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Ant cole

Ruggerini rm278

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Hi guys. , re last few posts. , 

we have had ongoing issues with smoke , at the moment we have changed  injector nozzles , all clean fuel and at the moment the fuel pump is under trial with feeler gauges to shim it at different heights, 

 Everything I read says advance timing , ie remove shims to advance to get less smoke , 

we have tried all shims removed and it was worse, , now we have .8 thou gap and it’s way better, ,

Our engine has no glow plugs , since altering timing we have to use hot air gun to warm manifold , so it’s a pig to start but runs ok , 

Its hunting a bit however , engine temp is about 57 degrees measured on digital device at top of manifold where temp sender is , ? 

Any ideas on temp or timing ? There are no timing marks on our pulley , it’s basically an Italian tractor engine , 

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My first thoughts are that it could be a bit hotter but the hunting could be a sign that its too retarded. Difficult starting also. A retarded engine will squirt fuel into the combustion chamber when the piston is at, or even after TDC, it needs to be a few degrees before Top Dead Centre so it gets squashed and hot and goes Bang. Too advanced and it tries to drive the piston back down the cylinder before it goes over TDC, with a hand start engine this can be painful Hopefully others who are more familiar with the  engine will be along to comment (Warning: I am not an expert!)

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Over advanced is hard to start too,generally with lots of white smoke before it starts.Not to mention excessive bearing loads.......do not over advance any diesel to cure smoke ,it doesnt work,and may wreck the motor......I suggest you look at ways to increase the running temp.........intake air from around exhaust,blanking part of the cooling air,or recirculating cooling air........I still think you may have the wrong nozzles, pistons,or pistons in back to front........white smoke is caused by fuel spraying on cold metal ,and not burning fully.

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I have been in a similar situation with unknown timing and have spoken to a few real experts about this.

The best solution I found was to make small timing changes and listen to the engine, though its only a half hours work to adjust the timing on mine.

In general an over advanced engine sounds bad due to the high combustion forces and this is a much better indicator than the increase in smoke at retarted timings.

I had the huge advantage that I knew what the engine sounded like before I removed the injection pump, and also its a modern engine (JD3) with clearly audible combustion.

It is possible that some older engines have such soft combustion that its not really audible at the correct timing, but I don't have enough first hand experience of vintage engines to be sure of this.

A hotter exhaust is also a sign of retarted timing but again this is of little use unless you have something to compare it with.

 

By co-incidence I did an injection pump swap yestarday and now my engine sounds lovely, but sadly I think I need to advance it a little bit.

 

................Dave

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One sign of over advanced injection timing is increased cyclic irregularity ,both at idle and to a lesser extent thru the whole rev range.....if you look in any book on diesel engineering,you will find that a few extra degrees of advance increases peak cylinder pressures greatly ,and its not difficult to actually double peak pressure to the order of 1000psi or more.......and in my experience retarded timing can cause black smoke,not white,which is unburnt fuel,but does not make starting  more difficult.......always providing its a matter of 5deg out or so.

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Ant - how did you get on in the end? Did you replace the engine? I've never had hands on an RM278 but have had a PM105/2L, the larger water-cooled twin, for 30 years. It does have a tendency to smoke when cold and unloaded (e.g. after 15 mins idling) and soot up, but the smoke is not 'abnormal'. It's just what you would expect from a 3000 rpm DI unit running at 600 rpm much of the time, and the exhaust is completely clear under load once fully warm. At first, we had excessive exhaust valve seat wear, as the soot tended to cause leakage and wiredrawing. When the limitations of the plain cast iron seats became apparent, we put hardened seats in and never had any more leakage. But this brings me to a point; amongst your various tests, did you take compression readings and were they OK?

 

Re. lack of timing marks:  The bellhousing on our engine had no inspection hole, but once added, we were able to see the flywheel marks.

Re. temperature, as I say I don't know your model but I am surprised there is no thermostat. Ours is under the outlet elbow on the manifold and holds the engine at a nice constant 82 degrees at all loads, although the engine has a tendency to drop below this during extended idling.

Edited by Lucien

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Hi, we didn’t need compression tests as it has had new liners and piston rings , , I pulled the fuel pump off and all the shims , then put feeler gauges under it and ran it  with different heights ,at this moment in time the smoke is ok when she’s warm , as the temp only seems to get to about 70 degrees. I’ve clamped a hose down a bit  to limit water to get it to run hotter,,, we have been running like this since summer , as the fuel pump has no shims under ,slight oil from its mount but not major , , it’s usable , we still shut it off in locks. , but as a holiday weekend boat it’s ok , , we will probably upgrade  the boat in about a year so don’t want to spend ££££ On new engine unless a real good cheap new one comes along,   To be fair , it always starts good, and people seem to like the 2 cylinder pop pop , , ,, never a dull moment and always something to alter ,   Ant 

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