Calling all Yanmar/Diesel engine enthusiasts

[MagicalArmchair]

Okay, so I've had a very rapid response from Rydlymes director of sales no less:

The instructional sheet that we provide is intended to be as generalized as possible so that we can cover most systems. As an example; on most inboards, the thermostats are only on the freshwater side and do not require to be removed to clean the raw water side. As far as your Yanmar 2GM20, we have had numerous customers successfully flush these motors using RYDLYME Marine. I have attached a diagram of your cooling system which shows that removing the thermostat should free the path to allow your entire raw water system to be cleaned.

By all means please let me know if you have any additional questions or concerns.

This leaves me not a great deal clearer (seeing as we don't have a fresh water side on a 2GM20) - the diagram was interesting though. Question - So, err, does the water come out of the block the same way it goes into the block? Via the Thermostat? .

This is from vyv_cox on another related post here: http://www.ybw.com/forums/showthread.php?378468-Yanmar-thermostat-not-closing/page4

Which is very useful

 

[vyv_cox]

I am not familiar with the raw water cooled GM other than information that people have kindly sent me. From this information it is my understanding that the Yanmar layout is exactly the same as the Bukh in my diagram. The Rydlyme info confirms this. As far as I can see there is nothing that will persuade the Rydlyme solution to pass through the engine in any quantity, it would far prefer to pass through the bypass. Assuming that there is a hose between the injection T into the engine and the thermostat housing, clamping it closed, as suggested earlier, will solve the problem. I have always used a Mole wrench for similar jobs, I have at least half a dozen of them so I would personally not buy a special clamp that I would probably never use again. A small G-cramp would be just as good.

 

[RichardS]

Okay, so I've had a very rapid response from Rydlymes director of sales no less:



This leaves me not a great deal clearer (seeing as we don't have a fresh water side on a 2GM20) - the diagram was interesting though. Question - So, err, does the water come out of the block the same way it goes into the block? Via the Thermostat? .

They'v not shown the return from the block but it comes out of the bottom of the block through the pipe on the right hand side and joins back into the cold hose shown in blue though the right-angle bend.

The Halfords tool I bought was plastic rather than metal but it's the same thing. I bought it for brake hoses and needed something light because I don't want a heavy weight like a mole wrench or G-clamp hanging off the pipe. It's not so critical for your hose because yours is supported at both ends so any kind of clamp will do although be careful that it doesn't have sharp edges which might cut the rubber.

Richard

 

[vyv_cox]

They'v not shown the return from the block but it comes out of the bottom of the block through the pipe on the right hand side and joins back into the cold hose shown in blue though the right-angle bend.

Surely not? Water goes in at the injection fitting, lower right hand in the pic, and comes out of the thermostat housing. Just as in my sketch of the Bukh arrangement above.

 

[RichardS]

Surely not? Water goes in at the injection fitting, lower right hand in the pic, and comes out of the thermostat housing. Just as in my sketch of the Bukh arrangement above.

Errrrr... isn't that exactly the same pipe in the lower right hand that I'm referring to? It's just that it's not coloured in blue?

Richard

 

[vyv_cox]

Errrrr... isn't that exactly the same pipe in the lower right hand that I'm referring to? It's just that it's not coloured in blue?

Richard

No. How can water come out of that fitting against the pump flow? Their drawing is correct. Cold water goes in at the bottom, is heated by the engine and comes out of the top. The only thing 'wrong' is that they don't show the red flow through the block.

 

[RichardS]

No. How can water come out of that fitting against the pump flow? Their drawing is correct. Cold water goes in at the bottom, is heated by the engine and comes out of the top. The only thing 'wrong' is that they don't show the red flow through the block.

Red flow through the block ........ to where?

Richard

 

[vyv_cox]

Red flow through the block ........ to where?

Richard

As I said, out through the thermostat housing connection. In their drawing the flow of red water is NE to SW.

 

[RichardS]

As I said, out through the thermostat housing connection. In their drawing the flow of red water is NE to SW.

