Espos4
Well-Known Member
There’s been a lot of discussion regarding how to properly winterize and protect the engine from freeze damage. Particularly the raw water cooled small block with single point drain system.
I decided to gather some data and present it here so you can be better informed about how well that single point drain system actually drains the system.
if you want to skip the long read, here’s the one thing to know:
Water should flow from the distribution housing for approximately 2 minutes and 15 seconds.
Shorter drain times are an indication that one or more of your exhaust manifold and/or block drains is clogged and not draining.
Here’s how I tested the system.
2007 240 Sundeck 350 MAG
505 hours (200 hours on manifolds and risers)
Salt water it’s whole life
raw water cooled.
Every fall, I clear the block drains and exhaust manifolds of debris that accumulates over the season. They are always plugged with debris from the shallow water and occasional mud encountered in The Great South Bay.
With this in mind, before pulling the boat out at the end of this previous season, I timed how long it would take to drain the system with what I (correctly) assumed was clogged block and manifold drains.
With the motor fully warmed and thermostat open (engine off), I removed the distribution drain and thermostat plug. Water flowed forcefully for 45 seconds, and then slowed quickly so that at the 1 minute mark, there was no more water flowing from the distribution drain. I did this several times and got the same results.
Fast forward to today. The boat is on the trailer at home. I ran the boat on muffs to warm the motor.
Again, draining took the same 45-60 seconds as when it was in the water.
I then proceeded to remove the block and manifold drain hoses and push pressurized water back and forth to ensure they were all clear. Each one was initially plugged, mud and debris visibly flowed out once cleared.
Once reassembled, I rewarmed the motor and recorded the new drain time. Water flowed forcefully for 1:20 and the total drain time was 2:15.
Water flowed forcefully for 35 seconds longer that it did with the clogged drains. Water also continued to drain for a full 1:15 longer than it did with the clogged drains.
I decided to gather some data and present it here so you can be better informed about how well that single point drain system actually drains the system.
if you want to skip the long read, here’s the one thing to know:
Water should flow from the distribution housing for approximately 2 minutes and 15 seconds.
Shorter drain times are an indication that one or more of your exhaust manifold and/or block drains is clogged and not draining.
Here’s how I tested the system.
2007 240 Sundeck 350 MAG
505 hours (200 hours on manifolds and risers)
Salt water it’s whole life
raw water cooled.
Every fall, I clear the block drains and exhaust manifolds of debris that accumulates over the season. They are always plugged with debris from the shallow water and occasional mud encountered in The Great South Bay.
With this in mind, before pulling the boat out at the end of this previous season, I timed how long it would take to drain the system with what I (correctly) assumed was clogged block and manifold drains.
With the motor fully warmed and thermostat open (engine off), I removed the distribution drain and thermostat plug. Water flowed forcefully for 45 seconds, and then slowed quickly so that at the 1 minute mark, there was no more water flowing from the distribution drain. I did this several times and got the same results.
Fast forward to today. The boat is on the trailer at home. I ran the boat on muffs to warm the motor.
Again, draining took the same 45-60 seconds as when it was in the water.
I then proceeded to remove the block and manifold drain hoses and push pressurized water back and forth to ensure they were all clear. Each one was initially plugged, mud and debris visibly flowed out once cleared.
Once reassembled, I rewarmed the motor and recorded the new drain time. Water flowed forcefully for 1:20 and the total drain time was 2:15.
Water flowed forcefully for 35 seconds longer that it did with the clogged drains. Water also continued to drain for a full 1:15 longer than it did with the clogged drains.