Serviced Engine (2GM20) For First Time - Problems !

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capricorn

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Hi All,

Serviced my Yanmar 2GM20 (or at least started to) yesterday afternoon. Changed oil and filter, changed belts, replaced impellor, all OK. Had some problems replacing the primary and secondary filters and bleeding the system which I need some help with. Here goes:

- The primary filter is the type with a metal fitting at the top, a filter element underneath and glass bowl at the bottom, all held togethet with a bolt that runs through the middle. I removed the bowl and filter, cleaned bowl, replaced filter element and reassembled. How do I prime it ? There's another bolt on the top of the metal fitting at the top that I imagine is a vent but this is stuck fast and I couldn't move it with a spanner, will try again next week with a wrench after a squirt of WD40. The filter won't self prime with the lift pump. I assume that I need to remove the stuck vent bolt and prime it from there. Any advice on how to prime the filter much appreciated.

- I couldn't loosen off the tightening ring for the secondary filter housing my hand. What tool do people use for this.

- Finally, I couldn't find the zincs, I understand there are 2, one on the head and one on the block. If anyone could post a schematic like someone did for the 1GM last week that would be great.

Many thanks.
 
You can bleed the system up to the filter by removing an outlet screw if you cant move the bleed screw. Look on top of the housing and you will see arrows. If you have a spare port. i.e. a plug in one of the holes with an arrow pointing out remove that and it should do the same job. If the tank is higher than the filter gravity should do the job for you. If not, or there is a syphon loop you can usually coax the first flow by using a bit of plastic pipe stuck in the 'ole an suck. Make sure it is a clear plastic pipe and stop sucking when it comes through though as diesel does not taste very good. I know cos I got a gob full yesterday doing the same thing! Once you have the fuel filter full the engines lift pump should do the rest but again you may have to prime the secondary filter first. Not sure if the 2gm20 is self bleeding.
As far as removing the old filter is concerned it can be a through bolt type in which case just slacken the bolt and give it a tap to dislodge it. Or a spin on type wherethe time honoured method is to wack a screwdriver through the old one to get a purchase on it just like a car oil filter.
There should be an anode in the water manifold somewhere, probably on the drain plug. again not sure but your user manual should tell you. This is the most important (assuming fresh water cooling)
 
I've had a Volvo & a couple of different Bukhs, and none of them would bleed successfully using the lift pump lever - I use the decompressor(s)& wizz the engine over with bursts on the starter motor. The primary filter you describe is normally mounted below the fuel level and will fill as you bleed the next filter. It helps if the tank is fairly full. On my Bukh DV10L, after bleeding the engine filter & lift pump, I had to loosen the fuel pipe at the injector & bleed that before the engine would start.
 
Thanks Mike,

Yes, there's a blanked off port on the outlet side of the filter housing. That was stuck fast as well, but with 2 spanners (which I didn't have yesterday) on the housing and the blanking plug should be easier to shift than the stuck bleed bolt which is so firmly stuck that I reckon I would risk pulling the whole assembly off the bulkhead if a tried any harder.

Plan B is I can't move the blanking plug is to disconnect the fuel line at the fuel pump and use my Pela Oil extractor pump to suck the fuel all the way through from the tank.
 
Have done this a few times on a friends boat.
The pre-filter can be bled by loosening the bleed screw on the top of the filter (or the blanked-off oulet, as already said) and then by sucking the diesel through (I do it with my mouth directly on the bleed hole - if you're quick you don't get too much in your mouth!!! in any case you can treat yourself to a beer later after a job well done ...)

Then on the fuel filter itself there is another bleed screw which you should loosen off a few turns and then manually pump the fuel pump until fuel starts to come out of the bleed hole with no air bubbles (another way is turn the engine over on the starter a few times until fuel comes out - if you have a switch in the engine bay or someone to help you outside).

That is usually enough to get the engine to start; however sometimes (particularly if you have run out of fuel altogether !!!) it is necessary to bleed also at the injectors. Follow the same procedure: loosen the injector feed pipe and turn the engine over.

When the engine us running, make sure that you can achieve full revs. Sometimes all appears OK, but the engine is actually running on only one cylinder, and will not reach full revs. I find it difficult to tell by ear on the Yanmar 2-cyl when both cylinders are firing or when its only one ............ but then I'm not a mechanic!!