We're talking at cross-purposes somehow! That red flow is shown on their diagram. I'm talking about the section of the flow which is not shown in any colour which is why the OP in post #21 is wondering whether the red flow which is shown is bi-directional. I thought that the blue "missing" section was the T-pipe at the lower right hand side but perhaps I'm wrong.

Richard

 

[MagicalArmchair]

Ah, okay Richard. The flow of water was drawn by me thus is open to plenty of error! So the part of my water diagram missing is the yellow section below which returns water that has entered through the thermostat?

That being the case sort of makes sense, in that thread I posted from the yanks above, the Diesel engineering chap suggested clamping the hose BENEATH the thermostat, which then makes sense as the water would then be forced (albiet the wrong way) up the return and back out of the hole vacated by the thermostat as below.

Just don't pinch the line off the TOP of the t-stat that goes to the exhaust elbow or you won't get any flow. You want to squeeze the one between the by-pass and the bottom of the t-stat that would force flow through the block and through the t-stat housing then out the exhaust.. Should be a short length IIRC.

The green 'blob' at the bottom being our pump along with our bucket o' Rydlyme.

Are there any drawbacks to putting water the wrong way through the block?

edit: Hang on half a minute... DOES the water enter through the thermostat? Or does the water enter through the BYPASS at the bottom and exit the head at the thermostat, thus keeping the flow the right 'way up' (Edit 2: I've just re-read what you both wrote, and that backs this up ) - The American adds:

On the 2 GM10 the coolant path looks like this

Path 1: Seacock, raw water pump, bypass junction, injection elbow of exhaust

Note: There is ALWAYS water flowing out the exhaust on this engine despite the orientation open/closed of the t-stat. So just because you saw coolant out the exhaust does not mean it went through the block.

Path 2: Seacock, raw water pump, bypass junction, engine block, cylinder head, t-stat, exhaust injection elbow.

So in short, does the above circulation diagram work for flushing then?

(thanks for the assist once again chaps, fascinating figuring out how my lovely little 2GM20 works after all these years)

 

[vyv_cox]

Your diagram is fine, with flow direction following the normal coolant route. If you are not running the engine I would think it makes little difference which way the flow goes, except maybe more crud is going to come out of the top end and it would be better not to block water passages in the cylinder jackets. Will your Rydlyme solution be warm? I assume it will be more efficient that way. When I use it in my central heating they recommend running the boiler for a while.

 

[RichardS]

Ah, okay Richard. The flow of water was drawn by me thus is open to plenty of error! So the part of my water diagram missing is the yellow section below which returns water that has entered through the thermostat?

Sorry Mark - my misunderstanding, I thought the coloured bits were on the original.

It's interesting that you used yellow rather than blue or red. I was struggling to decide whether the convention is that red should show water that is actually hot when the engine is running or should show the "hot-water circuit" which would be cold at the input end even when running. Your choice of yellow is the perfect compromise!

Richard

 

[MagicalArmchair]

Thanks chaps! All very clear now, I'll do my usual OCD write up on albinballad.co.uk once I've completed my Rydlyme flush to pass on the information.

The final version of the coolant flow is below (quite right Richard, gone a bit colour loopy there) - Red shows the route when the thermostat opens and the engine is hot, blue when its closed:

So, to force water down block and head route, the little tiny pipe below the thermostat and above the t piece needs to be clamped. This should also be done if trying to run coolant through the engine with the thermostat removed and the engine cold.

And for the flush, the following should work great:

Phew, what fun.

 

[RichardS]

So, to force water down block and head route, the little tiny pipe below the thermostat and above the t piece needs to be clamped. This should also be done if trying to run coolant through the engine with the thermostat removed and the engine cold.

I guess that might also be useful in an emergency if the engine starts to overheat because of a broken thermostat or suspected broken thermostat. You could take the thermostat out, as I've sometimes done on cars as a temporary measure, but in the case of a marine engine it seems that you might still continue to overheat unless you also clamp that pipe.

