Beta BD722 heat exchanger stack removal

[DoubleEnder]

I havent taken the stack out for too long. It is quite cruddy with salt? scale? Is it best to tap it out from the front, thus sliding it aft. Or is it better though more awkward to to tap it out from the back, thus sliding it forward?
Or does it make no difference? This is not the latest version, as it's about 8 years old but I don't actually think there are any changes to this part of the engine.
All other tips gratefully received as well!
Thank you
Graham

 

[BabaYaga]

I havent taken the stack out for too long. It is quite cruddy with salt? scale? Is it best to tap it out from the front, thus sliding it aft. Or is it better though more awkward to to tap it out from the back, thus sliding it forward?
Or does it make no difference? This is not the latest version, as it's about 8 years old but I don't actually think there are any changes to this part of the engine.
All other tips gratefully received as well!
Thank you
Graham

It comes out either way, not much difference.
After removing the end caps, don't forget to take out both o-rings or it will not move.
Be gentle if tapping is necessary, on engines of about this age the alloy sleeves which hold the stack in the exchanger are epoxied into the body (this was later changed).
On my 722, from 2006, I mostly take the stack out though the forward end because there is a exhaust high riser blocking the rear. Instead I have to take the alternator off, but this might not be mandatory if there is enough room to swing it to the side.

 

[Hydrozoan]

I havent taken the stack out for too long. It is quite cruddy with salt? scale? ... All other tips gratefully received as well!
Thank you
Graham

It's likely to be carbonate scale, not salt. Unless it's obviously restricted by heavy scale, I'd be cautious about very strong acid cleaning, which some have recommended. Taking it right back to bare metal will increase anode consumption again for a time, until a new protective layer forms.

Mine (on the similar 622) has to go out backwards because of the alternator, but the injection point on the new aluminium exhaust elbow has made that more difficult. Also, don't forget to align the indents on the rear cap when refitting (I think the 722 has them, too). And as BabaYaga advises, if you do have to do any tapping with a suitable wood drift (which I suspect may be needed if it's been left for too long), go gently and patiently!

 

[DoubleEnder]

Thank you. I was going to use kettle descaler and a thin bottle brush rather than anything more aggressive. Does that sound right?

Graham

 

[Hydrozoan]

If it were just a very thin surface layer, I wouldn't bother at all - I normally just flush it well, poking out obvious bits of anything (there's normally nothing) in the tubes with a long wooden skewer. But if you've a heavy build-up, then I think descaler for a limited period - and with a good flush after - would be fine. What I don't see the point of is routine cleaning with strong HCl (or descaler for that matter) to remove all traces of scale, as that just destroys the passivation layer.

 

[Mudisox]

I took mine out and put it in vinegar. Lining up the groove as already stated is most important, [also helps to indicate which way round it goes]

 

[Eyore]

I havent taken the stack out for too long. It is quite cruddy with salt? scale? Is it best to tap it out from the front, thus sliding it aft. Or is it better though more awkward to to tap it out from the back, thus sliding it forward?
Or does it make no difference? This is not the latest version, as it's about 8 years old but I don't actually think there are any changes to this part of the engine.
All other tips gratefully received as well!
Thank you
Graham

I asked exactly that question to our local Beta agent last week and was told it comes out either way ,but backwards avoids moving the alternator. He also said to jiggle it gently both ways until its loose or you will loosen the centring spacer on the back which is supposed to stay on the stack. Its a job I have to do next weekend also.

 

[neil1967]

Never managed to get mine out when I had a beta 722. Even gentle persuasion with a hammer failed to shift it, so I just used to rod it through in situ (not that it got very cruddy anyway) - I never had any problems with the engine, so I didn't want to introduce any by applying more force! Do keep an eye on the anodes though, which seemed to crumble rather than dissolve.