Manual didn't say it was plastic...

[Mark42]

Thought I would check to see if there was a thermostat in my 93 40hp motor. Put a wrench on the thermostat cover and it promptly snapped off. Not the wrench, the hex head on the cover. I could not believe it was PLASTIC! On a head no less. Lucky for me it is thick, and I epoxied the piece back on just to prevent any possable water leak I may have caused. Now I have to order a new piece, figure out how to get off the old one, and get new thermostat just to be safe.<br /><br />So how do you get those old plastic thermostat covers off without breaking them?

 

[russeller]

Re: Manual didn't say it was plastic...

i will take a guess you could drill, maybe heat to melt it not to sure about that one but i will say drill with a small bit and get a pick in there and kind of break it apart

 

[Richard Petersen]

Re: Manual didn't say it was plastic...

Time to call the company for Technical Support.

 

[Fl_Richard]

Re: Manual didn't say it was plastic...

My 150's have plastic covers too. I've broken them several times by over torqueing them when replacing thermostats. Just use a screwdriver and gently tap counter clockwise and the center piece will slowly un thread. new ones cost about $15.00 for my motor. It's no the end of the world, just dont over tighten them

 

[Walker]

Re: Manual didn't say it was plastic...

They seal on the outer surface with rubber o-rings. No need to torque them down very tight.

 

[Fl_Richard]

Re: Manual didn't say it was plastic...

Yea, I've found this out... the hard way. I had four thermostats to replace. I bought the kits, installed no problem. <br />Over the course of a month or so two different covers snapped off. Man am I glad I throw good-old parts in a small box onboard.<br /><br />I didnt think I over torqued them. Now I know. Regardless they come out really easily when busted

 

[Mark42]

Re: Manual didn't say it was plastic...

Thanks for the info. I'll be picking up the new cover Monday. Hope installing it goes smooth.

 

[Dhadley]

Re: Manual didn't say it was plastic...

Now you know why its a good idea to lightly grease the threads and, like Wlaker said, dont over tighten them.

 

[Mark42]

Re: Manual didn't say it was plastic...

Thought I would update this thread. I went to install the new cover. Had to remove the old one, so I tried a pipe wrench on the cover thinking it would grip and the cover would come off. WRONG! The cover was on tight. Pieces broke off every time I tried the pipe wrench. I finally got a small cold chisel and started chipping away at it. Darned thing is a very thick casting and flakes away, doesn't break off in big pieces. So I get the whole top removed exposing the thermostat and leaving the threaded part in the head. I remove the thermostat and start working with a sharpened awl. What a pain. Flicking tiny pieces of black plastic away trying not to mess up the aluminum threads. I finally get it all worked out, then clean with a wire brush, then parts cleaner. I did notice that it looked like it was assembled with white 3M 5200. I could shoot that idiot. Manual says to use gasket sealer on the threads. I think I'll just use the o-ring and some teflon tape on the threads and leave well enough alone. <br /><br />Now that temperature sender under a plastic cover looks like it hasn't been out in a while.....

 

[Dhadley]

Re: Manual didn't say it was plastic...

I wouldnt use teflon tape either. We dont use gasket sealer either even though thats what is on it from the factory. Like I said, grease is the product of choice and a light hand on the wrench for tightening. Think about what Walker is saying. They dont rely on a tight thread fit to seal. Thats what the O rings are for.

 

[CATransplant]

Re: Manual didn't say it was plastic...

I hate plastic engine parts. All plastic engine parts. It cost me over $300 once to replace a stupid plastic elbow on a Dodge van. It was for the heater bypass hose...buried under a mountain of junk that all had to be removed. Cracked at the top of the threads.<br /><br />Yeah, it cost Chrysler Corp. 10 cents less to use that plastic junk, than to use a proper metal fitting. It cost me $300 more. <br /><br />Plastic, of whatever type, has no place on an engine. Heat and vibration will eventually take their toll on it and, as happened here, overtightening will make it impossible to remove later.<br /><br />I like the nice aluminum casting that is the thermostat cover on my ancient Johnson. Three screws and it pops right off. It'll outlive the engine, me, and probably still be usable 100 years from now if someone finds the outboard in a scrap heap.<br /><br />Of course, it would cost a buck or two to make now. The plastic one only costs half that much. The customer pays later.

 

[Mark42]

Re: Manual didn't say it was plastic...

Ok guys, seeing as I haven't assembled it yet, I'll take your advice and use a little Trippleguard grease, a fresh o-ring and just snug it down.<br /><br />Thanks!