Oil from intercooler

[NavaraNavara]

Whats the problem and how to fix it? Seems one of the cells is leaking and from where the oil is coming?

 

[ericcs]

what is a cell, other than what's in a battery?

 

[Old.Tony]

Oil in the intercooler is normal. I'll explain why, and what you can do to reduce it.

Diesels are high compression engines and the pressure in the combustion chamber is quite considerable. Some of the combustion gas seeps past the piston rings (we call this "blow-by" ) and enters the crankcase. This gas is understandably very hot. It does cause the oil in the crankcase to heat up enough for a small amount to form a vapour.

So that the crankcase doesn't pressurise to the point where it explodes, blow-by is vented through an opening in the top of the camshaft housing (usually) called the Positive Crankcase Ventilation (PCV) valve. It usually passes through a cooler before reaching the PCV, in an attempt to extract most of the oil.

This blow-by is then piped to the air intake just in front of the turbocharger, where it enters the engine's intake and is combusted to remove the oil from the environment. Of course, the air path from this point has to pass through the intercooler, which is designed to cool down the air heated up by compressing it through the turbocharger (air comes out of the turbocharger at higher pressure, and somewhere between 200 and 250 degress celcius). As the air cools, some of the remaining oil mist also cools, and stays inside the intercooler.

So that's HOW it happens.

You can reduce the amount of oil by putting a "catch can" in the hose that goes from the PCV to the air inlet. This won't get rid of the oil altogether, but it will catch a great deal of it, particularly if the catch can is mounted forward of the engine where the ambient air is a little cooler. You won't get rid of all of the oil, and you'll have to empty the catch can manually (or add a fitting that allows you to open a tap and drain the oil back into the engine's sump).

You can't get rid of the oil altogether without venting the PCV directly to atmosphere and I don't recommend that you do that now, because of the risk it presents to other vehicles. We used to do that, and anyone who used to drive back in the 80s or earlier would remember the dark patches on the roads at the traffic lights. Motorcyclists learned very quickly to stay off those!

So you'll have to clean the intercooler. Petrol is a good solvent for this job, it mostly dries right up and won't harm your car. I've done it myself. One hand over one opening, pour about 100ml of petrol in the other. Put your other hand over the top opening then invert the intercooler, releasing the upper hand. Swish it around a few times. Repeat until the petrol comes out clear.

 

[NavaraNavara]

Thank you tony how can we live without you. :/

Ok the other part if there is an air leak should I replace the intercooler?

 

[Old.Tony]

Ok the other part if there is an air leak should I replace the intercooler?

If the intercooler itself is leaking, it CAN be repaired. It has to withstand slightly higher pressures than a cooling system so you can't just use chewing gum. It may be an opportune time though to purchase something that is a little more efficient if you want to throw the coin at it, and if you want more efficiency than the stock "air to air" intercooler, you might consider a "water to air" (W2A) intercooler (I cannot easily find an example but I know they're available). These W2A units are more efficient but require some expense to set up. Personally I'm happy with the stock unit - less things to go wrong!

If mine developed a hole, I'd first look at the option of having the hole soldered, and if that was not a good option, I'd look at a new aftermarket unit.

 

[OldManBeard]

Ok the other part if there is an air leak should I replace the intercooler?

Before jumping straight into the replacement of the intercooler check that the leak is in fact in the intercooler. It could be where one or the other hose connects to it and the oil leaking down, giving the appearance that the leak is elsewhere. I'd start with the good old soapy water test. With the engine running, preferably a bit above idle, brush, pour or spray soapy water wherever a leak might be and watch for bubbles. Don't forget to test where the boost sensor attaches as well.

If the intercooler is indeed leaking I suggest talking to a radiator replace place, as it's really the same thing and they have both the know-how and gear to effect a repair, if a repair is feasible. Whatever you do, don't try to repair it yourself, as such attempts pretty much always just make matters worse.

 

[NavaraNavara]

what is a cell, other than what's in a battery?

Tubes not cells .. sorry for my english