2.5 still steaming at idle...?

[Bartman39]

After running my 94 model 2.5 EFI 150 fishy motor at speed either WFO or just at mom & kids speed and come down to an idle it quits pee`ing and steams...? I can leave it neutral and idle it up to 2000 rpm`s and it will start pee`ing again but if it drops much below that it will again steam until it basicly cools off more...? I dont have a temp gauge but the light does come on until I get it pee`ing again...

I have replaced the thermostats, poppet valve (seat and all), water pump impeller (housing looks almost new) and all the plumbing is stock and correct... The water pressure is rather low too, like 5-7 psi at 4000rpm and only around 10-12 psi @ 5500rpm... (seems low to me and checked with 2 different gauges)

I am very open to suggestions for sure I just dont want to roast this power head its very low hours around 150-200 hours at most since new... (sat for a long periods of time just no use to speak of)


Did notice one rather strange fact today though... In forward and at idle it steams or quits pee`ing but in reverse it seems to keep pee`ing...? Strange...?


HELP...! :confused:

[Lanceonthelake]

Have you checked the water passages in your gearcase for junk that got sucked in? Maybe wrong sized or damaged guide tube?

[boilerdawg]

this may not be your problem but......do you have a jack plate? how high are you runnin your mota? ive seen some guys run the "scoop plate" over the water pick holes to allow for more mota height. this works ok while on plane but during idle times it can suck in air.

[maverick1]

Drop the lower unit, look down at the water pump ( still assembled) the assembly you discribed attaches to an "adapter plate" on most lower units, then below the adapter plate ( about 1/2 thick) it has another gasket which mates to the lower unit ( metal).

IF any of the gaskets below the impeller are broken (one of mine was) then the impeller will "suck" air at low RPMs out of the exhaust cavity and thus little or no pressure and little or no "pee" at low rpms.

Just my 2c

MAV

[Bartman39]

Hey thanks for the replies for sure... :) The motor is on a jack plate but sits rather low in the water its on a Skeeter ZX175 boat... Very sure its not due to the intake vents being exposed... Also I had back flushed the entire system without the lower unit in place and checked for flow with just the hose connected to the supply line and it seemed to point to the water pump, just not sure... But the other possible issue with the gasket really makes sense...? Might very well explain things...? I`ll drop the lower unit possibly tomorrow evening and see if there are any problems with the gaskets...?

I did make sure when I put the lower unit back on to put high temp silicone across the divider to the exhaust passage but did not think about a gasket possibly leaking in that same area...?

God I love this site... :D

[Dave S]

The rubber gromet that the water tube goes into. Sometimes it can get cut buy the water tube not going in rite. Then ya don't get good pressure. And what I do on All V6 motors is drill a small hole1/16 inch in the thermostats, that way you allways see water coming out of the peehole.:) If not drilled the water only pees when the themos open or the poppet pops.;)

[Lanceonthelake]

The rubber gromet that the water tube goes into. Sometimes it can get cut buy the water tube not going in rite. Then ya don't get good pressure. And what I do on All V6 motors is drill a small hole1/16 inch in the thermostats, that way you allways see water coming out of the peehole.:) If not drilled the water only pees when the themos open or the poppet pops.;)
Yeah, I don't run thermos in my 200, just quarters ($.25) with 1/16th holes.

[HighVelocity]

Why doen't anyone on this subject wonder what the actual temp is of the motor is?? I think installing a temp guage is the first step, does anyone else agree? Tic, Tic, Tic, MELT!

I would do what these guys are saying. Take the lower unit off and shoot water up the inlet tube. Make a connection with an old garden hose and a hose clamp. Maybe take the T-stats out and see if she's flowing like it should.

[Fish]

Why doen't anyone on this subject wonder what the actual temp is of the motor is?? I think installing a temp guage is the first step, does anyone else agree? Tic, Tic, Tic, MELT!

Sometimes temp gauges can be misleading, espeically if you have a problem on one side and the temp sensor is on the other. I agree it is a good idea to have it, but take it for what it is worth. If you really want an accurate temp, buy a infrared and point it at different parts of the motor. it will give you an exact temp in the exact location it is aiming at.

[merctech5591]

i would check the water pump adapter plate. it is below the water pump ans is blue in color on your motor. if it looks melted replce it. i have seen this many times and is a leading cause to low water pressure at idle.also the water pump housing may look ok , but take a closer look under the stainless cup there are small passages there, if the housing ever overheated it will melt the passages closed.

[Dave S]

A shop down here had a hot runn merc. So the heat gunn said. Put a Yammi on the boat. I bought the motor...... Fixed the pistons....... It was a bad popet suff of SALT ..... it couldn't open it was jammed full.:D We allways learn.;)

[Bartman39]

Sorry havent replied but did not get home last night till after 1am and this evening it was 8pm (plus I get up at 5am every morning)... I work for an oil field support company and have been working on a problem with a turbo pump at a remote site about 3 hours from my house... Soon...soon though... :o


After reading some of the replies of late it really makes me think it may be in the adapter or that area... Also wondering on the washer Vs. thermostats...? Wont that make the EFI run rich most all the time...? I see post going both ways but most say leave them in if your running a fishy motor like what I have...? (they are stock temp and brand new)

[Dave S]

Pull them Themos and get the Oil rig to drill them. Do that first. Try it . Then drop the lower unit to look for other problems. Ya could also have a blown head gasket or O ring , depending on year. I have seen a Merc have a O ring head with a Gouge that didn't seal ...... from the factory...... new.....screw-up.:eek: 2 years later it showed up. Found it fixed it.:cool:

[Bartman39]

Well think I found the problem... I took the water pump all the way down including the adapter plate/seal and found what I had been told was a new water pump was BS... :rolleyes: The impeller is very worn and the fins are folded over quite well and stay that way... :mad: Also found the gasket under the adapter plate was in pieces so it was not helping matters...

maverick1 hit the nail on the head... a big thanks to all that replied too...

So looks like racer rick`s will get some more of my midnight oil money... :eek: But hey some nice people there for sure... ;)

[Bartman39]

Well finaly got a pump kit (local shop was a big help) and the nail has been hit on the head for sure... I could tell even as soon as I put it on the hose the water pressure was at 5 psi at idle... :)

So when to test it on the water and at its lowest idle in gear it keeps 3-4psi and never quits pissing even after hard runs and runs about 20psi @ 5400rpm (full load of fuel and people and stuff) No temp light or anything...

Man I love this site... :D Thanks guys...

[HighVelocity]

"water pump impeller (housing looks almost new)" and all the plumbing is stock and correct... "


When you change things you want to rule them out right as the problem right?
LOL

I'm glad you found your problem, enjoy what's left of the summer.

HV

[Bartman39]

Sorry but like I said I was told it was new but you know how that can go... :eek: Also could not see the problem with the gasket under the adapter and did not want to take it that far down till I was sure that was the problem area... But thanks to maverick1 who pointed me in the right direction (other idea`s were noted too)... I realized this would explain why it seemed to happen all of the sudden (a gasket gave way)... Also I`ve been a mechanic for over 25+ years on auto`s and heavy equipment & machinery but not outboards so please bear with my inabilities but not short comings... :o


BTW here in southeast TX its summer almost all year round as is the boating... :D

[HighVelocity]

No, No, No, You misunderstood me. You did great, I was just saying how it sucks to think that something you were told was good and looked new, was actually bad. It's happened to me few times over the years. Sorry about that, I meant no disrespect.

HV