Rust on exhaust elbow - Nanni 4150HE diesel engine

RichardS said:
Alu alloys and copper-grease work fine together but the OP can also use bearing grease, alu-grease or silicon grease if he has any concerns. :)
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I shall order some more copper grease, but the grease of which I have most supply is some kind of lithium bearing grease, found on board when I bought the boat.

http://starbrite.nl/260xx

Think this would be suitable?

A google suggested that lithium grease should be good up to about 150°c, but I'm a bit doubtful seeing as the Starbrite is all in Dutch. This does lead me to wonder why copper grease is ever specified, if engines never get that hot.
 
KompetentKrew said:
I shall order some more copper grease, but the grease of which I have most supply is some kind of lithium bearing grease, found on board when I bought the boat.

http://starbrite.nl/260xx

Think this would be suitable?

A google suggested that lithium grease should be good up to about 150°c, but I'm a bit doubtful seeing as the Starbrite is all in Dutch. This does lead me to wonder why copper grease is ever specified, if engines never get that hot.
Click to expand...
I have replaced 2 of these elbows sans any grease
 
KompetentKrew said:
I shall order some more copper grease, but the grease of which I have most supply is some kind of lithium bearing grease, found on board when I bought the boat.

http://starbrite.nl/260xx

Think this would be suitable?

A google suggested that lithium grease should be good up to about 150°c, but I'm a bit doubtful seeing as the Starbrite is all in Dutch. This does lead me to wonder why copper grease is ever specified, if engines never get that hot.
Click to expand...

Bearing grease is not as temp resistant as copper grease and is best for gaskets which are used for coolant/water carrying components. These tend to operate at lower temperatures so bearing grease is fine.

On something like an exhaust component I would definitely make sure that there is plenty of copper/alu grease on the bolts/studs/nuts so would lightly coat the gasket with the same stuff at the same time.

Richard
 
KompetentKrew said:
I'm all geared up with the parts for this, but have been procrastinating. I really should get to it this week.

It occurs to me I should probably shut off the raw water seacock before proceeding. I also need to drain and flush the coolant, which is pretty manky. Is there anything else I should look out for, please? Hylomar on the gasket? Does it need torquing when refitting the elbow?

jVX2kKj.jpg
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Hi! if you have the time post some pics of the old elbow internal so we can see whats the situation inside. I am curious to see the extend of corrosion.
Thanks
 
Akestor said:
Hi! if you have the time post some pics of the old elbow internal so we can see whats the situation inside. I am curious to see the extend of corrosion.
Thanks
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the inlet spigot ( in the CI type ) rots off due to the interface of seawater & air in the stationary engine
 
Akestor said:
Hi! if you have the time post some pics of the old elbow internal so we can see whats the situation inside. I am curious to see the extend of corrosion.
Click to expand...
I wouldn't fail to update you all, but the post you quoted mentioned my procrastination. I wasn't very enthusiastic about anything for a few weeks in rainy October, but am pleased to have done my outboard this week, so will probably take it out for a blat testing today "to test it". I might just get to the exhaust elbow tomorrow.
 
I did take a crack at this today, after all. Managed to get all the bolts undone easily enough, but the elbow is held in place between the L-shaped hose and the exhaust hose. The latter at least seems to have perished in place, and I can't seem to get it off.

I stopped with the fading light, but am tempted to cut the L-shaped hose that I am replacing. Perhaps then I'll be able to wiggle the old elbow better to get it off the exhaust hose. I am ruminating on this for the evening, but any suggestions are welcome in the meantime.
 
KompetentKrew said:
I did take a crack at this today, after all. Managed to get all the bolts undone easily enough, but the elbow is held in place between the L-shaped hose and the exhaust hose. The latter at least seems to have perished in place, and I can't seem to get it off.

I stopped with the fading light, but am tempted to cut the L-shaped hose that I am replacing. Perhaps then I'll be able to wiggle the old elbow better to get it off the exhaust hose. I am ruminating on this for the evening, but any suggestions are welcome in the meantime.
Click to expand...

If you have a new L-hose then definitely just cut off the old old. Being able to squirt a bit of WD40 down the exhaust hose and then twist the old elbow clockwise and anti-clockwise is definitely the best way to free it off. Some boiling water or a hot-air gun/ hairdryer will also help considerably.

Richard
 
Old elbow off, and pics as promised:

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Lb6NzyF.jpg

Boosted the shadow slider on these to try and show the inside better:

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After reviewing this thread I was reminded that Old Harry's concern was the inlet spigot, that it would be rusted away and fall off. I removed the remains of the hose and hit it with a hammer - it survived, so does not seem quite as bad as feared, although the end of the spigot deteriorated further:

bOkP1eD.jpg


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vJ9FviN.jpg

​

Finally, because it was so hard to photograph the dark interior of the elbow with my phone's camera, I broke out the USB endoscope:


I hope this post helps meet your daily PBO requirements.

I dislike the state of the inside of the spigot where, it seems to me, flow must be restricted; the deterioration at the exhaust end and at the end of the spigot don't look too good, either, but it's not clear to me that this elbow *needs* to be replaced. I would appreciate your thoughts.

Finally, the replacement elbow has a threaded hole in the top, where the old one does not:

W5GZh78.jpg

Anyone know what that's for, please?
 
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