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Discussion Starter · #1 ·
The noise from my Secondary Air Pump when starting from cold had been getting worse and worse and was slightly embarrassing. It sounded like a very loud vacuum cleaner for 90 seconds, followed by a huge dump valve noise.

After reading on UKMKIVS about repairing the secondary air pump, I decided to repair mine today. I tried to search for a guide but couldn?t find one, so here is mine.

The whole job took 2 hours. By far the longest part of the entire process was removing the pump from the car, especially getting to the Allen bolts. Putting it all back together was easy.

Tools used:
Trolley Jack
Axle Stands x 2
T20 Torx screwdriver
8mm Allen Key
10mm Socket
Flat bladed screwdriver
Electric drill with 4mm drill piece.

Parts required:
Six of each of the following:
4mm by 50mm bolts (I could have probably used 45mm long bolts but wasn?t sure until I got to that stage. They don?t get in the way of anything though)
4mm flat washers
4mm split washers
TOTAL COST LESS THAN ?3

Step 1
With the car jacked up and supported by axle stands, remove the front splash guard from behind the front bumper. There are 4 T20 Torx screws.
Step 1


Step 2
Remove the hoses from the air pump. There are two hoses, one is hidden in the picture. These are held on by plastic clips and can be pulled off whilst squeezing the opposite sides of the hose to the clips (RED ARROWS). If they get stuck use a flat bladed screwdriver to carefully work the clips loose (YELLOW ARROWS). Remove the electrical connector from the pump (BLUE ARROW). Use a flat bladed screwdriver to gently prize the clip open and the plug will come off easily.
Step 2


Step 3
Undo the three nuts holding the pump to the bracket using a 10mm socket. This allows easier access to the bracket bolts (one hidden in picture)
Step 3


Step 4
Reach just above the pump using the long end of the 8mm Allen key and undo the lower two bracket bolts. The bolts are separated by two or three inches. You can move the pump as necessary to allow easier access and visibility. You may need to add an extension bar to the end of the Allen key to provide more leverage. The diagram shows the direction and position of the bolts obscured by the pump).
Step 4


Step 5
With the bracket held on by only one bolt you can push the bracket towards the passenger side of the car, allowing the pump to be extracted.

The following shows the separation of the pump allowing air to escape.


Step 6
Using a 4mm drill piece CAREFULLY drill each rivet until it breaks. The remainder of the rivet can be pushed out using the drill with it switched off.
Step 6


Step 7
Replace each rivet with a bolt. Insert a flat washer then a split washer before the nut. The flat washer should stop the split washer from sinking in to the plastic casing and the nut working loose. You could also use threadlock in addition.
Step 7


Step 8
Refit all the parts in the reverse order they were removed. Here it is finished.


Albo [8-|]
 

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Excellent guide. Very clear instructions and brilliant pictures. Im going to have to do this job on the girlfriends car sometime in the near future.

Well done.
 

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Albo

Top stuff mate! Mine is starting to do the same thing. And as you have posted what it was and how to rectify it, I can sort mine out.

How did you jack it up and where about? As I have the same axle stands but not sure where is the best place to put them!

Cheers
 

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Discussion Starter · #4 ·
How did you jack it up and where about? As I have the same axle stands but not sure where is the best place to put them!
I wasn't sure where to put the axle stands either and was quite nervous. I jacked up the car where the main frame that spans the car joins the wishbone with a bolt. This seemed to be the most solid part the jack could reach to. You have to jack it up quite high to get the stand under. I placed the stands under the main chassis that spans the car from one side to the other behind the engine. When you have put the first under, let the jack down extremely slowly until the stand has taken the weight. Then repeat for the other side. I left the jack in place once the second stand had taken the weight as a safety backup. See picture in step 1.

Please don't rely on my info here though. I have no idea if this is the proper way to do this.

Albo [8-|]
 

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superb mate [y][:D] I was thinking earlier today I needed to do this and your guide has just made my life a lot easier - thank you [:)]
 

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Is this the part that makes the car sound really rough and diesel like when you first start it when its cold? If so iI think I may need to change mine too [:S] Is the part expensive?
 

