Cummings 120hp Diesel

[Cooper man]

Hi just purchased a coast Worker 21 with Cummings 120 hp inboard diesel.
First a friend bought this boat from Devon with hole in piston brought home and got a garage to fit a Vauxhall Charlton Isuzu 1.7 Diesel engine which everybody says is the same engine. They have had 2or 3 try's on the water it only goes 8 knots anyway I got it right money started to look at it and took Turbo. Off the gate valve stuck tried to find information out on the engine to compare if it is the same engine as the car but no luck,is the any body that could help me as I'm looking of taking engine out to give it a rebuild thanks Cooper Man

[phoenixpete]

Some of these engines only produced 60hp, not sure which one you have exactly. Did you not know if the engine was a good runner before fitting it?

[HDAV]

There are lots of Vauxhall Isuzu 1.7 motors about not sure which one Cummins rebadged.... 120hp is quite high for that motor. I know there are a few marinised ones I think mercruiser is one.

Have a look here:
http://www.rib.net/forum/f36/1-7-die...ers-13173.html

[Tim M]

The 1.7 Mercruiser is indeed apparently the same engine. Terrible engine, as said its pumping out quite a lot of power for the size. Stick it in a boat where its revving quite high a lot of the time.... lots of them went bang. I had one such engine!

What's it revving up to when its pushing the boat along at 8 knots?

[Poly]

Originally Posted by Cooper man

... have had 2or 3 try's on the water it only goes 8 knots ... started to look at it and took Turbo. Off the gate valve stuck ...

If I am understanding correctly it was only doing 8 knots with the gate valve stuck. Has it been tested since fixing that?

[Searider]

1.7 Vauxhall / Izusu engine is the same basic block and the Cummins Mercruiser Diesel.

The issues they often had were that the wastegate on the turbo would stick shut. This would give you loads of boost and hence power - right up until one or more of the pistons failed.

If yours has stuck open you won't get any boost and hence no power.

[Cooper man]

Originally Posted by Searider

1.7 Vauxhall / Izusu engine is the same basic block and the Cummins Mercruiser Diesel.

The issues they often had were that the wastegate on the turbo would stick shut. This would give you loads of boost and hence power - right up until one or more of the pistons failed.

If yours has stuck open you won't get any boost and hence no power.

Yea mine was seized I'm thinking of rebuilding the engine and getting the turbo checked out but I wasn't sure if the engine was the same as the van engine.The other option I have got is to take the Diesel engine out with the leg and replace it with 90hp Honda outboard engine cheers cooperman

[Cooper man]

Originally Posted by Searider

1.7 Vauxhall / Izusu engine is the same basic block and the Cummins Mercruiser Diesel.

The issues they often had were that the wastegate on the turbo would stick shut. This would give you loads of boost and hence power - right up until one or more of the pistons failed.

If yours has stuck open you won't get any boost and hence no power.

Yea thanks it was seized but the was no power don't no weather to rebuild engine and turbo or to replace with Honda 90 hp outboard any ideas cheers cooperman

[beamishken]

The waste gate can stick open or closed first thing you need to determine is if it's getting boost pressure if the waste gate sticks open all the turbo boost is lost down the exhaust
A pressure guage on the inlet manifold will give you an idea should see 15psi ish under load if not then there's your problem
Although they got a bad reputation in the early days they can live a happy life if looked after ie not run with waste gate stuck closed and not overloaded or ran at full chat for long periods
When running they are an eager little engine with very good power to weight & surprising performance for their size.
Unfortunately the turbo isn't from a car so not available from automotive suppliers or breakers yards

[georgec]

Did they change over the fuel pump and injectors? They are different. You also need to change over the drive cogs as one of them [fuel pump from memory] is one tooth different from the car engine

[John Kennett]

Originally Posted by beamishken

When running they are an eager little engine with very good power to weight & surprising performance for their size.

Maybe so, but really not well matched to a boat this size in my experience. I drove a 6.5m RIB with one of these engines a few years ago and was utterly underwhelmed. It had a top speed of about 25 knots and was horribly sluggish.

[Last Tango]

Originally Posted by John Kennett

Maybe so, but really not well matched to a boat this size in my experience. I drove a 6.5m RIB with one of these engines a few years ago and was utterly underwhelmed. It had a top speed of about 25 knots and was horribly sluggish.

At 725KG (bare boat) the Coastworker is probably going to be even heavier than a 6.5 mtr Rib.
I'd think, all factors taken into account, there wouldn't be much difference in performance between the 90hp Honda OB and the 120hp IB even if it was running ok. & with that power to weight ratio both of them are going to be pushed quite hard with the Honda more likely to survive it.

[georgec]

I have one in a Tohatsu One Design (7m), and it performs well. Top wack is 34knts, cruising 25-28knts and returning about 2.5 gah. That's two up with full tank.

[John Kennett]

The Tohatsu RIB is pretty quick and performs better than most with a modest engine. The originals had 90hp outboards and were surprisingly impressive.

If I was the OP I'd be thinking about a 150 outboard.

[Xk59D]

Originally Posted by georgec

I have one in a Tohatsu One Design (7m), and it performs well. Top wack is 34knts, cruising 25-28knts and returning about 2.5 gah. That's two up with full tank.

25 knots in a 7m boat is 11lph...nice!

[beamishken]

Originally Posted by John Kennett

Maybe so, but really not well matched to a boat this size in my experience. I drove a 6.5m RIB with one of these engines a few years ago and was utterly underwhelmed. It had a top speed of about 25 knots and was horribly sluggish.

I'm not familiar with the coast worker but have owned two boats with this engine one 18ft bowrider and a 6.5 raider rib and both went well but as I said the engines don't like being overloaded or overworked so if the boats a bit lardy then probably not a good combination. I doubt the 90 Honda will be much if any better, although it may hang together longer if worked hard

The automotive engine uses different pistons with different volume & shape combustion chambers the injectors and pump will be different too so if the automotive engine wasn't modified then it's possibly not going to work well anyway

[Cooper man]

Originally Posted by beamishken

I'm not familiar with the coast worker but have owned two boats with this engine one 18ft bowrider and a 6.5 raider rib and both went well but as I said the engines don't like being overloaded or overworked so if the boats a bit lardy then probably not a good combination. I doubt the 90 Honda will be much if any better, although it may hang together longer if worked hard

The automotive engine uses different pistons with different volume & shape combustion chambers the injectors and pump will be different too so if the automotive engine wasn't modified then it's possibly not going to work well anyway

Thanks for that information regarding pistons I was told they swapped injector pump over but not to sure over injectors but can't a lot of information on this engine it might be better engine if I stick to Honda 90hp I just don't want to spend lot of money on this engine and it would be wasted thanks cooper man

[Cooper man]

Originally Posted by georgec

Did they change over the fuel pump and injectors? They are different. You also need to change over the drive cogs as one of them [fuel pump from memory] is one tooth different from the car engine

Thanks for that information cheers cooper man.