496 mag HO longevity
#1
Registered
Thread Starter
Join Date: Oct 2015
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
496 mag HO longevity
I know that this is a question that has come up on here many times, but the answers are usually more theoretical. I am wondering if anyone has actually seen over 1,000 hours on a 496 mag HO? I am looking at a boat with twin HO's that has just over 1,000 hrs. The scan shows that more than 3/4 of those hrs were under 3,000 RPM. Still, that is a scary number. I know that both motors will need freshening up soon, but how soon is the question.
Any help would be appreciated.
Any help would be appreciated.
#2
Platinum Member
Platinum Member
iTrader: (6)
Its a crap shoot really, a roll of the dice, All depends on their maintenance how well they were taken care of, .......what have they been pushing around for the 1000 hrs. is it big/heavy ? or ?
#5
Banned
iTrader: (9)
I rather see most of the hours spent around the 3600 to 3900 rpms. That's in the peak torque range. Below 3000 rpms is lugging the engine and really the owner is lucky to even make that far running at those rpms most of the time. Most production marine engines at 1000 hrs will need the bottom end done if not touched before. and most would have done bare min first top end job before a 1000 hrs. .
#6
Registered
iTrader: (8)
Compression and leakdown tests will tell the overall picture of the engines. 1000 hr 496's should make for a nice bargaining chip when negotiating with the seller.
Freshen up the bottem ends, set of Diamond forged pistons, Raylar 525HO topend kit. Would make for a nice setup.
Freshen up the bottem ends, set of Diamond forged pistons, Raylar 525HO topend kit. Would make for a nice setup.
Last edited by Ryan00TJ; 01-24-2017 at 06:42 PM.
#8
Banned
iTrader: (9)
Compression & leaked down tests. They are good testing procedures but not 100 percent viable. Years ago I had a broken valve spring that passed the leak down but did not pass compression test. Had broken roller lifters that passed leak down. And even one that passed compression to. Also the other side of the coin - Had good compression and fair to minus fair leak down numbers - turned out some scoring on the cylinder walls and so on.
#10
Registered
Thread Starter
Join Date: Oct 2015
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
It is already at a considerable discount vs. comparable boats, and I have not even begun to negotiate. I am just trying to get an idea how much time (if any) that I would have before sinking more money into the motors.