We overheated the engine on the way back into the marina a week ago–the gauge pegged out at 230 and we had to run it in that state for a few minutes until we were safely in the slip. I was mad at myself when we discovered that the cause was low coolant. On saturday morning Jon and I put some coolant in and traced the leak to the gasket under the thermostat housing. A pretty significant leak. So we pulled it off to replace the gasket, and while we were at it we replaced a hose and flushed the coolant system really well (used a commercial coolant system cleaner also). It was gunky and nasty, so getting it clean and fresh was satisfying.
While we were at it we replaced the thermostat. We tested the old and new side by side in a pot of water (heated it till they opened) and noted that the new one reacted much more quickly than the old one. They both seemed to open/close in the same range of ~165 degrees F, though it was interesting to see the range over which they opened more or less, etc.
We used a gasket from Perkins (didn’t make out own) and put Permatex sealant (the purple stuff) on both metal surfaces before installing it
We decided to use propylene glycol instead of ethylene glycol. Ethylene is the normal stuff that everyone uses (same thing in cars), but it happens to be extremely poisonous and bad for the environment. The propylene glycol in comparison is super safe, and can even be discarded safely into the ocean (it is neither toxic nor harmful to marine life). It has similar performance, but I believe it is slightly more expensive. It’s not hard to find–we got ours at Kragen (marketed for RV camping safe-for-children applications).
So far our seal hasn’t leaked, and the engine seems to be running at acceptable temperatures.
Leave a Reply