the train bridge and the alarm went off again temperature gauge at 200. Allowed to idle to keep water flowing until alarm went silent and temperature gauge dropped back to 175. Started back up and the whole temperature thing started all over again. I am out of answers and out of money taking to the mechanic to help. I got close to 1500.00 in repairs in this catastrophe. I am also out of answers?except for the Filler block 67891 in the gear housing that I was told might be passing exhaust gas through?ANYONE GOT A SUGGESTION?PLEASE....Note pee is kinda week at idle but increases as the RPM'S go up.

 

[Texasmark]

In a similar engine of my son's stats are stamped 143F for opening temp. Kickin of the popoff according to similar engines is in the range of 2500 rpm, above which the stats are basically out of the picture. OT sensor is 195F plus/minus small tolerance.

If I were going to trouble shoot your problem with what you said, I'd pop the lower unit gaining access to the water tube at the output of the WP. I'd pull off the hose to the popoff allowing free circulation through the block. I'd connect the hose to the water tube sealing as well as can be expected and shoot water through the block expecting a good flow from the popoff port, or if not available separately, just pull both stats and leave the ports open, gaining access to the block cooling passages and look for good laminar flow.

If you passed that test then I'd look for an exhaust leak as specified. Faztbullet probably knows where they occur most often. Problem with it being exhaust due to a faulty gasket is the intermittency of the problem as I see it. A blown gasket is a blown gasket, similar results with similar engine performance data points. Seems like something floating around in the block....piece of impeller blade for one, chunk of corrosion that broke off from somewhere either floating with the water flow and jamming the popoff port in the block when it gets in the right position.

You said you had the right pressures.....well pressures don't mean flow is correct necessarily since the pump is of a centrifugal design. It just says the water pump is alive and well and wants to push cooling water

My 2c.

 

[gstuck1956]

Thanks for the feed back...All the flow looks good out of everything you mentioned...I am still chasing this heating issue...new poppet has not arrived (04/03).

 

[Texasmark]

Poppet fed by a ⅜" hose from the top of the block? If so, pull the hose at the input to the poppet and point it overboard of the engine and run the engine checking flow without it. Then shut off the engine and pull the poppet and put the water hose you are using in it's socket and run hydrant water through the midsection and out the LU. How does the flow look in both instances?

 

[gstuck1956]

I will get to the poppet check on Saturday...the boat is 3-1/2 hours away from me now. I am going to install a new split poppet valve 884423 recommended by Mercury. It is a new "design" to open at a lower pressure and give relief according to engineering at Mercury Marine. And I am putting in another set of Thermostats (143) after checking them outside the engine. I had one mechanic tell me that the water flow on the 2.5L was a nightmare for Mercury (only rumor at this point). And I had one mechanic tell me to cut one loop off the poppet spring (not real keen on that idea) to open it faster and at a lower pressure.
Thanks

 

[Dukedog]

I will get to the poppet check on Saturday...the boat is 3-1/2 hours away from me now. I am going to install a new split poppet valve 884423 recommended by Mercury. It is a new "design" to open at a lower pressure and give relief according to engineering at Mercury Marine. And I am putting in another set of Thermostats (143) after checking them outside the engine. I had one mechanic tell me that the water flow on the 2.5L was a nightmare for Mercury (only rumor at this point). And I had one mechanic tell me to cut one loop off the poppet spring (not real keen on that idea) to open it faster and at a lower pressure.
Thanks

if tha thing won't do right with "factory parts" it has a problem... tha 2.0, 2.4, 2.5 cooling system is just fine tha way it comes outta production.. thousands that do and still performing right prove this point.. your listening to a coupla "hacks".... when tha pump "kit" was installed what parts were changed?

 

[JimmySmackdown]

I'm dealing with the same thing on a freshly rebuilt 1997 175 EFI. I get overheating buzzer when accelerating from idle to 2500 rpm. I shut the motor down, restart it and no buzzer. I'll be following your posts to see if and when you get your issues figured out. Hopefully it might help me solve my problem. The person I bought it from said it might need a new poppet.

 

[Texasmark]

I'm dealing with the same thing on a freshly rebuilt 1997 175 EFI. I get overheating buzzer when accelerating from idle to 2500 rpm. I shut the motor down, restart it and no buzzer. I'll be following your posts to see if and when you get your issues figured out. Hopefully it might help me solve my problem. The person I bought it from said it might need a new poppet.

Poppet is for high speed operation. You might need a new thermostat..sounds to me like one sticking. Poppet is pressure activated, just a disc pushing against a spring. Stat is a piece of wire getting hot and expanding to move a butterfly to a different position. Lots more to go wrong here and get stuck or not stuck and does the controlling below 2500.

 

[gstuck1956]

OK it is fixed and running just fine...Installed 2 new 143 degree thermostats and replaced the poppet valve (see note below***) and the water pump. Old thermostats would not open until 180 degrees outside the engine (1st issue). Water pump impeller in backwards (probable my fault turn the wrong way on installing it (2 issue). AND finally from Mercury I installed "You could install a notched poppet valve. This allows poppet to open at lower water pressure to allow increased cooling at low rpms. Part number 884236. MSRP $14..." Ran both low and high speed for a long time Saturday out of Pascagoula MS and yes it was a rough windy ride. Had no temperature problems at any RPM...Idle, low speed, plowing (not on plane) or AT WOT. Thank you to everyone that made a comment for me. I believe it was the combination of the three issues and new poppet that was driving me crazy. And I am looking for new marine dealer. I does make me sad that that no local place could help me without making several house payments for assistance in chasing this.

 

[Texasmark]

Thanks for the reply. Helps when you help someone and find out that you did in fact help them instead of them just leaving you hanging..... Have fun.

 

[JimmySmackdown]

Congratulations gstuck, I got mine figured out too. Took it back to the builder. He replaced the thermostats with OEM and checked the impeller. Did a load test in the water and got a horn after 3000 rpm. Replaced the poppet with OEM and presto! No more horn. My builder says this is the 3rd aftermarket poppet that has given him problems. He's going to stick with OEM from now on. (By the way, he tested the non-oem thermostats he replaced and they were working properly)