Mercury 2.4l thermostat question

**Partonjoshua** · 03-14-2019, 07:44 PM

Hey guys i have an 89 2.4l mariner 175. Just replaced poppet valve and water pump for a on plane overheating issue which fixed the problem. Issue now is it does not want to get up to temp at idle. I pulled the thermostats and they seem to be working properly, open at around 140 and close around 115. I have noticed water coming out of the telltale immidiatly after starting, so is water supposed to be able to get past the thermostats before they open? I checked them and did not see any debris clogging them, but if i pop off the hoses coming from the housing there is still water flow before they open. Are they supposed to be water tight or do they always allow a bit of water past them? Ordered a new set, just want to hear what you guys think thanks.

**Motv18** · 03-15-2019, 12:21 AM

Pee can be befor the stats.

Popets might be stuck open.

Assuming your useing temp gauge : with a good system not getting to 140 is normal. If reveling in neutral to start. the popets open , and if you run over 6psi at idle they might not close back up.

**Partonjoshua** · 03-15-2019, 12:56 AM

Originally Posted by Motv18

Pee can be befor the stats.

Popets might be stuck open.

Assuming your useing temp gauge : with a good system not getting to 140 is normal. If reveling in neutral to start. the popets open , and if you run over 6psi at idle they might not close back up.

Thanks for the reply, just replaced the poppet valve. At idle there is no water coming from the hose coming from the bottom port side of the block which is where i assume the poppet valve controls, right. The water is coming from the outlet on both thermostat housings. New water pressure gauge should be here tommorrow so that should help me narrow it down. I was just worried about cold seizing the motor, that would suck right after rebuilding it.

**FORBESAUTO** · 03-15-2019, 05:22 AM

The stats seal pretty good, you may get s little trickle of water out of them closed, but not much flow at all.

**Partonjoshua** · 03-15-2019, 05:37 AM

Originally Posted by FORBESAUTO

The stats seal pretty good, you may get s little trickle of water out of them closed, but not much flow at all.

Gotcha, thanks i ordered new thermostats and seals, should be here in a couple days. I'll slap those in and see what happens

**Motv18** · 03-15-2019, 10:19 AM

Trying to run the route in my head.

piston height on the thermostat is probably off spec that would allow water through.

**Partonjoshua** · 03-15-2019, 11:49 AM

Originally Posted by Motv18

Trying to run the route in my head.

piston height on the thermostat is probably off spec that would allow water through.

Im thinking it probaly is, the thermostats look like they close all the way, but i can easily blow air through the top of the thermo past the seated valve/piston. I bought a different stlye thermostat. The ones installed now look like an automove thermo where the piston moves down in the middle of the body, the new ones ordered the piston moves up above the top of the thermostat.