Re: 93 40 HP VRO - Overheat Alarm w/ Great Water Flow
I'm getting the steady buzzer...which I believe is the overheat alarm. Not an on/off buzzer which I believe would be the alert for not getting oil.
Steady buzzer is overheat condition. If you shut engine off immediately, then turn key back on without starting, buzzer should still sound constantly and will continue until engine cools back down. Buzzer sounds at approx 200 degrees.
I was told if I had a bad thermostat that the engine would run cold, not hot. So I ruled that out.
Themostats can freeze up in a closed position as well and therefore never open, thus restricting water flow. This is more common in a motor that's been sitting for a while. The thermosats are the last component in the water circulation path prior to water entering the exhaust stream.
If I had a dirty oil tank with clogged screen or water in it and oil wasn't getting to the motor would I not be getting the beeping on/off buzzer vs the overheat buzzer?
There are two oil alarms... One indicates oil tank is low. Other indicates that the VRO pump is not moving back and forth in harmony with the engine crank turning. (Crankcase pressure drives the pump). Neither tells you it's not pumping oil. In other words, both alarms could be silent because neither abnormal condition is happening, but a flow restriction could still be preventing oil from flowing. Lack of oil on pistons = overheat. Use a portable tank with some pre-mix 50:1 to help rule this out.
How can an engine be overheating while at the same time be peeing out a super strong stream of cool water? That's what I don't understand here. If there was say a chunk of impeller partially blocking the water route, causing the engine to overheat would I not see less water coming out and the water coming out would be at least warm from the overheating engine?
Usually the water from the tell-tale should be warmer (but not necessarily too hot to touch) during overheat, but the tell-tale outlet is further upstream in the water path and before other possible restrictions. Again, good stream only indicates water pump is likely doing its job.
This is what was leading me towards suspecting the overheat alarm is faulty. Is there an easy way for a guy to test the overheat alarms? Can they become overly sensitive with age?
Sensor could be faulty. When it triggers an alarm, check the temp on the heads yourself. Either carefully by touch or better with an IR gun.
My guess is thermostat. Look for approx 1" hose that exits the head and goes to thermostat housing. Take loose from thermostat housing and use a larger hose (old radiator, etc) and deflect flow to outside the pan and thereby bypass thermostat. Don't run it too long like this since you're no longer spraying water into the exhaust gas stream. If the heads stay cool, aprox 100 degrees (on hose at idle), you've found your problem.
