Tandem Diesel pump: Replace or repair?

Lee-bo

Member
Hi, my 2004 TDI has the common intermittent starting issue where you have to sometimes crank for 2/10/20 seconds before it will fire and start.
Ive read through as many posts here as i can, and it seems the tandem pump is drawing air and allowing the fuel to return to the tank.

So, ive looked at replacing the tandem pump, which seems to be around £180 trade.

BUT ive also seen a tandem pump ‘repair kit’ with seals and gaskets etc, so im wondering if anyone has had the same issue as me, but replaced the seals/gaskets instead of the whole pump and had any reliable success?

Obviously its considerably cheaper in parts, but not in labour as its virtually the same job.

Any comments and advice is welcome!

Thanks,

Lee


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froggy

Member
If you go down the gasket route make sure it is the one with 2 blobs of blue silicone on it. Tandem pump should be available slightly cheaper than that - around £150 for a Bosch one.

Edit* see audifan’s post - the Bosch tandem will really only fit AMF engines.
 
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audifan

A2OC Donor
Your engine is either a BHC or ATL as such the better Bosch tandem is not a direct swap for your current LUK one. Another LUK would be a direct swap after obtaining the OEM quality gasket with the 2 tracts of silicone.

A reseal kit is available but from personal experience a waste of time and money, just replace the tandem pump with new.
 

Lee-bo

Member
Ok, thanks. I imagined the better option would be to just replace the whole pump, but wanted to get your advice first. I got quoted £180 from my local motor factor, but obviously i need to add labour on top. Is it a particularly difficult job to do?

The next question, is how do i tell which TDI engine i have? I ‘think’ its the 90, but im not sure. Is there an obvious id tag/or any definitive numbers on the engine/chassis number to confirm? I apologise if this is a amateur question!

Thanks,

Lee


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AndyP

Member
Before you go down the new tandem pump route I would suggest you eliminate the camshaft position sensor. I had "that" problem and chased it for ages before changing the CPS for a second time and 100% fixed. I have a gut feel there there are two CPS failure modes, one where it fails totally, give you an ECU error code and just takes ~10 revoutions to start the engine. There is another where it gives the engine some sort of signal, perhaps an occasional ECU error but prevents it starting altogther, until you give up and come back later - guess which I had ...
 

Lee-bo

Member
Before you go down the new tandem pump route I would suggest you eliminate the camshaft position sensor. I had "that" problem and chased it for ages before changing the CPS for a second time and 100% fixed. I have a gut feel there there are two CPS failure modes, one where it fails totally, give you an ECU error code and just takes ~10 revoutions to start the engine. There is another where it gives the engine some sort of signal, perhaps an occasional ECU error but prevents it starting altogther, until you give up and come back later - guess which I had ...

Ok, the camshaft sensor was replaced 2-3 years ago (not saying that it hasnt gone bad again!)

I havent had any error codes come up either, so put it down to the tandem pump.

Lee


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audifan

A2OC Donor
Easiest way (usually) telling an ATL engined car is that is has rear disc brakes, the AMF, BHC and ANY all all rear drum braked cars. I say usually as some have converted the rear brakes from drum to disc. Only the TDI 90 had a red I in the badge.
There is an engine code stamped on the right front of the block where the gearbox flange is. Your options sticker in the service book and in the car battery compartment also provides the engine code..

The CPS could produce similar issues as could an old fuel filter, although I still think it is the tandem pump.
 

audifan

A2OC Donor
Tandem pump replacement is not too bad a job...BUT if there is no external fuel leaking from the tandem then you have probably saved all the rubber coolant pipes - the diesel destroys them VERY QUICKLY. So provided you completely cover the area below the tandem to fully protect everything it is a job that can be done DIY. After removing the air inlet pipe for more access, there are three pipe connections on the tandem that need to be removed, the fuel feed, the fuel return and the vacuum pipe on the rear. Once those are carefully removed and the fuel hoses blanked off and their ports on the tandem then there are only 4 bolts holding the tandem pump onto the side of the head. Before removing those bolts give the area a good clean then slacken the bolts in a diagonal pattern first before removing them.

Assuming this has or has not put you off I can guide through the refitting and other items required before you fit the pump.
 

audifan

A2OC Donor
I am a bit confused though... Your profile states a 2002 1.4 tdi.

Possible you have more than one A2, may even be someone else's.

If we work on the principle that you are going to get a replacement LUK pump then it does not matter which year or engine you have. Only becomes important if you want to fit the Bosch pump as the BHC and ATL both need an extra spacer to clear the tandem and ASV.

That is another way of telling if the engine is an AMF or BHC/ATL if there is an ASV between the air inlet pipe and the EGR valve. On the AMF the air pipe connects directly to the EGR.
 

