MD2030 Exhaust Elbow De-carb

[ozzyb]

Having done 975 Hours & Due to loss of power & revs together with Black Smoke. I removed the exhaust elbow to find a severely restricted fitting. Has anyone got a pic. of how a clean one should look. I don't want to go too far in striping out the existing fitting. any help would be appreciated.

 

[J Neeves]

No picture but most of the deposit is calcium, the carbon is more a pigmentation of the calcium. 1,000 hours is about par for the course. You can clean them with acid, but the acid does tend to attack the steel (or any corrosion of the steel). So you might be able to acid clean once. New original elbows cost a King's ransom. Cleaning takes time, concentrated acid overnight.

I do not know whether buying a stainless elbow reduces the deposition but here it is possible to have a stainless one made up more cheaply than buying an original.

Jonathan

 

[ozzyb]

No problem in cleaning out the deposits. I've polished & ported a few engines in my youth. I'm a bit unsure as to the internal layout, is there an internal sleeve where the water is introduced or can the bore be fully opened out.

 

[J Neeves]

From memory,

I do not recall it being a sleeve, but I might be wrong - I thought it was a simple plate that covered the water inlet port. Attached at the end furthest from the heat exchanger and opening to toward the heat exchanger

Hopefully some one has looked at one more recently will educate us both!

Jonathan

 

[Stork_III]

From memory,

I do not recall it being a sleeve, but I might be wrong - I thought it was a simple plate that covered the water inlet port. Attached at the end furthest from the heat exchanger and opening to toward the heat exchanger

Hopefully some one has looked at one more recently will educate us both!

Jonathan

There is an inner sleeve, water injected into the annulus.

 

[cimo]

if it's a common or garden water injection elbow, then there is no sleeve.

the water injection spigot is located on the outside bend?
then water is injected straight into the elbow.

you may clean out to full bore.
(I had to use a hammer and screwdriver, but would be interested to know of a better method).

 

[Stork_III]

if it's a common or garden water injection elbow, then there is no sleeve.

the water injection spigot is located on the outside bend?
then water is injected straight into the elbow.

you may clean out to full bore.
(I had to use a hammer and screwdriver, but would be interested to know of a better method).

There is a sleeve on the VP MD2030 elbow.

 

[cimo]

apologies stork, saw your post only after i posted.
got me wondering if volvo had it's own special design.

this sleeve is there to deflect the water jet from hitting the opposite side of the elbow? or is there more to it than that?

 

[J Neeves]

MD2020 Exhaust Elbow

I happened to be looking for something else and found this. It might be a valid image, its the new exhaust elbow from a MD2020 and the insert is a sleeve.

Jonathan

 

[john_morris_uk]

I agree that there is a sleeve as we have a Volvo 2040 (identical exhaust injection elbow).

The last one I cleaned, I used a variety of acids and alkalis that are commonly available. (i.e. brick cleaner etc) I very much regret that I can't remember which one worked best, but perhaps someone with some knowledge of chemistry will be able to suggest something.

I also used physical methods such as poking small screwdrivers etc around to dislodge the major bits. The problem is that you can't reach everywhere and you need to soak it in some corrosive chemicals to get the thing properly clean. The good news is that mine came up like new after a while.

 

[nigelmercier]

I had to use a hammer and screwdriver, but would be interested to know of a better method).

I used a screwdriver on my MD22 elbow, right through the side. Better to have it fail at that juncture than when in use.

 

[J Neeves]

I used a screwdriver on my MD22 elbow, right through the side. Better to have it fail at that juncture than when in use.

I did the same when I tried to clean a second time with acid - simply dissolved a hole in the casting (the acid goes, very quickly, for any corrosion). I found hammer and chisel too laborious (we need to do 2 at the same time), the build up is incredibly hard, and not a very clean finish (you'd still need the acid) but the first time the acid seemed adequate and we gained another 1,000 hours.

I find it odd its not part of the schedule of maintenance in the workshop manual.

Jonathan

 

[parbuckle]

I have had good results with spray oven cleaner on carbon deposits on my generator exhaust I imagine it is a caustic foam and less likely to attack the metal than acid.

 

[yotter]

I cleaned my MD2020 elbow on my previous boat, the hole left for the exhaust before I started was about the size of a 5 pence piece (little power and much black smoke)! I used a selection of screwdrivers and a hammer very carefully. It worked just fine. My new to me boat has a MD2030, and I was pleased to find that in the servicing records, the elbow had been removed and cleaned (but perhaps it was choked).
Regards
Angus

 

[duncan99210]

I cleaned the elbow with a combination of elbow grease and a selection of screwdrivers. Took time but we were in the Peloponnese at the time and had nothing else available. Worked well enough and I haven't had to revisit it yet - about 400 engine hours ago.

 

[ozzyb]

Thanks for replies. The pic. was very useful. My elbow was so restricted there was barely a screwdriver slot hole for exhaust gases. I've damaged the sleeve slightly near the rear edge but I don't feel it will make any difference. I'll find out on refitting.

Cheers

 

[sailaboutvic]

Firstly forget this .

(I had to use a hammer and screwdriver, but would be interested to know of a better method).

I do mine every year now to keep it clean , the first time that I used an screwdriver it ended up cost me a new elbow .

I use a toilet acid which you can buy in most supermarket in Spain Greece and Italy , not sure about the UK . Soak it I. It for a few hours the. Slowly use a hacksaw blade to go around the water jacket , you may have to do it a few times .
Take your time and it will work , rush it and get you check book out .

 

[Heckler]

There is a sleeve on the VP MD2030 elbow.

there is indeed, and at that age the inner sleeve is probably corroded away as mine was. The OP needs to get out his wallet, about £170 quiddish?
Or do what I did, make one from bits and ASAP
Stu

 

[ozzyb]

Went to Keyparts today to get a spare as they were close to my travels today. They were out of stock!!! due to the spring rush, as they said. This must be a very common problem. After a bit of cleaning the inner sleeve on mine looks to be quite badly corroded, not sure how usable.

 

[cimo]

and the purpose of the inner sleeve is?