120hp Johnson Outboard??

greateastern · #1 07-06-2010, 11:44 AM

I long since sold my V-20, but still remmeber all the great advice I received from this web site. I now have a simple 1750 Vector Hydro Sport which has been very good to me, I was wondering on my 1998 120hp outboard do you really need to run thermo-stats? Seems now that the bay temp has hit 80 degress the engine runs on the warm side, when your up on plane it is just about in the white zone the danger zone. No alarms or beeps are going off... but i'm just wondering why the thermo-stats? The cooless water temp. the outboard runs in is about 60-50 degrees in the fall. I'm just so tempted to pull these stats out.

Hope you can help.

Skools Out · #2 07-06-2010, 01:14 PM

i ran the sister motor a 140 with no stats it ran fine just it ran rich in colder temps. you could buy lower temp t-stats. they made 2 different motors some went north to dealers that had higher temp stats than those of the southern motors. you may have the wrong set for your water temps.

tsubaki · #3 07-06-2010, 02:03 PM

Pay attention to what Skools is saying.
Most of the time the only discernible difference with or without t-stats would be the initial warm up and when trolling for long durations.
Me, I'd put them in to rule out other problems that might arise later.

THEFERMANATOR · #4 07-06-2010, 02:52 PM

First things first, what is the model number on the engine? According to the catalogs they didn't make a 120HP in 98. If it is a late model V-4 90 degree looper then I would suggest checking the water pump first as that system uses water pressure to bypass the stats at upper RPM's. Weak impeller will make the engine run right at the redline for temp when under power. And if it was mine, I would leave the stats in it. Even down here in Floridas warm water I lost an engine from carbon build-up due to no stats. Loopers need alot of engine heat at idle in order to burn the fuel and not carbon up really bad. Figure out exactly what engine you have first, and then make sure the cooling system is working like it is supposed to. It could just be some salt build up on the stats that isn't letting them pop off there seats under pressure causing it.

phatdaddy · #5 07-06-2010, 06:39 PM

all good advice above, i would add just one thing, test your t-stats and verify at what temp they are operating. i've tested brand new ones and had them not open at the suggested temp or open at two temps 20-30 degrees apart from each other.

greateastern · #6 07-07-2010, 06:44 AM

Ok, I knew I could count on you guys, it is a 1990 not a 98. and Yes, I have have installed a new water pump, and yes I have put the stats in water to check operation temps.(I feel that they open way to late 180-190 degrees) I have even changed the sending unit to make sure of all things. Next I'm going to go with a new gauge no more colores I need numbers) To me the stats open up way to late, I heard about the stats that where mentioned, that they use down south asked my local supplier and he said that he has never heard of it. The stats I have in are white in color I read about a black colored stat that runs cooler??? any thoughts on part number??

Also I bought new stats and the motor overheated in the drive way with the garden hose. Put the old ones back in and it is fine. Just in the bay, running up on plane (4000 rpm) she runs to hot for my comfort.

Thanks,

Skools Out · #7 07-07-2010, 02:31 PM

here's a link from MJ's issue with his

http://www.wellcraftv20.com/communit...ead.php?t=7580

ok tool time

this is a V4 motor but same exact part as V6

here's the valve

here's where it gets water from when it's under 3000 rpms

here's where it is going to under 3000 rpm

here's where it goes above 3000 rpm out to the pisser on the lower housing from the above pic

here it is under 3000

here's above 3000

first you need to remove below screws and nuts

then GENTLY pull out on the throttle arm till pin is out of the valve

now GENTLY pull out till accessible

now mark a location of the center part to out side so you replace correctly then pull out slide pin

then pull out the insert carefully

heres the valve taken out

clean this part very well

here's the inside of the valve with a seal in this ones case some have o-ring

you can grease the rubber seal if in good shape and then light grease on the valve and reinstall usually stops the leak.

or you can use the cap covers as below better to use the bypass system

THEFERMANATOR · #8 07-07-2010, 03:27 PM

If you have the white housings, DITCH THEM IMMEDIATELY! OMC issued a bulletin years back about overheating caused by the white housings. The white t-stat housings have a guide on the end of them to help center them in the seat, but all it did was cause overheating as the rubber got older in the seat and wouldn't let them move out when the valve would drop pressure. The black housings are the only housings you are supposed to use now. Inside they both use the same vernotherms, and open and close at the same temp. Clean out the valve that SKOOLS posted, and make sure the linklage is hooked up working to it. Next get a set of the black t-stats and diaphrams and your problems will most likely be over. Also the stats should open up at 160, so it sounds like the springs inside your stats are work hardened from the years anyways. Also pay attention to how the valve comes apart as the valve can be installed 180 degrees out and it won't function properly that way.