DuncanA2

Member
What about the injector bushings? Have you considered changing them first? The PD element tend to work their way into the head and make the round hole somewhat oval. Especially on a hot start is more difficult. A revision set consists of new rubber rings and burnplates (is that the correct name)and cost about 13£ per element. When you don’t have any leakage, I would start there, saves time and money.
👍
 

Lee-bo

Member
Easiest way (usually) telling an ATL engined car is that is has rear disc brakes, the AMF, BHC and ANY all all rear drum braked cars. I say usually as some have converted the rear brakes from drum to disc. Only the TDI 90 had a red I in the badge.
There is an engine code stamped on the right front of the block where the gearbox flange is. Your options sticker in the service book and in the car battery compartment also provides the engine code..

The CPS could produce similar issues as could an old fuel filter, although I still think it is the tandem pump.

Ok thanks,
Mine has rear discs and the red ‘I’ in the rear TDI badge, so im edging towards a 90, but ill check the ID tags in the morning as you described.

Lee


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Lee-bo

Member
Tandem pump replacement is not too bad a job...BUT if there is no external fuel leaking from the tandem then you have probably saved all the rubber coolant pipes - the diesel destroys them VERY QUICKLY. So provided you completely cover the area below the tandem to fully protect everything it is a job that can be done DIY. After removing the air inlet pipe for more access, there are three pipe connections on the tandem that need to be removed, the fuel feed, the fuel return and the vacuum pipe on the rear. Once those are carefully removed and the fuel hoses blanked off and their ports on the tandem then there are only 4 bolts holding the tandem pump onto the side of the head. Before removing those bolts give the area a good clean then slacken the bolts in a diagonal pattern first before removing them.

Assuming this has or has not put you off I can guide through the refitting and other items required before you fit the pump.

Ok great, i dont ‘think’ there is any diesel leaking, just a small dusting of oil! Im reasonably competent so will try and do it myself, but its great to have some pointers and tips from the pros!

Lee


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Lee-bo

Member
I am a bit confused though... Your profile states a 2002 1.4 tdi.

Possible you have more than one A2, may even be someone else's.

If we work on the principle that you are going to get a replacement LUK pump then it does not matter which year or engine you have. Only becomes important if you want to fit the Bosch pump as the BHC and ATL both need an extra spacer to clear the tandem and ASV.

That is another way of telling if the engine is an AMF or BHC/ATL if there is an ASV between the air inlet pipe and the EGR valve. On the AMF the air pipe connects directly to the EGR.

Apologies, ive updated my account with info to the best of my knowledge!

Ill confirm exactly what engine code i have, then i can be more accurate.

Lee


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Lee-bo

Member
What about the injector bushings? Have you considered changing them first? The PD element tend to work their way into the head and make the round hole somewhat oval. Especially on a hot start is more difficult. A revision set consists of new rubber rings and burnplates (is that the correct name)and cost about 13£ per element. When you don’t have any leakage, I would start there, saves time and money.

The injectors were replaced 2 years ago, so id hope that the seals were replaced at the same time, but you are right, for a small cost it might be worth replacing them again for peace if mind.

Lee


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Lee-bo

Member
If you go down the gasket route make sure it is the one with 2 blobs of blue silicone on it. Tandem pump should be available slightly cheaper than that - around £150 for a Bosch one.

Could you possibly give me a link to the correct set i need?

Cheers,

Lee


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audifan

A2OC Donor
No think @froggy had his wires crossed. The reseal kit is a different thing to the external gasket that fits between the head and tandem pump. It is this external metal gasket that contains the 2 tracts of silicone.

This is the metal gasket...

s-l1600.jpg
 

AndyP

Member
Ok, the camshaft sensor was replaced 2-3 years ago (not saying that it hasnt gone bad again!)

I havent had any error codes come up either, so put it down to the tandem pump.

Lee


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Ok, try disconnecting the CPS and see if it behaves consistently.
 

froggy

Member
No think @froggy had his wires crossed. The reseal kit is a different thing to the external gasket that fits between the head and tandem pump. It is this external metal gasket that contains the 2 tracts of silicone.

This is the metal gasket...

s-l1600.jpg
Yes listen to @audifan on this and definitely not me! I did get my wires crossed, I assumed you wanted the metal gasket, but after reading your post again I realised you need the seal kit for the pump itself. Here is a link another member helped me with that has tandem pump seal kits. They seemed very happy with this solution, personally I would always replace the whole thing but the mileage after using the seal kit speaks for itself…..

Post in thread 'TDi 75 AMF coolant leak from hoses tandem vacuum/fuel pump seals?'
https://www.a2oc.net/community/inde...ndem-vacuum-fuel-pump-seals.47764/post-462261
 
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Lee-bo

Member
Easiest way (usually) telling an ATL engined car is that is has rear disc brakes, the AMF, BHC and ANY all all rear drum braked cars. I say usually as some have converted the rear brakes from drum to disc. Only the TDI 90 had a red I in the badge.
There is an engine code stamped on the right front of the block where the gearbox flange is. Your options sticker in the service book and in the car battery compartment also provides the engine code..

The CPS could produce similar issues as could an old fuel filter, although I still think it is the tandem pump.

Hi, just to confirm - mine is the ATL engine. So am i correct in thinking the bosch pump wont work?

Lee


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