Engine Guru's...Need help on Thermostat/housing

[BurnMac42]

So end of last year the boat overheated on our last time out...immediately shut the boat down and took it into the shop...sadly I never got a chance to take it back out but the shop could not replicate the overheat...they ran it both in the Ohio river and in their drop tank in the shop...so fast forward to today and of course what does the boat do the first time out...over heat

I shut it down before any alarms went off and got it back on the trailer....I just took the housing off and boiled the thermostat. I'm guessing it's the thermostat and/or housing. The thermostat didn't open until 190ish (I don't have the most accurate reader however I thought we were suppose to have a 160 right?)

While taking the thermostat out of it's housing I really wonder if it's just time to replace this 16 old housing...you guys tell me but here are some pics today of both the housing and the thermostat...I haven't worked on a ton of marine engines but to me this housing looks like it's just old...

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So the next two show where I was trying to take the thermostat out and that white sleeve or whatever it is was super brittle....not sure if it was part of the thermostat or housing itself?
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Lastly what kind of sealant do I use to put the housing back in place? You can see in some of the pics it has an orange sealant that was used to seal the housing onto the head of the engine....

[UNSTUCK]

Get a new 160* T-stat, a new plastic sleeve, and the gasket with the rivets on it. No need for silicon. Put the housing in a container and fill it with coke or something a bit stronger to clean it all out. Leave the housing in there for a few days. My sleeve had a notch on it so it went in only one way. I'm sure yours is the same way. If you put it in backwards it won't flow any water.
How old is the water pump? Look for the weep hole to be leaking water. My old boat got hot a few times last summer. I replaced both of these this spring. First time out it never got hot. I think these fixed my issue.

[BurnMac42]

I honestly have no clue how old the water pump is...I might have to replace that if the new thermostat doesn't fix it....I'll buy some coke and soak the housing to clean it out and hope that fixes the problem....

So the silicon shouldn't have been used to install the housing?

[chpthril]

take the sensors out before dipping. I would pick/scrap away all the rust from the ports as I could and then reexamine.

[BurnMac42]

take the sensors out before dipping. I would pick/scrap away all the rust from the ports as I could and then reexamine.

Yep....good point...

So just to be clear when I reinstall I shouldn't use sealant?

Also do you guys buy marine thermostats or just go to auto zone and grab a 160 degree thermostat off the shelf?

[chpthril]

I like a thin film of RTV on both sides of paper gasket for water jackets. Fills in the normal pits you see in steel pieces.

[BurnMac42]

I like a thin film of RTV on both sides of paper gasket for water jackets. Fills in the normal pits you see in steel pieces.

Sounds good I'll grab some RTV as well. You wouldn't happen to know the torque spec on the bolts for the housing would you?

If this doesn't work I'm dropping it off at my mechanic...The frustrating part about it is, they ran it in the river back in the fall, and then dropped it in their dunk tank in the spring to double check and make sure everything was kosher and unless they are flat out lying, the boat didn't over heat either time they ran it but the last two times I have taken it out it has.....

Would the water pump be the next logical piece to examine?

[BurnMac42]

Well, my schedule just changed again so I'm just towing the thing back down to my mechanic and having them deal with it while I'm gone the next week and a half. They are going to also check and make sure the impeller didn't implode, the water pump is gtg, and run a compression test just to make sure the head gasket isn't the culprit.....

[BurnMac42]

Figured I would update to close the thread. Shop took a look, pressure tested all possible systems and determined the block was bad so I'm actually getting a new crate motor under warranty. Not a bad deal but sucks my entire month of June is shot

It's really got me thinking about pulling the trigger on a new R20 or 21

[TeamAllen]

Glad they figured it out and sorry to hear the solution is so extreme.
Water time is valuable, if you can swing the purchase of a new one sounds like a better direction.

[BurnMac42]

Glad they figured it out and sorry to hear the solution is so extreme.
Water time is valuable, if you can swing the purchase of a new one sounds like a better direction.

Well from my understanding I should only be a few hundred bucks out of pocket for the engine which is obviously a "dodged bullet" but I won't lie a small part of me will be nervous every time I drop this thing into the water....

The turn key option w/ 5 yr warranty is enticing on the new ones...I just don't think the wife can stomach the cost without a decent chunk down and sadly, we just put most of our none investment cash into the down payment on the house we built this year....I'm considering putting the boat up for sale asap to see if I get any serious bites...I might bite the bullet if I do....I want to run the engine thru its break in period asap so the shop can do the 10 hr inspection and confirm that it's a solid motor before selling it...it will be tight because mid-July is bumping into the market softening for Ohio but I want ot make sure I'm selling a solid boat to someone...