AQ145A to a AQ170, good idea or no?

Hello everyone, first post on the site and with all the good information I am finding I am hoping someone can help narrow down my search.
I recently picked up a 17' Calglass with an AQ145a mounted to a 280 with hydraulic trim.
The previous owner said that his mechanic had done a partial rebuild on it and found a cracked piston. I pulled out the boroscope to find out which one and low and behold piston 3 has a small crack. Compression test is within 15 psi between all 4 cylinders but haven't had the boat out on the water in fear i am missing something. I was expecting a drop in compression for #3 but there wasn't much.
I am having trouble finding a new or replacement piston for this motor so I am thinking of doing a swap to an aq170.
I can get the 170 motor with a 280 leg without trim for free. Motor runs great and the water pump was just recently rebuilt but has a leak between 3 and 4 which i have been told is the head gasket. The head gasket for the 170 is a lot easier to find then a piston for the 145
My question is, is this engine swap a good idea? if not, then what should I do? if yes, then will the 170 bolt right on to my 280 leg, or do have to change out my whole set-up and install his engine and leg on my boat?

Any and all help is appreciated.

Thank you
Eric

Do you have the room for a strait 6? You will need to put in forward engine mounts. Ricardo will know for sure but my guess is you just need to swap out the flywheel housing/PDS and the lower gearbox and just use your existing hydraulic trim. Free is always good wait for the experts to tell you if it is worth the money and effort.

You know what, the very first thing you consider and it totally slipped my mind. I think your right.
Thanks kimcrwbr1, looks like i'll be taking out the tape measure.

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EricJ said:

Hello everyone, first post on the site and with all the good information I am finding I am hoping someone can help narrow down my search.
I recently picked up a 17' Calglass with an AQ145a mounted to a 280 with hydraulic trim.
The 280 PT drives are few and far between these days.

The previous owner said that his mechanic had done a partial rebuild on it and found a cracked piston. I pulled out the borescope to find out which one and low and behold piston 3 has a small crack.
A partial rebuild..... yet the cracked piston was still down in the cylinder????
I would take any of the seller's comments with a grain of salt only.

Compression test is within 15 psi between all 4 cylinders but haven't had the boat out on the water in fear i am missing something. I was expecting a drop in compression for #3 but there wasn't much.
I am having trouble finding a new or replacement piston for this motor so I am thinking of doing a swap to an aq170.
I can get the 170 motor with a 280 leg without trim for free. Motor runs great and the water pump was just recently rebuilt but has a leak between 3 and 4 which i have been told is the head gasket. The head gasket for the 170 is a lot easier to find then a piston for the 145
Run, don't walk.
Not that you need one right now..... but look up a price for a 170 exhaust manifold!

My question is, is this engine swap a good idea?
NO!

if not, then what should I do?
Find another Volvo Penta OHC 4 cylinder engine, or continue searching for pistons.

if yes, then will the 170 bolt right on to my 280 leg, or do have to change out my whole set-up and install his engine and leg on my boat?
The 170 can be made to work..... however, the lower gear unit will need to be changed to a 1.89:1 reduction. But again...... I would strongly encourage you to NOT DO THIS.

Any and all help is appreciated.

Thank you
Eric

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