Hi,
Here is my story...
I have a late model A4 that is raw ater cooled, the season prior (2008) we developed an overheating problem which I thought was due to a plugged raw water strainer as it was late in the season... this came to light in an initial event that was a bit scary becuase the engine severely overhead to the point of burning off excess fogging oil 200+ degrees (causing us to shut off the engine ASAP and briefly freak out at the possability of fire--- very unsettleing--- not to mention at the high temp the engine did not want to turn off even with teh key out.... why is that?). As I went about the engine compartment I found a fairly full strainer dumped it... let the engine cool for a couple hours and sailed slowly back to our mooring. After the night of cooling and the cleared strainer the engine got up and running no problem. Seemed like problm solved... I bought the MMI oil and temp alarm kit... needed some piece of mind...
Last season (2009), as I was opening up the engine with the usual MMO in teh cylinders etc. I got her to turn over but she ran real rough for about 15 seconds... scratchy metal sound... then a crazy bang... and I immediatly shut the engine off. Thinking i had just snapped a valve or something I petitioned the devine and we went at it one last time... started up and sounded fine. Odd.
Throughout the 2009 season I noticed an oil drip from where the circular plate attached to the prop shaft enters the reverse gear housinig box. I believe I have a direct drive 1:1... if it matters. Wast this teh cource of my bang???
Well this post is about cooling... all the above is connected to this issue... maybe...
So on my way to pull out the boat ending the 2009 season we got caught by the tide and wind and had to motor some 4 hours. About 1-2 hours in the heat alarm went off... thinking of the strainer i said easy fix... there was some crud so I dumped it... the boat started, temp dropped, along we went. As we approached the drawbridge with a 3kt exiting tide coming straight at us we needed to throttle up, again the alarm goes off... so we circle around... I dump the strainier and blow through the lines, check seacock for ample waterflow. Again start the engine, temp dropped and through the bridge we go... just through the bridge the alarm sounds... explatives as the temp rises and the current is trying to push us back into the now closed bridge. Our only hope is fighting the tide to an open slip at a marina up ahead, engine required current now 4kts. Thankfully we make it to the slip under power. Shut down engine and furiously thumb through my MMI rebiuld manual on board... we figure out we have a gummed up thermostat, cool... but no spare... after fiddeling around we decide to let the engine cool a bit and just remove the thermostat entirely for the last leg of our journey... this way water will just dump through the header and I can replace over the winter.
Everything appears fine, we start up and head up river... feels like a victory and an answer to the previous year's over heating... junk thermostat... maybe, maybe not...
We go about 1-2 miles up river and suddenly this steam engine sound emerges from the engine compartment and there appears to be somewhat a loss of power. I open the door to find a rythmic exhaust smelling steam powering out from an area beneath the thermostat cover (remember I removed my thermostat and did my best to crank down the housing with a pair of pliers to get us home). We had no choice but to keep on... was this the result of a missing thermostat like a bad gasket or an actual crack in the header?
My boat under power typically does 5.5 kts under full power with no wind. We we headed into 5 ft seas and 30 MPH winds. Under full power we had barely 1 kt on the GPS. After a few hours me had made enought progress to get out of the wind and the tide had become slack. We made it home but now my big question is...
Why do I have exhaust pressuring out of a space between my thermostat housing and the header, and why does this result ina loss of power? Did the crash bang at the begining of the season indicate somthing that woudl cause the oil leak or somthing that would cause exhaust to leak into the coolant chamber? HELP!
Just FYI at the begining of 2008 I tested pressure on all cylinders and they were up over 90psi and shes never had a rebiuld, I haven't tested since the crash bang but there was no detectable power loss until I removed the thermostat.
Thanks for any and all ideas!
Here is my story...
I have a late model A4 that is raw ater cooled, the season prior (2008) we developed an overheating problem which I thought was due to a plugged raw water strainer as it was late in the season... this came to light in an initial event that was a bit scary becuase the engine severely overhead to the point of burning off excess fogging oil 200+ degrees (causing us to shut off the engine ASAP and briefly freak out at the possability of fire--- very unsettleing--- not to mention at the high temp the engine did not want to turn off even with teh key out.... why is that?). As I went about the engine compartment I found a fairly full strainer dumped it... let the engine cool for a couple hours and sailed slowly back to our mooring. After the night of cooling and the cleared strainer the engine got up and running no problem. Seemed like problm solved... I bought the MMI oil and temp alarm kit... needed some piece of mind...
Last season (2009), as I was opening up the engine with the usual MMO in teh cylinders etc. I got her to turn over but she ran real rough for about 15 seconds... scratchy metal sound... then a crazy bang... and I immediatly shut the engine off. Thinking i had just snapped a valve or something I petitioned the devine and we went at it one last time... started up and sounded fine. Odd.
Throughout the 2009 season I noticed an oil drip from where the circular plate attached to the prop shaft enters the reverse gear housinig box. I believe I have a direct drive 1:1... if it matters. Wast this teh cource of my bang???
Well this post is about cooling... all the above is connected to this issue... maybe...
So on my way to pull out the boat ending the 2009 season we got caught by the tide and wind and had to motor some 4 hours. About 1-2 hours in the heat alarm went off... thinking of the strainer i said easy fix... there was some crud so I dumped it... the boat started, temp dropped, along we went. As we approached the drawbridge with a 3kt exiting tide coming straight at us we needed to throttle up, again the alarm goes off... so we circle around... I dump the strainier and blow through the lines, check seacock for ample waterflow. Again start the engine, temp dropped and through the bridge we go... just through the bridge the alarm sounds... explatives as the temp rises and the current is trying to push us back into the now closed bridge. Our only hope is fighting the tide to an open slip at a marina up ahead, engine required current now 4kts. Thankfully we make it to the slip under power. Shut down engine and furiously thumb through my MMI rebiuld manual on board... we figure out we have a gummed up thermostat, cool... but no spare... after fiddeling around we decide to let the engine cool a bit and just remove the thermostat entirely for the last leg of our journey... this way water will just dump through the header and I can replace over the winter.
Everything appears fine, we start up and head up river... feels like a victory and an answer to the previous year's over heating... junk thermostat... maybe, maybe not...
We go about 1-2 miles up river and suddenly this steam engine sound emerges from the engine compartment and there appears to be somewhat a loss of power. I open the door to find a rythmic exhaust smelling steam powering out from an area beneath the thermostat cover (remember I removed my thermostat and did my best to crank down the housing with a pair of pliers to get us home). We had no choice but to keep on... was this the result of a missing thermostat like a bad gasket or an actual crack in the header?
My boat under power typically does 5.5 kts under full power with no wind. We we headed into 5 ft seas and 30 MPH winds. Under full power we had barely 1 kt on the GPS. After a few hours me had made enought progress to get out of the wind and the tide had become slack. We made it home but now my big question is...
Why do I have exhaust pressuring out of a space between my thermostat housing and the header, and why does this result ina loss of power? Did the crash bang at the begining of the season indicate somthing that woudl cause the oil leak or somthing that would cause exhaust to leak into the coolant chamber? HELP!
Just FYI at the begining of 2008 I tested pressure on all cylinders and they were up over 90psi and shes never had a rebiuld, I haven't tested since the crash bang but there was no detectable power loss until I removed the thermostat.
Thanks for any and all ideas!
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