How long does it take for Merc 150 HP outboard to pee after starting?

jaciehart

Recruit
Joined
Nov 28, 2011
Messages
3
Just received a used boat (Boston Whaler Outrage) from the mainland. Put muffs on and applied water source, but nothing out the pee hole. We heard that it takes a couple of minutes, but want to make sure as not to seize anything up. Is it true that it either takes a couple of minutes and/or the thermostate temperature has to reach around 120 degrees? Mahalo from Molokai, Hawaii.
 

N3UP

Petty Officer 2nd Class
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Aug 14, 2010
Messages
125
Re: How long does it take for Merc 150 HP outboard to pee after starting?

It should start as soon as the waterpump starts moving water, just a few seconds.
You could have a blockage somewhere or a bad impeller.

First thing I would try is to make sure the telltale nozzle is clear. I usually keep a spray tube, like the little red plastic ones that come with WD40 on the boat to push into the nozzle to clear it.

If the motor has a flush port (where you connect a hose) that should be able to be used to put water in the cooling system to check for blockages or leaks. Don't run the motor that way though, at least on my Mariner 225, the owners manual says that not enough water gets to the water pump to run the motor that way.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Re: How long does it take for Merc 150 HP outboard to pee after starting?

Nah, most of those V6 Mercs have the telltale downstream of the thermostats. The 'stats must open to have any telltale. Sometimes when running on the flusher, the 'stats never open.

Look at the prop and the grating above the antiventilation plate for water discharge. if you see it the motor is pumping.

BTW, since the motor is new to you, it is a good idea to rebuild the waterpump with new impeller, gaskets and wearplate.
 

bassman284

Commander
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Jun 24, 2006
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2,839
Re: How long does it take for Merc 150 HP outboard to pee after starting?

I've never had a V6 Merc so maybe they're different. Every motor I've ever had started peeing in a couple of seconds. IMO, a telltale that doesn't start peeing until the thermostat opens is totally useless.
 

N3UP

Petty Officer 2nd Class
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Aug 14, 2010
Messages
125
Re: How long does it take for Merc 150 HP outboard to pee after starting?

My mariner 225 is a V6 (3.0L) and it pees on the hose or the muffs and starts peeing within a few seconds of startup.

Mariner is just a gray Merc. I'm not sure how different the 150's are. Not sure if they are 2.0 or 2.5L blocks. Is the 3.0L that much different?

I agree with Bassman, if it won't pee until the t-stats open, why bother.
The whole idea is a visual indication of cooling water being circulated.

I had a 74 Merc 650 (65HP 3cyl) and it peed as soon as it started too.
 

j_martin

Admiral
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Sep 22, 2006
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7,474
Re: How long does it take for Merc 150 HP outboard to pee after starting?

Bassman and N3,
The Merc V6 engines have always had the tell-tale downstream of the t-stats. In normal boating weather and water, it usually takes 10 - 30 seconds at idle for the engine to warm up enough to put out a stream. Before that, there is a risk of cold-seizing the engine if you go right to WOT. That's probably why it's a good idea to have it that way.

If your engine streams from the tell-tale right away, something is wrong. Usually someone had removed the t-stats thinking they're improving the cooling. Don't work that way. Others replace the t-stats with washers because they heard that racers do that. It's like the teenager with no muffler thinking it makes his wreck go faster.

A real cold source of water on the muffs can sometimes actually prevent the t-stats from opening at idle. On a lake, in gear and slightly advanced throttle will quickly warm it up enough to open them.

hope it helps
John
 

bassman284

Commander
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Jun 24, 2006
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2,839
Re: How long does it take for Merc 150 HP outboard to pee after starting?

j_martin, I've been doing some searching (internet wide) for the last few hours and have found some folks who swear that slow pee is the norm for Mercs. Can't find anything that tells me why this should be so other than the "downstream of the thermostat" theory. You say 10 - 30 seconds but I've found several who think 4 or 5 minutes is reasonable. Guarantee if your impellers are not working for 4 or 5 minutes you will fry that motor. IMO, the pee stream exists to tell you your impellers are functioning, NOT to tell you your motor is up to temp.

I currently have 2 Mercury outboards - a 2001 60 hp 4 stroke and a 2003 9.9 4 stroke. If either of them took as long as 10 seconds to start peeing I wouldn't know because I would have already shut them down long before that and pulled them out for a tear down. I truly cannot imagine waiting 30 seconds for a pee stream. Don't have that kind of nerves. Apparently it takes a very brave man to own a 80's or 90's Merc.

To the OP:

1st) What year is your Merc?

2nd) If it's an 80's or 90's motor (which according to popular opinion can take minutes or days to start peeing), try REMOVING the thermostat and then run it. Following the popular theory, it should start peeing imediately. If not, I would say you have a problem.

