Mercedes Engine

[rivonia]

About to buy a Mercedes Engine OM346 6 Cyl. Only done 10000 miles and is a 1980 model. Any views/info appreciated

 

[jaycee]

Hi,have a mercedes om636 with approx.3000 hrs..Still runs very well however a bit hard to start if left for more than a few days.

 

[saltwater_gypsy]

I have the smaller 4 cylinder OM314 engine and excellent it is too. The great thing is that you just go to the local Mercedes Commercial spares desk and get your bits at a fraction of the cost of well known Scandanavian and Japanese makes. Bowman parts for marinisation are available through ASAP.
At 10,000 miles the engine will only have done about 3,000hrs and is probably in good shape for at least 10,000hrs.
Another key feature is that you can dismantle and reconditionthe engine in the boat if you really have to since a side panel off the crankcase comes off to reveal the big ends.
Good luck.
PS These engines are now available new from Iran and are used in all the buses there.

 

[Eventide26]

[ QUOTE ]
Hi,have a mercedes om636 with approx.3000 hrs..Still runs very well however a bit hard to start if left for more than a few days.

[/ QUOTE ]

Hi Jaycee
Your starting problem? Not knowing that engine, but assuming you have pre-heaters (glow plugs)? these often give problems on all diesels, both marine and road, if one or two are on the way out or duff, it will be hard to start, 3 to more even harder if not impossible in cold conditions.

One test which can determine this before going down the route of dismantling them is; Try a start from cold, if it starts, stop the engine and with a moist cloth or a wetted finger, which ever you are braver with /forums/images/graemlins/smile.gif, moisten the glow plug terminal, and see which dries quickest or feels hotter.
This helps (sometimes) as to which one may be duff.
If that fails, disconnect each glow plug, test after each one, and see if there is any improvement or deteriation in starting characteristics.

Hope this has helped a little....If it has I'm Adrian Cox, if not I'm Davey Jones and I've just got me coat.
/forums/images/graemlins/laugh.gif
Adrian

 

[rivonia]

Once again thank you all for the feed back. I am doing well on this forum as I seem only to generate posotive results back
Thanks again

 

[saltwater_gypsy]

"but assuming you have pre-heaters (glow plugs)? "

The Merc engines of that series don't have glow plugs. They are direct injection engines which should start well at all times.
A possible problem is a small air leak clklose to the injector pump. The leak can be so small that the fuel evaporates once the engine is hot and it can be impossible to detect. The engines are self bleeding so the problem disappears once it starts.
It may be worth while to check the washers on all the banjo couplings as they are made of an alloy which is prone to corrosion with seawater.

 

[damo]

The OM636 does have glow plugs - originally series plugs with a ballast resistor, and a glow indicator on the dash, so if one is duff then none of them work. Mine have been now replaced with parallel fast-start plugs.