thermostat cover on 9.9 johnson

bquick8

Seaman
Joined
Sep 7, 2002
Messages
59
what's the trick to remove the thermostat cover on a 1985 9.9.I've taken out all the bolts and the cover is loose from the head.problem is there's only 5/32" between the cover and the engine cover lower latch bolt.Not enough clearance to pull it back and clear the spring and thermostat.What am I missing?How do you get that lower latch bolt loose and out of the way enough to remove the water cover?
 

OBJ

Supreme Mariner
Joined
Dec 27, 2002
Messages
10,161
Re: thermostat cover on 9.9 johnson

The trick is to take the cover latch off. It's tight I know but the alternative is pulling the power head. Once the cover latch is off, pull the cover off with the bottom retaining bolt with it and put it back together the same way. It's not best of jobs to do but it's doable...
 

bquick8

Seaman
Joined
Sep 7, 2002
Messages
59
Re: thermostat cover on 9.9 johnson

I planned to pop the cylinder head after I check the condition of the thermostat.Is it possible to do that with the water cover and thermo attached and still clear the rear latch?There's one bottom headbolt that could be a problem.Thanks for the help OBJ
 

OBJ

Supreme Mariner
Joined
Dec 27, 2002
Messages
10,161
Re: thermostat cover on 9.9 johnson

Yeah, the one head bolt can be tricky to torque...<br /><br />The head and T-stat cover will come right off...no problem. Some guys will do just that instead of fighting the latch.....really it's the easy way.....by the by....in my first post I stated that the alternative was to pull the power head....meant just the head....sorry bout that...... :) :)
 

Xcusme

Commander
Joined
Apr 21, 2003
Messages
2,888
Re: thermostat cover on 9.9 johnson

The last one I did, I just pulled the head. Things are a bit tight in there. The only complication I had was the thermostat cover had a hole in it from wearing against a loose latch bolt.
 

BaitThrower

Petty Officer 2nd Class
Joined
Jul 17, 2008
Messages
112
Re: thermostat cover on 9.9 johnson

Hi folks,

I have the same problem on the '86 15hp johnson which I believe is essentially the same motor. Couldnt even get enough clearance from the thermostat cover to get the latch bolt out so hopefully taking the cylinder head off will do the trick. I tried getting the water jacket off to access the thermostat but just not enough clearance. I did managed to peak down inside and looks like there was a lot of built up crap around it. My engine is overheating so I'm assuming its thermostat issue as I have good solid water flow otherwise from the telltale.
 

BaitThrower

Petty Officer 2nd Class
Joined
Jul 17, 2008
Messages
112
Re: thermostat cover on 9.9 johnson

As an update, I had problems with removing the latch completely as the latch bolt couldnt be removed with the thermostat cover and head getting in the way. I got the head off and the thermostat cover and took a look. Yep thermostat quite cruddy and a neoprene seal or bit of rubber lodged in there too. Out with the old, in with a new thermostat and seal.

Again the problem was going to be tool clearance for the bottom head bolts when getting them back on. I can't find any tool that would really do this... maybe one of those through socket wrenches, but that might even be tight. I have found a solution to tighten the bottom two bolts, and adding it here for future reference.

I took a 1/2" socket that has a 1/4"hex shaft, i.e. a socket designed to be chucked in a drill. I reduced the hex shaft length so it would fit inside the outboard lower cover but still have the shaft project out enough past the plane of the thermo cover so I could attach a 1/4" spanner. I purchased a high quality Sidchrome 1/4" ring spanner, making sure it fit the hex shaft of the socket bit firmly... this is key to be able to apply enought torque to the bolt head. You dont want a loose fit on the hex shaft or else it will just slip, or a poor quality ring spanner will just strip... Anyway use the ring spanner on the sockets hex shaft to tighten up the bolts. Works really well!

For those not familiar, there is not enough room around the head of the bolt for a ring spanner to be attached directly to the bolt, or the head of any 1/2"spanner for that matter.

Anyway hope that helps any future readers who have a similar problem.
 
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