MD11C OVERHEATING

"HI,WHEN UNDERWAY MY MD11C TEM

"HI,WHEN UNDERWAY MY MD11C TEMPERATURE GOES FROM HALFWAY IN THE GREEN TO THE RED FOR 1-2 MINUTES THEN DROPS BACK TO THE GREEN FOR 3-4 MINUTES THEN CYCLES AGAIN. THOUGHT THE THERMOSTAT WAS STICKING BUT ON INSPECTION FOUND IT HAD BEEN REMOVED. ANY IDEAS. THANKS, ANDY"

Flow thru manifold is restrict

Flow thru manifold is restricted. Water ports are probably closed up or totally covered over. Sender is reading flow from bypass into thermostat housing to front of manifold.

"Thanks Dickv, To fix this do

"Thanks Dickv, To fix this do i remove manifold and scrape away rust from ports or is there something else i need to do to the engine block as well. Thanks, ANDY."

"When you remove manifold, if

"When you remove manifold, if ports are totally closed up then ports between head and cylinders are probably the same way. Heads would then have to come off to check and clean out ports. Worst case is cylinders are packed full and liners would have to be removed from cylinders."

"THANKS DICKV FOR YOUR ADVICE,

"THANKS DICKV FOR YOUR ADVICE,WHEN I HAVE REMOVED MANIFOLD AND INSPECTED WILL UPDATE POST. ANDY."

"REMOVED THE MANIFOLD AND FOUN

"REMOVED THE MANIFOLD AND FOUND THE PORTS CLEAR WITH VERY LITTLE RUST. WITH THE MANIFOLD OFF I REMOVED THE CYLINDER DRAIN COCKS AND THE WATER RAN OUT WELL. I THEN CONNECTED A HOSE TO THE CYLINDER DRAIN COCKS AND BACK FLUSHED THE CYLINDERS, THE WATER RAN OUT WELL. WOULD NOT HAVING A THERMOSTAT INSTALLED CAUSE THE FLUCTUATING TEMPERATURE. ANY OTHER IDEAS. THANKS, ANDY."

What first described is normal

What first described is normally a initial sign of cracked heads and/or leaking cyl head gasket. If blocked passages the temp normally stays up.

"Message to ANDY DOUGHERTY. A

"Message to ANDY DOUGHERTY. Andy you can email me at [email protected]. I have an MD11C and have had it for over 20 years. This engine develops overheating problems as you describe for a number of reasons and many times it is something simple. I have always found that the best way to troubleshoot this problem (and it develops periodically) is to start back at the thru hull intake and work your way through the cooling system step by step checking for good waterflow, backflushing and checking hose clamps as you go. It is not a difficult process and chances are good you may find something simple. I can tell you that over the years my MD11c has had this kind of problem many times and I have found a multitude of reasons that were not serious. e.g. junk in the xmission flow through, worn water pump plate, marginal impeller, clog at exhaust elbow water bypass insertion, clogged engine ports, deteriorating hose interior, seepage at thermostat housing, bad water pump seal etc. etc. etc."