Md2020 cracked exhaust elbow and overheating. Which came first?

[Zippysigma]

The Overheating alarm sounded when motoring at about 3000 rpm Head to wind and waves.

turned before the wind and dropped revs. Alarm stopped. Exhaust water coming out of stern ok.

a few minutes later, saw smoke from engine breather vents.

once sails up, stopped engine.

I found a crack Or hole in the exhaust elbow by engine and black soot all around it.

So my question is, would the hole cause the overheating Or is it likely something else caused the overheating that then caused the elbow to crack / blow?

I don't want to just replace the elbow if it is a symptom rather than the cause.

thanks

 

[garymalmgren]

I don't want to just replace the elbow if it is a symptom rather than the cause.
Bite the bullet.
Replace the elbow. It dosen't matter which came first if you have a hole in the elbow now.
You don't have to use an original, there are loads of options.
gary

 

[pvb]

That exhaust elbow design wasn't one of Volvo Penta's better efforts! The elbow is prone to extensive corrosion which can reduce the size of the cooling water inlet, resulting in overheating, not to mention corroding right through as yours has. Once you take it off you'll have a better idea of whether corrosion contributed to overheating. There are various replacements in stainless steel.

 

[TSB240]

I am not sure the op doesn't intend to replace the elbow.

It is possible your overheating alarm is a symptom of either an underperforming water pump, impeller failure and a consequential blocked heat exchanger.
I would prefer to replace impeller and check and clean heat exchanger in addition to replacing elbow.
Ours was nearly completely blocked when it cracked.

We never had a temperature alarm.

 

[PetiteFleur]

I also had this problem with a Perkins Perama 20hp(same engine as VP) exhaust elbow choked up, only 10mm hole, tried to clean it and elbow disintegrated! New elbow fitted, VP elbow cheaper than Perkins...

 

[ithet]

With the elbow off it is easy to remove and clean the heat exchanger matrix . You can get a nice shinny SS elbow and some new heat exchanger rubber boots and clamps all from Parts4engines.

 

[pvb]

VP elbow cheaper than Perkins...

That's a first!

 

[Zippysigma]

Thanks everyone. Yes, I intended to replace the elbow, but was worried there was something else causing it.

as suggested I will clean the heat exchanger and replace the impeller. have a good look round.

 

[Venus1]

That exhaust elbow design wasn't one of Volvo Penta's better efforts! The elbow is prone to extensive corrosion which can reduce the size of the cooling water inlet, resulting in overheating, not to mention corroding right through as yours has....

question: Do we know if Volvo improved this design? ie Are the newer D series elbows better than the older 20xx ones?

 

[scottie]

It is a Perkins design used on a range of engines and it looks like current part number is unchanged from original

 

[richardbrennan]

I now have a D1-30 and have had to replace the exhaust elbow. It did not look ant different to me to the one on my previous 2030 which I also had to replace.

 

[pvb]

I now have a D1-30 and have had to replace the exhaust elbow.

May I ask how many hours the engine had done? I have a D1-30 too.

 

[richardbrennan]

I would have to get down to the boat to check, but from memory, about 500 hours. The symptom was that the engine was a little down on maximum revs. Unfortunately I needed it done in a hurry, so had to refit a Volvo replacement.

 

[pvb]

I would have to get down to the boat to check, but from memory, about 500 hours. The symptom was that the engine was a little down on maximum revs. Unfortunately I needed it done in a hurry, so had to refit a Volvo replacement.

OK, mine's only done about 300 hours. But I do tend to motor around fairly quickly, which I believe reduces exhaust problems. Do you charge around, or motor sedately?

 

[Venus1]

OK, mine's only done about 300 hours. But I do tend to motor around fairly quickly, which I believe reduces exhaust problems. Do you charge around, or motor sedately?

Following this with interest, as I have similar experiences with 2030, and now have a D1-30.
500 hours seems a depressingly short interval to replace an elbow.
I got about 1000 hours - don’t know if running hard helped (almost zero idling).
(not wanting to hijack the thread too much - thinking the OP would be interested in this too)

 

[duncan99210]

I cleaned the elbow on my 2030 out at the 11 year point: it’d done about 2,500 hours by then. I fitted a new one after the old one got blocked again but cracked when. I tried to clean it at about 3,750 hours. I usually motor at about 2,000rpm and do a fair bit of fast idle to charge batteries at anchor (say about 1,200 rpm). I now tend to check the elbow every couple of years before launch so that any build up of stuff can be easily cleared.