Fuel Bleeding Problem - Need Advice Please?

Dougal

Dougal

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Perkins 4108 (direct cooling)
Been doing some well overdue maintenance and come across a problem....

1) Removed fuel filters, only to discover what I thought was the primary filter/separator, is ONLY a separator. It's a large CAV unit located between fuel tank and engine fuel filter. Should there be a filter in that big EMPTY bowl????

2) After putting everything back together, I'm having real problems bleeding it! The fuel tank is only just above the CAV unit (and full), but I did hear it filling when I opened the fuel tap and loosed the top bolt. With the lift pump being downstream of this, do I just have to rely on tank pressure to bleed this first bowl?

I've had several Perkins engines in the past, but none being the 4108. They were all MUCH easier to bleed than this little bugger. I believe the fuel pump maybe one of those 'intermediary' ones that Perkins used before switching over from jerk to rotary. Also, the water injected exhaust manifold on this, is tight up against the bleed nuts on the pump. Never seen one like it:-( Getting access is bad enough, but it has to be done by 'feel' as i can't really see it. So, i'm hoping i won't need to bleed beyond the engine filter;-) Can see me having to remove the whole manifold to get at it otherwise!!!

Any input much appreciated, as i'm now onboard with no running motor;-(
 
Sadly this is all too familiar to me. We have exactly the same system as you I suspect. I have fitted a fuel bulb, similar to those found on an outboard fuel line, which has helped, but not solved the problem. The only solution that I have found is to bleed the high pressure pump. This is a devil as the bleed bolt (8mm) is on the side of the pump which is obscured by the oil filter and the exhaust manifold; it's also impossible to turn the nut by more than one flat at a time. Then crack the nut on each injector. Never done it in less than three attempts tied up in the marina. God help us on a lea shore!
I hope some one replys with a post that begins...you Wally, all you have to do is........
 
CalicoJack said:
Sadly this is all too familiar to me. We have exactly the same system as you I suspect. I have fitted a fuel bulb, similar to those found on an outboard fuel line, which has helped, but not solved the problem. The only solution that I have found is to bleed the high pressure pump. This is a devil as the bleed bolt (8mm) is on the side of the pump which is obscured by the oil filter and the exhaust manifold; it's also impossible to turn the nut by more than one flat at a time. Then crack the nut on each injector. Never done it in less than three attempts tied up in the marina. God help us on a lea shore!
I hope some one replys with a post that begins...you Wally, all you have to do is........
Click to expand...

lol thanks;-)
I guess I AM that wally 'cos I'm pretty sure I didn't NEED to try bleeding the high pressure side after only changing the filter. BUT, as I tried (and failed) to do so, I'll probably have to do the lot.
The lift pump is only a couple of years old, so I'm sure is ok, just don't seem to able to pull it through from the separator!!!
 
Just as an after thought, I have a friend who has a 4108. He swears that after bleeding the low pressure side all you need to do is make sure the water inlet is turned off and have a really big starter battery! I have never had any success with this method, but he swears by it.
 
As others have said, fit a bulb in the fuel line to pump fuel along. Makes it much simpler and quicker. Bleed until no more air at filter, then move to next bleed screw, all the while pumping. I only bleed as far as the fuel lift pump at the engine and once it is primed and working I let it bleed the rest by turning it over.
 
Thanks for all the feedback. Ended up doing as suggested by getting just enough pressure in the fuel tank. Left fuel filler cap tightly closed and fitted a pipe snugly into fuel tank vent pipe;-)

As for the first separator/filter.. Anyone know if there's meant to be an element inside it? If not, then I guess really I should fit another filter.
 
If it has a marking on it you could check it online. I got rid of my CAV type filters and replaced with the more expensive Racor filters. They are much easier to change it comething goes wrong and you don't end up with orings in the bilges. They also bleed really easy as you can take the whole top off and watch it fill, then screw the top back on as it gets close. They have a turbine seperator and glass bowl. I had problems with fuel contamination and had a few engine failures early on so I decided to make a system that would be easy to get sorted in a tight spot. I also moved my filters to a nice convenient location.
 
KevinT1 said:
Best option is to use a Pela oil extractor to suck the fuel through - you can do it at any bleed point including on the diesel pump.

Really easy - no mess, and takes approx 2 minutes

Kevin
Click to expand...

I'm sure they're great. I use something similar for brake bleeding on cars and motorbikes, and swear by it. In order to use them for this though, you MUST FIRST have access to the bleed points. On my setup (and many others), there is only the tiniest of sideways access points, JUST allowing 1/4 - 1/2 turn with the baby spanner. I can't even remove the bleed screw on my fuel pump, as it hits the exhaust manifold well before the threads end. A truly awful setup:-(
 
CalicoJack said:
Sadly this is all too familiar to me. We have exactly the same system as you I suspect. I have fitted a fuel bulb, similar to those found on an outboard fuel line, which has helped, but not solved the problem. The only solution that I have found is to bleed the high pressure pump. This is a devil as the bleed bolt (8mm) is on the side of the pump which is obscured by the oil filter and the exhaust manifold; it's also impossible to turn the nut by more than one flat at a time. Then crack the nut on each injector. Never done it in less than three attempts tied up in the marina. God help us on a lea shore!
I hope some one replys with a post that begins...you Wally, all you have to do is........
Click to expand...
Just the same with mine!! I have cut down an 8 mm box key to improve the process
 
My first CAV separator has just a cone in it, to catch the big bits, before it goes to the filter on the engine. Look at ASAP supplies, Part Nu Cav Type Fuel Separator (45LPH / Alloy Bowl) PREFILTER / SEDIMENTER ALLOY BOWL
Part No. 302005
In stock
 
david_bagshaw said:
There is a version with a cone inside instead of a filter, to help water and sediment settle out.
Click to expand...

+1 I have one on my boat, its a cav water/ sludge separator. Then next to that I have two switchable filters, the glass one used to take all the crud out before it blocked my primary filters. A fuel tank clean and fuel polish hopefully has cured that.
 
>Racor filters

That's what we had, they come with a pump on top. We inherited a glass bowl with no filter, it was for water catchment. We replaced it with a Racor filter which have a clear bowl on the bottom so you can see any water and you can et rid of it with the screw at the bottom.
 
Ok so that's what I have... It just has the cone in the upper section for water removal. Should I place a filter inline before or after the separator? Or maybe just replace the separator with a combo unit?
 
Dougal said:
Ok so that's what I have... It just has the cone in the upper section for water removal. Should I place a filter inline before or after the separator? Or maybe just replace the separator with a combo unit?
Click to expand...

Probably easier to replace with a clear bowl Racor 500FG filter / separator. The filters are easy to check and replace and the housing is easy to fill with fuel so no bleeding required.

The only problem I had is that making up the correct hose fittings for the filter body and the fuel hoses can be a bit of a puzzle but Hyphose or ASAP will both help you and supply the parts.

Richard
 
RichardS said:
Probably easier to replace with a clear bowl Racor 500FG filter / separator. The filters are easy to check and replace and the housing is easy to fill with fuel so no bleeding required.

The only problem I had is that making up the correct hose fittings for the filter body and the fuel hoses can be a bit of a puzzle but Hyphose or ASAP will both help you and supply the parts.

Richard
Click to expand...

Nice piece of kit but very expensive. Its at least 7 years since the water separator last came off, there was almost no contaminates in the separator, and zero water. It's more than three years since the last filter change, and it looked like new inside. Maybe French diesel is MUCH better than it use to be;-)
 
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