Don't give up trying to get the engine going yourself, as it is great experience for the day when you really need to do this in earnest. Its OK reading the book, and watching someone else do it ............ but there's nowt like doing it yourself. After the first time for gaining experience, you'll find it really easy.

Good luck,
Alan.
 
The zinc on the block is at the back on my 2GM20 and is a bugger to get to. You should be able to prime the whole system with the lift pump as long as there is no air ingress around the primary fuel pump ( mistake I made!!!) I like the idea of turning the engine over decompressed to prime it- will give that a go this year as it took ages to prime the system with the lift pump last time.
 
Beware turning over engine on starter to bleed,I turned a Volvo lump into an inefficient and subsequently expensive water pump doing this.I was told later that I should have turned water inlet stopcock off!
 
There should be no need to suck on filter bleed screws etc. A couple of ideas might make a huge difference.
1) Make sure that the fuel tank is full to above the filters.
2) If not it will be a struggle, ASAP make a priming priming attachment to go onto the inlet of this type of filter/separator
3) If the lift pump is hard to operate, turn the flywheel to move the cam on the shaft. Using the lift pump should take no more than a few minutes to bleed the main filter.
4)Some engines eg the VP200X range are self bleeding at the injectors
 
Sorry, should have mentioned this. I never turn the water on unless I'm sure the engine is going to start straight away - including during & after bleeding the fuel & first start after long period without use.
 
2gm20.gif
 
Thanks very much everyone. Agree about not giving up and calling an engineer, understanding how my boat works certainly increases my confidence in it.

Just to clarify, the secondary fuel filter on the block isn't a throwaway spin off type, it's a disposable element inside a housing which is attached by a knurled locking ring. It's this ring that I'm having trouble removing. The ring is about 5cm diameter. I have a filter wrench but it's the chain type and there isn't enough clearance to wrap the chain around it. Might invest in a strap type filter wrench as I think I could get one of those round the ring. Failing that I'll take a pair of Mole grips to it unless anyone has any better ideas.
 
You want a Baby Boa to shift the filter. Try this possible supplier and search on boa. I tried to create a direct link but it didn't work due to the way their site is coded.
I am sure there are cheaper suppliers but I picked up two when I nearly sank the boat due to a jammed but not properly seated transducer. Very good bits of kit for only a few pounds.
 
If your first filter is above the tank like mine is it is a bitch to get it filled after changing filters. I used an oil extraction pump at first but it takes quite a bit of effort. I got clever and bought a big syringe and allways have spare diesel 1 or 2 litres I then fill the syringe and squirt it into the filter it is much easier. once the filter is full the primery filter pump should have no problem drawing it down. You will need to get the blanking cap (filler cap) off though. If your filter was below the level in the tank I dont think you would have had this problem as gravity would have filled it by now.
As for bleeding the injector lines if you loosen one and swing the motor for a couple of secs it usualy works.
 
the first year i had mine serviced the yanmar man used a flat ended blunt screwdriver/chisel type tool to slacken and tighten the ring you are speaking about.
He only tapped it gently


steve
 
Mechanic I saw tapped it (gently) with a blunt screwdriver and rubber hammer. He did the same to tighten it that last bit - else it drips he said. I have done the same - on a friends boat. Be careful not to wack it too hard and damge the knurled ring or compress the rubber 'O' ring too much when tightening. Also make sure the rubber 'O' ring is scrupulously clean on re-assembly ...... according to said mechanic even a grain of sand is enough to cause a drip.
I have to say that I think that filter is a crap design - you just cant get your hand on to it properly.

Alan.
 
Good idea with the syringe. May raise a few eyebrows when vistitors go through my tool box but whatever!

The top of the filter is just about level with the top of the tank. I think the tank is about a third full (yes I know I should have left it full for the winter). I'll try filling it to the brim and see if it gravity fills or at least reduces the amount of suction I'll need to apply to get the fuel to flow. Of course with a non functioning engine it'll be a series of long walks to and from the fuel pontoon with a jerry can rather than a quick motor across the marina. Someone please remind me that we do this for fun, sometimes golf seems very appealing !

Thanks again everyone.
 
As the primary filter is before the lift pump you are trying to pull fuel through it rather than push as for the engine mounted filter.

I solved the problem by fitting a squeezy priming bulb between the tank and the filter. To make sure it was diesel-compatible i bought one for a diesel car. (peugeot 306D)
 
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