Perkins 4108 - oil loss... is it dead?

[Mildew52]

Hello:

Mr Perkins 4108 was running fine but due to unforeseen circumstances it lost most of it's oil whilst running, and I'm afraid it took me a awhile to notice.

anyway, I've fixed the leak and replaced all the oil and filters and fuel filters and re-bled the engine. Whilst I was at it I sorted a leak on the Raw water pump.

The engine seems to start OK and runs OK, but when I get past 2000 revs it ramps up on it's own to over 3000 before I panic and pull back the throttle. So it settles OK at lower revs, but surges out of control over 2kRPM

I am hoping because it starts OK and runs OK at 2kRPM that there is no serious damage from the loss of oil, but am wondering what else could be the cause of the surging issue.

Can anybody give me some reassuring advise please?

Mark

 

[Slipstream 34]

Similar symptoms discussed here

http://www.endeavourowners.com/dscsn/systems/propulsion/surging.html

 

[RichardS]

The oil loss on its own might well have not caused any damage to the bearings unless it was running for a long time with zero oil circulation. However I don't know how that might have caused the surging unless something else has indeed worn excessively which is clearly not good news. :-(

Richard

 

[PaulRainbow]

I think the oil loss and surging are not connected. The first thing that would be destroyed by oil loss will be the crank bearings, so it sounds as if you ran it short of oil, not out of oil and you got away with it.

I'd guess the surging is connected to the work done on the fuel system. Check the filters are properly sealed, check all the connections, check there is no air in the system.

 

[jimbaerselman]

If you've got "cold start" fitted with its own fuel input, check its fuel input is not sticking open. Causes a variable trickle of fuel into the air intake . . . a great way of causing un-expected surges of revs at idle. Smaller surges when under load.

Don't ask . . . took me ages to find that one.

 

[No Regrets]

You didn't say how it lost it's oil in the first place!?

However, it might have a blocked engine breather which is causing the engine to digest it's own oil, which in the worst case could cause 'runaway' which, unless you can block the air inlet PDQ it will overrun until it blows up.

If the mains or big ends have gone, the engine will sound much more clattery as you rev it up (I know....they already sound like that! LOL)

Worth checking the Diesel lift pump diaphragm hasn't gone, which would leak neat Diesel into the sump, making the engine fume badly and thus run on the thinned out oil vapours from the sump into the breather.

 

[snowbird30ds]

Air in the fuel system can cause surging, my old boat was a bugger for it.

 

[john_q]

Air in the fuel system can cause surging, my old boat was a bugger for it.

+1 my problem was caused by a 28 year old faulty mechanical fuel pump

 

[Mildew52]

Thanks to everyone for the replies and suggestions.
I'm feeling more confident that there is no serious issue, but a secondary problem that is not serious but might be a bugger to fix.
I'll work through the fuel system and try and find the cause of the problem.

 

[snowbird30ds]

A tiny air leak around on of the seals on a cav (I assume thats what you have) filter can be a PITA to find if the filter is above the level in the tank as it leaves no sign, check all seals including the centre bolt and make sure there is not an old seal wedged in the grooves under a new seal (I had that).

 

[danielefua]

The last time I had a similar problem with my 4.108, I found the cause in a clogged diesel filter, namely the secondary made of paper. Starvation of fuel made me inadvertently push more on the throttle to get the same RPM but occasionally a temporary relief in clogging would make the engine rev up according to the high throttle position.

Daniel