Engine overhaul - Worth it?

[annageek]

We've had three great seasons on our boat now. She's 19 years old and had at least 450 hours on her Mercruiser 3.0 engine, which has never actually let us down at sea yet!

The thing is, she is getting tired. As I understand it, 450 hours isn't 'high', but it's the 'high end of moderate' in terms of engine hours on a petrol Merc. Oil is slowly now starting to disappear, but doesn't appear to be leaking, and frankly, I really feel like she's on borrowed time. We were planning on doing the manifold and elbow this winter (as they need doing) and considering replacing the starter motor and alternator because according to the service history (and by the looks of them) they're the originals. Although they still seem to work fine, I understand that they often go with little warning, and I expect they too are on borrowed time.

Anyway, with all this in mind, I've been getting quotes to have a full engine out, strip down, clean, and total rebuild. Quotes are coming in at around the £3.5k mark (half the value of our boat!) including removal and refit. It's certainly cheaper than a new engine (even if we were to sell ours as a runner) and if we were somehow to sell our boat during the winter and add £3-3.5k to the proceeds, we'd end up with about 9-10k at a push - not anywhere near enough to justify changing to something else (which will also need £££ spent on it most likely). Add to that the fact that we love our boat and she is the way we want her, so we don't want to change her.

As I see it, we have 2 options.

1. Do the minimum that we had planned to do, and

2. Go ahead with the complete overhaul

Assuming we are, shall we say, 'tolerant' to the idea of spending 3.5k on an overhaul, is it worth it? Is there a chance that with the overhaul, it will actually make the engine less reliable for a while, as teething problems show up (bolts not torqued up quite right coming loose, for example)?

Thanks in advance for your thoughts!

Anna.

[Xboatboyx]

Are you sure a new engine is too expensive?

http://repowermarine.com/index.php/repo ... er-v6.html

[Ianfs]

Good point James, except to upgrade to a 4.3 would cost a lot more as its a base engine.

However..............

Repower 3.0 L GM Base Block £2,640

However, 450hrs is not a great deal and these engines are pretty burst proof. If you're loosing oil, how much, do you think it is burning oil and is it possible that you have a seal which needs replacing?

Replacing the Exhaust is a good idea, but a complete overhaul on a marine engine is usually good money thrown into the water, especially as they are raw water cooled. Exhaust, Elbow and gasket change is a piece of cake on the 3.0l.

If the starter and alternator need replacing then they are very easy to do yourself, just needs a bit of contorting for the starter.

As long as she has had regular servicing with new oil every year, the engine should be ok. If anything you could get someone to do the cylinder head, but again it will probably be fine.

What makes you think she is not running too well? Apart from the oil, that is.

[annageek]

What makes you think she is not running too well?

Nothing really. It's running fine (as far as I know). Just the nagging doubt that something must surely be due to go wrong soon.

The new engine is slightly cheaper than I though. Perhaps, after all is said and done, a re-engine will be roughly equivalent to an overhaul (although, I expect a touch more, depending on how much we could get for out existing one).

I think the master plan is to probably change boat in two or three years. As it stands, If I look forward a couple of years, I can't see our boat selling then for much more than, say 4-5k and taking an absolute age to sell (all the while depreciating, rotting and costing money)... it's just too much of an unknown, but with an overhauled/new engine fitted 2 years ago, then I could imagine the boat selling for a touch more and crucially, selling quicker and costing less when you consider dilapidation over time, storage and the need to faff around dealing with fewer fender kickers. I therefore feel this could be worth at least 1k in real terms. Add an extra 0.5-1k in value to the boat, then you're at £2k difference in overall cost. If it costs 3.5k to overhall/re-engine, then in essence, we'd be paying 1.5k for a couple of relatively hassle free / worry free boating.

Make sense? Or am I just convincing myself of something that is impossible to predict, or totalling up all the worse/best case scenarios?

[_Ed_]

Anna in real terms, 400 or so hours on an engine is really not a lot. I would inspect and maintain the obvious, risers and the like, but at 400 hours there is no way the engine should require a rebuild, unless for example the engine is rotted due to corrosion etc. They are not even highly stressed, and generate about 50hp/litre (engines I work on are as much as 6 to 8 times that) which is absolutely nothing (135 at prop is after losses so will be around 150-160@ crank)

It's much more important that the ancillaries around the engine are in good working order. Keep an eye on that and the engine should see 800++ hours. Even light aircraft engines are expected to last around 2000 hours before major overhaul, and those are run under quite similar load conditions to a boat engine.

If you want to be really quite clever, and keep an eye on your engine then do oil analysis on it. http://www.theoillab.co.uk/product-cate ... ng/engine/

Do one of those every engine oil change, ideally from new and you will catch problems many many hours before you even knew they existed. Anther good thing to do is get a decent oil pressure gauge, and start to keep logs every 10-20 hours or something. Oil pressure first measured cold then hot at every 1000 rpm to WOT. Compare this over time and gradually the oil pressure will drop as 1, it ages and 2, the engine ages. (2 more so) if you have a big drop in oil pressure in most cases that's caused by the mains/big end bearings wearing out and the oil clearances increasing. Again - an EARLY sign of problems WAY before any damage happens.

