[sailak]

I took a peek at the coolant this weekend expecting to find the nice green of antifreeze, instead finding an ugly brown/rust colored water.

Normal?

Any tricks to draining the coolant, flushing and refilling?

Yanmar 3GM30F...where the heck is the heat exchanger? <G>

 

[pdqaltair]

Normally really brown orange or rusty AF is a sure sign that oxygen is getting in...

I took a peek at the coolant this weekend expecting to find the nice green of antifreeze, instead finding an ugly brown/rust colored water.

Normal?

Any tricks to draining the coolant, flushing and refilling?

Yanmar 3GM30F...where the heck is the heat exchanger? <G>

Such as an air leak or a head gasket. Sometimes electrolisis from a bad ground. AF doesn't generally fail to that extent on its own....

But it could be that you are looking at orange AF (Dexcool or similar) or just plain neglect over a long time.

I would change it and then watch closely.

 

[timebandit]

So, how long since you last looked at it??

Changed it how long ago??

 

[sailak]

So, how long since you last looked at it??

Changed it how long ago??

Just took possession of her on May 19th...unknown how long since it was changed. I've been watching the level of coolant in the overflow bottle, just decided to dig deeper as I go through systems to figure them out.

 

[timebandit]

It could be that perment antifreeze or it could be a problem.

I would change it out so I would know where I stand.

Talk to someone in your marina for what to use.

I'm in an area that we call that stuff "COOLANT".

 

[sailak]

I'm planning on changing the coolant out on Monday when I go back down to the boat.

Drain from the bottom or pump it out like the oil?

 

[captbillc]

if you have the engine manual it will show the drain plugs or valves. or you can drain all the low spots in the coolant side of the system. the engine block, heath exchanger ,oil cooler if it has one & transmission cooler unless that is sea water cooled. i would put water in & run it & drain it again to clear out the crud.

 

[badsanta]

There are several drain valves on this engine that you need to open. On mine it has a little clear 1/4 inch tube attached to each one. The heat exchanger is the part with the radiator cap. If the engine is cold it is safe to take it off for a look. You should have it loose for it to drain properly.There is no one drain valve like a car radiator. Your heat exchanger is the radiator. Also change the oil and filter. My 3GM30F calls for #30 diesel oil and the same for the transmission. I change both at the same time I do it at 100 hours or twice a year. Good luck

 

[badsanta]

Also the little pump with the small fan belt is your fresh water pump. The inside impeller has to be replaced. Most people do it every wear. The easiest way to do this is to remove the whole thing because the plate you take off is inboard to the engine. It is impossible for me to replace the impeller with out removing the pump. But that's me. Lots of info on this engine. Keep searching.

 

[sailak]

Flushing the coolant went well but is rather time consuming with the repeated draining, bringing up to temp, draining, etc.

As for changing out the impeller...since I started up with the engine with the through-hull closed -- (hmmm, that's odd...I don't hear that splashing sound...OH CRAP) -- I thought it wise to change the impeller even though it did put out a good flow of water after I opened the through hull.

I did as others have posted and removed the pump. The pics below are of the impeller I removed. To me it appears to be in good condition. I have no idea how long it's been in service.

Where do you guys buy your Yanmar parts? I went to the local "Yanmar dealer" and was underwhelmed by the response I got. They don't stock impellers, seemed indifferent to ordering parts for me. Any online options?

Thanks for the help.

 

[k1vsk]

Just do an online search for Yanmar parts, Yanmarhelp.com, or Yanmarmarine.com, or for part numbers call Torreson Marine.

By the way, your impeller has definitely seen better days and should be replaced.

 

[garymcg]

ebay

Current yanmar part number is 124223-42092

I picked up a couple on ebay for $19.95 each but I don't see any on there currently. Torreson has them for $33.74:

Yanmar 124223-42092 Ships Store Torresen

Gary

 

[RichH]

How long has this engine been sitting idle?

"Brown" coloration of the cooling water is most probably a symptom of the antifreeze's rust inhibitors being consumed. In cast iron engine blocks the normal course of action is - the constantly flowing HOT water produces a layer of 'black' or 'blue-black' ferrous rust ... and this is protective. Upon long standing and without repeated heat/hot cycles the ferrous oxide slowly converts back to "red" or ferric oxide which is destructive. Long term storing such an engine by draining it (but leaving high humidity in the cooling passages) is the worst possible scenario with respect to ferrous to ferric oxide formation.

Suggest you drain the brown water, refill with at least 50:50 mix of antifreeze/water .... then RUN THE HELL OUT OF THE ENGINE (hours and days) to be sure that you redevelop the important 'black' ferrous oxide (black rust) layer inside all the cooling passages and channels; make sure that the engine is 'soaked' with 180 def. F water temp.

If the engine HAS been recently and long term been run hard and hot .... change as above and if the discoloration reappears, .... then check for a 'blown head gasket'. Your local 'automotive machinist shop' can give you 'tips' on adding a 'blacklight' dye to the water, etc. to check for blowby carbon monoxide/dioxide in the cooling water ... from a blown head gasket.

 

[sailak]

Rich,

I just bought the boat in May. It had been out twice before I took possession. It had probably set since Sep or Oct of the year before (long stinkin' winters up here <G>).

I've run it quite a bit. Several times of motoring for 2-3 hours at a stretch (I use 2600-2800 RPM for cruise).

Would a head-gasket problem show up in the exhaust as well? smoke perhaps? I haven't seen any symptoms of any problems, other than ugly coolant fluid.

 

[sailak]

By the way, your impeller has definitely seen better days and should be replaced.

Those large scars I think are from the grips when I removed it.

So those little striations along the edge of the paddle are a big deal? Or is there something else you're seeing that I don't?

Thanks

 

[sailak]

Current yanmar part number is 124223-42092

That's what I found searching the 'net. The part I put in was a -42091 - which I'm not finding any reference to but matched what I took out (it was in the spares kit for the boat).

 

[RichH]

Rich,
Would a head-gasket problem show up in the exhaust as well? smoke perhaps? I haven't seen any symptoms of any problems, other than ugly coolant fluid.

Not necessarily if the leak is very slight but enough to pass high pressure combustion gases into the cooling fluid. Notice any liquid level drop in your reservoir tank? if so the suspicion for a blown head gasket somewhat increases.

 

[sailak]

Thanks Rich

The coolant level is holding steady, no indication I'm losing coolant.

About that sea water pump...what is the pump body made of? It looks like brass or bronze, I'm wondering because I want to get some spare screws and want to minimize the chance of corrosion. As I understand any dissimilar metal is a bad idea.