Thanks for posting Mark. I've learned from this thread.

Richard

 

[MagicalArmchair]

I guess that might also be useful in an emergency if the engine starts to overheat because of a broken thermostat or suspected broken thermostat. You could take the thermostat out, as I've sometimes done on cars as a temporary measure, but in the case of a marine engine it seems that you might still continue to overheat unless you also clamp that pipe.

Thanks for posting Mark. I've learned from this thread.

Richard

Thanks for both 'hanging in there' and all the help with my myriad cobbled together graphics and musings. And vyv_cox, I will warm the mixture up for sure, although nowhere in the Rydlyme guide do they suggest you do this, which is curious? I might pester them some more for clarification (wonder when they will block my email address... )

 

[MagicalArmchair]

Ah, just found the answer here: http://www.qflush.com/engels/products/rydlyme-marine

3. RYDLYME Marine should be applied at ambient temperatures with no heating required.

So no heating required!

 

[RobF]

Well, I did my engine this weekend with considerable success. A few things which I found which helped were as follows:
a) turn engine seawater cooling stop cock off and remove hose from sea water stop cock (with bung at hand - just in case)
b) put this hose into a bucket of fresh water. It's then really easy to run the engine with a fresh water hose filling the aforementioned bucket whilst the engine removes water to pump around the system.
c) run engine for 15 mins at a fast tick over to ensure that the salt water is completely removed
d) turn off engine, fill bucket with rydlyme. Restart until Rydlyme is coming out of the exhaust (Rydlyme is black so it's pretty obvious when it's coming out the exhaust)
e) leave for 3 hours then flush through with freshwater by running the engine as before
f) undo the hose attached at the impeller end rather than the connector bypass end. It's much easier to catch the water (and Rydlyme) this way when emptying the block as the hose can be emptied straight into a bucket
g) the thermostat housing came off reasonably easily and a funnel with 40 cm of garden hose attached was used to fill the block with Rydlyme
h) the Rydlyme frothed quite a bit on the first application. It pays to fill up very slowly.
i) I did 3 x 2 hour cycles with the Rydlyme in the block
j) Run through the block with freshwater 3 times (until the water runs clear)
k) Fill block with antifreeze
l) fill bucket with antifreeze and turn on engine so that it circulates through the entire engine
m) put everything back together again, with Copaslip on the thermostat bolts to make them easy to remove next time

Whilst this was happening I also stuck the thermostat in a pan of hottish water and noted it didn't open more than 1mm. I thought it should open a bit more than that - so ordered a new one.

 

[MagicalArmchair]

Thanks Rob, Triola is out of the water (till March, then she is going in the drink and going sailing finished or not!), and I have a little electric pump that I used for flushing the heater core on my RX8, so opted for this approach.

So I set up as per the below diagram this morning (in all this delightful weather we have been having)...

And that looked something like this:

I dumped my anti syphon in the bucket and my old thermostat (now replaced), and after running it through for the full four hours, I tell you, its pretty powerful stuff:

Thermostat before:

And after (The one on the left, the new one being on the right):

It also ate my pump

So that's one job done...

 

[MagicalArmchair]

One question remains - I tried getting the exhaust elbow back on the wet exhaust hose, and it would not budge, no matter how much I heated it, how much force I applied I couldn't get the hose back on the bleeding exhaust elbow. Any tips...?

 

[Champagne Murphy]

I believe that the thermostat on a raw water cooled Yanmar GM is similar to the one on a Bukh 20, in which the opening due to heating of the block simultaneously closes the bypass. Circulating water, Rydlyme or anything else with the engine cold will simply pass the fluid through the bypass and out of the exhaust. It has been suggested that if treating the engine cold with Rydlyme it is best to remove the thermostat and fill the block with the solution. If treating it hot by circulating via bucket under the exhaust then leave the thermostat in.

Viv,
Are these thermostats interchangeable? Much as I like the lads at Bukh their thermostats are horribly expensive so a cheaper alternative is a nice idea.