Sierra Thermostat Life?

[tank1949]

I replaced my thermostats last summer in both of my 1994 MC Alpha 1 Gen 2 350 V8s. They were Serra raw water stats and supposed to break at about 142. I got very little boating due to other problems. A month ago one motor's temperature alarm went off at about 220, and yesterday the second motors went off. I have removed the stats. Is replacement a yearly maintenance requirement? The short life seems to be odd?

I would suspect to get at least two seasons and maybe four out of them. I flush with fresh water after each usage and trailer boat.

 

[Bondo]

Re: Sierra Thermostat Life?

Ayuh,.... When were the Impellers last done,..??

 

[tank1949]

Re: Sierra Thermostat Life?

Motors have less than 50 hrs on each, according to meter. Former owner replaced port impeller at about 25 hrs due to screwing up and not noticing muffs that had fallen off. I have had major problems with getting this boat sea worthy. Motors are all but new. I don't know life expectence on impellers. They have not been abused in sand/water. THX!!!

 

[Lou C]

Re: Sierra Thermostat Life?

Are you in salt water?
I've found that even with OE stats, I get about a year to a year and a half before they start sticking open slightly which causes the opposite problem...running too cool, like 100-120*. I wind up putting in a new one at the start of each season so I don't have to fiddle with it during boating time. Never had one stick closed and cause an over heat. Did you test the stats and see if they open and close properly?

 

[thumpar]

Re: Sierra Thermostat Life?

Put the stat in a pot of boiling water and see if it opens. I bet it does and you have impeller or blockage issues.

 

[alldodge]

Re: Sierra Thermostat Life?

Motors have less than 50 hrs on each, according to meter. Former owner replaced port impeller at about 25 hrs due to screwing up and not noticing muffs that had fallen off. I have had major problems with getting this boat sea worthy. Motors are all but new. I don't know life expectence on impellers. They have not been abused in sand/water. THX!!!

I would suggest pulling the hose going to the power steering coolers and have a look. Could be some crud or left over pieces of the impeller. Back flush from the thermostat to the PS cooler.

 

[tank1949]

Re: Sierra Thermostat Life?

PS on stb side. Motors have not been used hardly at all and risers and block seemed cool. Sent first tats back to Sierra after my digital thermomenter indicated that the stats were opening at 160+. Sierra contacted me and sia that they had examined 142 stats an thet they were OK. Sent me new ones. Hum? Back to drawing board, sometime after Christmas????????

 

[tazrig]

Re: Sierra Thermostat Life?

Tank, Impellers should be replaced every other year even if the boat isn't used at all or at 300 hours whichever comes first. If you don't you're looking for trouble.

 

[Fun Times]

Re: Sierra Thermostat Life?

I have removed the stats.

Since you have removed the thermostats, are the engines not overheating now?

 

[tank1949]

Re: Sierra Thermostat Life?

Impeller or impeller kit?

 

[Bondo]

Re: Sierra Thermostat Life?

Impeller or impeller kit?

Ayuh,... Go for the Kit, it's got the gaskets, 'n stuff,...

 

[tank1949]

Re: Sierra Thermostat Life?

Removed one then overheating went away.. Have not removed one last tested. After Christmas job.