Possibly a tandem pump issue?

Robin_Cox

Member
Wondering if there are any thoughts from the collective brains trust.

Clue 1:
Last couple of times starting up, Cosmo has taken several turns over cranking as if the fuel isn't right there in the engine - and I found that it was necessary to use the throttle to get the engine to catch. Once it has run for a few minutes, restarts are instant and don't need any extra pedalling. The battery is off my other car and is in good condition.

Clue 2: when I had the wheels off the other day, I noticed that there was something that looked like an oil leak on the UK passenger side of the engine above the driveshaft. Hoped it might be oil pressure switch or similar but in good light today I could see that this was as dry as a bone.

Clue 3: when I reversed out of the normal parking space the other day when it had been raining, about a meter back from the stationary position rolling down the wee ramp I had to stop - this normally causes water that is sitting somewhere under the engine bay (aircon drain, rain drains etc) on the undertray or subframe to run off and pool under the car more or less under the passenger footwell. On this occasion, while the water has evaporated the substantial wet patch on the gravel remains - and I checked the wet-looking gravel in the dry to find that it was reeking of fresh diesel. I can't see any obvious dripping under the car - all the exposed fuel system stuff is on the driver side of the car (fuel cooler, fuel filter etc) whereas this is under the passenger side.

Clue 4: I had the headlights off earlier doing smaller jobs, and in the approximate area of the coolant temperature sensor (AMF) and below there it looks seriously oily / wet - including on top of the gearbox casing. I haven't yet got an endoscope to be able to have a proper look.

I've not had the engine cover off, but wondered if these all sound plausible symptoms of the tandem pump or some other pipework there seeping diesel? If so I am aware of the potential issues for all rubber pipework in the area - is this something than can just be swapped like an EGR or is it a proper garage job?
 
It is easy to swap, but use new bolts and do them up to the correct torque. I rebuilt mine with a kit from eBay and it was ok just took an hour to strip down, inspect and rebuild with new parts. The risk is that when you get your pump apart the rotor is worn or scored. Make sure you get the right part/kit. There are subtle to major differences between the letter variants, some use metal gasket, others rubber o-ring.
Matt


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Unfortunately it does sound like the tandem pump is leaking. You can waste time and money trying to reseal it but in the end it costs more than replacing it first off. As you are aware the diesel will VERY quickly destroy all the rubber hoses it comes in contact with, and does not do the electrics any good either. Good chance at least some of the hoses will be eaten so not a very cheap job but it is do able at home although if you have a good mechanic and supply all the parts the trouble and mess you save yourself pays their bill. As you have a 75 dont bother with another LUK pump go for a Bosch one instead. The important part is the head to pump gasket as there are 2 different versions and make sure you buy a QUALITY OEM one.
 
Thank you - I've seen the link for the Bosch pump on another recent thread - do I take it from your wording above that the Bosch pump doesn't come with a suitable gasket (the specifications of the bosch do tend to suggest this).



By the look of things, the gasket is the combined unit referred to as 2A in the 7zap diagram, rather than the earlier part with separate seals and gaskets (parts 1+2) - some actual VW ones out there so I'll go for one of those.
 
That is correct the new pump comes without a gasket. The Bosch uses the crush metal type gasket. Stricktly speaking there are three types of gasket, the individual O rings, a metal plate with the main O rings built in ( inside the pump ) and the crush all metal type. It is very important that everything is perfectly clean when refitting the pump and do the bolts up first finger tight, then just starting to tighten before you torque them down in a diagonal pattern.
 
>It is very important that everything is perfectly clean when refitting the pump and do the bolts up first finger tight, then just starting to tighten before you torque them down in a diagonal pattern.

Whatever happened to battering a load of sealant on then cranking the bejasus out of re-used single-use bolts, followed by more sealant? You'll be giving me actual torque settings next ....;)
 
Since you asked so nicely.. its 20 Nm upper 2 bolts 10 Nm for the lower 2

a2-1662.png

:D
 
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