M.A.N. EGR Cooler Leaking?

There are a number of M.A.N. trucks on the road today that have a common problem, The EGR cooler starts to leak water. A replacement unit could set you back in excess of a £3000.00 or you can have it professionally repaired for around a fifth of that price.

EGR cooler which looks like this.

When we receive the coolers they are generally in the above condition, We then strip the tubestack from the casing and soak the components to soften any carbon and dirt deposits.

The stripped parts are thoroughly cleaned and rinsed and a test plate is bolted on the tube-stack. It is then prepared for testing.

Tube-stack under test - notice the bubbles under middle bolt?

You can see from the pictures there is a fairly big leak coming from the tube-stack. The test plate is removed, then the tube-stack is dried and mounted in a jig ready for the repair to be carried out.

This is the point that determines whether the repair is carried out professionally or botched. I have seen in the past where supposedly "specialists" have carried out  repairs on these units using either  soft solder or braze - I've even seen one glued!! None of these methods will qualify for a lasting repair!

If your going to have them repaired do it RIGHT!!

Here is a finished unit which is reassembled after final testing using new gaskets and 'o' rings where needed. On this particular unit the convoluted exhaust gas pipe (which is located on the far right of the picture) was cracked. This is made of stainless steel and needs to be tig welded. Again I've seen "specialists" try to braze them which is a total waste of time. Below is the before and after photos of a repair carried out correctly.

You can see in the photo there is a crack on the third flute from the left.

Here on the right you can see that the crack has been stainless steel tig welded. This can be carried out safely as long as there are not to many flutes cracked and the pipe still retains some flexibility. 

Well that's about it for this item I hope it was informative and showed that carried out  correctly, these units can be repaired successfully. I will try to bring you more soon.