Cummins Mercruiser 1.7L 120HP Bowrider

[Seadoctor]

I am interested in buying a second hand 18ft Bowrider (Searay 180, 2005) with a Cummins Mercruiser 1.7L 120HP engine. Boat and engine both look in great nick but I’ve read some old threads here and elsewhere casting doubt on the reliability and performance of the engine.

In terms of use, I am planning to use the boat for short trips (maybe 5 miles in a day total at the outside, usually less) and a bit of water skiing but I’m not interested in flying around at top speed and don’t plan to tow anyone heavy.

A couple of questions I’d really appreciate some knowledge on:

1. Is the engine reliable enough for the purpose on the understanding that it’s been properly maintained?
2. Is the engine realistically powerful enough for the purposes stated?

Thanks for your wisdom!

 

[Ferris]

Looked into one of these in a RIB. The engine is based on the 1.7 Isuzu/GM car engine and the issue is with the wastegate pivot seizing and the wastegate remaining closed. This can cause an overboost situation which usually burns a hole in a piston, which grenades the engine. Boats operated in salt water appear worst affected, especially those with poorly baffled/waterproofed engine bays. Also the turbo blanket appeared to exacerbate the issue as it soaked up moisture and was wrapped around the turbo. Also believe cooling was marginal.

Other than that they seemed well regarded but like any engine they won't like being flogged all the time.

In a sports boat I would have thought a nice 3.0 or 4.3 petrol engine would be nicer to operate and more reliable.

 

[Seadoctor]

Thanks Ferris, much appreciated. Agree I would be aiming for a more “standard” petrol engine for a basic Bowrider but that’s the problem buying second hand- can’t buy bespoke.

How easy is it to regularly inspect/replace the wastegate??

 

[Jsu]

1. Is the engine reliable enough for the purpose on the understanding that it’s been properly maintained?

I had one of these engines destroy itself despite annual maintenance by a dealer and looking good from the outside, so I would be cautious (would not buy again). It was a total loss and new engine required.

2. Is the engine realistically powerful enough for the purposes stated?

I had it in a 22 feet daycruiser and it always felt a bit underpowered, not a major issue in use, if you are not set on a high top speed, but in a small boat and when the sea is nice and flat it was clear the boat could easily have handled more power. Also imagine running the engine hard probably contributes to the problem. I know some have no issues and as you have also seen online others have also suffered catastrophic failures.

I would go for an outboard in the size of boat you are looking at. Much more quiet engine at lower speeds, likely cheaper to buy and maintain and for the use you describe any additional fuel costs or extra fuel consumed is going to be a very marginal thing compared to the total costs of keeping the boat. You also get an engine you can lift out of the water and avoid the outdrive and associated potential problems there.

Good luck.

 

[Andy Cox]

Looked into one of these in a RIB. The engine is based on the 1.7 Isuzu/GM car engine and the issue is with the wastegate pivot seizing and the wastegate remaining closed. This can cause an overboost situation which usually burns a hole in a piston, which grenades the engine. Boats operated in salt water appear worst affected, especially those with poorly baffled/waterproofed engine bays. Also the turbo blanket appeared to exacerbate the issue as it soaked up moisture and was wrapped around the turbo. Also believe cooling was marginal.

Other than that they seemed well regarded but like any engine they won't like being flogged all the time.

In a sports boat I would have thought a nice 3.0 or 4.3 petrol engine would be nicer to operate and more reliable.

+1 on all the above.

I have seen three of these engine with holes in No. 3 piston.

For the type of use you're talking about, I agree that a good, well looked after 3.0 or 4.3 V6 would be a better option.

One big problem which affects lots of these engines and stems from poor boat design, is large amounts of water being dragged over the back of the boat on wetsuits etc, that then finds it's way down past the engine cover and onto the engine, bringing on all sorts of corrosion problems.

Andy

 

[stelican]

You could find the performance a bit marginal.
I have not tried that boat and set up, I have tried the Regal 1800 bowrider with that engine and we have pulled a skier with 3 people onboard.Top speed 32 knots without skier!
The Regal had a stepped hull which makes it plane easier and quicker and at lower speed than the Searay planes.
It would be worth you paying for a demonstration run if you could persuade the owner.
As others have said problems with turbo wastegate seizing due to corrosion important to keep well lubricated and dry if possible. good power output for such a small engine but worth soundproofing engine bay.
The best engine set up for that size boat is without doubt a V6 petrol 220/225 hp very quiet very smooth plenty of speed at lower revs and an absolute flyer with the throttle down. So fast it makes you laugh! probably £50 for a day out that you suggest.

 

[Seadoctor]

Thanks all, very helpful. Planning sea trial before buy but will keep an open mind...!

 

[rafiki_]

I had a pair of these engines in a Sunline were fantastic for me. If you Google these engines, then I think you will find most of the problems in the US with fast fishers. My understanding is that the fisherman run them at full throttle, and the engines are quite exposed to the elements. In your bow rider, the engine should be well shielded from any salt water. I sprayed the waste gate rods every year with WD 40 type stuff. Engine is used in the Vauxhall Astra and Van in the early 2000’s, so parts regularly available from a Vauxhall dealer. Should be mated to a Alpha 1 Gen 2 outdrive. These are easy to maintain, and in my experience very reliable if properly maintained.
Need to check that the cam drive belt has been changed at the right hours. I can’t recall the hours, but it is easy to find.