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Discussion Starter #1
Hi all,

have an issue with my van, a 2003 SWB, short-nose 102bhp 2.5 TDi, Combi (twin slider) van with 103k on the clock. I've owned the van for a couple of years and know its full history. Cam belt was done when I got it with 90k on the clock.

Its had the "problem" since I've owned it, but it's not really bothered me as there is a workaround BUT, I have to sell the van, so I'll need to fix it.

It goes like this - when about 50% of the time it will start first time, whether the outside temp it high or low makes no difference. The glow plug light stays on for a very short time - around 2 seconds, then goes out. If it is going to start first time, I don't even really need to wait for the glow plug light, I just get in, turn the key and (if its going to) it starts.

If it doesn't start, the only way to get it to start is

turn on the key, watch the glow plug light go out, listen for the "click" of the secondary glow plug relay. Immediately turn off the key and back on and listen for the relay again, then of and on once again (making three relay "clicks" and when the relay clicks on the third time, start it. Never fails. If I only let the relay click twice and try it will start but needs a lot of cracking and runs rough and smokes like anything. Thre times, and it starts instantly every single time.

When I first got it, I thought I'd fix it - so did a bit of research and changed the glow plugs and both temp sensors as they seemed to be prime candidates.

looking around tinterweb it could be a number of things from ignition barrel, to relays to dodgy earths. I have VCDS and there are no codes showing. Assuming its not timing as a) the belt was done by a specialist and b) its intermittent.

Anyone had/ seen anything like this?

Cheers

Griz
 

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Remember reading on here some time ago about wiring issues being the culprit of the issues you describe so do a google search and it should give you some results if you include VW T4 in the search ...
 

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When it fails to start does it coincide with being a cold engine or does it do it when hot too?
Does it still have the original injectors? They normally need a re-con around that mileage.
If they are not atomising fuel correctly it will be harder to start when cold.
The cheap option would be to increase the primary glow plug heating time using VagCom.
That's if it is an injector atomising problem, if you intend to flog it on.
 

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Discussion Starter #4
When it fails to start does it coincide with being a cold engine or does it do it when hot too?
Does it still have the original injectors? They normally need a re-con around that mileage.
If they are not atomising fuel correctly it will be harder to start when cold.
The cheap option would be to increase the primary glow plug heating time using VagCom.
That's if it is an injector atomising problem, if you intend to flog it on.
Yes, still has the original injectors

Its on "cold" start where cold means it hasn't run for several hours, BUT, crucially, it can be -5 or plus 25C ambient and half the time it will start just fine. I could accept the injector theory if it wasn't so intermittent and inconsistent with regards to when it happens.

I've had a brief look for how to change the primary glow time because it seems such a short time that the glow plug light is on, but have only got as far as figuring its some adaptation that I need to do. ... if you know which I'd appreciate some pointers.

Cheers

Griz
 

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first off replace your injector leak off pipes.
It could be that you are getting fuel running back to the tank when sitting for long periods.
Air get sucked into the pipes by the contracting hot fuel with just the slightest weakness in the seal.
You should notice your problem gets worse after longer journeys the night before, as the fuel all the way back to the tank gets hotter.
These are cheap & easy to replace & eliminates this potential well known problem.
Also check the connections to your fuel filter & look for air in the fuel pump supply pipe.
Let me know how you get on.
 

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To me this sounds like a faulty 103 relay. On mine the glow plug indicator light stay on longer the colder it is.
 

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To me this sounds like a faulty 103 relay. On mine the glow plug indicator light stay on longer the colder it is.
They all stay on longer mate when the temp gets colder.
If you lengthen the primary cycle it will stay on longer than standard when cold.
I suspect with it being intermitant that air in the fuel may be the problem. He says he can hear the relay working.
 

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Discussion Starter #8
first off replace your injector leak off pipes.
It could be that you are getting fuel running back to the tank when sitting for long periods.
Air get sucked into the pipes by the contracting hot fuel with just the slightest weakness in the seal.
You should notice your problem gets worse after longer journeys the night before, as the fuel all the way back to the tank gets hotter.
These are cheap & easy to replace & eliminates this potential well known problem.
Also check the connections to your fuel filter & look for air in the fuel pump supply pipe.
Let me know how you get on.
thanks - will take a look and I'll replace them anyway, just so as to eliminate the problem.

