Do you flush your diesel engine after use?

zip · 12 July 2015, 17:58

On the recent survey and attempted sea trail of a boat I have an interest in, I noticed a hose nozzle on top of the engine.
Is this used to flush engine after use, or just used for service?

Mollers · 12 July 2015, 18:29

Quote:

Originally Posted by zip

On the recent survey and attempted sea trail of a boat I have an interest in, I noticed a hose nozzle on top of the engine.
Is this used to flush engine after use, or just used for service?

Dunno about the specific engine in question, but the deciding factor is 'closed circuit' or 'raw water' cooled.

If 'closed circuit', which I'd guess that most inboard diesels are now, flushing after every use is not necessary. If raw water cooled, it would be desirable, but not catastrophic if it didn't happen.

Us leisure users can become overly concerned with flushing, washing, winterizing, fretting etc.

willk · 12 July 2015, 18:46

Quote:

Originally Posted by zip

On the recent survey and attempted sea trail of a boat I have an interest in, I noticed a hose nozzle on top of the engine.
Is this used to flush engine after use, or just used for service?

I'm gonna take a wild guess on this one: Was that a US Navy RIB?

If so, the hose connection may have been for a water supply to allow the engine to be run while being davit launched, RNLI stylee...

Mollers · 12 July 2015, 19:01

Quote:

Originally Posted by willk

I'm gonna take a wild guess on this one: Was that a US Navy RIB?

If so, the hose connection may have been for a water supply to allow the engine to be run while being davit launched, RNLI stylee...

Good call. Run 'em up and bung 'em in.

zip · 12 July 2015, 19:05

Yep, ex military boat.
So I can run the boat out of the water with that hose outlet attached to a water source?

Mollers · 12 July 2015, 19:15

Quote:

Originally Posted by zip

Yep, ex military boat.
So I can run the boat out of the water with that hose outlet attached to a water source?

It may pay to have it confirmed before you flash her up out of water. It doesn't take too many seconds to cook an impellor if run dry.

zip · 12 July 2015, 19:21

ok. good info.

I have been told to replace a impellor on a Konrad 520 isn't that difficult.
I understand that difficulty is a relative term depending on someone's knowledge, abilities and other factors, but is it necessary to remove the whole lower end?

Mollers · 12 July 2015, 19:24

Quote:

Originally Posted by zip

ok. good info.

I have been told to replace a impellor on a Konrad 520 isn't that difficult.
I understand that difficulty is a relative term depending on someone's knowledge, abilities and other factors, but is it necessary to remove the whole lower end?

We're not familiar with Konrad outdrives over here, but I'd imagine that the principle is the same as any other leg.
Yeah, you need to drop the gearbox and the impellor housing will be sat at the bottom of the driveshaft on the top of the box. The only tricky bit can be disconnecting and reconnecting the gear selection rod.

ShinyShoe · 12 July 2015, 19:25

Quote:

Originally Posted by zip

ok. good info.

I have been told to replace a impellor on a Konrad 520 isn't that difficult.
I understand that difficulty is a relative term depending on someone's knowledge, abilities and other factors, but is it necessary to remove the whole lower end?

No idea - but replacing an impellor that is old but intact, and replacing one that has disintegrated are two different tasks. The disintegrated one will have kindly filled all the nice little tubes around the cylinder head with bits of impellor that then impede water flow.

Mollers · 12 July 2015, 19:28

Quote:

Originally Posted by ShinyShoe

No idea - but replacing an impellor that is old but intact, and replacing one that has disintegrated are two different tasks. The disintegrated one will have kindly filled all the nice little tubes around the cylinder head with bits of impellor that then impede water flow.

Gawd! Yeah, don't be tempted to sacrifice an impellor in a hose fitting/cooling experiment.

willk · 12 July 2015, 19:47

Quote:

Originally Posted by ShinyShoe

No idea - but replacing an impellor that is old but intact, and replacing one that has disintegrated are two different tasks. The disintegrated one will have kindly filled all the nice little tubes around the cylinder head with bits of impellor that then impede water flow.

No, it will fill the raw seawater strainer basket with bits - assuming that the engine cooling circuit is closed (most serious kit is)

ncp · 12 July 2015, 23:52

Quote:

Originally Posted by willk

If so, the hose connection may have been for a water supply to allow the engine to be run while being davit launched, RNLI stylee...

Quote:

Originally Posted by zip

Yep, ex military boat.
So I can run the boat out of the water with that hose outlet attached to a water source?

Yes, standard garden hose. I flush mine on the trailer in the driveway after every use. Just don't close the seacock, the raw water pump will suck the hose flat!

Quote:

Originally Posted by zip

I have been told to replace a impellor on a Konrad 520 isn't that difficult.

There is no impeller in the Konrad 520 drive leg.

There is no transmission in the Konrad 520 drive leg.

This is what makes these drives so robust - nothing but the oversized gears in there.

zip · 13 July 2015, 01:38

Tom, assuming the engine is running?

Where is the impeller?

ncp · 13 July 2015, 02:06

Quote:

Originally Posted by zip

Tom, assuming the engine is running?

Where is the impeller?

On engine, gear driven.

On a Cummins, it can be any of three different pumps - M72, GC1, 1716 (listed smallest to largest). All have different inlet and outlet sizes and run different impellers.

At 180 or 210hp, you only need the smallest pump, the M72. The GC1 is meant for the 250/270hp rating while the 1716 is meant for the aftercooled 300hp and up engines. I currently have a rebuilt 1716 on my boat (largest of the pumps but that's what came with it) but have also run a GC1 (for a couple of months while the 1716 was getting rebuilt). I have a brand new (due to warranty issue) in my garage as a spare.

Raw water pump is on the port side under the fuel injection pump.

beamishken · 13 July 2015, 10:25

Quote:

Originally Posted by willk

No, it will fill the raw seawater strainer basket with bits - assuming that the engine cooling circuit is closed (most serious kit is)

Seawater strainer is usually sited before pump to prevent debris entering pump
A disintegrated impeller usually warrants a cooler strip to remove the bits of impeller

zip · 14 July 2015, 15:16

Well alrighty then. I had no idea. If I ever get a boat, probably have more questions.
Thanks.

jwalker · 21 July 2015, 17:41

Quote:

Originally Posted by beamishken

Seawater strainer is usually sited before pump to prevent debris entering pump
A disintegrated impeller usually warrants a cooler strip to remove the bits of impeller

Well it must depend on the motor then cos my Volvo has the strainer after the pump as willk has said. It's surprising what can get through the pump - I've even had a fish in the strainer!

To the op, I flush my inboard after each outing and then fill it with antifreeze mix to retard corrosion of the raw water system. I collect the antifreeze mix for reuse before launching. Obviously you can only do this if you trailer the boat or lift it out after use.

beamishken · 21 July 2015, 18:22

Quote:

Originally Posted by jwalker

Well it must depend on the motor then cos my Volvo has the strainer after the pump as willk has said. It's surprising what can get through the pump - I've even had a fish in the strainer!

To the op, I flush my inboard after each outing and then fill it with antifreeze mix to retard corrosion of the raw water system. I collect the antifreeze mix for reuse before launching. Obviously you can only do this if you trailer the boat or lift it out after use.

Ah I see I've never owned a volvo powered boat but had several with mercruiser diesels & yanmar diesels & my pal's ford powered boat all have the strainer before the pump

You can inhibit with antifreeze in the water on a total loss basis if your worried about hard frost or corrosion we close the sea cocks & pour the antifreeze into the strainer & wait till you see the coloured water out of the exhaust