My engine trouble - sorry long post.

[iangrant]

Sorry about the long tale.. Volvo TMD31a

Filled up the tank in Yarmouth on Tuesday from about a quarter and sailed off to Poole. As we motored up the Harbor the revs “dipped” about 200 rpm then picked up again, it did this two or three times, then when I throttled back to tick-over the engine stopped. Turned the starter and off it went again. Next morning motored out of Poole and sailed back to Chichester entrance around the south of the Isle of Wight.
Engine started OK and then I thought I’d open it up to full throttle then the revs dropped again, so throttled back and crept onto the pontoon where it abruptly stopped and wouldn’t start again. Had to go home, brownie points all used up.
Went back Thursday to fix it for an important trip on Friday.
I bled the air out using the lift pump lever but no real success so I took apart the seepar glass filter, (one of two in parallel) and cleaned it out, put it back on and with the lift pump drew the fuel up to fill the filter and bowl.
The world was happy again but could only pull 2800 revs.
Did the trip Friday, motored for about and hour all OK.
Saturday morning convinced Mrs G that it would be a lovely day to go to Bembridge so motored off about 07:30. In a force 5 southerly, green stuff spraying the decks just north of the shipping channel I throttled back to wait for a ship to pass then the bl**dy engine stopped.
I rapidly turned and sailed back into Chichester and dropped anchor in the calm waters north of the mooring buoys at Hayling Sailing club.
I bypassed the glass filter(s) and bred the system up to the injectors and off she went again so we motored back to the pontoon where I spent the rest of a sunny day changing the filters and cleaning out the glass bowls. I found that one of the Seepar units had been dripping fuel.
All tightened up now and I can pull 3100 RPM on the pontoon in gear and the revs stay up throughout the rev range.

So what does the panel think, is it fixed, what did it in the first place?

BTW The pain from the beating I took is subsiding the bruises are going down..


Ian

 

[Rustyknight]

Last year I had similar engine problems. It would run fine for hours, then the revs would drop.... sometimes picking up again, sometimes stopping altogether. After stopping, a laboured restart, but then seemingly normal operation.

For some reason, (sods law I guess), it always seemed to happen in the places you really didn't want it to.... Poole entrance with the chain ferry, Lymington river passing the sailing club tec etc)

Changed both filters, although it was still early in the year and hadn't run much... and all seemed fine for a week or two. Then the problem returned.

New filters once again, although the ones taken off looked fine. Thought a bit more exploration was needed, so I disconnected the feed pipe in the fuel tank. It was totally blocked with black gooey muck..... almost like sodden blotting paper. Inside the fuel pipe was a long wire, with a coil at the end, obviously a very basic filter, and it was clogged almost solid.

Cleaned the pipe out, and then had to remove the fuel tank and strain loads of muck out of there too. Luckily it's only a small tank.

The tank hadn't been cleaned out for 10 years, so I guess it's my own fault..... but being opaque plastic, the only way to have seen the goo would be to remove the tank anyway.

Hopefully your problem isn't the same........

 

[iangrant]

Mike

Thanks for your reply. The only thing I didn't do was to check the pipe in the tank!

I did however draw up some fuel from the bottom of the tank (there is a small brass pump fitted for just this purpose) and it looked clean as a whistle.

I'll do as you suggest though and poke a wire down the pipe.

Thanks again

Ian

 

[chas]

While you are at it, I suggest you blow down the fuel return pipe from the FDU to the tank. I had similar problems to the ones you list a few years ago and discovered the return pipe was blocked. When it was cleared, the problems disappeared.

 

[iangrant]

Thanks for that - there is a strange girgle from the return when priming the lift pump! I'll do that too..

Thanks again.

Ian

 

[Rustyknight]

If... and thats probably a big if..... your problem is similar to mine, the quantity of goo in the tank will probably work it's way bank into the pipe quite quickly.

Out of a 5 gallon tank came about 2 pint pots worth of gunge.... not sure if it was the dreaded deisel bug or the dregs of a tank when from we filled up somewhere.

Like a lot of raggies, I only use the engine if I can't avoid it.... and normally thats when it needs to be relied on.

Hope you sort it anyway. At least for me the tank came out easily! It was just a case of trying to filter a few gallons of diesel on the mooring that made the mess.

 

[iangrant]

The tank coming out is a no no - it's under the engine! There is a big inspection hatch just out of arms reach though! I'm not sure it is sludged up ad the brass pump drew clean from the bottom..

