17 year old boat with twin mercruiser 4.3l (205hp)

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Paul-F

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I am looking at a year 2000 30ft boat with twin Mercruiser 4.3l (205hp) and sterndrives with 580 hours on them. The port engine had an oil leak but don't know how severe as I don't know when the bilge was last cleaned. This was with the boat moored and they were not started up. Both engines have a few bits of rust showing on closer inspection. I have the paperwork since 2012 showing engine services in 2012 & 2015 and drives serviced in 2014 & 2016. The services seem comprehensive but I don't have any idea how much use that they had over that period (since 2012) or how they were started/stopped, used at cruise/idle etc. I know what my 25 year old 5.7lt engine/drive has cost to maintane over the last 6 years (rebuilt 12 years ago) so have doubled that for this one which is ok but I don't fancy a couple of unexpected engine/leg rebuilds too soon!

I guess its fuel consumption is at about 14gph cruising at 24kts, my family likes so they will want to use it (current boat is too small to overnight in for us) so am thinking of getting a sea trial.

How well do these engines last and are here any specific issues to look for. I have not decided yet whether to offer low to cover an engine/leg service off or offer near asking insisting that the service be done as part of the deal but am thinking about it as a potential purchase ..
 
Is that fuel burn correct as my twin ad41s use 10 gallons at 21 kts.
Several years ago I did lots of hours on a single 240hp mercruiser...coats £600 in petrol to go from Yarmouth to Cherbourg and back...that was at £0.50 a ltr ish.

I seem to remember that the burn was about 20 gallons at 20 kts.

So you might be right with 16 gallons per hour but per engine also.
 
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I think you can apply what ever you have learned from your 5.7 to the 4.3s.
If raw water cooled it is frost damage or internal exhaust manifold water leaks that probably most often kills these engines. Even close cooled engines carry the risk of leaks at the exhaust elbow.
Compression checks and check for water in oil (dipstick and oil filler cap) should help peace of mind. Any signs that the exhaust components are old or leaking on the outside should prompt replacement or at least inspection and gasket renewal of those components.
I would hunt the oil leak down as it could be costly to fix (in labour).
You hear of oil pans rusting through and I have experienced this myself
 
Sailorsam101 said:
Is that fuel burn correct as my twin ad41s use 10 gallons at 21 kts.
Several years ago I did lots of hours on a single 240hp mercruiser...coats £600 in petrol to go from Yarmouth to Cherbourg and back...that was at £0.50 a ltr ish.

I seem to remember that the burn was about 20 gallons at 20 kts.

So you might be right with 16 gallons per hour but per engine also.
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If
that's the case then I am out!!
 
dpb said:
I think you can apply what ever you have learned from your 5.7 to the 4.3s.
If raw water cooled it is frost damage or internal exhaust manifold water leaks that probably most often kills these engines. Even close cooled engines carry the risk of leaks at the exhaust elbow.
Compression checks and check for water in oil (dipstick and oil filler cap) should help peace of mind. Any signs that the exhaust components are old or leaking on the outside should prompt replacement or at least inspection and gasket renewal of those components.
I would hunt the oil leak down as it could be costly to fix (in labour).
You hear of oil pans rusting through and I have experienced this myself
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Raw sea water cooled and will have a survey done in any case - Inc comp check.

Its in decent condition for age and will be with us for a long time if purchased so engine rebuilds will be a part of future spend I daresay, just not too soon :)
 
I suppose if you guess 1.5mpg at 25mph giving just under 16gph you will be in the right ball park...that's for both engines.
You used to be able to find boattest.com reports for similar configuration boats to get an idea, though I havn't looked lately.
 
Paul-F said:
Not quite the best for a spot of fishing then! Hope its not that high lol.
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Depends how fast you go!
Slowing down to a more moderate cruise could be 15-16 gph, but someone else might have got to your favourite Sea Bass Spot before you? :)

.
 
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Paul-F said:
I have used this site for fuel consumption: http://www.boat-fuel-economy.com/me...7.4-8.1-8.2-fuel-consumption-imperial-gallons

I have assumed cruise RPM to be 3500 so that equates to approx 6.5 gph I reckon per engine so 13gph for both @ 3500 (Imperial!) ...
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Interesting site,
Not sure the figures quoted are correct thou, have just run a comparison between the Suzuki DF115 and the DF140
I think both engines share the same block, anyway apart from WOT the 140 looks more economic???
The difference at 4.5k is huge.
 
Boat2016 said:
About 8 gph per engine is about right for them, I had a boat with single 205 and that's what you use at cruising speed
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That I can live with, tested gph says nothing about the state of sea/wind/bottom so yeah that's sort of what I expect ... I have asked but don't have an answer on this from the broker/vendor.

My main concern was those engines really which from what I can glean from the good auld internet are good if looked after properly and I can expect to see around 1500 hours or more use from them, or from other sources much less if not looked after properly (regular oil/filter and some oil temperature management) - if I had them from new I'd be more confident of achieving good hours with general maintenance and starting/cooling procedure like I do with my cars & bikes over the years .. My rebuilt 5.7 vp is on 850 hours and going strong after having replaced various bits over time. So purchasing with 580 hours running in itself says nothing really except that there could be premature wear ..... engineer's report, history and sea trial are what I have to go on for this so if they stack up I'll be happy! Its not an exact science, but the more info the better :)
 
Hi
Having had 2 boats with the vp and Merc 4.3, I can tell you they are great engines. Mine were only single engines but nothing goes wrong with them as long as you service every year (really cheap parts) and watch out for exhaust and riser corrosion.
At about 3000rpm each engine will use about 6 gallon per hour.
I'd imagine that application and both engines running at 3000 rpm, you would be using about 12 gallon per hour and doing about 25 mph....not too terrible !
 
QBhoy said:
Hi
Having had 2 boats with the vp and Merc 4.3, I can tell you they are great engines. Mine were only single engines but nothing goes wrong with them as long as you service every year (really cheap parts) and watch out for exhaust and riser corrosion.
At about 3000rpm each engine will use about 6 gallon per hour.
I'd imagine that application and both engines running at 3000 rpm, you would be using about 12 gallon per hour and doing about 25 mph....not too terrible !
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OK ... have taken note.
 
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