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Volvo Penta AQ131A Low Compression

T

tthenry

New member
Hi
My husband and I are new to boating and this forum and are looking for a little advice and help.
We purchased a 1987 Bayliner Capri with a AQ131A -275 4 cylinder.We got it cheap but knew it would need some work. Floor and transom is good and boat is in good shape. The motor when running sounds rough. Had a cylinder leak down test done #1 86% #25% #3 75% #4 32%.
Also Compression test is 145 PSI dry and 245 PSI wet. Mechanic states leak is mainly going by rings and can hear it come out dip stick as well.

Now he also states that the timing sounds wrong and that could be the problem or rust in the cylinders. My husband is handy with car motors rebuilding and such and is going to see what he can do himself on this motor.We are looking for some help on where to start. Any help would be greatly appreciated.

Many thanks in advance
Tina
 
If the compression is being lost through rings, I would pull the engine apart and check the bore sizes. If the engine just needs new rings that would be a comparatively cheap fix. Even if the block needs reboring and new pistons that would still be comparatively cost effective, as automotive pistons will fit your engine (they are identical to the overpriced OEM "marine" version). However, you may find that the head needs to be rebuilt and also it may have corroded exhaust ports # 3 & 4, timing gears may be pitted if used in salt water ...... A cheaper overall option you may want to consider is buying a used car engine in good condition from an auto wrecker and marinizing it by using a number of parts from your current engine (carb, manifolds, distributor, starter, raw water pump, etc). Car models with a compatible engine would be Volvo 244 85-93 and 85-92 740 8 valve (non-turbo).

Cheers.
 
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