How long should you flush ?

[Seahuff]

Hi all
Wondering what the difference was between flushing your O/B motor whilst relatively cold (few minutes only) as opposed to full operating temperature.
Eg: When the motor reaches proper operating temperature does the thermostat open and let water through extra cooling passages within the motor?
If so, how do you know when the thermostat opens? or do you just flush for a set time to allow that to happen?

[scottar]

If you don't have a temp gauge it's a bit hard to tell but on my E-tec it takes about 3-4 minutes to come up to temp. I usually flush for about 15.

[Noelm]

I just connect up the hose and flushers as soon as I get home, start the motor then unload the boat, when everything is out, I then hose the rods and reels and gear, connect up the other motor, it flushes while I put everything away, and then I start washing the boat, so, depending on how long each task takes, determines how long I flush for.

[Noelm]

I might add, I put the bucket with the washing stuff in it under the tell tail, by the time both motors are flushed, I have warmish water to sponge the motors and the boat.

[sharkymark2]

My 40hp Yamaha oil injection motor takes about 1 minute before the thermostat opens. The tell tale triples in flow. I normally give it about 5 minutes.

[hainsofast]

I use a big plastic 44 gal for my motor (150hp) usually do it till the water is bath temperature, about 7 - 10 minutes

[Spaniard_King]

My 40hp Yamaha oil injection motor takes about 1 minute before the thermostat opens. The tell tale triples in flow. I normally give it about 5 minutes.

This is very Interesting as when a thermostat opens the block pressure drops ????

I am thinking your tel tale pressure increases when the block fills up hehehehe

[Spaniard_King]

Best practise is to flush until the water coming out of the prop is warm to hot, thermostats will be open by then :)

[Fed]

I think my hose water pressure holds the poppets open so my motor never gets hot when flushing and the thermostats never open, I only ever get coolish water out of the prop.
Nowhere near 145 degrees F thermostat opening, water at that temp can burn you in under 5 secounds.

It wouldn't surprise me if a lot of people had the same condition without realising it.

I'm going to put a riser in the hose to give me volume without pressure & let it run on the water pump as if it was submerged.

Thoughts people?

[Seahuff]

Noelm
Good idea collecting and saving the tell-tale water
So , you need to get to operating temperature and then with the thermostat open, this results in the water getting too extra areas of the motor to flush? as opposed to not being at operating temp and the thermostat still closed??

[RayLamp]

I first read the topic, and thought "I flush till the ol' porcelain bowl is all clear!"

I then gave myself an uppercut.

I then read "Wondering what the difference was between flushing your O/B motor whilst relatively cold (few minutes only) as opposed to full operating temperature."

In winter, I'm always cold when I flush my outboard. I would go through too much water in the time it would take me to warm up.

I gave myself another uppercut.

I've got Yamahardness. This comes with a fresh water flushing port. I use this and probably run it for 5 minutes.

No more uppercuts.

[Spaniard_King]

I first read the topic, and thought "I flush till the ol' porcelain bowl is all clear!"

I then gave myself an uppercut.

I then read "Wondering what the difference was between flushing your O/B motor whilst relatively cold (few minutes only) as opposed to full operating temperature."

In winter, I'm always cold when I flush my outboard. I would go through too much water in the time it would take me to warm up.

I gave myself another uppercut.

I've got Yamahardness. This comes with a fresh water flushing port. I use this and probably run it for 5 minutes.

No more uppercuts.



Are you saying you run the engine whilst using the fresh water flushing port?

[tunaticer]

2-3 minutes is all i give my motor......i never let it sit unflushed.....first thing i do when i get home.

[scorpo92]

I just unplug the fuel and let it run on whats In it. About 5 or six minutes

[sharkymark2]

Hey Spanyard_king When my tell tale flows when i first start it, the water is cool until the flow dramatically increases and the water then becomes quite warm. Thats why I thought that the flow increases is because the thermostat has opened because of the water becoming quite warm. Am I wrong?

[Stuart]

I use to fish with a metallurgist years ago, he told me it takes 12 minutes for salt build up in the block to dissolve. So probably not far off from what Spaniard king said, run until prop water is warm, to hot.

[Spaniard_King]

Hey Spanyard_king When my tell tale flows when i first start it, the water is cool until the flow dramatically increases and the water then becomes quite warm. Thats why I thought that the flow increases is because the thermostat has opened because of the water becoming quite warm. Am I wrong?

Most engines take a lot longer than 5 minutes to get to operating temp, so yes you are wrong.

[CatMoupland]

I just begin flushing the outboard before I do all cleaning and by the time I've finished everything else I think I've given it a decent flush time.

[RayLamp]

Are you saying you run the engine whilst using the fresh water flushing port?
I don't run the engine while flushing through the fresh water flushing port.