Blocked cylinder jacket (volvo penta)

[shorty]

During winterising last year, opened and removed lower drain cock on 25 year old Volvo Penta MD5B. No water came out, even after pricking with wire. Removed head and pricked again from above. Some black powder could be removed from the drain hole. Seems that lower waterways around the cylinder are blocked with black sludge, which is almost impossible to remove by pricking or flushing with cold water. Engine otherwise runs well, with good water flow out and does not appear to overheat (temperature alarm never triggered). Anyone any ideas how to resolve this problem, without further dismantling of the engine.
Thanks, Shorty.

 

[seaesta]

I have found that unscrewing the drain fitting and poking "straight in" with stiff wire rather than through the fitting has worked on my MD1.
You should make sure the water remaining in the block is full of anti-freeze rather than water for obvious reasons.
Previous postings have suggested that this accretion needs dynamite to shift it.
If it has taken 25 years to build up to present level it could be another 25 years before it becomes a show stopper.
Martin

 

[kgi]

what i did with my MD7 is to take the head off put a masonry bit in my drill switch to hammer action and start gently drilling out the waterways keep looking at the tip off the drill and you will see when you have reached the other end of the passage........worked for me.....keith

 

[Trevor_swfyc]

I think I would get a small wire brush like a test tube brush and as already suggested use a drill and get rid of any deposits.
A friends Volvo siezed without warning when one cylinder overheated due to the cooling channel blocking. Luckily the bore survived but it required a new piston and rings. Its now fresh water cooled, I also fitted a fresh water system as it cost less than his repair to convert.
So do not leave it, this would be foolish in my view.
Would not recommend the use of chemicals as they might do more harm than good.
Keep it clean.
Trevor

 

[Peegee]

Had this problem with my 2002. The black powder is the iron oxide and I almost gave up on the job. In the end ( with drain tap removed from block ) I used a stainless steel bicycle spoke which I fashioned into "T" handled prodder with sharp flattened tip. I twisted and shoved like **** and eventually broke through. It was like magic, once water started to flow it was easy (Using some pokeink from above) to dislodge it all and flush the block right out. Good luck

 

[shorty]

Thanks for your contributions. I think I'll try the wire brush first, then may have to resort to masonry bit!