Thinking about a repower.

[winstonwilliams]

I have a 1991 290 Searay with a mercruiser 502. The engine started knocking, so I cut open the oil filter and found it full of metal shavings. So I think it is time to replace the engine. I was thinking about either a 454 or a 496 because they are more reliable, easier to find parts, and drink less fuel than the 502. What do you guys think?

 

[sbw1]

502s have never been very good because of the oil consumption issue. 454s are bullet proof. 8.1s are pricey.

 

[sprink56]

Don't mess around and wait too long....GM stopped production of these engines a few months back at the Tonawanda, NY plant.:smt009

 

[HUMPH]

check out ebay!

http://cgi.ebay.com/ebaymotors/Crus...9043116QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

http://shop.ebay.com/i.html?_trkpar..._Accessories_Gear&_trksid=p3286.c0.m14&_pgn=2

 

[keokie]

I've owned the 454, 496, and 502. The 502 is my favorite by far. It is the only one with all forged internals, has the best torque curve and can handle the most abuse. the reason the early years were oil burners is because it is a siamese block, which means there are no cooling passages between the cylinders. Because of this, and because Merc expected the motors to get a lot of abuse (mostly installed in recreational performance boats), they set them up very loose to reduce the risk of seizing the motor. This allows some oil past the rings. It is very manageable, and does not lead to problems unless you never check the oil. In later years, they tightened them up a bit and stopped the oil burning. A competent machine shop can do the same in a rebuild.

The 496 is very smooth, with great midrange. But it is very (overly, in my opinion) complicated. It also has cast internals.

The 454 is a fine motor, but it produces noticeably less power than a properly running 502.

Of all the motors I have owned, I put the most hours on the 502. It was by far the most trouble free, and best performing.