2GM20 raw water engine flush

[UK-WOOZY]

renewed the exhaust elbow and thermostat over the weekend. noted salt deposits by the thermostat where the hose attached, the hoses were pretty clear but replaced those. looking into the engine i saw it looked quite scaled up inside the engine so could do with a flush. looking at getting proflush -
Proflush - Marine Engine Descaler - Wessex Chemical Factors

i have read some say to remove the thermostat and some say to leave in situe, remove the anodes too of course. i plan to have two buckets, one with a hose to the raw water pump and the other end from the thermostat housing which usually connects to the elbow then a pump to pump between the buckets to circulate the fluid? Or suck the fluid into the engine and leave then flush out? Unsure which to do or how to go about it properly as theres conflicting advice online as usual.

to note the thermostat opens fine in hot water and closed fine when put back in cold, the same for a spare i have too.

Also how much cleaning fluid do people reccomend?

thank you

 

[black mercury]

Hi, can't comment on the concentration of flushing agent needed, but you will need to remove the thermostat, otherwise it won't circulate around the engine block.

 

[Dellquay13]

I did this on my 1gm10, I don’t know much about the 2gm engine.

I used 1/2litre of Rydlyme and 1/2L water in a bucket
Remove the thermostat refit the cover and clamp the thermostat bypass hose. Put the thermostat in the bucket with the mix.
Remove the block anode. (I turned the anode mounting plate round so the anode was outside the engine but the hole was sealed)
I took the hose from the water pump output and fitted an old basic bilge pump, and the hose off the mixing elbow back to the bucket as return.
I pumped the mix around the block in 5minute bursts for about 2 hours, until the mix stopped fizzing.
I flushed with a bucket of fresh water, and the internals looked completely salt free when I put the anode back in afterwards.

 

[UK-WOOZY]

Hi, can't comment on the concentration of flushing agent needed, but you will need to remove the thermostat, otherwise it won't circulate around the engine block.

this older post here says to not remove the thermostat

Flushing Yanmar 2GM20 Raw cooled - Rydlyme

 

[UK-WOOZY]

I did this on my 1gm10, I don’t know much about the 2gm engine.

I used 1/2litre of Rydlyme and 1/2L water in a bucket
Remove the thermostat refit the cover and clamp the thermostat bypass hose. Put the thermostat in the bucket with the mix.
Remove the block anode. (I turned the anode mounting plate round so the anode was outside the engine but the hole was sealed)
I took the hose from the water pump output and fitted an old basic bilge pump, and the hose off the mixing elbow back to the bucket as return.
I pumped the mix around the block in 5minute bursts for about 2 hours, until the mix stopped fizzing.
I flushed with a bucket of fresh water, and the internals looked completely salt free when I put the anode back in afterwards.

that sounds like using a pump other than the yanmar water pump to pump through the engine/ can that not potentially hydrolock the engine?

 

[Dellquay13]

In what way? The outlet from the engine block went up through the anti syphon valve and back to the bucket, not to the mixing elbow. It worked fine for me, I’m interested how it could’ve hydrolocked?
You can only use the Yanmar pump on a 1gm10 if the engine is running as it is gear not belt driven, then you have to have the water cooling your exhaust elbow, and you lose all your Rydlyme out through the exhaust.
I was told to pump it around that way by my local marine diesel engineers, who have been doing it to local 1gm10s and raw water bukhs for years.

 

[Dellquay13]

this older post here says to not remove the thermostat

Flushing Yanmar 2GM20 Raw cooled - Rydlyme

If you leave the thermostat in place in a cold engine, it will stay closed and stop the flow through the block, so take the thermostat out and clamp the bypass pipe to stop the mixture taking the easy bypass route instead of through the block.
I did mine one evening last January, and it worked fine at I guess about 10deg C

 

[UK-WOOZY]

anyone with a 2GM20 experience? thanks

 

[black mercury]

Yes. If you use an electric pump to circulate the flushing agent it won't pump through the engine water pump. Remove the hose that goes from the water pump to the engine block connection. Attach your hose from the bucket and electric pump to the engine block connection. Ideally clamp the short bypass hose that goes from this connection to the thermostat. REMOVE the thermostat. Take the rubber seal off the thermostat and refit this to the thermostat housing so that it still makes a seal. Remove the hose at the exhaust elbow and direct this back into the bucket. If you don't remove the thermostat the flushing agent won't circulate around the block and will be a waste of time and money.

 

[MagicalArmchair]

I wrote this many moons ago when I flushed my 2gm: Clean the raw water passages on your engine with Rydlyme - Triola - Albin Ballad #50 hope it helps!

 

[UK-WOOZY]

I wrote this many moons ago when I flushed my 2gm: Clean the raw water passages on your engine with Rydlyme - Triola - Albin Ballad #50 hope it helps!

perfect, just what i was looking for. Are you still by Chatham, if you are would you be happy to help me at Gillingham marina?

 

[Dellquay13]

I wrote this many moons ago when I flushed my 2gm: Clean the raw water passages on your engine with Rydlyme - Triola - Albin Ballad #50

 

[UK-WOOZY]

I wrote this many moons ago when I flushed my 2gm: Clean the raw water passages on your engine with Rydlyme - Triola - Albin Ballad #50 hope it helps!

So you didnt run the engine and use the waterpump, you used a normal pump to pump the fluid?

My waterpump is only a few years old, I assume i can just use a submersible bilge pump to pump through the engine?

thank you in advance

 

[Dellquay13]

So you didnt run the engine and use the waterpump, you used a normal pump to pump the fluid?

My waterpump is only a few years old, I assume i can just use a submersible bilge pump to pump through the engine?

thank you in advance

You don’t run the engine. You pump it round with a separate pump. I used an old Rule 500gph basic bilge pump. The pipe wasn’t the correct size, but it fitted inside the pump nozzle close enough to maintain enough pressure, and any leakage didn’t matter as it was sat in the bucket of Rydlyme anyway.

 

[UK-WOOZY]

HUGE thanks to MagicalArmshair for the article you wrote and Dellquay for the confirmations, and thanks all for the help.

I descaled the engine last weekend. took overall about 5 hours. this was the first flush with the chemical which got clearer as the hours went on-

I looked into the hole where the thermostat sits and it looked a lot clearer. thanks

 

[Dellquay13]

HUGE thanks to MagicalArmshair for the article you wrote and Deliquay for the confirmations, and thanks all for the help.

I descaled the engine last weekend. took overall about 5 hours. this was the first flush with the chemical which got clearer as the hours went on-

I looked into the hole where the thermostat sits and it looked a lot clearer. thanks

Happy to be of help

 

[Daverw]

Thats

HUGE thanks to MagicalArmshair for the article you wrote and Dellquay for the confirmations, and thanks all for the help.

I descaled the engine last weekend. took overall about 5 hours. this was the first flush with the chemical which got clearer as the hours went on-

I looked into the hole where the thermostat sits and it looked a lot clearer. thanks

also very useful as this job is on my list and was not sure how most carry it out

 

[MagicalArmchair]

Glad to help and glad someone has found the write up useful. You do often wonder when you write this stuff if anyone will ever read it. Glad you can cross another job off your list!!

 

[UK-WOOZY]

engine did seem happier on the weekend

 

[jfkal]

I use a T valve at the water intake to flush the engine after each saltwater use. For descaling I run the engine to operational temp. Flick the valve to draw the de-scaler solution. Stop the engine let the chem do its magic. A couple of cycles and all good. No need to fidle around with the thermostat which also gets cleaned with my method. Once done replace the anodes or replace them with blanks before starting.