In addition compression and leak down tests are another way to see engine health. I even cut open oil filter on the engines I work on and build to catch any problems early as well.

Armed with all of the above, there really is not a lot that can go wrong without you knowing it.

Any questions let me know, this is a specialist area of mine...

[Ianfs]

I think you are being an engineer and looking ahead to predict a solution to a potential problem, which in this case may or may not exist.

If you are able at some stage it would be beneficial to arrange a trip out with Ed, sorry Ed arranging your diary. However Ed is the Chuck Norris of Internal Combustion engines, he can remove a spark plug and tell you when the Dinasaur died which made the oil and where the petrol was refined.

[betty boop]

I know nothing and read in Awe of these comments trying to remember these for my own engine problems. Easy to write but Id go with the don't worry stance, just worry about regular maintenance stuff as mentioned. I have a starter rebuild planned for 2016, mainly as I have/had an external water leak above the starter thats caused no end of rust issue on the block and motor mounts, doesnt need doing but is a constant worry. Im reminded of 'if it aint broke don't try to fix it'

But 'I' wouldn't go for any £3.5k work on a boat or car come to that worth only double that. In there ned its only a machine and you have to think of it in a business way sometimes - best to get rid and start again may be add the £3.5k to a new purchase esp as its good money after bad if it goes further wrong.

I have the same with my Nissan Pathfinder 4x4- Want to keep it but the garage has just put us on 'be prepared for a quick sale' alert as the drive failure repair may = over half the motor value.

just my thoughts - good luck

[Bigplumbs]

I think there is a lot to be said for the old adage.............................. 'If it aint broke don't fix it'

[annageek]

Thanks for all the comments! Very helpful indeed!

I had two options:

1. Work out what REALLY needed to be done, then worry about the cost of doing what needed to be done to the engine.

2. Work out the worse case scenario of MIGHT need to be done, and attempt to come to terms with the costs involved.

I chose number two, as dealing with a smaller than expected amount of work/cost was always going to be easier to swallow than the other way round! It's just in order to really get my head around it, I needed to truly believe that the worse case scenario REALLY needed to be done - a bit of boaty method acting I suppose!

To my surprise, the idea of spending 3.5k on the boat to be able to keep her does two things. It proves that I really LOVE the boat and all that she has to offer, and that I am a total nutter with my head in an almighty bucket of sand... but then we're all boat owners, so I'm sure that doesn't come as any surprise!

Anyway, I think it's time for a bit of pragmatism, and Ed's ideas especially seem a perfect mix of cost effectiveness with a touch of going the extra mile for the sake of peace of mind. There's some things that really do NEED doing like the exhaust manifold/riser so they will of course be done. What's the thought on changing the following:

Starter and alternator. As mentioned, they're still the originals. Although not the biggest issue if they do break, but it will mean a call to ssea start if we are out, and likely a couple of precious boating weekends lost by the time we've sourced another and gotten around to fitting it. Plus, I assume if the starter does go, it'll be when you're just about to leave some far flung marina, meaning you have to pay for a tow back to your home port or pay to store the boat in the marina while you sort things out - either way incurring more expense.

Oil analysis - I can certainly see the benefits. Could the oil wizards glean anything from the 'absolute' data the first time around, or is it about establishing a 'baseline' and then making comparisons as oil changes go by? Or is it a bit of both? That said, either way, I guess a baseline will always be of value, and it's no good waiting for something to actually go wrong before establishing the baseline.

Carb rebuild - We had this done three years ago, but this season, when you accelerate hard from a slow speed, the engine bogs down. Accelerating gradually is fine. Is this something to do with the accelerator pump or something like that, and would a carb rebuild sort this? Also, in real terms how hard is this to do? I'm guessing it's got a lot og 'bits' but as long as you have a decent manual detailing the process and setup procedure, then with a bit of patience and fastidious following of the instructions, it can't be overly complex. My dad always talks about the carb on his old mini and how he always had that in bits. If he can do it... Plus, although I understand how a carb works in principle, I am itching to see inside one to see how it actually does it's thing.

Compression test - I think I may start with this, as, although I doubt it, there's always a chance that the engine is running like a pig and I just haven't realised as I have nothing to compare to. Are the cheap compression test kits of any use, or are the readings they give too hit and miss / unreliable to be used? For a leakdown test, do you need an air line to pressurise the cylinder or is there another way of providing the air pressure (e.g. a tyre inflater with a check valve)?

Oil pump and petrol lift pump - what's the life expectancy of these? Are there any signs before they die?

Anything else that I've missed?

It's funny... I expect this winter is going to cost close to £1000 by the time we've done everything. I seem fine with that, but if I had to spend £1000 on my car, which I rely upon and use every day, I'd be livid! Do you know how many pairs of shoes £1000 can buy you!!!! At least two!

[annageek]

Crap! Long post... sorry!