Alarm at WOT?

[joeim8]

All,

I recently dropped a reman powerhead in on my 2002 Merc EFI 200HP (SN#0T443994).

Majority of the break in was well going well 0-4500 RPMs no problem at all smooth, however the first time I tried to run @ WOT I received a alarm (constant Beep one tone, NOT Beep Beep Beep etc.)

I am not sure what this could be but here are the things I have found since:

1. It only happens at WOT.

2. The the expelled water is peeing maybe slight week at idle, and maybe just a touch less than typical under load more than idle really tough to tell. (ALso brand new water pump kit and thermostats installed with new powerhead)

3. The temp gauge is running slightly warmer than usual, mt temp guage basically has 4 lines so I guess 0,25,50,75,100% and its running near 60-75% above 4,000 RPMS.

4. My water pressure gauge seems to be running high as well 20-27ish, which makes no sense to me as I would think it would be low not high if I had a water pump issue or clog etc.


Not sure guys appreciate any thoughts.

[joeim8]

IMG_1315.jpg

[joeim8]

HEy guys I should probably verify that the gauge just above the RPM Gauge is indeed water pressure and not oil pressure? (96 Ranger 391V)

[JOE54]

check poppet valve for sticking

[joeim8]

Ok so I pulled the thermostats checked them and both seem to open at around 140F. As I mentioned brand new water pump kit was installed, I also flushed the system.

However still get alarm at continuous alarm at WOT which subsides as soon as I back of throttle, water stream still seems a little weak at times but fine at other.

I don't know what else to really check concerning the water system as there isn't much to it, maybe a slight obstruction somewhere I don't know at this point?

Any more thoughts guys? Thanks.

[SilverFox579]

Did you check/inspect poppet as recommended by Joe? If poppet is sticking you won't have adequate coolant flow at higher speeds. Gauge is water pressure.

[willwork4fish]

I just ran into something similar, changed stats, poppet and water pump...still happened. Turned out I had a leak at the base of the powerhead. You wouldn't see the leak on the muffs but could see it if you put it in a tank (or I'm sure if I would have looked harder when it was in the water). I could idle around all day with no problem.

[joeim8]

Thanks for replies guys, I have not checked the poppets yet but will do so after work today and report back.

How should i go about inspecting the poppets or what am I looking for, also where are they located on my motor I am kind of learning on fly.

thanks

[leonreno]

The poppet valve is on starboard side at the bottom of the powerhead, below/behind trim/tilt relays. Usually have to remove lower cowl to access. There is a replacement kit with the parts you need, it’s cheap and I would recommend replacing it to be sure. A stuck poppet valve can cause high pressures like you have.

check poppet valve first but as stated above, a bad gasket between powerhead and midsection can also cause similar problems. A leaky gasket will reduce water flow and can allow exhaust gases in to water jacket.

[EuropeanAM]

One more thing to consider- let's make sure that the Water Pressure Gauge (above the tach) returns to ZERO with the engine OFF.

If it does NOT, you cannot believe anything that gauge is telling you (replace it, it's been damaged).

[joeim8]

Ok guys I took out and inspected the poppet valve, it was pretty tough to get out kind of stuck to gasket tough to tell if maybe it was stuck but after I pushed it a few times it seems ok and appears brand new as it should be considering it came with powerhead.

I guess I just need to put it back in and take it to lake to see if it worked, I’d there anyway part of it that I should grease at all?

Out of curiosity I checked the poppet on the blown motor that I just replaced and since it is not mounted on anything I was able to get my hand on the backside of it and it was definitely stuck closed on my first push then seemed ok after that, so I’m not sure if that’s from sitting or what but I assume the reman I bought may have been sitting a while as well and it looks like they paint them semi carelessly so maybe just a dab of pain made it where it should not have just a thought.

Don that’s a good catch I Do not belie it does return to exactly zero, I will replace as I bought gauges to replace all years ago and never got around to it.

Thanks

[leonreno]

Don’t grease the poppet valve.

[JOE54]

^^^+1

[EuropeanAM]

Make sure that the plastic poppet valve will move in and out of the seat/grommet SMOOTHLY as if it were buttered. NO effort should be required until the spring is compressing.

If it binds even slightly while in your hand on a cool engine, it will stick and bind under running conditions.

[joeim8]

Ok thanks Don.

[joeim8]

Update on issue guys.

So to recap here is what I have inspected/replaced so far Poppet (New with powerhead), Thermostats (New), Water pump kit (New), all lines for clogs and all seem to be functioning as they should at this point. Since I was still getting high water pressure readout on my gauge and kept throwing an alarm at WOT I installed a Mercury Vesssel View Mobile to capture a fault code etc.

So today was the first time I took it out for a test since checking the Poppet as recommended and first time since installing vessel view, and again I got a constant alarm at WOT and only at WOT.

The fault detail read:
"Block coolant pressure"
Engine: STBD
"Water pressure sensor is not working properly"

As Don pointed out above my water pressure gauge read up to 30 and at WOT I was really close to maxing it out however it doesn't return to 0 when off, but according to the vessel view I was around 5psi or so at idle but closer 35-40psi at WOT.

Any thoughts guys I'm not sure what else I can replace, maybe the sensor itself. I did notice when I looked up the sensor which has a part#859596 on it it mentions 0-30psi however it also says it has been replaced with Part#881879A7 and this paticular water pressure sensor kit reads 0-50psi???

Any thoughts are really appreciated guys, I really can't finish breaking the motor in until I figure this deal out.

Thanks

[EuropeanAM]

Correct on the Block (Water Pressure) Sensor, and make sure you use ONLY, ONLY, ONLY the OEM Mercury Part. DON'T mess with the aftermarket, bay and zon stuff... seen far more than enough problems with those now.

I'm wondering if you don't have a broken/damaged gasket at the powerhead, adapter plate, or a cylinder head. Difficult to achieve that much pressure on that setup.

Just out of curiousity- what pressure is shown on the VVM with the engine OFF (key turned on)?

[joeim8]

Ok thanks for the info Don.

I will report back with water pressure result.

Would I physically be able to see signs of any of the mentioned potential gasket issues if I remove too/bottom cowl and hook up to muffs? Or might there be a simple test for each?

thanks

[joeim8]

Ok thanks for the info Don.

I will report back with water pressure result.

Would I physically be able to see signs of any of the mentioned potential gasket issues if I remove cowls and hook up to muffs? Where is the adapter plate located? Or might there be a simple test for each?

thanks

[leonreno]

Can’t normally see adaptor gaskets or problems. It’s between the powerhead and the midsection. To check the powerhead has to come off. Now head gasket you can check by removing the cylinder heads.