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Hello,

I am new to Unimogs (and first time poster) and I can hear an air leak when the engine is off. I have been trying to find it with no avail.

Are there any tips and tricks that people can share on how I can go about finding the leak?
 

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85' U1300L Holset Turbo VA A/C, 66' Propane 404.1 rock mog, 1975 416 Doka, G500, Volvo C303
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Bottle of soapy water. Start spraying anything and everything until you see bubbles.
 

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1976 416 Unimog
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74 Posts
I have one of these. (Leak detector) Best investment ever! You can hear a tiny refrigerant leak on a reefer unit while standing at the rear of the semi-trailer. I've used it to find a water leak in a semi-trailer roof by going inside the trailer and having a co-worker blow compressed air across the roof of the trailer. I've also used it to find a water leak on a window in my home. It would only leak when there was a strong wind coming from the west. I purchased it & used it for most of the time for conducting safety inspections on trucks & buses,
 

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1986 Unimog U1700L (435 series)
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312 Posts
I purchased a large refill bottle of bubble making liquid (the product used by kids to make bubbles) from the local $2 shop. It is a much cheaper option than the commercial product.
Don't forget behind the instrument panel, as there are two connections to the display unit showing air pressure, and connections to the top right switch (2x4, 4x4 selector)
 

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1991 U1550L37, 2019 G550
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2,019 Posts
Hello,

I am new to Unimogs (and first time poster) and I can hear an air leak when the engine is off. I have been trying to find it with no avail.

Are there any tips and tricks that people can share on how I can go about finding the leak?
But have in mind that your air dryer purges air after you turn of the engine and ignition. That sound of air escaping is by design.
 

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1986 Unimog U1700L (435 series)
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312 Posts
The Ex ADF U1700 does not have air dryer as standard, so unlikely he has one. Stewie 110 might want to look at my recent post re U1700 air leak. I eventually found that the main unloader/regulator was leaking to atmosphere all the time due to some swarf inside.
 

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1988 U1300
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52 Posts
You are very fortunate that you can hear the air escaping. Shut the Mog off in a quiet place and take your time. The bubble spray bottle works excellent, but don't discount the value of some quality time with your ear hovering over the lines. Neighbors may get a chuckle. I recently developed a leak in pressure when the U1300 was parked for more than 30 minutes and rolled up my sleeves in anticipation of a major head cramp. I found it within a minute - a banjo fitting had come loose from vibration. A quick snug with the wrenches and totally remedied. I have the advantage of the box being off the truck presently so everything is easy access from the top.
 

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1988 U1300L RW1 Working gears Mogauspuf Dual Tanks Other Goodies 91 F250 HD 4x4
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139 Posts
I just bought on of these https://www.dhgate.com/product/gas-detection-ultrasonic-leak-detector-transmitter/499190288.html If it works I'll let you know. For $100 AUD, can't really go wrong
Definitely want to hear (Ha!) how this works. Got curious, and checked the link, but long wait from China seemed pretty sketchy, especially for those of us topside on the globe.

Here is a link on Amazon, available in the US, cheaper, quicker shipping. I'd wager a discarded Mog part that this is the exact same item.

 
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