Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

[JoLin]

I may be in the market for another boat soon, and wondering about the common differences between these 2 engines in terms of servicability. I'm talking about an I/O arrangement.

I've owned SBC-based engines in several iterations, and on the whole it's pretty easy to change belts, hoses, water pumps, thermostats... all the most common maintenance and repair items.

I'm not familiar at all with the big blocks. Are they any harder to service? Are there any 'gotchas' where they're concerned? Problem areas that the SBC's don't have?

Thanks.

 

[Fishermark]

Re: Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

Same basic engine - even many of the parts are interchangeable. A big block will give you more torque and may not have to work as hard... so one could say it would last longer.... but the basic misc items are the same.

 

[thumpar]

Re: Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

Since you posted this in the Mercruiser section I am going to assume that is what you are asking about. The biggest difference in most setups will be the drive. Most 5.7l come with Alpha drives while the 7.4l came with Bravo. In the engine bay you may find the 7.4l a little more snug making for a little less room to get to stuff.

 

[haulnazz15]

Re: Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

Most things can be easier to get to "on" the engine due to everything being a bit more spread out. However, like thumpar mentioned, it can get tight in small engine bays, especially when twin big blocks are side by side.

 

[Walt T]

Re: Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

Nobody ever complained of having too much power

 

[MarkSee]

Re: Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

Now if you can get a higher output 5.7 mated with a Bravo drive then you may have the best of both worlds.
I know some model 5.7s had almost as much hp as my 310hp 7.4; not sure about the torque spec though. If it's a slightly bigger and heavy cabin cruiser you'd want a Bravo 3 where other models a Bravo 1 is the best choice.

Mark

 

[thumpar]

Re: Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

Now if you can get a higher output 5.7 mated with a Bravo drive then you may have the best of both worlds.
I know some model 5.7s had almost as much hp as my 310hp 7.4; not sure about the torque spec though. If it's a slightly bigger and heavy cabin cruiser you'd want a Bravo 3 where other models a Bravo 1 is the best choice.

Mark

One of the reasons I bought my boat is because I have lots of room if I want to upgrade the engine and not have to worry about too much HP on the drive.

 

[tpenfield]

Re: Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

The maintenance and repair stuff is going to be similar, as they are both V8 engines. As mentioned, the 7.4L might be a little more 'snug' in the engine compartment.

The bigger difference will be in the not-so-common repairs . . . the 5.7L is more prevalent and cylinder heads, long blocks, etc. can be had for about 1/2 the cost of the 7.4L.

BTW - the 7.4L is on the endangered species list, as they have been phased out in favor of the 'jacked up' 6.2/377 engines.

 

[JoLin]

Re: Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

Thanks for the input, guys. Good point about 7.4's maybe being a bit more expensive to fix and maintain. I ran into that with my 4.3's- the (Volvo) mani's and risers cost a fair amount more than they do for a 5.7. That was an eye opener.

As far as power vs. size of boat, etc... yeah, I know. I know better than to buy one that's seriously underpowered. In the 10-15 year-old 26 foot class I'm researching a 5.7 is fine (and preferred), but there are a fair number of 7.4's floating around. If I find a boat I like, I want to know whether to be 'concerned' if it has a 7.4. Sounds like it's mostly a toss-up in the repair/maintenance dept, so that's good to know.

 

[thumpar]

Re: Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

I wouldn't want a 5.7l in anything bigger than a 20' unless it was a mag or hopped up somehow.

 

[JoLin]

Re: Ease of Maintenance and Common Repairs - 5.7 vs. 7.4?

I wouldn't want a 5.7l in anything bigger than a 20' unless it was a mag or hopped up somehow.

That's you. One of the points I constantly have to make is that when you're boating in a bay that nearly always has 1-2 feet of chop, that kind of power becomes largely academic. "High speed cruising" for an under-30 foot boat around here is 25-28 mph. Anything higher throws the passengers around like rag dolls and makes a helluva mess in the cabin. In addition, my passenger load is the wife and I, 95% of the time. A 260 hp 5.7 in a 26' express is a good combo here.