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Discussion Starter · #1 ·
Hello all,

I have been facing this problem for months now, when i start the engine of my MK4, and if it cold, the sound of it is very harsh and loud for about 2 minutes and then it stops and remain the normal sound of the motor. It happens sometimes while driving as well for 5-10 seconds and vanish again!

Any idea/suggestion on what this sound might be?

I hope i don't have to change the whole motor for that!

Your help is much appreciated!!
 

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Potentially bad SAI pump.

The pump is at the front of the engine bay, low down. If you jack up the front end of the car, you should be able to unplug it easily enough. If the noise goes after unplugging it, then you found your problem. Unplugging it will cause your engine light to come on and a fault code will be stored.
 

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That is the SAI pump - the hoses become brittle and snap. It's to blow fresh air into the exhaust to heat the cat faster. Because it's leaking, it's just blowing fresh air into the bay and sounds like a vacuum cleaner.
 

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Discussion Starter · #8 ·
OK, so i went down and checked the SAI Pump, and i found the two hoses coming out of it COMPLETELY out!!

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And the very loud noise is coming from one of the hoses touching the fan as you can see here:
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Just moving the hose away from the fan already removed the sound. But i tried to pull the hoses back but they are lose and come out immediately after leaving them. I was in a hurry and did not try for long time but Is there a technique to insert those two in the SAI pump?
 

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They push in and click when they're all the way home. I can almost guarantee your mounting brackets for the SAI are broken, so you may need to hold the unit while you push the hoses back in place.
 

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They push in and click when they're all the way home. I can almost guarantee your mounting brackets for the SAI are broken, so you may need to hold the unit while you push the hoses back in place.
There's 3 mountings for it that wear really easy, they're located on the ring mounting for the pump. Those pipes that popped off are difficult to get back on if the clip is broken. Ebay does some cheap replacements but I've heard of SAI deletes so that might be the best option?
Tbh mine pops the pipe at the valve beside the engine the whole time, stupid plastic connections. Fck planned obsolescence

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Discussion Starter · #11 ·
There's 3 mountings for it that wear really easy, they're located on the ring mounting for the pump. Those pipes that popped off are difficult to get back on if the clip is broken. Ebay does some cheap replacements but I've heard of SAI deletes so that might be the best option?
Tbh mine pops the pipe at the valve beside the engine the whole time, stupid plastic connections. Fck planned obsolescence

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That's what i have right now, a broken connector but on the hose itself. see here:
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Trying since yesterday to find a replacement part of this hose, with no success. Ebay, Amazon, original, different auto part markets... no success!!
 

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That's what i have right now, a broken connector but on the hose itself. see here:
View attachment 52586

Trying since yesterday to find a replacement part of this hose, with no success. Ebay, Amazon, original, different auto part markets... no success!!
runmade Secondary Air Injection Pump Hose Pipe SAI Set Kit 2Pcs Compatible with VW Jetta Bora Golf MK4 1.8T Compatible with AUDI A3 TT S3 1.8T

Try that

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Discussion Starter · #13 ·
runmade Secondary Air Injection Pump Hose Pipe SAI Set Kit 2Pcs Compatible with VW Jetta Bora Golf MK4 1.8T Compatible with AUDI A3 TT S3 1.8T

Try that

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Thanks for sharing @IrishBen, this is not the same unfortunately. It is for 1.8 Motors. I have 2.3. It does not even look the same, have a look here:
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