Mercruiser/Cummins 4.2L Diesel

[eshell]

I am looking at different boats and am drawn to one with a 4.2L Mercruiser diesel. The little bit I have found through basic internet searching seems to say it is a bad engine.

Any comments? What in particular is the weak link? Has a fix been developed? Is there a particular maintenance shop that is considered the experts on this engine?

(I tried searching archives here and didn't find comments)

Thanks,

Ernie

 

[Don S]

Re: Mercruiser/Cummins 4.2L Diesel

Are you sure it's a Cummins diesel, you don't give year or any other info so hard to say.
Merc did use a 4.2L BMW diesel for a lot of years, I wouldn't recomment that one to anyone.

 

[eshell]

Re: Mercruiser/Cummins 4.2L Diesel

Don,
Thanks for bringing up the BMW issue. I just went back and reviewed listing and in fact does say BMW/Mercruiser. Don't know how I missed such an obvious fact. I think the newer Mecruisers are Cummins and I guess I just projected that back.

So, I'l ask the same about the BMW engines then: What are the problems? Who are the repair experts? Has there been specific problems identified and fixes introduced?


BTW, the boats are Bayliner 2859.

Ernie

 

[Don S]

Re: Mercruiser/Cummins 4.2L Diesel

Slow pigs in the 2859. You will be looking at a boat that can barely get to 20 mph. Noisy, smokey, and EXPENSIVE to repair.
I would avoid at all costs.

 

[eshell]

Re: Mercruiser/Cummins 4.2L Diesel

Thanks for comments, Don. Very good info to have.

Ernie

 

[Wandalen]

Re: Mercruiser/Cummins 4.2L Diesel

Slow pigs in the 2859. You will be looking at a boat that can barely get to 20 mph. Noisy, smokey, and EXPENSIVE to repair.
I would avoid at all costs.

You are stepping on my toes now I Have a Bayliner 3058 With this type of engine installed. Is a verry common engine here in Norway , in moast boats here we using diesel engines due to the price on Gassoline its about 4x more then in USA. The Weak link on thise engine was the flyweel with the vibration dempers got loos and was falling off and couse damage to the crankshaft. This problem was solved in the early 90`s. The Mercruiser 4.2 inline 6 sylinder engine got nothing to do with BMW. The Engine is a VM Motori LI 706 Bulidt in Italy and Belgium. Now the engine is called Cummins Meruiser.
And it depending on the HP on this engine, but if its a 250HP it should do around 30 knots.
I dont think you should have anny problems with that engine in this type of boat.
Here is a image of the engine installed in my boat, same engine.

 

[wetspot]

Re: Mercruiser/Cummins 4.2L Diesel

Hi Mate, you say you get 30knots, what drive have you got? and what is your gph?

 

[Wandalen]

Re: Mercruiser/Cummins 4.2L Diesel

Hi Mate, you say you get 30knots, what drive have you got? and what is your gph?

I dont get 30knot , i got 25 knots but a Bayliner 2858 with the same engine should be doing 30knots.
I got a Mercruiser bravo2 drive with ratio 1:1,81 and propeller is 19x19.
Shal see if i find my video of the test tour and put in a link here.

 

[wetspot]

Re: Mercruiser/Cummins 4.2L Diesel

I dont get 30knot , i got 25 knots but a Bayliner 2858 with the same engine should be doing 30knots.
I got a Mercruiser bravo2 drive with ratio 1:1,81 and propeller is 19x19.
Shal see if i find my video of the test tour and put in a link here.

I have had a 300 d-tronic mercruiser in line 6 fitted in my bayliner 2556 command bridge (a bit smaller than yours) but having a bit of trouble getting it to run right, when the problem is finally fixed I will be over the moon if I get 25kt, which hp is yours?

 

[Wandalen]

Re: Mercruiser/Cummins 4.2L Diesel

Wow ! You should get 30 knots maybe more. I got 250HP and my GPS was showing 24-25 knots. 250HP got 2800RPM and the 300HP should do 2900RPM. The 250HP and 300HP is exactly the same engine, only different is the ECM module. I gone send in my for an upgrade to 300HP ca 800-1000$
Then i should get ca 27-28 knots.

Here is a video i made

http://www.youtube.com/watch?v=te22cbq7xqc&fmt=18

 

[MOUELLETTE]

Re: Mercruiser/Cummins 4.2L Diesel

I have d tronic 4.2 l with bravo 3 in a 340 sundancer and it cruises at 26-28 mph and tops out at 40-43 mph its a great engine no problems at all