Strange Westerbeake overheating problem

[tranmkp]

Just some additional om this - ok, so the elbow skin is not cooled - but, would a partially or poorly designed nozzle contribute to a slow but steady rise in coolant temp? Again only at rpms higher than 3200-3400. Below that there is no problem - Backing off brings temp down almost instantly. Its a though there is a high speed restriction that backups the hot discharge water in the heat exchanger?

any thoughts?

[FAST FRED]

On many larger engines the sea water coolant volume is so large that only a portion is dumped to cool the exhaust elbow.

You should consider a by pass setup where only some water is used to cool the elbow ,and exhaust , the rest is dumped OB with a thruhull.

However this is NOT an industrial diesel, NOT up for very much time at FLANK, full throttle.Could be expensive engine time.

I would pull back 10% from full tilt , say to 2800rpm , and use that as max high speed cruise. Mark the tachometer!

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[tranmkp]

I Pulled the exhaust elbo - PO for some reason replaced the Westy elbow with a home brew - welded a SS elbow on the steel flange of the old Westy elbow?

This is what I found (will post pics soon) the injector is just a tube with a welded SS tab at the end, it does not cover the entire tube, water can flow. At the end of the tube there are several holes drilled around the circumference (rather shoddily) there is no obstruction. What is happening is this. Only the last 2 inches of the elbow is being cooled. The exhaust hose, when I installed it can slip over 3 inches on elbow. So, I have 1 inch of elbow and hose uncooled.
At the higher speeds/heat it starts to cook.

After I post the pics - we can discuss further.

[tranmkp]

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[baeckmo]

Well, that's exactly what was highlighted in post no 44! This elbow is complete sh-t, is this really how it is delivered from factory or has some "Joe the plummer" been there? The water must of course be introduced along the perimeter where the rubber needs cooling....no rocket science!

[tranmkp]

yes, agreed. The elbow is a piece of crap. For 600 bucks I can have the RIGHT elbow and be done with it.

I can however, replace the exhaust hose with some HT silicone and mount it not as far up on the elbow. And have the problem go away.

My real concern is the tube within a tube installation and its effect on performance. Seems I would really take a hit at my upper rpm with the restriction - burning aside - the latter seems more important -

am I wrong here?

[baeckmo]

That inner pipe is an awkward restriction already! Take the piece to a welding shop and ask them to remove the center pipe and modify the elbow according to the sketch attached. It is a compromize, but it will work fine (and comes ready far from 600 bucks!). Don't forget to chamfer the upstream edge of the restrictor (only!). Flatten the cooling pipe slightly.

[tranmkp]

Built as spec'ed

Works - sort of - it takes much longer for the hose to get hot now - I am beginning to think that the exhaust velocity is just too high for this type of design...

[baeckmo]

OK, hot...how hot? Can you hold your hand onto the hose 1´ from the elbow? What does it look like at the outlet opening- solid water flowing/bursts or all in a spray?

[tranmkp]

pretty much to your spec however we protruded about 10cm into the pipe angled downstream. Solid water not spray. The hose is not hot to the touch aft of the connection of the pipe, or it is only hot on the outer edge of the connection. I believe it is because the heat moves down the pipe with increased exhayst velocity. This can be solved by extending the pipe a few inches thus moving the hose further away from the dry hot exhaust stream. No?

Just glad to have the restriction gone.

[baeckmo]

As long as you use an approved wet exhaust hose, according to SAE j2006 or equivalent, you should now be safe against "blowouts". If my memory is correct, the standard max allowed temp is ~120 C. Special hoses for up to ~180 C and above are available, but certainly not necessary for your purpose. Increasing the stub length won't do much for the temp at the connection point, so get on to the water and enjoy life, good luck to you!

[FAST FRED]

Having a Volvo and being stuck with parts that are worth their weight in PLATNUM, my suggestion is to look on the engine parts sites that offer stock conversion parts. BARR?

Find an exhaust elbow that is properly engineered and close to what you require.

Have a shop create an adapter and your out from under the mfg UNOBTANIUM pricing.

We have heard of a Volvo MD 3B exhaust elbow in SS , but have been unable to locate a source , so second (or perhap$ ) first choice is an adapter.


Here is a style that might work for you , tho the hose size is large.



BAR20-0031
Swivel-type 90 degree exhaust elbow connector
Swivel-type 90 degree exhaust elbow connector with internal water discharge. Accepts 2 1/2” to 3” I.D. exhaust hose. Requires (1) mounting hardware kit #20-0002P per elbow.
$94.93


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