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Discussion Starter · #1 ·
Hi folks, first post. Bit of desperation and frustration, hope the brains trust can help.
We have a marinised OM 636 in our boat, head gasket went recently between 3rd and 4th cylinder. Now replaced. Blocked 4th injector also replaced ( was blowing fuel when opened after attempts to start, all other lines/injectors behaving normally ). Rockers retimed to 0.2 and 0.25 all round.
We were expecting her to start right up but now we seem to have minimal fuel arriving at the injectors. She starts well with an accelerant applied to the air intake. We have bled both filters ( replaced filter 1 as it was dirty, cleaned fuel tank too ). No air coming from top of filter 2 indicating no air in system. Bled fuel pump, no air, opened exit lines from pump to ascertain fuel pressure to injector lines, looks ok. Bled fuel lines to injectors, looks ok ( they use so little fuel it's hard to tell if it's enough or not ).
Are we missing something? Fuel return lines in the wrong spots? Blocked? Timing out? Help! Cheers Simon. Stuck on a small island in a big sea.
 

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HANUMAN
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No nothing of your engine....just off the cuff.... check the microns on the new filters. Is it possible you bought the wrong filters and the fuel pump can't handle them?
 

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Discussion Starter · #3 ·
Thanks Rob, good suggestion, filter checks out ok. It seems to be delivery from the fuel pump which might be partially blocked. We've done a fast rev test to try to clear them with the injector lines removed, hoping this might work but we are killing batteries in the process!
 

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You shouldn't be cranking for more than absolute max 10 seconds at a time!
If you google OM636 one of the replies is OM636 Diesel Engine Spares also [email protected] This is in the UK, of course. But I'm told that the guys there (ask for Manfred) are REALLY good. I have a 21 ft displacement motor boat in the South of England, now over 40 years young. The builder was an MB agent, and he put the OM636 into many of his 21 footers - hugely over-powered of course, though mine hasn't got it. I hope Westfield are helpful to you.
The OM636 is a really old design, and it was put into all sorts of things like small plant, cement mixers, dump trucks, etc., as well as boats. MB built a prehistoric HMUV called a Unimog, and it went into that. It was the prime mover for some ThermoKing truck refrigerators, as well, I believe.
Best Regards
Andrew
 

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Discussion Starter · #5 ·
Thanks Andrew, Manfred and I have been working on this and associated problems for months, still battling an air leak in the vacuum side of the fuel line and a bit of fine tuning. Cheers Simon.
 

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Great - I'm delighted that the reports of Westfield/Manfred are well founded. Where are you based, what boat do you have? Mine is a 21 ft Parkstone Bay, built in Poole. But, mine has a 24hp Bukh, not an OM636.
Sounds like you've got a "man who knows" on the job!
V Best
Andrew
 

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Simon, You dont say if your fuel lift pump is mechanical or electrical?

1) If mechanical pump most (but not all) have a fine filter inside the pump it's self -you can normally recognize these pumps as they are of the serviceable types (ie: bolted together).
2) If your engine is not firing up and you have a raw water cooling system and your engine is below or on the water line shut off the raw water inlet until it's firing and running other wise you can fill your engine with salt water,
3) For starting you obviously need Air/Fuel/Compression and with that a clear and free exhaust,
4) Getting all the air out of the system in some engines tend to be a nightmare , in the trouble some ones I always have the injector high pressure lines cracked at the injector while turning over (raw water closed) , once fuel is flowing nip up one (should hear it start to fire-then number 2 and so forth)
5) As long as you haven't touched the Injection pump timing should not be an issue,

Cheers Steve
 

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Discussion Starter · #8 ·
Thanks Steve,
It's the little lift pump. Current theory is that the replacement pump was defective so we have remounted the old pump but kept the new pump base. Combination of incorrect sized washer and degraded inner rubber seals could be leaking in air.
Motor has a Bowman heat exchanger so no raw water.
Motor is now turning over as it should, yet to tell if the leak is fixed but it's holding a vacuum after six hours so looking good. Fortunately I got the pump timing right at the third attempt, not easy with hard lines resisting any change!
Thanks for your thoughts mate, cheers Simon,
 

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Simon,

unless you are keel cooled, you must have a raw sea water pump to cool your Bowman heat exchanger?, this sea water exits through the Riser/mixer down to the water trap?, if the engine is turned over to long with out running the sea water can back up and enter the engine,(glad to hear yours is running,

Cheers Steve
 

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Discussion Starter · #10 ·
Sorry Steve, I misunderstood your message. Yes our Bowman has been faultless but I get your point. This can be a real problem in the canals and rivers where we spent last year, fortunately it all went well and we have had zero issues this year.
Cheers Simon.
 

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Hey guys,
I removed my fuel pump without knowing that timing would be an issue. Now I have no idea how to reinstall it and time it properly. Can someone please tell me the proper procedure or post a link to a description so I can figure this thing out?
 

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Dirt Free
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Hey guys,
I removed my fuel pump without knowing that timing would be an issue. Now I have no idea how to reinstall it and time it properly. Can someone please tell me the proper procedure or post a link to a description so I can figure this thing out?
There should be marks scribed on the pump base and the mounting plate to line up.
 
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