Monsoon 350 thermostat location?

[bjgreenbucknell]

Hi everyone,

My boat (2010 wakesetter vtx with monsoon 350 engine) suddenly started running at a cold temp. It used to be always around 160, but now it's hovering around 110-120.

I'm suspecting the thermostat because the temp gauge seems to be working (ie from a cold start I can see it creek up until it hits about 110).

So I got the new thermostat to try changing that. I was told its directly above the raw water pump. When I look there I see a bigger what I assume is a pump on a pully and above that is a flat metal area with a bunch of hoses plugged in man anyone describe or better yet show a picture of where the thermostat housing is?

Thanks!

[Brad B]

Right above the water pump on the front of the engine. 4 hoses go into it.

Its right on top and ez to get to

[Ndawg12]

Should be right here

[rcuadro]

You can always test it by taking it out, putting in a pot of water, and turning on the stove

Then again, if it is failed open, like it seems to be, it will be open when you take it out. You can try and put it in cool water to see if it closes

[Brad B]

Or pay 15.50 for a new one and be done with it for 200-300 hours

[Ndawg12]

You can always test it by taking it out, putting in a pot of water, and turning on the stove

Then again, if it is failed open, like it seems to be, it will be open when you take it out. You can try and put it in cool water to see if it closes

I tried that and mine actually opened and closed. But I put the new one anyways and it fixed my problem. I think it was sticking but I freed it up by manually pulling it open and twisting/spinning the housing around several times. It's not worth all that work to put the old one back in imo, I think they're $15 plus 1 or 2 gaskets.

[jwl019]

Just make sure to test it before installing a new one that it to make sure it works. Put it in a pot of water on the stove and watch a thermometer as it raises to around 160 and you should see it opens. I always tie a string to it and dangle it in the water so that it is just not sitting on the bottom of the pot (not sure if it matters or not).

[rcuadro]

It does matter if it touches the bottom. The metal to metal contact will heat up the thermostat housing and it will open before the water reaches 160 and that may lead you to believe it opens too soon

[bjgreenbucknell]

Sweet. Thanks for the help everyone. Found it and fixed it! Wasn't too bad at all!

Even better I have already even tested the fix and it's working like a charm.

I can't really tell what was wrong but it was pretty messy in there so one guessing something just sort of gummed it up.

Thanks for the help!

[jgates237]

To replace the thermostat do you need to unhook all 6 hoses and take off the the cover that has the Monsoon logo on it? Looking at the picture above it almost seems it can be done without removing either of those items.

Thanks...

Edited June 2, 2013 by jgates237

[wakeparadise]

To replace the thermostat do you need to unhook all 6 hoses and take off the the cover that has the Monsoon logo on it? Looking at the picture above it almost seems it can be done without removing either of those items.

Thanks...

Did you ever get a reply on this? Im at the same place right now...

[wakeparadise]

Found it, you gotta remove those six hoses and the black manifold that has two long bolts, the thermostat sits right in there.

[Fman]

How long should a thermostat last in a marine engine? I am guessing at least five years?

[shagens]

Found it, you gotta remove those six hoses and the black manifold that has two long bolts, the thermostat sits right in there.

I am this same place right now. How did you get those 2 long bolts out? Did you have to remove the cast aluminum cover on the intake?

[Ndawg12]

I am this same place right now. How did you get those 2 long bolts out? Did you have to remove the cast aluminum cover on the intake?

Yes you have to remove the intake plenum, probably 6 allen head bolts on top.

[wakeparadise]

Uhm.... Just use an open crescent wrench... You don't have to remove the cover !!!

[Slayer]

On 8/7/2014 at 3:19 PM, Ndawg12 said:

Yes you have to remove the intake plenum, probably 6 allen head bolts on top.

 

I have to replace the stat on my boat right now.  I was thinking that the plenum had to be removed prior to removing the stat housing.  Even if you could get a socket on it, you'd never get the bolts out without removal of the plenum.

 

Now, since I have yet to do this, do you need to replace the plenum gasket when removing and reinstalling the plenum?

 

On 8/8/2014 at 2:03 PM, wakeparadise said:

Uhm.... Just use an open crescent wrench... You don't have to remove the cover !!!

Yeah....not so much.  There's no room, at least on my boat, in the cut out for the rear 2 bolts on the stat housing.  You can fit an open end, or a crescent wrench on it but there's no room to turn it on the starboard side.  On the port side, the engine lifting ring doesn't allow for rotation of the wrench.  

[blk93jeepzj]

I replaced mine (04 Monsoon) without removing the plenum.  Started with a socket after they were up a bit then switched to an open end wrench. Bolts are long but it can be done, they are only threaded in at the most an inch, iirc.   Plenty of wiggle room.  

[Ndawg12]

3 hours ago, inlandlaker said:

 

I have to replace the stat on my boat right now.  I was thinking that the plenum had to be removed prior to removing the stat housing.  Even if you could get a socket on it, you'd never get the bolts out without removal of the plenum.

 

Now, since I have yet to do this, do you need to replace the plenum gasket when removing and reinstalling the plenum?

 

Yeah....not so much.  There's no room, at least on my boat, in the cut out for the rear 2 bolts on the stat housing.  You can fit an open end, or a crescent wrench on it but there's no room to turn it on the starboard side.  On the port side, the engine lifting ring doesn't allow for rotation of the wrench.  

I've had mine off several times without haviing to replace the gasket.  Mine gasket stays on the plenum.  

[Slayer]

1 minute ago, Ndawg12 said:

I've had mine off several times without haviing to replace the gasket.  Mine gasket stays on the plenum.  

Thanks, @Ndawg12.  I was hoping that's the case.  I ordered one in the event it's needed.