96 Mariner Magnum 3, 150hp: Quick Help

[will941s]

I have a 1996 Mariner Magnum 3 outboard, 0G383790, 150hp outboard. I did a compression test, and plan to replace the water pump this week. All 6 cylinders were 110 psi even. Heres the following issues:

#1: Kinda rough idle, and VERY hard to start after it sits for a little while. Heres what I noticed. On the Fuel Pump, there is some gas/oil mix on the outer plate, and the vac hose running to the outer plate don't seem to be seated well, as well as some gas oil mix dripping from the "dry" side of the outer plate gasket. If im correct, gas should not be in this section of the assembly right? It should be flowing through the middle only right? If so then I guess I need to replace the gaskets and diaphrams, and maybe that will correct that issue?

#2: Motor don't pee well, sometimes won't pee at idle, but ALOT of steam comes out the pee hole. Motor feels hot, pees like a race horse at full throttle. Alarm has never gone off and it does beep when the key is turned on. I assume the t-stats are opening due to the amount of steam, so should I just replace the impellar, or do the impellar and poppet valves? I just got it, everything seems well...runs very well pushes a 19' Keywest at 60mph. I just need to correct these issues. What else should I look for?

Also, when I drop the lower unit, do I need to disconnect the shift shaft somewhere first, or does it just slids part when the lower unit is removed?

THANKS IN ADVANCE!!

 

[will941s]

Re: 96 Mariner Magnum 3, 150hp: Quick Help

Bump

 

[will941s]

Re: 96 Mariner Magnum 3, 150hp: Quick Help

BUMP...thanks for the overwhelming responses so far, really need some advice here guys.

 

[ufm82]

I'm surprised

I'm surprised

People here are normally very fast to respond.

1) My 150 is EFI so i can't say from experience but gas/oil anywhere but IN the fuel system is not correct. You may have the fix with the gaskets/rebuild deal. As for the rough idle my 150 doesn't sound like a sewing machine. Do you have spark everywhere at idle?

2) If you just got the engine and don't know the service history t-stats, poppet and a water pump kit will be the best $150 you can spend on it. Plus they are all relatively simple to do. Shouldn't take more than a couple of hours and you'll gain the confidence that the cooling system is good to go as well.

 

[will941s]

Re: 96 Mariner Magnum 3, 150hp: Quick Help

Thanks, I do have good spark all the way through, and that led me to believe it was the FP. Hopefully my parts will be here soon and I can get a look at it. It runs well, just takes alot to start it first thing, and if it sits. I also ordered a water pump kit and a poppet valve kit so hopefully that will cool the motor down. FP is wet though, the face plate is sopping with gas/oil. Does the lower unit just disconnect from the shift shaft when you drop it, or do I need to disconnect something manually?

Have to say though, I had a 150hp Yamaha once, it was quick....but this Mariner beats that motor in every aspect of running. My Garmin showed the KeyWest 1900 running 62mph at one point @ 5100 rpm's. It actually blew my sunglasses off my face. Friend of mine has a 19' SeaPro with a 96' Yamaha 150hp Saltwater edition motor, and gps shows it running at around 50-55mph @ 5400 rpm's, it's only about 100 pounds heavier. It's a AWESOME motor so far.

 

[snakeguy46]

This is a very old thread and hope someone can answer my questions. I have the same mortor runs perfect. It is on a 96 Procraft 180 bass boat that looks nearly new. Not sure what the very large 2cy oil reservoir is by the gas tank? Engine has its own reservoir above where the carbs would be located? Why 2? Also looks like a hose fitting by the pisser, is this used instead of ears?

 

[Dukedog]

you need ta find an oem (forget tha aftermarket manuals.. they're junk) manual for your motor and do some serious readin'........ jmo... send me an email addy and i'll send ya and oem manual (pdf file) that has your motor in it

or ya can find someone that actually knows your motor and make him your new "best friend"!

 

[Chris1956]

Gee, thread is still open. Merc V6 engines have an oil reservoir on the engine, and can also have one in the bilge. Engine crankcase pressure forces the bilge reservoir to refill the engine reservoir continuously. The engine oil reservoir is gravity feed to the oil pump.

Low speed (<2000RPM) cooling water temp is controlled by the thermostats located on each cylinder head. If you have steam at low RPM, they are likely your issue. A lot of V6 Mercs have the telltale downstream of the thermostats. So if the 'stat doesn't open, there is no telltale.

High speed cooling is controlled by the poppit valve. It sounds like yours is working.

 

[snakeguy46]

you need ta find an oem (forget tha aftermarket manuals.. they're junk) manual for your motor and do some serious readin'........ jmo... send me an email addy and i'll send ya and oem manual (pdf file) that has your motor in it

or ya can find someone that actually knows your motor and make him your new "best friend"!

largereptiles@aol.com, thanks in advance.

 

[snakeguy46]

Gee, thread is still open. Merc V6 engines have an oil reservoir on the engine, and can also have one in the bilge. Engine crankcase pressure forces the bilge reservoir to refill the engine reservoir continuously. The engine oil reservoir is gravity feed to the oil pump.

Low speed (<2000RPM) cooling water temp is controlled by the thermostats located on each cylinder head. If you have steam at low RPM, they are likely your issue. A lot of V6 Mercs have the telltale downstream of the thermostats. So if the 'stat doesn't open, there is no telltale.

High speed cooling is controlled by the poppit valve. It sounds like yours is working.

Thanks for the info, I thought this may be the case but since the reservoir on the engine had a fill cap it confused me. Would you know it the cap by the pisser is a hose fitting to run the motor out of the water instead of ears?

 

[Chris1956]

Sorry, I do know understand your last post. As far as I know you, and a guess at your question, you need the flusher device to flush the motor.

The cap on the engine oil reservoir is to refill it, if it is low. Not all motors had the in-boat reservoir, and sometimes the reservoir refill system failed.

The thermostats are usually on the top of the cylinder heads. They have two 5/16" bolts each. The rubber gaskets on the thermostats can fail, so get replacements if you need to replace the 'stats. The last aftermarket thermostat I installed rotted out in a couple of years. It was unexpected.

 

[snakeguy46]

Sorry, I do know understand your last post. As far as I know you, and a guess at your question, you need the flusher device to flush the motor.

The cap on the engine oil reservoir is to refill it, if it is low. Not all motors had the in-boat reservoir, and sometimes the reservoir refill system failed.

The thermostats are usually on the top of the cylinder heads. They have two 5/16" bolts each. The rubber gaskets on the thermostats can fail, so get replacements if you need to replace the 'stats. The last aftermarket thermostat I installed rotted out in a couple of years. It was unexpected.

Thank you for the info,

 

[Dukedog]

file sent.. that plug is to flush motor.. garden hose with house pressure.. don't run motor when ya have it hooked up to tha garden hose........
use "ears" when ya want ta run tha thing on tha trailer...

"READ THA BOOK"

 

[snakeguy46]

file sent.. that plug is to flush motor.. garden hose with house pressure.. don't run motor when ya have it hooked up to tha garden hose........
use "ears" when ya want ta run tha thing on tha trailer...

"READ THA BOOK"

Got it, just completed winterizing. Thanks for the book.