Ian

 

[Rustyknight]

I was going to add, please don't spend 5 days taking the tank out only to find it's clean, unless as a very last resort! /forums/images/graemlins/smile.gif

 

[Anonymous]

It sounds as though the cause is (or was) air in the system, causing a fuel blockage. Do your Separ filters have a bleed screw on the very top? Mine does, and has been installed with a bulkhead over, so that even the stubbiest stubby screwdriver can't fit! This makes priming the Separ very difficult. The other thing that sticks out is the weep around the Separ. Separs will cause a vacuum (mine has a vacuum guage across to show a blocked filter) so if you had a weep, with the fuel pump running you could have been drawing air into the system.

The injectors should cope with a modest amount of air and push it back into the return so I suspect that your problem is most likely to be a conventional airlock. If it was my boat, I would leave well alone but keep an eye open for weeps - and keep in mind distrust of the engine until you have a dozen or so hours of cruising under engine to give confidence.

 

[iangrant]

The separ filters have a chuffing great t bar screw on the top. I should really fill them up with fresh fuel because I guess there must be air in them.
I seem to have no bubbles coming through now at the engine pre filter bleed screw.

I think I poke thorugh the main tank feed and blow down the return.

I am becoming adicted to the taste of desiel now..

Ian

 

[pvb]

You also need to check the pick-up pipe\'s filter...

HR tend to use standard Volvo Penta fuel systems. The VP tank plate (green-painted casting about 200mm diameter) has a removeable pick-up pipe. At the bottom of the pick-up pipe there's a fine mesh metal filter - this can get clogged with rubbish. You can't clear it by poking a wire down it, but it's a fairly easy job to remove the pipe and clean the filter. It looks like this:-

 

[iangrant]

Re: You also need to check the pick-up pipe\'s filter...

Top man - a big thank you for that picture - the mist is clearing !

I'll have a go at taking the plate off but i fear I'll have to drill the heads off the screws as it is a might bit rusty around that area.

Ian

 

[pvb]

Don\'t take the whole plate off...

The pickup pipe is held in with 6 little screws, round where the feed and return hoses connect.

 

[Anonymous]

If your Separs are like mine, then ideally you bleed them by opening the vent with enough fuel in the tank to gravity-fill and bleed the filter. If you clean the Separ when there is insufficient head to gravity-fill the Separ then you could get an airlock - which could be your problem. You might be able to get enough head by filling the tank brim-full to the top of the filler pipe. If not, it is pretty hard to purge it.

 

[iangrant]

Re: Don\'t take the whole plate off...

Yes thanks I've found them, i'll have to clean them up they are pretty rusty - I do have an impact screwdriver so I'll give it a go - more pulled muscles and raw hands. Who wants to go sailing anyway?

Ian

 

[iangrant]

The whole top of the filter comes off and I can fill it up from there as both filters are above the engine. I did draw up fuel through them with the hand prime on the lift pump, one squirt at a time!

I'm pretty convinced it is the strainer in the tank.

Ian

 

[iangrant]

Re: You also need to check the pick-up pipe\'s filter...

I went back down to try to take off the lid - no chance - the screws are just too rusty. I took the pipe off and blew down it, there was little or no resistance, even when sucking it up - eugh desiel taste ......

I've re-tightened up all the clips, took the top off the separ filter and topped it up to the brim, run a full revs (first time I got that) . A quick check at the lift pump and bingo - no air bubbles.

One last check to do, the tank vent.

Thanks to all for your help and suggestions -

We're out this weekend so I'll let you know.

Ian

 

[Anonymous]

Re: You also need to check the pick-up pipe\'s filter...

What worries me is the weep you found around the Separ. The Separ is (presumably) in the low pressure side - i.e. between the tank and the fuel lift pump - and air could get in and get trapped in the Separ again. Worth nipping up all the unions and/or find a way to bleed the Separs without taking the tops off.

Good luck - hope you get it all sorted out.

 

[iangrant]

Re: You also need to check the pick-up pipe\'s filter...

It was a drip where I'd rushed the job and not put it back together again properly - loose allen keys!!

No air getting in since I tightened it up.

ian

 

[LeonF]

Ian,don't know if this is a help at all. On previous boat, a Sigma 33, Beta engine, I was about 15 miles off Ostend, getting dark, first crossing as skipper. Motoring, pulled back on revs as we unfurled genoa to motor sail, and engine stalled. In panic I whipped speed seal off to check impeller.. all fine. I had never bled engine, but noticed secondary fuel filter was empty....glass bowl with paper filter type. Started engine, bled filter and all was well, then did the same some while later..same solution. Got into Ostend, very disheartened, but next day sailed north, and realised that is was essential to keep revs up... idle meant the engine stalled. Got to Middleburgh by knocking it into neutral. Was a club cruise so fellow member helped to check through...turned out to be rubber bits between the tank and primary filter, from dodgy fuel from Kent garage selling pink diesel. And I hadn't used a strainer ! Max revs forcing it through, idle causing it to starve engine. Problem solved.. and the primary filter had'nt even been contaminated..they were all in the first section of the fuel line.