Engine rebuild

[barryassheton]

Hi, I recently posted for advice on repowering my Senior 31 and have come to a conclusion of trying to rebuild the AQ171c engines myself. I have been told by the mechanic that for him to repair them it would get very expensive as labour isn't cheap. From what I understand the cylinders have had water enter them so the springs are rusted. I plan to strip the engines any way as I have nothing to lose by doing this. now for the questions I need advice on, I have found out some information on the engines please correct me if I am wrong.

The AQ171c is a basically a Volvo redblock B230 with a 16 Cylinder head.

Could I buy a second had b230 engine attach my cylinder head (after reconditioning) and then attach the marine parts (ie heat exchanger, oil cooler, etc). Would this work

or

Buy a b230 block replace pistons and rings and rebuild the block from some of my existing parts and attach my cylinder head and marine parts.

I know alot of the b230 parts are the same part numbers as the AQ171c for example the rotor arm in the distributor is exactly the same just about £15 cheaper if bought for a car.

I am hoping some of you with experience with the volvo redblock will be able to help. I have dabbled on cars for over 15 years so I am not quite a newbie when it comes to engines but this is my first rebuild.

Thank you Baz

 

[moresparks]

Please forgive the response as I am no expert, Just interested in the thread as I also have twin AQ171C’s. They are great engines and fairly economical in comparison to other petrol engines around the same HP.
But... They do need a hell of a lot of looking after and gentle nursing as they are getting quite old now. So I am faced with the same dilemma!
I have to ask ... how do you suspect that water entered the cylinder heads?
You may have to take off and inspect the exhaust manifolds to check any tell tale signs. If it is the exhaust manifolds then you are scuppered as they are very rare and only come up second hand occasionally. I believe you can get stainless steel ones made, but they can cost a fortune.
I did send one of my cylinder heads away to a specialist precision engineering workshop who completely overhauled it replacing some of the valves and springs. That worked a treat but will cost around £750.
I am guessing you knew that already, but I read somewhere that the valves, springs and pistons etc were not the same as the B230 they were up-rated for marine use. I cannot confirm this so maybe someone more knowledgeable can advise.

 

[barryassheton]

Please forgive the response as I am no expert, Just interested in the thread as I also have twin AQ171C’s. They are great engines and fairly economical in comparison to other petrol engines around the same HP.
But... They do need a hell of a lot of looking after and gentle nursing as they are getting quite old now. So I am faced with the same dilemma!
I have to ask ... how do you suspect that water entered the cylinder heads?
You may have to take off and inspect the exhaust manifolds to check any tell tale signs. If it is the exhaust manifolds then you are scuppered as they are very rare and only come up second hand occasionally. I believe you can get stainless steel ones made, but they can cost a fortune.
I did send one of my cylinder heads away to a specialist precision engineering workshop who completely overhauled it replacing some of the valves and springs. That worked a treat but will cost around £750.
I am guessing you knew that already, but I read somewhere that the valves, springs and pistons etc were not the same as the B230 they were up-rated for marine use. I cannot confirm this so maybe someone more knowledgeable can advise.

I was told by the mechanic that water got in through the exhaust. After I bought the boat I was told by the harbour master that he phoned the owner once as the stern was sitting very low in the water. So I guess the stern had a lot of water in the engine bay. I haven't checked how much it would cost to recon a cylinder head yet as its early days still but looking at the part numbers for the Aq171c and for a volvo b230 car engine the valves, springs and piston rings are all the same part numbers.

Baz