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Discussion Starter · #7 ·
Is this the part that makes the car sound really rough and diesel like when you first start it when its cold? If so iI think I may need to change mine too [:S] Is the part expensive?
The only parts you need are the nuts, bolts and washers mentioned in the guide. Less than ?3
 

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Sorry to sound dumb but what does it do exactly?

How do i know if this needs doing?

Cheers, Sam
Sam, as far as I know it helps get the cat get upto operating temp

On a cold start it will be in operation for around 70-80 seconds and your RPM will hover around 1200. When it's finished it switches off and your RPM drops to normal 750-800. They get noisy with age and lately mines getting worse. I remember Graham EJO posting a WAV of his - it sounded horrible like a bag of nails when he fired the car up then after so long it suddenly went off and idled normally. Nobody seemed to know back then what the problem was so this guide is very very useful [y]
 

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How did you jack it up and where about? As I have the same axle stands but not sure where is the best place to put them!
I wasn't sure where to put the axle stands either and was quite nervous. I jacked up the car where the main frame that spans the car joins the wishbone with a bolt. This seemed to be the most solid part the jack could reach to. You have to jack it up quite high to get the stand under. I placed the stands under the main chassis that spans the car from one side to the other behind the engine. When you have put the first under, let the jack down extremely slowly until the stand has taken the weight. Then repeat for the other side. I left the jack in place once the second stand had taken the weight as a safety backup. See picture in step 1.

Please don't rely on my info here though. I have no idea if this is the proper way to do this.

Albo [8-|]
No thats fine dude, just interested to know how. At least I can look at getting mine done now. Again brill write up!
 

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99 Ronnie
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Thats a great write up [Y] Thanks!

My 2003 1.8T now has 90k on it and has this problem, slowly getting louder/worse when first turned on in the morning. Sounds like a mixture of a Hoover and a boy racer dump valve - basically it sounds knackered when starting up!

I'll get on to this job soon
 

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mine is doing this now.. woohoo . sounds like a jet fighter about to take off.. if i do not "fix" it.. whats the worst could happen?

steve
 

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lol well steve, I did mine last weekend and I had oil burning though the engine before the fix. After that not a problem, IIRC the secondary pump feed air to the crankcase breather, and something else not sure what. Other members have recommend its best to fix.

Cheers for the write up on this guys I did mine in 40 minutes the other weekend.
 

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Albo, thanks again - I just did mine this morning (in the rain). 1 of my rivets had gone, and 1 was about to go, the other 4 were sound. I bolted all 6 up nice n tight though! [y]
 

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I'm so happy I read this guide. I've had my Golf for 9 months (45K miles on the clock) and every morning I've been baffled to what "that sounds" coming from under my car was? Sounds like a diesel on steriods!!

This repair is getting done tomorrow....nice one mate!!
 

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99 Ronnie
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Well I finally did this repair tonight. My car has done 94k and I can't really remember how long I've been tollerating this hoover sound on cold starts, but I'll be interested to see how it sounds tomorrow first thing :)

I'd say this job along with throttle body cleaning is essential for any Mk4!

Thanks Albo!
 

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99 Ronnie
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It comes on when starting from cold. In my case if I started the car and then stood outside a noise can be heard that sounds literally like a Hoover or Dyson is inside the engine bay, a medium-high revving electric motor, sucking or blowing air. I think for a while I kind of ignored it because it goes on and off intermittantly, as the engine warms up. I used to think it was perhaps the radiator fans doing odd things, but since the car ran ok I didnt worry about it.

Anyway now I've fixed mine, I do still hear the hoover sound, but about 90% quieter and less noticable. I only hear it now because I kind of listen out for it.

The air pump unit in question, does only need slight 'seperation' as displayed in the pics earlier in the thread and it causes a loud noise. I remember another user on here with a 1.8T Seat Leon Cupra said that it was more than just a noise problem on his car, it caused real problems cold starting, with the car lurching and stuttering.

Hope this helps!
 
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