Mercruiser 5.0 V8

[moonshine33uk]

Hi I am looking at a boat that has the above make of engine fitted. It's a carb version not efi and has an Alpha 2 leg. Any thoughts on Mercruisers? I need all the help I can get as I have just seen the light after 25 years of sailing, and whilst I could bore you s******s on tell-tales, cunninghams and leech lines, I bow to your superior knowledge with regard to the noisy bit that is going to cost both arms and legs /forums/images/graemlins/confused.gif thanks in advance

 

[Broombroomput]

I have a 5.7 Mercruiser Fitted (but not working /forums/images/graemlins/frown.gif) to one of my boats, that has carb and Alpha 1. what do you want to know?

 

[Broombroomput]

My advice is not to break it as it costs a lot to replace.

 

[jhr]

I've got the efi version of this engine and (famous last words) haven't had any problems in a couple of years' boating with it. Mercruiser are pretty ubiquitous in the States and part of the Industrial Group that also owns Sea Ray, Bayliner and Maxum (and also Sealine, I think) hence they are to be found in lots of US sourced small powerboats. Many will say that Volvo are preferred in Europe, because that's what a lot of Euro boats have, but spares and maintenance for Mercs are easily available here.

They're based on a big block US car motor (of GM Provenance?), and the basic engine is fairly unbustable; it's the bits added on to marinise it that add the fun. I'm fairly scrupulous about getting the correct servicing done, at the proscribed intervals, in a probably vain attempt to keep it all working. Just had the leg (Alpha 1) serviced, new impellor, bellows, gaiters, oil change, everything taken off and put back on, etc. etc. and the bill came to £500.00, so you are right about the imminent loss of all your limbs. Don't look for a raw water strainer or inlet on the engine, 'cos it all happens in the leg. This makes lots of people jump up and down in panic, but seems to work fine.

Corrosion issues have arisen with Bravo 3 leg (see posts passim) but I think the Alpha 2 is OK from that point of view.

On the whole, I reckon they're fine, though on a non efi model, the carburettor may add further potential for dampness to foul things up? Poster "Mercman" is, gasp, a Mercruiser mechanic and knows all about them.

Caution: I know nothing (and I mean nothing) about engines - this is just my experience as a consumer.

 

[gjgm]

I d say the EFI would be better bet. Sort of 1980s mechanics otherwise, but , hey, they still sell them. think about re-sale... Dont know the exact margin, but the carbs are going to drink a bit more (and of you're new, petrol engines can drink an aweful lot of fuel ! not sure the boat, but 5.00efi will guzzle 7-10 gals per hour without too much trouble,- and you can always open full throttle- and carbs even more !)

 

[Alistairr]

I have a Merc 5.0 MPI, with the Bravo 3 leg, and i think its a great package.

If you have any questions about it, then you really need to just come out with them, we can't help if we don't know what they are!!!!

Also i would suggest you PM Mercman, as he was very help on a recent thread regarding Volvo v Mercruiser. And knows what he's talking about.

The thread in question can be seen HERE.

All the best with it,

Alistair.

 

[moonshine33uk]

Thanks guys ... no specific questions yet as I am new to all this. Really guess I just wanted NOT to hear '' avoid at all costs'' ''unreliable'' ''can't get parts'' etc etc. Sounds ok so far. Have always had Volvo diesels on my saily boats and apart from the spares prices didn't have much to grumble about. Rgds Steve

 

[MadMat]

It's a GM/Chevrolet small block (not big block) V8. So all the engine internals are pretty standard stuff. IMHO, while injection is nice, wiring really suffers on older engines and I can imagine a lot of hassle ironing out bugs in a dodgy efi system. The carbs are all pretty basic stuff, usually either quadrajet or holley. I would guess quadrajet on your motor. The 5.0 isn't going to be a hugely stressed motor - I think they come in up to 330hp on the small block motor in a 'Scorpion' variant. Beyond that is the big block stuff.
Main thing to watch for is corrosion on the manifolds between the manifold and riser, this can leak which would fill up 3,4,5 & 6 cylinders with salt water. Nice!
However, a yearly service to check the corrosion situation and to replace the riser gaskets should be enough.
If it's raw water cooled, I would consider dry berthing so you can flush the motor out ashore after use (like you would an outboard) if it has to be berthed afloat consider a flushing attachment. This can greatly extend the life of the manifolds and motor. Overall GM V8's are pretty trusty and reliable. Change the oil & filters religously, and keep all the ignition system wiring clean and tidy, there's not a huge amount that can go wrong with them.

For engine internals in the UK I've used Rodley Motors and Real Steel. For spare parts, American Marine Imports are pretty good for non genuine spares and have a good stock, or you can rip yourself off with genuine stuff from your local mercruiser dealer. (17 quid for 1 single a riser gasket for example!!!)

One thing to watch on the alhpa drives is they have a direct gear engagement, like an outboard. So make sure the rev's are nice and low when you go into gear, plus also be 'positive' in getting it in gear. Many people think tickling them into gear is the way to go, all this does is chip bits off the teeth.

Changing from sail boats with a diesel to a powerboat - have you satisfied yourself you're prepared to spend a LOT more on fuel?

Also, other thing to bear in mind is the fire risk from petrol compared to diesel. Make sure the fuel system is in good order, if you ever suspect a leak into the bilge of any sort, do not use the boat until it's been corrected and the bilge has been well vented. It should also have a decent engine bay auto fire extinguisher, bilge blowers, and a petrol vapour detector.

Hope this is useful to you.
Cheers
Matt

 

[moonshine33uk]

Many thanks to all .... some very useful stuff. Didn't realise powerboat owners could be so nice /forums/images/graemlins/blush.gif /forums/images/graemlins/blush.gif /forums/images/graemlins/blush.gif