1996 3.0LX Mercruiser Thermostat & Housing question

[AquaholicMike]

Hey guys, problem started with the temp gauge not working. The gauge itself checked out so I bought a new temp send sensor, installed it, overtightened it putting it in and cracked the housing. Before It started leaking too bad I ran the engine but the gauge didn't move. Not sure if I looked at it close enough to know if it moved at all or was just running very low temp. I'm thinking maybe the thermostat needed replacing too. Anyway, bought new housing kit #861493A3. Couple questions, first there seems to be an extra port on the new housing. It's on the right side under the inlet fitting. The other two ports on the front (temp send and audio warning switch) are the same. I'm assuming I just plug this? Maybe it's the new drain fitting? Second question is the thermostat it came with is a 160 degree. The service manual I looked at listed two, one was a bronze 143 and a stainless 160? Is the 160 good for this engine or should I get a 143? I've attached some pics of the old (still on the boat) and new housing. btw, you'll probably notice in the pics, I plugged up the old temp send port and used JB weld so I could get the boat out on the water and it held up just fine with no leaks. Engine serial #0F758125 if that helps. Thanks

 

[Bt Doctur]

Re: 1996 3.0LX Mercruiser Thermostat & Housing question

Did you test the wiring also or just the gauge. With the key in the "on" position,ground the wire from the sending unit. gauge should peg .
When installing a new sendr DO NOT USE TEFLON TAPE, sender must be grounded to operate properly.

 

[alldodge]

Re: 1996 3.0LX Mercruiser Thermostat & Housing question

Hey guys, problem started with the temp gauge not working. The gauge itself checked out so I bought a new temp send sensor, installed it, overtightened it putting it in and cracked the housing. Before It started leaking too bad I ran the engine but the gauge didn't move. Not sure if I looked at it close enough to know if it moved at all or was just running very low temp. I'm thinking maybe the thermostat needed replacing too. Anyway, bought new housing kit #861493A3. Couple questions, first there seems to be an extra port on the new housing. It's on the right side under the inlet fitting. The other two ports on the front (temp send and audio warning switch) are the same. I'm assuming I just plug this? Maybe it's the new drain fitting? Second question is the thermostat it came with is a 160 degree. The service manual I looked at listed two, one was a bronze 143 and a stainless 160? Is the 160 good for this engine or should I get a 143? I've attached some pics of the old (still on the boat) and new housing. btw, you'll probably notice in the pics, I plugged up the old temp send port and used JB weld so I could get the boat out on the water and it held up just fine with no leaks. Engine serial #0F758125 if that helps. Thanks
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:welcome: to iboats

You have a carb so the 140 thermostat should be used. The 160 is for fuel injected engines. Just use brass plugs to close up the ports not needed. The extra ports are for other models which need them

 

[AquaholicMike]

Re: 1996 3.0LX Mercruiser Thermostat & Housing question

I did ground the wire at the sender with the key on and the gauge pegged.

Thanks for the info on the stat. I was thinking it should be the 140.

 

[AquaholicMike]

Re: 1996 3.0LX Mercruiser Thermostat & Housing question

fyi...I just pulled the old thermostat out and it was stuck open. It was a 140. Can you buy these at an auto parts store? If so how do you cross reference? Also, should I use a thread sealant on the temp send? It came with some sort of sealant on it but I think it's gone now after I put it in and took it out. Thanks again.

 

[alldodge]

Re: 1996 3.0LX Mercruiser Thermostat & Housing question

It is a standard GM 140 degree thermostat. Take the old one in with you and they should be able to pull one off the shelf. The compound on the threads is usually just pipe dope (thread lubricate). Don't bother with putting any back on it, just snug it, don't put a lot of mussel in it. There is next to no pressure, and it it does leak it won't be much (and probably won't), but if so just give it another 1/4 turn.

 

[AquaholicMike]

Re: 1996 3.0LX Mercruiser Thermostat & Housing question

Yea, I've learned the lesson on too much mussel! thanks I'll try the parts store later.

 

[Fun Times]

Re: 1996 3.0LX Mercruiser Thermostat & Housing question

Your best bet is to find a Napa auto store as they usually have aftermarket marine parts like sierra marine part # 18-3650. Especially if you run in the salt being in Florida.

http://www.iboats.com/Thermostat-Kit-Sierra/dm/view_id.172864

 

[AquaholicMike]

Re: 1996 3.0LX Mercruiser Thermostat & Housing question

FYI, in case anyone else goes through this, the original thermostat is much smaller diameter. The correct part # for the new housing is 807252-1 (Sierra #18-3551) the one that came with it is 807252-2 (160). I checked Napa but it was actually less at West Marine.

 

[AquaholicMike]

Re: 1996 3.0LX Mercruiser Thermostat & Housing question

Problem solved, installed new housing, thermostat, and sender. Ran the boat all day yesterday, no leaks and temp stayed pretty constant between 140 and 150. Thanks for the help guys.