On my Smart craft gague when I start the motor (250 Pro XS) the Engine temp reads around 90 degrees & after several minutes at idle its reading the same temp. When I get on plane the temp will rise to around 111 to 115 degrees. I know or feel that the thermostats are stuck closed. My question is how hard is it to get to them and replace then or clean them up? Do I need to replace the gaskets or not if they are not torn or rip. Thanks for any advise - Glenn
When Don comes along, he'll ask for engine serial number. Also would be useful to know water pressure at idle and how much flow from the tell-tale.
Based on what I've read on this forum, I would not use the motor again until confirming what the problem is. If the motor is run before being sufficiently warm (90 is WAY below expected warmup temp reading) you risk catastrophic engine damage. Read
http://www.bbcboards.net/zerothread?id=25496
There are possibilities other than t-stats - Don will recommend how to diagnosis and fix.
So many honey-dos . . . . . so little motivation
My guess would be stuck open or debris is hung up in one.
<table width="90%" cellspacing=0 cellpadding=0 align=center><tr><td>Quote, originally posted by Coldheart »</td></tr><tr><td class="quote">My guess would be stuck open or debris is hung up in one.
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My first thought, too. BTW, best practivce is to replace the gaskets every time. They don't cost much.
So many honey-dos . . . . . so little motivation
Glenn:
You will need to have two (2) 8503181 gaskets ON HAND when you remove thermostats for inspection.
ANYTHING that holds the pintle off it's seat (even so much as a grain of sand) can result in cool engine temps at idle.
DO NOT accelerate your engine if it does not reach operating temps (120+ degrees).
You'll need to address this IMMEDIATELY.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Don:
On my 250 proxs the fuel rail is in the way to remove the starboard Tstat. Looks like two bolts hold it on. Does this just pull off when I remove the two nuts???
Cary Seekins
201 XLE, 250 Pro XS
Yes, it does.
However... you NEED to relieve the AIR PRESSURE prior to loosening the rail. Air pressure is relieved at the schrader valve on the PORT SIDE fuel rail.
Before reinstalling the rail- lubricate the o-rings for the direct injectors LIBERALLY with 2-stroke oil.
Rail must be installed squarely (and carefully) to prevent damage to Direct Injectors (or their o-rings).
Thermostat cover bolt torque: 100 INCH (yes that's INCH) lbs.
Rail retaining nut torque: 35 FT. LBS.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Thanks for all the information about the thermostats for the motor. I have ran the motor in excess of 50 miles with the thermostats being stuck. I notice this late last week, I don't think there is anything hurt with the motor.
I took the nuts off the fuel rails & pull the rails back just enough to get to the housing for the thermostats. Took the bolts out and pull out the thermostats. Both of them had small pieces of stems in them. I remove the debris and replaced everything to include new gaskets.
Put the boat in the lake, fired her up, no leaks, & water temp went up to 120+ at idle. Shut her down, put her in the garage, going out tomorrow.
Thanks again - Glenn
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