Stuck thermostats

[ReelDrag]

Just started my motor after sitting for 3 months and the t-stats are not opening. I shut it down before the alarm went off. It does this everytime I let it sit for more than a month. Usually I can hear the t-stats pop open after I shut it off and it sits about 10 mins. I replaced them in Nov. when I put it away for the winter. I've tried the stainless ones as well as the brass ones, oem and aftermarket, same problem. It's a 92 Johnson 115 crossflow with 57hrs on a rebuild. Anyone have an idea what's wrong here?

 

[angus63]

Re: Stuck thermostats

Had a 1964 Rambler Classic with a similar problem. Turned out the thermostat could be put in upside down and I did that. Sometimes it would open, sometimes it became old faithful. Drove me nuts till I figured it out. Just a thought....

 

[ReelDrag]

Re: Stuck thermostats

Thanks, but they are in correctly. Since I first posted I went out and started it again. Still overheating, but I noticed the pee stream looked like it had air mixed with it, kind of spurting out, not a steady stream. I pulled the lower unit, pump looks ok, impeller has taken a set, (vanes aren't sticking straight out). The plate under it is smooth, no grooves. I'm putting a kit in it now. Hope that solves the problem.

 

[rodbolt]

Re: Stuck thermostats

hello<br /> its a common problem with the crossflow engines. try using a dremel and addint the vent to the poppet. the new stainless t-stats have no way to allow water to get past them. you may also try opening up the vent hole in the phenolic t-stat housing to 1/8 or 3/32's. I use the sierra t-stats in jonny/rudes and mercs cause they still have the self flushing poppet with a steam vent ( mercs and aqua powers dont) and open the vent holes up some. sand here is bad about clogging them. they will run fine but the hose will have cold water in it while the powerhead overheats. if water cant escape the t-stats it will stay cold while the heads over heat. heat rises.<br /> good luck and check those areas

 

[ReelDrag]

Re: Stuck thermostats

Thanks Rodbolt, but you've kind of lost me here. Are you talking about the center of the t-stat being the poppet? I don't have the stainless ones in now. The ones in there now are aqua power. Also after looking at the metal housing the impeller lives in I noticed the hole for the drive shaft isn't round anymore and it's cutting a groove in the shaft. Is this normal?

 

[rodbolt]

Re: Stuck thermostats

hello<br /> nope thats abnormal. some of the later 2 piece shafts will do it when the imperrer wears out but the old 1 piece should not. yours may have been updated.yes the poppet is the center piece on the OMC factory t-stats. the junk style AP ones that the valve pulled in towards the t-stat body were terrible. good for my business though . OMC had some real nice brass ones worked graet had a steam vent . the poppet opened away from the body so it was self flushing. then came the stainless steelies. junk again. the poppet fits so tight that no water can get past.<br /> if water cannot get past either from the housing vent or the t-stat vents the complaint is as follows. first thing in the mornin she overheats, shut it down for a few min then restart and she runs great.<br /> if when it overheats that first time immediatly feel the t-stat housing and you will see its cold. no water can flow.<br /> heat rises. it takes a few min for the hot water in the heads to open the t-stats after sitting a bit.<br /> does that help the confusion <br /> good luck and keep posting

 

[ReelDrag]

Re: Stuck thermostats

Thats exactly what my motor was doing. Anyway, I removed t-stats and cut a small groove in the poppet, opened up the hole in the housing to 1/8 in. I'll put it back together tomorrow with a new pump kit. Is that groove in the drive shaft going to give me problems in the future? Thanks for your help Rodbolt.

 

[ReelDrag]

Re: Stuck thermostats

Everything's back together and working fine. Just wondered what could be causing the groove in the drive shaft. Maybe aftermarket impeller housing off center a little??