Crankcase vent hose for petrol engine

somitomi

somitomi

Member
248103050_Zylinderblock_mit_KolbenÖlwanne.webp
A while ago I had a bit of an oil leak scare, but it turned out to be just the hose that vents crankcase gases into the intake manifold (no 36 in the diagram above), nothing too serious. Still, I wanted to fix that, but the part (part no 036103493AH) seems to be pure unobtainium. So far the only place I found that has it is Audi Tradition, but with shipping that'd come out to somewhere north of 70€, which is rather ridiculous for a 20-centimeter-ish length of hose. Undeterred, I decided to remove the one in my car to see what diameter and length it is, but I also found out it has a weird plastic piece on the end (which alone took an hour to dislodge) connecting it to the oil separator. That means I can't just buy some generic hose, cut it to length and call it a day.
IMG_20241212_164842[1].jpg
Once again I find myself asking the forum if anyone knows where to find this or a reasonable substitute.
Edit: forgot to mention, I have the 1.4 litre petrol engine (AUA)
 
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Hi,
I haven't repaired one of these, but it seems straightforward enough. Check to see if these are barbed fittings, as I am unsure.
You can cut the old rubber to remove it from the barbs, then measure and order new rubber hoses.


20241212_162819.jpg


EDIT
I am hopeful that all the internal diameters match, if they do that makes the repair a little easier.

If they are different diameters at opposite ends of a pipe that can easily sorted by using a inline joiner with different sized barbed fittings.
🙂👍

They are called reducers

BARPC23.png
 
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@rotifer II That seems like a viable option (maybe even something that has been done already judging by the twist in the lower part of the hose) and as far as I can make out, the hoses are all the same diameter
@birtyA2 That's correct, I should've probably clarified that.
 
Hi,
The hot oil vapour transported inside the hose reacts with the rubber and it becomes weaker and unable to hold its shape.
🙂

EDIT

When buying the replacement hose be sure it's rated for use with oil.
 
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rotifer II said:
Hi,
The hot oil vapour transported inside the hose reacts with the rubber and it becomes weaker and unable to hold its shape.
🙂

EDIT

When buying the replacement hose be sure it's rated for use with oil.
Click to expand...
From the flat state of your old one, check the crankcase end is clear, as it looks like it's been under negative pressure for a long time. Maybe the PCV valve is not opening?
Mac
 
Hopefully it is not this bad 🫣

EDIT
If you remove the crank case oil separator it has 2 rubber seals that will most likely need replacing.
The rubber contracts and hardens over time and this stop them sealing.
If you reuse the seals the risk is that the crank case pressure is affected, which may cause the engine to run rough.
🙂👍
 
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rotifer II said:
Hopefully it is not this bad 🫣

EDIT
If you remove the crank case oil separator it has 2 rubber seals that will most likely need replacing.
The rubber contracts and hardens over time and this stop them sealing.
If you reuse the seals the risk is that the crank case pressure is affected, which may cause the engine to run rough.
🙂👍
Click to expand...
If there were leaks, I'm not sure the hose would be sucked flat.
More like blocked?
Mac.
 
PlasticMac said:
From the flat state of your old one, check the crankcase end is clear, as it looks like it's been under negative pressure for a long time. Maybe the PCV valve is not opening?
Mac
Click to expand...
I think the PCV valve does work, at least the car tends to leak a little oil through this hose after some highway driving, that's why I looked at the engine and noticed the state of this hose. Then again I suppose it wouldn't hurt to have a look while I'm under the car anyway.
 
somitomi said:
View attachment 132625
A while ago I had a bit of an oil leak scare, but it turned out to be just the hose that vents crankcase gases into the intake manifold (no 36 in the diagram above), nothing too serious. Still, I wanted to fix that, but the part (part no 036103493AH) seems to be pure unobtainium. So far the only place I found that has it is Audi Tradition, but with shipping that'd come out to somewhere north of 70€, which is rather ridiculous for a 20-centimeter-ish length of hose. Undeterred, I decided to remove the one in my car to see what diameter and length it is, but I also found out it has a weird plastic piece on the end (which alone took an hour to dislodge) connecting it to the oil separator. That means I can't just buy some generic hose, cut it to length and call it a day.
View attachment 132635
Once again I find myself asking the forum if anyone knows where to find this or a reasonable substitute.
Edit: forgot to mention, I have the 1.4 litre petrol engine (AUA)
Click to expand...
I recently broke a 1.4 AUA, I will check on Saturday to see if I have the 3 item you are after, If I find them I will pm you pictures.
Ami
 
somitomi said:
I think the PCV valve does work, at least the car tends to leak a little oil through this hose after some highway driving, that's why I looked at the engine and noticed the state of this hose. Then again I suppose it wouldn't hurt to have a look while I'm under the car anyway.
Click to expand...
Browsing other threads, it seems the oil separator gets blocked over time, so definitely worth a check and if it is, would explain the flat hose.
@mtl video attached.
Mac.
 
Ami said:
I recently broke a 1.4 AUA, I will check on Saturday to see if I have the 3 item you are after, If I find them I will pm you pictures.
Ami
Click to expand...
Thanks, but I'll probably try using some generic hose with the fittings from this one after all. I'd worry that a salvaged hose might not have too much life left in it and shipping stuff from the UK can be a bit of a hassle due to customs taking forever.
PlasticMac said:
Browsing other threads, it seems the oil separator gets blocked over time, so definitely worth a check and if it is, would explain the flat hose.
@mtl video attached.
Mac.
Click to expand...
Yeah, I dissected the hose today and ordered the oil separator seals after seeing the crud inside the hose. Peace of mind is definitely worth that little extra cost. Anything I should pay attention to while cleaning the separator?
 
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