Anyway, just my opinion, I could be wrong. /rant
 

N3UP

Petty Officer 2nd Class
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Aug 14, 2010
Messages
125
Re: How long does it take for Merc 150 HP outboard to pee after starting?

FWIW My Mariner is a 96.
It only takes about 5 or 10 seconds to start peeing. When flushing on the muffs after a day on the bay, I start it up, then walkl to the back of the boat to check and it's squirting away by then. Seems a reasonable amount of time to fill the block up with water.

Same thing when in the water, about 5 or 10 seconds after startup.
Mine will also pee when using a hose on the flush port, but I've never done that with the motor cold. I always flush for 5 or 10 minutes running on the muffs, then use the hose port for another 5 or 10 more.
 

aussiejake

Seaman Apprentice
Joined
May 19, 2010
Messages
41
Re: How long does it take for Merc 150 HP outboard to pee after starting?

My 2006 mercury EFI 150 hp takes about 2 minutes for thermostats to open at 64 degrees Celcius and then starts peeing.

Water pressure is on 3 psi until thermostats open and drops to 1.5 psi..all read from smartcraft. (on idle)

Yours sounds OK.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Re: How long does it take for Merc 150 HP outboard to pee after starting?

Bassman, On lots of the V6 Mercs, it isn't a theory that the telltales are downstream of the thermostats. It is fact, and can be verified by inspection. I cannot speak for all Merc V6s, since I have not worked on each model.

The older inline Mercs didn't have thermostats, so the telltale was active as soon as the water reached the outlet on the cylinder head waterjacket.
 

CharlieB

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Joined
Apr 10, 2007
Messages
5,617
Re: How long does it take for Merc 150 HP outboard to pee after starting?

Drill a 1/8 inch hole in the stat flange to allow a small amount of water to bleed thru each stat, you will see a dribble of water from the P tube til the motor warms and a steady stream flows normally.
 

ufm82

Master Chief Petty Officer
Joined
Jul 29, 2003
Messages
827
Re: How long does it take for Merc 150 HP outboard to pee after starting?

My 150 is a '93 and it's obvious that the pee hose comes off the engine AFTER the t-stat housings. My engine will pee within a minute or two after starting and that varies on ambient temps. Once my gauge hits about 140 the stream starts. The stream remains steady (but not "firehose strong") after that. Plenty of volume but not pressure. Mine runs about 6 psi at idle and hits a high of 12 psi at full blast. Just because the pee stream doesn't pee right away doesn't mean it's useless- as mentioned above, it's a good indicator that the engine has warmed properly and is ready to go.
 

hl

Petty Officer 1st Class
Joined
May 2, 2010
Messages
237
Re: How long does it take for Merc 150 HP outboard to pee after starting?

I have a 86 150 and it takes only about 10 seconds to show water from the pee hole, and about 30 seconds for a strong flow. I also have had problems with over heating. Try weedeater line to check the pee hole for blockage.
 

bassman284

Commander
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Jun 24, 2006
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2,839
Re: How long does it take for Merc 150 HP outboard to pee after starting?

I guess if you're comfortable waiting 2 to 3 minutes to find out if your water pump is working, it's all good.

\backtomycave
 

frankie g

Petty Officer 1st Class
Joined
Nov 14, 2007
Messages
388
Re: How long does it take for Merc 150 HP outboard to pee after starting?

Bassman and N3,
The Merc V6 engines have always had the tell-tale downstream of the t-stats. In normal boating weather and water, it usually takes 10 - 30 seconds at idle for the engine to warm up enough to put out a stream. Before that, there is a risk of cold-seizing the engine if you go right to WOT. That's probably why it's a good idea to have it that way.

If your engine streams from the tell-tale right away, something is wrong. Usually someone had removed the t-stats thinking they're improving the cooling. Don't work that way. Others replace the t-stats with washers because they heard that racers do that. It's like the teenager with no muffler thinking it makes his wreck go faster.

A real cold source of water on the muffs can sometimes actually prevent the t-stats from opening at idle. On a lake, in gear and slightly advanced throttle will quickly warm it up enough to open them.

hope it helps
John
sorry to agree with this mans post, I have a 2004 and I've never timed it but there is a delay,the stat's will open then she pees. down buy the cav. plate you will see another stream and that will show that the pump is pumping
 

Pgpd324

Cadet
Joined
Nov 6, 2011
Messages
9
Re: How long does it take for Merc 150 HP outboard to pee after starting?

My 1988 XR-4 150 starts peeing after the stats open, on the muffs in about 1-2 minutes..
 

aussieflash

Lieutenant Junior Grade
Joined
Feb 5, 2011
Messages
1,004
Re: How long does it take for Merc 150 HP outboard to pee after starting?

Sorry to take this into another year but my V6 merc takes 20 seconds almost everytime on muffs to pee.Starting to get warm under idle and low rpm out on the water,thats another thread though.
 
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