AQ 231a Compression

I recently bought a 1989 Teka cuddy 20' with AQ 231a in it. The seller told me the engine was froze after sitting 3 years, he informed me that he sprayed PB Blaster into cylinders when disovering sieze. The engine will turn over now, so I took to local repair to figure out why there is no spark. After doing a compression test he said I have 80 lbs on 2 center cylinders and 170 lbs on the driver side cylinders. Question is should I get repaired or just by a new rebuild. I can get fresh block with heads for $1300. Not sure what a rebuild cost will cost for that. He told me he could rip the engine apart to see why the low compression. But at $45 an hour that could get costly. The boat is in great shape. Or should I cut the lsses and let someone else deal with it. Wuld the boat run the way it is, and just be a dog?

Thanks for your opinions

Re: AQ 231a Compression

A competent tech would know how to find the reason for low compression without tearing it down. It would run like warmed over #### with compression the way it is, if it ran at all.

Re: AQ 231a Compression

So I got the boat back and ran compression test myself. The 2 center cylinders on drivers side have 90 lbs and rest are around 170 lbs. It was seized when I got the boat and I broke free. What would you guys think it would be. Rings, head, gasket? I'm going to make this a winter project and would like to know where to start. Thanks in advance

Re: AQ 231a Compression

A leakdown test is designed to show if the compression leak is in the valves, gasketing, or rings. To test a cylinder it is brought to TDC on compression stroke, then compressed air is introduced into the cylinder via a special fitting in the sparkplug hole. Don't need much pressure. The exiting air will be audible in the intake or exhaust, or into the crankcase (may need stethoscope), or external leak between the head and block via a compromised head gasket. Air hissing into the crankcase indicates rings or even compromised piston. Air hissing into the intake manifold or exhaust manifold indicates valve or valve seating or other valvetrain problems.

I am mentioning the leakdown test first bcause the engine has to be together to do one.

You could just remove the heads and take a look. I am sure the engine could use a head refresh anyway. I would not just put them back on even if they look ok without some deck checking/machining and freshening work.

The cause of the siezing is a big factor in what all should be done to the engine. If it was hydrolocked or water just got in while sitting for so long then there will be major rust damage to the heads and affected cylinders. Could mean boring and new pistons, just have to tear down and get an engine machinist's opinion on it.