Looking for Thermostat in pieces in a 3.0 L Mercruiser

[eavega]

So, While I was waiting for some other parts to arrive, I decided to look into another "when I get time" items on my boat. My temp gauge never seemed to move much beyond 120 degrees (I've owned the boat for less than a year, and have had it out about 5 times since I bought it last August). I check the gauge (working), replaced the temp sender (working, but not within spec), and still temperature would not come up above 120 degrees. Since it was not overheating I didn't think much of it. Well, yesterday I got curious and decided while I had some down time I would check the state of the thermostat. When I opened the t-stat cover, I found the thermostat in pieces. The top part of it was lodged in the opening to the water circulating pump(luckily it did not block the water tube), the middle part of it was still in the seat, and the spring had fallen down but was visible (so I fished it out). As to the rest of the thermostat, I have no idea where it might be. I know there has to at least be a piece of metal that would hold the spring in place, probably some odd bits and pieces after that. My questions is, where would the rest of the thermostat be? Seeing as the main body of the thermostat was still in the seat, I would assume that whatever held the spring in place didn't make it past the thermostat housing and into the water pump, and perhaps worked its way down into the engine block and cylinder head? I'm looking at the water flow diagram in the #10 manual, and the water flow diagram shows that water comes in on the right side of the thermostat housing, and passes to the left to the circulating pump, then water returns from the block and head into the thermostat housing and is either recirculated or proceeds out the exhaust manifold. If something had come off of the thermostat, It would stay behind the t-stat body on the block/head side, but could fall back into that passage when there was no water pressure coming from the head/block. Is this something I should worry about, or only worry about it if I start noticing the motor running warm somewhere. My concern would be that something has blocked a cooling passage somewhere in the bowels of the motor, and while the temp sender would not indicate an increase in temperature, some part of the motor would be lacking cooling water. Any suggestions or observations?

In case it matters, the motor is a 1988 3.0 L Mercruiser SN 0B922590

Rgds

 

[alldodge]

Re: Looking for Thermostat in pieces in a 3.0 L Mercruiser

As you say the pieces could b anywhere. Most items would wind up in the block or in the power steering cooler (if you have one). My only thought would be to pull some hoses off and the outdrive. Other then that just hope the pieces are small enough to not cause an issue. Only other way as I'm sure you know would be to take the engine apart. If it where mine I wouldjust hav fun and keep and eye on lookout. Good luck