Raw water mixing elbow blocked

[mikewhite7314]

I have a yanmar 3gm 30f engine and the raw water system is blocked. I was getting water through to the anti-syphen but it was blocked up at the mixing elbow. I removed the 90 bend that threads into the mixing elbow and drilled all the crud out. I also had to drill out the crud where the 90 bend threads into the mixing elbow as this was blocked too. Can anyone tell me is there anything else inside the mixing elbow that could be causing blockage as I am still not seeing water through the exhaust system?

Thanks Mike

 

[seadaddler]

Really

Drilling wow,did you take the 2 pieces apart and clean it out.
I used ice pick type of tools to clean mine out and hitting it with hammer as I picked with tools and hitting to loosen all the crude.
Nick

 

[Steve Dion]

Mike:

The mixing elbow has an internal jacket where the raw water enters the elbow. I would suggest that you purchase a new elbow and see if that takes care of the problem. Quite often this area gets corroded from the acids in the exhaust.

If that does not take care of the problem you need to check you hose for blockage too.

I "assume" that you know that you have water from the thru hull to the elbow without restriction.

If you have not checked out the raw water intalke thru the heat exchanger you need to be sure that it is flowing properly too.

 

[s sauer]

"U" shaped mixing elbow

I have twice cleaned out the carbon from the 'U' Shaped mixing elbow on a 2GM20F and see from my SELOC Yanmar Manual that the 3GM30F may have the same type of mixing elbow. If so, taking the assembly off the engine in one piece is reasonably easy; however, separating the exhaust elbow, stainless steel left & right hand thread riser joint and 'U type mixing elbow takes some serious wrenches and a large vise. I usually have an auto shop do it for me, then I have been able to clean out the coke deposits in the exhaust side and in the water injection channel by using a power drill and Dremmel tool with various types of heavy duty wire brush attachments. Soaking in carburetor cleaner may or may not help. The initial 90 degree elbow off the back of the exhaust manifold hasn't had much in it but a coating of loose carbon. The bronze water injection fitting that screws into the 'U' type mixing elbow obviously unscrews to allow using about maximum of 1/2"grinding bits or Dremmel tool elements.
In my opinion, it's worth a try given the cost of the replacement parts, and its relatively easy to see if you've accomplished the cleaning task down to bright metal.

 

[Steve Dion]

Mike: This may give you a better idea of what the internals look like.

http://www.ipyoa.com/photos/62-hayden/album?albumid=118

If you decide to replace the elbow it can be quite a chore to get the manifold apart from the elbow (unless you have already done that).

We ended up using a torch to heat everything up and two pipe wrenches (large) with breaker bars on the wrenches to get them apart. The coupling is left hand threads on one side and right hand on the other.

 

[amcmahon]

WOW, great link Steve. Can any one tell me about how many hours were on these engines that got so clogged. I have a 'new' 6 yr. old YM15 with 2200 hours and am having some flow problems - not sure if its Elbow yet. Thanks.

 

[Rick D]

Varies

WOW, great link Steve. Can any one tell me about how many hours were on these engines that got so clogged. I have a 'new' 6 yr. old YM15 with 2200 hours and am having some flow problems - not sure if its Elbow yet. Thanks.

My first 3GM coked up about 600 hours. Yours probably needs service.

 

[RAD88]

At this point we all pretty well know the bad design pitfalls and of the Yanmar exhaust elbows. Does anyone have any better designs?

What if you were to insert a silicone tube into the water jacket side of a new elbow? If there was a way to hold it in place and inject the raw water through the tube - the water side would never "coke up". The silicone can handle the heat.

If only there was a way to cast an elbow entirely out off silicone or some other inert material.

Just thinking out loud - any other ideas???

 

[jcalluaud]

Mine blocked as well (on a 2006 H27 with a 2YM15) down to a small finger size causing engine to overheat. Replacement only about $125. I reckon that the hot gases get cooled causing them to condense and leave deposits which is what causes it to clog up. My Yanmar manual tells me it should be inspected and cleaned every 250 hrs or annually.

 

[amcmahon]

Prices are rising- Torrensen Marine now gets $186 for the mixing elbow (be careful, there are 2 designs, 1 is straight back, the OEM unit is U shaped and more $). So I removed mine and took to my prop shop. They have a sandblasting booth, but I will say they used hammer and chissel to get the worst out. Anyway $40 for the job (they also separated elbow from nipple.)

 

[Claude L.-Auger]

Don't know if they're any good but I've seen aluminum ones on E-Bay for $159. Has anybody used them and if so what is satisfactorily ? Post on E-Bay says they don't clog up !