View Full Version : 2006 Mercury Opti-200 HP-(Thermostats)
I have a 2006 Mercury Optimax (200 hp). I would like to know are there any tips or tricks to changing the two-engine thermostats?
staylor
07-14-2009, 07:39 AM
On most Optis one or both stats will have one of the attach bolts on the stat cover close to- or even under the fuel rails. You can slightly loosen the rail mounting bolts and very very gently lift the rail a small amount. Just lift enough to get the cover off and the stat out. If you go too far in lifting the rail some O-rings will pop out of the rail and things get a bit "messy" to re-assemble. Find the wrench in your box that fits best- and don't be afraid to grind the wrench until it fits right- a new little wrench is a lot less hassle than re- mounting the rails with new o-rings.
Doug
After taking a good look at the Opti. I can see that the fuel rail assembly is in the way of both stat covers/bolts. The fuel rails are attached with two nylock nuts per rail. With the caution that was mentioned about the o-rings. I’m started to think about what I may be getting myself into. It appears as if I were to loosen the nylock nuts, but NOT take them all the way off, this may give me the clearance I need to get the stat covers off and not have a problem with the o-rings. ANY feed back on this issue would be appreciated.
staylor
07-16-2009, 03:07 PM
You're right- if you take them off and lift the o-rings may pop if you do an "Oops- too much". On my 150 I loosened the stat bolts, removed them if I could, then only lifted the rails a little bit at a time until I could sneak the stat out. I used the nuts essentially as a stop and backed them off whenever I needed to lift up a little bit more. I had planned on a 10 minute project but ended up taking two hours. I mentioned this to my dealer's Merc Mechanic and he said he had always done it about the same as me and so far had not had an o-ring pop out. I joked with him that changing the stats was still easier than changing the bottom plug on the port side bank on the Opti.
Doug
Staylor, Thank-you for talking to me about this T-stat issue.
I was able to change the Port-side T-stat yesterday. This was the easy side. As I had to only disconnect a ¼” ID rubber hose, (appox. 4” long.) that was on top of the fuel rail and then turn a 90 degree plastic elbow just a few degree’s in order to make room for a 8mm combination wrench to get the lower T-stat cover bolt off. There was enough room to get the cover off and out of the way and T-stat out without having to move the fuel rail. As far as the Starboard side I will in deed have to loosen the nylock nuts and lift the fuel rail a little in order to change the T-stat. That will have to wait for a new day and a clear-mind.
staylor
07-17-2009, 01:01 PM
....on my 150 Opti I also did the port side first but had to raise the rail only about 1 turn on the nuts. The starboard side was much harder and I was very concerned about popping an o-ring- but it did work out OK.
Doug
The starboard side T-stat has been changed out. As it turned out. All I had to do was, on top of the fuel rail there is an allen bolt that holds down a retaining plate, this plate holds in place an air hose and fuel hose. Once the bolt and plate are removed you just lift the two hoses out. Then the T-stat cover can be removed. The two hoses have an O-ring on them; I put a little bit of lube on them before reinstalling. The job is completed.