Tandem pump

JHB

Member
Hi the tandem pump on my tdi90 is leaking slightly. After a close look at it and reading various posts on here it seems that it is a fairly straightforward job to replace it. However I've noticed a few members suggesting that the Bosch pump is better than the currently fitted Luk pump. The Bosch pump is also cheaper. Can anyone tell me why the Bosch pump is better, or conversely persuade me that it is wiser to replace like for like.
 

audifan

A2OC Donor
As your car is LHD then the far better Bosch pump is a direct swap for the LUK one. Just remember to also get the OEM quality gasket with the two tracts of blue silicon as the plain ones will leak.
 

JHB

Member
Thanks for the reply. I have now ordered a bosch pump and gasket from Autodoc Germany for 161 euros which I think is a bargain. I added Mannol oil, an oil filter, a cabin filter and a pair of anti roll bar bushes. So I should receive a large parcel within a couple of weeks. After that I'll be busy for a while
 

Tipptop

Member
As your car is LHD then the far better Bosch pump is a direct swap for the LUK one. Just remember to also get the OEM quality gasket with the two tracts of blue silicon as the plain ones will leak.
Hi audifan, can you elaborate on your knowledge there, is there a difference for RHD cars? I'm in the market for a tandem pump too, I have several in my shed but all from 1.9 cars. My pump is leaking slightly on the outer face plate joint, temporarily fixed with a dab or sealant. Might just buy a new one as Autodoc are 41% off today.
 

audifan

A2OC Donor
Yes I can. On RHD diesels the air inlet pipe feeds across the front of the engine then into the engine behind the EGR and ASV valves. BHC and ATL engine do not have enough clearance for the DIRECT fitment of the better Bosch tandem pump. They can still be used but an additional spacer is required to be manufactured from a second original spacer pipe to extend the ASV out past the end of the thicker Bosch pump. Note the AMF engine has no ASV valve and therefore the Bosch fits directly onto that engine.

You would have to source an additional spacer then send it to Paul @depronman for him to machine correctly.
 

Tipptop

Member
Thanks for that very informative. My egr is disabled and I wonder can I kill two birds with one stone here and get a replacement pipe for the EGR that also extends out the ASV a bit so I can fit bosch tandem pump? Is there a 1 pipe solution I wonder
 

depronman

Member
Thanks for that very informative. My egr is disabled and I wonder can I kill two birds with one stone here and get a replacement pipe for the EGR that also extends out the ASV a bit so I can fit bosch tandem pump? Is there a 1 pipe solution I wonder

Not without having a custom pipe manufactured


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depronman

Member
Not without having a custom pipe manufactured


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Funny you should ask about this mod to fit the Bosch tandem pump to the bhc/atl engines as I’m just on with the machining of a pair of spacers for another member
Biggest issue is getting old of another spacer

Cheers. Paul


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audifan

A2OC Donor
Could one spacer be cut into two and a pipe section inserted and the end correctly orientated? Only a thought especially if spacers are thin on the ground.
 

depronman

Member
It would be possible and I did look into this but finding a suitable size if ally pipe was proving impossible. The wall thickness on the spacer is fairly thin meaning the pipe is a rather specific size read as none standard
The nearest I could get was a thick wall ally tube but I needed to buy 10 metres as the MOQ and it was far to expensive to be viable

Paul
 

audifan

A2OC Donor
Could a suitable extension be 3d printed that has lugs to locate the bolt locations for alignment and also air tightness and longer mounting bolts be used?
 

depronman

Member
Not with the weight of the ASV and inlet pipe swinging on it. It would likely separate on the layer joints. Certainly not something that I would be trying on someone else’s car

Paul


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fbson

Member
Hi audifan, can you elaborate on your knowledge there, is there a difference for RHD cars? I'm in the market for a tandem pump too, I have several in my shed but all from 1.9 cars. My pump is leaking slightly on the outer face plate joint, temporarily fixed with a dab or sealant. Might just buy a new one as Autodoc are 41% off today.
Not sure if it helps - Just in the process of replacing my LUK tandem with the Bosch pump. Found it for just under £135 delivered (to a private individual), brand new - just checked and still available at that evidently. Also had to get a gasket of course, was about £6.
 

JHB

Member
I finally replaced my tandem pump and the coolant hose that runs underneath it and round to the egr valve.
The car is lhd which allegedly makes the job easier. However I struggled. First removing the hose from the egr was an absolute pain. It's held on with a spring clip which you can't see or reach with any tools. After fiddling about for hours I eventually cut through the clip with a dremel.
I replaced the Luk pump with a Bosch. Had problems fitting the new pump and then realised that it was fouling on the spigot for the water hose that runs to the expansion tank. The solution was to file a couple of mm of the pump casting. So be warned a Bosch pump is bigger all round than a Luk and may be a problem
Anyway glad to say the job is now done. The car is running and is no longer leaking
 

fbson

Member
I reckon there must be differences with the LHD, I'm sure someone will be able to confirm. On my RHD I recently changed to the Bosch tandem. I had no fitting troubles with it fortunately, though I did temporarily remove the EGR to clean it and that was half a mission.
Do you mean the spring clip on the rubber hose on the air intake where it connects to the ASV?
 

depronman

Member
I reckon there must be differences with the LHD, I'm sure someone will be able to confirm. On my RHD I recently changed to the Bosch tandem. I had no fitting troubles with it fortunately, though I did temporarily remove the EGR to clean it and that was half a mission.
Do you mean the spring clip on the rubber hose on the air intake where it connects to the ASV?

I am also suspecting differences on the LHD cars as I’ve fitted Bosch tandem pumps to a couple of bhc engines and one atl and other than the extension need to push the ASV further away from the engine to prevent the tandem pump fouling the ASV there are no other issues

Paul


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JHB

Member
I reckon there must be differences with the LHD, I'm sure someone will be able to confirm. On my RHD I recently changed to the Bosch tandem. I had no fitting troubles with it fortunately, though I did temporarily remove the EGR to clean it and that was half a mission.
Do you mean the spring clip on the rubber hose on the air intake where it connects to the ASV?
No it was the clip on the water hose that cools the egr gases. On a rhd car the hose is different because the egr is the other way round
 

JHB

Member
I am also suspecting differences on the LHD cars as I’ve fitted Bosch tandem pumps to a couple of bhc engines and one atl and other than the extension need to push the ASV further away from the engine to prevent the tandem pump fouling the ASV there are no other issues

Paul


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Yes it was odd. The pump housing only fouled the hose spigot by about a mm but it was enough to skew the pump and prevent it sitting flush with the head. I thought about just bolting it up and hoping the bolts would pull it in square but decided it was better to get the thing sitting flush and then bolt it up I did notice that the bit I filed off was mainly casting flash. So perhaps it was something that is not always a problem
 
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