But it makes no difference how long its been sitting - for example it sat on my drive for 4 or 5 days after having driven from Southend to Gloucester, when I got in to start (guessing the ambient temp was between 12°C and 15°C and it started fine when I wanted to move it off the drive to get one of my other cars out. So it was literally reversed off the drive, sat idling for 10 mins while I got my Saab out, then parked back on the drive and its been there for 10 days or so without moving. Ambient is currently 8°C and it didn't start on the first turn. I'll try again in the morning, if it fires then, we can assume its not the leak-off pipes?

thanks again for your suggestions - will update you on progress.
 

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Discussion Starter #9
They all stay on longer mate when the temp gets colder.
If you lengthen the primary cycle it will stay on longer than standard when cold.
I suspect with it being intermitant that air in the fuel may be the problem. He says he can hear the relay working.
I'm not entirely sure mine do - this evening the primary (when the glow light in the dash is lit) is 2.14 seconds (I videoed it and checked the timeline on my PC) - any idea how long the primary should be? (at 8°C) - supposed to be 0°C tonight, so will check again in the morning.

cheers

Griz
 

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Discussion Starter #10
I'm not entirely sure mine do - this evening the primary (when the glow light in the dash is lit) is 2.14 seconds (I videoed it and checked the timeline on my PC) - any idea how long the primary should be? (at 8°C) - supposed to be 0°C tonight, so will check again in the morning.

cheers

Griz
sorry - scratch that- bad maths! - its 1.14 seconds the primary is on for - I did the ignition on/of 4 times and the times for the primary glow light being on are:
1.14, 1.14, 1.14 and 1.86 seconds
 

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Check all the vacuum hoses even the ones that look OK. I had starting problems and VW and a VW expert were unable to fix the problem. I changed the hoses and problem solved.
 

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Discussion Starter #12
Check all the vacuum hoses even the ones that look OK. I had starting problems and VW and a VW expert were unable to fix the problem. I changed the hoses and problem solved.
thanks - will check them when I do the injector leak-off pipes in the week.
 

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My dads ban had the same issues. It would would intermittently not start and he said would have to turn the key 3 times or so before it would start. This went on for a few months. He changed the relays and temp sensor with no luck so thought it might be dodgy earth. then I went fishing with him and he parked it sideways on a hill and it wouldn't start at all. I looked at the fuel pipes and you could see air bubbles in there. He got the fuel pipes changed and its started first time every time since.
 

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Discussion Starter #14
My dads ban had the same issues. It would would intermittently not start and he said would have to turn the key 3 times or so before it would start. This went on for a few months. He changed the relays and temp sensor with no luck so thought it might be dodgy earth. then I went fishing with him and he parked it sideways on a hill and it wouldn't start at all. I looked at the fuel pipes and you could see air bubbles in there. He got the fuel pipes changed and its started first time every time since.
cheers - looking like Jock_Strap and you have certainly given me another avenue to investigate. Will keep you guys posted .
 

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sorry - scratch that- bad maths! - its 1.14 seconds the primary is on for - I did the ignition on/of 4 times and the times for the primary glow light being on are:
1.14, 1.14, 1.14 and 1.86 seconds
Not sure how long it is mate it's been about 5 years since I did mine. For numbers the old grey matter normally only
Goes back to last weekend at my age LOL:
 

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Discussion Starter #17
I'm back. . .

So, I have:-

replaced the injector leek-off pipes

checked all vacuum hoses (not replaced any) that I can see, they seem good to me.

replaced the fuel filter (not OEM)

problem is still there (I think its actually worse, although I have nothing to prove that other than gut feel)

front left suspension has started squeaking loudly over speed bumps especially . . . (not that that has owt to do with the starting! :)

cheers

Griz
 

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Did you get any further with your starting issue?
I have the same - has been hanging around for a few months, got much worse recently.
I have a 2004 2.5tdi 174

Changed glow plugs, wiring loom, battery, checked wiring under drivers seat, 2 x garages can't find anything, no error codes.

I suspect tank pump or small air leak somewhere in fuel pipes but could get expensive inspecting everything and nothing is coming up obvious...
 

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There are quite a few threads about clamping off the RF pipe on the fuel filter overnight to see if the lack of fuel is from a leak on the injector seals or if it's draining backwards. Mine appears to hold pressure overnight so am getting the tandem pump and tank pump / NRV checked out. Already spent a fortune on glow plugs, injector wiring looms etc etching no success...
 

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I spent ages hunting a similar problem on my 2.5, I changed the glow plugs, relays, leak off pipes, fuel filter, ignition switch and battery. None of this worked, then I noticed the problem only started when the tank was down to about 1/4, as soon as I topped it up the problem went away. This turned out to be the plastic fuel sender/pump in the tank, this solved the problem on mine and is a very simple fix, TPS sell the sender (worth buying a new seal at the same time). Hope this helps.
 
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