Fishermark
Vice Admiral
- Joined
- Oct 19, 2003
- Messages
- 5,617
I have a curious problem. First, a little background: I took the family out on the boat on New Years Eve, and as we were idling away from the ramp I noticed the engine was running hot - close to 200 degree! 
<br /><br />I shut it down and opened the hatch. (I have a 5.7 liter Mercruiser crate engine with a raw water pump attached and thru hull pick up. Engine serial number is OM657558.) Anyway, I started it back up and saw that water was being pulled in okay, it evidently wasn't flowing through the engine. I figured it was a stuck thermostat. I tapped on the housing a couple of times and the temperature suddenly and quickly went back to normal. We continued boating for the day and came home.<br /><br />Today I pulled the thermostat housing to replace the thermostat and SURPRISE I found four pieces of rubber in the inlet side of the housing. See pictures below.<br /><br />Here's what I saw when I removed the housing:
<br /><br /><br />Here's what I pulled out of the housing:<br /><br />
<br /><br /><br />QUESTIONS:<br /><br />1. Can I assume that those little pieces of rubber strips are from my raw water impeller? (Don, I know you don't like assumptions, but that is really the only likely candidate isn't it?)<br /><br />2. This engine is only two and a half years old with only 146 hours on it and has never been run dry. Isn't that uncommon for an impeller to go bad that quickly?<br /><br />3. The pieces would have had to travel through the power steering oil cooler. Is that a straight shot? In other words, how likely is it that there are other pieces still "downstream?" I only found four pieces. When I remove the pump I will see how many there should be.<br /><br />4. I have replaced the impeller in the lower unit before, (Alpha 1), but not the raw water pump on the engine. The impeller CAN be replaced without buying a whole new pump, right? (Before anyone asks, I have an Alpha 1, Gen 1, and yes, there is an impeller in the lower unit. It is simply routed back through the transom. My engine is set up for a thru hull pick up with the engine mounted raw water pump).<br /><br />Any help is appreciated!
<br /><br />I shut it down and opened the hatch. (I have a 5.7 liter Mercruiser crate engine with a raw water pump attached and thru hull pick up. Engine serial number is OM657558.) Anyway, I started it back up and saw that water was being pulled in okay, it evidently wasn't flowing through the engine. I figured it was a stuck thermostat. I tapped on the housing a couple of times and the temperature suddenly and quickly went back to normal. We continued boating for the day and came home.<br /><br />Today I pulled the thermostat housing to replace the thermostat and SURPRISE I found four pieces of rubber in the inlet side of the housing. See pictures below.<br /><br />Here's what I saw when I removed the housing:
but that is really the only likely candidate isn't it?)<br /><br />2. This engine is only two and a half years old with only 146 hours on it and has never been run dry. Isn't that uncommon for an impeller to go bad that quickly?<br /><br />3. The pieces would have had to travel through the power steering oil cooler. Is that a straight shot? In other words, how likely is it that there are other pieces still "downstream?" I only found four pieces. When I remove the pump I will see how many there should be.<br /><br />4. I have replaced the impeller in the lower unit before, (Alpha 1), but not the raw water pump on the engine. The impeller CAN be replaced without buying a whole new pump, right? (Before anyone asks, I have an Alpha 1, Gen 1, and yes, there is an impeller in the lower unit. It is simply routed back through the transom. My engine is set up for a thru hull pick up with the engine mounted raw water pump).<br /><br />Any help is appreciated!
