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Discussion Starter #1
Hi chaps. Just bought a 1991 2.4 5 cylinder diesel and it takes a lot of cranks before it fires up. There is also a very faint smell of diesel. Watching the clear diesel supply line we can see lots of air inside the pipe. I know these systems should self blieed so I am assuming there is an air leak somewhere. However when the engine is turned off you can see the diesel flowing backwards in the supply line back to the filter. Is this the cause of the prolonged starting as its taking time to push diesel to the pump and is this just caused by the air leak? Or is it normal to flow backwards when the engines off? Or is it missing a non return valve or something? The pipe routing is pretty shody so its obviously been played with by the previous owner.
 

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Discussion Starter #3
Brill thanks, are we think an air leak or fuel leak is the cause of the backwards flow? Or may there be something missing from the system to stop it?
 

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The smell of diesel . deffo a leak somewhere , just follow your nose , get underneath with a touch , shouldn't be too difficult to trace.
do these engines have a priming plunger on top of the filter , could be the diaphragm split .
 

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Discussion Starter #7
Update. We have changed all the leak off pipes for new stuff. This has helped a lot, the system now bleeds itself when running and there are no visible air bubles or any visible leaks. We cleaned it all off and its nice and dry still. Engines running good.
However when turned off the fuel in both the supply and the return are still flowing straight backwards to the filter! Meaning it takes ages to crank!

We have no idea why!
 

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You still have a major air leak on the pipework or pump.
Double check all connections to leak off pipes and end cap, all fuel line unions - are all the copper or ali washers where they should be? Are all the fuel lines ok and not cracked or perrished?
If these are ok, then it's either the pump drive shaft seal, throttle shaft seal or timing advance shaft seal. The last 2, you can try smothering grease or vaseline round the seals to stop the air being sucked in. The driveshaft seal may be more difficult to get to, and will need some dismantling to get to it.
 

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Discussion Starter #9
Thankyou for that I will do as u say tmo. If there is an air leak why does diesel not come in out when its presurised!?
 

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Have you changed the fuel filter recently? Some non-genuine ones don't have a non-return valve, I'm sure somebody has previously posted that the old 2.4 is not a sealed system?
 

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genuine ones do not have a one way valve.
I had the exact same issue as the OP with my 2.4, 2 years ago immediately when the van was brought home from a cam belt change, a very long story later & falling out with a shockingly bad local "VW Specialist" they fitted a non return valve and it's been fine since.

Had the belts change again somewhere else 6 months later as the water pump threw water out, should have taken it back to the original garage but just could not trust them to do it right so bit the bullet & paid again but on recommendation. Sorry I digress lol, but at the time I read a post on here from one of the experienced forum members that it's not a sealed system and should have a non-return valve by, or on the fuel filter? Mines good now but maybe it's just masking another problem?
Anyway maybe worth a try as a cheap fix.
 

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Could be just the thermo-valve on top of the filter, or you have a leak at the pump, the spindle seal is a common culprit. As you saw from my experience, I had a number of faults, so check everything and the replace the cheaper parts regardless to reduce the possibility of future failure / problems.
 

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Discussion Starter #16
Thanks everyone, all helpfull stuff. Thermo valve change nxt then, failing that a non return valve, failing that the pump will be coming off.

Where abouts do u fit the non return valve? In the supply or return pipe? Close to the filter or close to the pump?

Does anyone have a link to buy one please?
 

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Fitting an additional non-return valve would be masking the true fault. With everything working as is should, there is no need for one. If there is a small leak at the pump, then it will only get worse so you will have to deal with it later anyway. Before the starting issues on mine I had noticed a slight whiff of diesel, like you have. The spindle repair is a job that can be done yourself with care and cost me about £50 in parts, as apposed to £200+ that garages want for the job.
You will have many jobs to do on your van in the future, so if you attend to one area properly the first time, there should be no need to revisit it too soon!
I initially had issues with the fuel system and by doing all that I did, have had no issues there for over 12 months. When my rad failed I spent time cleaning up the fans & louvres, cleaning the pipes, expansion tank, new fan switch etc.. I then knew that my cooling system was bang on. When my cv joint failed, I replaced the driveshaft, diff output seal, lower ball joint, disc shield and went on to do the same to the other side later.
My point is if you are thorough enough in your work, then you are effectively giving that area a good service and do preventive maintenance, rather than just fixing thing that have broken. I have a list of jobs to do on mine and probably always will, but by prioritising and researching each job properly, you should only do it once!
Yes I have whittered on a bit, but hope that I have got the point across. One last thing, don't fit cheap partsT:
 

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Discussion Starter #19
Thanks Skippy. I am in that mind set! Literally just bought it tryin to sort all the nigglies! Currently mid way through changing all the belts.

Bit scared of removing the fuel pump as I don't have the expertise or tools to time it up! So was really hoping this was not the problem. Might have to hang on, save a few penny's and get a garage to do it!
 

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You just have to take the lid off, the pump stays in situT: Where abouts are you located, England is a rather vague location?
 
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