496 Reliability
 

Is a 496 a good engine? Are they reliable? Someone told me the will burn oil. Thanks for the help in advance.

Mine, which was built in Sept. 2003, has 320 hours on it and has never touched a drop of oil.

The merc 502's all burned oil especailly the carbed versions. The 496, haven't heard that.

Mine is an 02 model with 600+ hours on it. Runs great yet.

The marinized 496's don't burn oil, but the truck ones do. My Merc 496 HO's never use a drop but the 8.1 in my Avalanche does a quart about every 1000-1500 miles.

Go figure.....

02 496 mag 346 hours douesnt burn oil, runs strong! Just do your maintenance...

Got a buddy with an 8.1 in a 'burb and same thing, uses over a quart of oil between oil changes.

My old boat had the 496HO with 420 hrs. Never had any issues, turn the key and go.

The 496-8.1L Gen 7 engine is the most reliable BBC marine engine ever produced by GM. This fact is based on the numbers produced between 2000 and 2010 reported to be over 60,000 units. Thousands are in regular and performance boats all over the world and most all have seen and continue to see many long reliable hours for this fresh water cooled engine. With proper service and maintenance most stock 496's and even the Raylar upgraded engines see already over 750 hours with many over 1000 hours and still going strong.
The reason some of the bad raps this engine gets in the performance boat community come from the fact that early in its life between 2000-2004 the only upgrades for the stock 496 -8.1L engines were supercharger systems that when placed on stock block 496's would see a good quantity of engine failures caused mostly because of improper or no re-tuning the engines needed for supercharging and engine systems not properly prepared for supercharging.
The easily created detonation with the engine when supercharged would break the hypereuctectic pistons and sometimes grenade the engine. In 2004 when Raylar began producing our bolt on reliable engine kits for the engine that produced better power numbers normally aspirated the available performance upgrades for the engine became reliable and hundreds now enjoy this engine with more power as well as the thousnds of other performance boaters who continue to see wondeful reliability and extended hours from the stock 496's.
I have commercial 496 -8.1L users who have these engines with over 2000 hours of continuous failure free operation. Sure there are 496-8.1L marine engine owners and users who had failures and issues but if you plot those numbers against the total number of these engines in the market you will see they are a very tiny percentage! There are no perfect families of marine engines, even the highly regarded Mercury Racing engines suffer failures in percentages larger than the 496-8.1L marine engine family.

Don't get yourself internet over-sensitized to engines and their supposed problems, do your research and you will find that the rumors and short knowledge comments are usually without real detailed factual basis and improper maintenance, use and service were in many times the cause of failures!
Don't always blame the engine, sometimes the blame lays elsewhere.
Again, don't always believe all the so called internet experts on the reliability of this or many other marine engines.
When it comes to this engine, I can honestly call myself one of the foremost experts on the 496-8.1L and I can honestly say that this is a great marine engine and it does not in anyway deserve some of the cheap shots thrown at it on the net and in the boating community mostly from non 496-8.1L owners!
Sorry, but these rumor comments really get me ruffled!

Hope you have great experiences with whatever marine engine you purchase and use!

Best Regards,
Ray @ Raylar

Ray, I don't see one negative comment here on the 496 ;). I am glad that I got rid of mine in favor of a 525 EFI though, even though it had been trouble free.

My wife was getting frustrated with high-perf boating when my last boat went through 3 engines in 5 seasons. I absolutely love the reliability of my twin 496HO's. We've had 3 seasons of trouble-free boating and these engines are now up to 420 hours and running strong. Plus, the wife now wants to go boating! :drink:

Our 496's in the cruiser has 780 hours on them. Not missing a beat. If you take care of them they'll take care of you. They are not build for tuning ect. but run as stock motors, just brilliant.

I had a 2004 496HO w/ around 250 hours when I sold it. It didn't use oil. I had to replace the map sensor and IAC while I owned it.

2002 496ho's, 620+ hours. Replaced seawater pumps and 1 IAC. Love them. I want to go boating, not wrenching.

I have no experience with a marine 8.1 496. I have heard nothing but good things about a stock marine 496. My friend had a 496 in his 2004 HD.Great engine for towing, always ran flawlessly but that thing would use more gas and oil than my 180HP 2stroke snowmobile. It was ridiculous.

Ray, do you have any idea why the big discrepancy between the 2 in those aspects?

Three reasons some of the 8.1L's use oil in the trucks and not as much in the boat uses.
1. 2000-2004 model 496's-8.1L engines had some cheezy-too thin plastic intake manifold gaskets and too short intake bolts (silver in color) versus (black ) for replaced (GM Re-call) and later models.
The truck engine intakes when heated to 200 degree or so on the road temperatures would start sucking oil up from the lifter galley past the thin gasket into the intake ports and burn it off in the engine.
Anywhere between 1 quart every 300-1500 miles or so very common in early model trucks.
2. The truck engines where GM recommended to use mostly 5-30W synthetic oil, I believe the engine with its big bore and long stroke does not like these weight oils especially in slippery synthetic and some of this oil gets past the rings. I have talked to many 8.1L truck owners who switched over to 15-40w synthetic and the problem disappeared.
Remember in the boat engines the 8.1L 496 are recommended to run 20-50W or 25-40W blended or synthetic oils.
3. The early 8.1L 496 engines had pressed pins in the piston/rod setup and the piston had a pretty good offset in its pin placement and this would cause some piston thrust and resulting piston slap that was easy to hear in cold truck use. This thrust (slap) can cause the ring pack to pass some more oil and when using the very light weight synthetics in the trucks the oil pass problem was increased. GM actually paid to replace thousands of these engines in the early trucks to eliminate customer complaints and possible class actions.
In 2004 GM changed the piston and rod design and went to a full float pin and piston with less offset and the slap and oil burn problem was nearly eliminated.
In the boats with louder exhaust you could not really hear the piston slap noise and it disaapeared after the engine warmed in both cases. In the early engine boats again the heavier oil weights seemed to also eliminate the oil burn.

Forgot to mention that in any case or use a 496 -8.1L engine with a piston or ring mechanical issue will use more oil like any 4 cycle engine.

Best Regards,
Ray @ Raylar

ok yall have convinced me that they are good engines thanks for the help

Would running the 15w-40 be too thick for the NE climates?

i've always ran 25-40 with no issues, though i am further south than you

Since its pretty rare for any performance boaters to be out boating in the Northeast when the temps are really low I would not recommend going down in lower weights when you are boating with a freshwater cooled 160-170 degree constant cooling temperature engine like the 496 -Merc..
Stay with the recommendations from the 496 marine engine manufacturers and stay with either 25-40w or 20-50w synthetics or blended synthetics.

Just my professional opinion.

Best Regards,
Ray @ Raylar

I meant to qualify that and ask if running the 15W-40 in my truck engine during the NE winter is a bad idea. Too think still?

I personally think that running the 15-40w synthetic or blended oils in the truck 8.1L (496) engine is the best choice in any climate, especially warm climates. I just don't like what I see in these engines when running the 5-30W and 10-30W.
I think the higher oil consumptions that show up in the trucks are partially attributable to the lighter oils in this particular engine.
Just my opinion though.

Best Regards,
Ray @ Raylar