Catch Can for the CRD

Be VERY CAREFUL if you are going to fit a catch can to the CRD !!

 

I've seen two engines destroyed because they have had inadequate catch cans fitted resulting in the engine pressurising and the oil being forced out.

In one case the can had been fitted for a number of years, with no problems, then one day, on the motorway the engine puked its oil and the engine knocked itself to bits (remember that the CRD has no oil pressure gauge or sensor, so you will get no warning)

 

These engines breath, even when they are new and need to vent this pressure build up

 

So if you still want to fit one, below is a list of requirements

1. Pipes to and from the catch can must be the same or larger in inturnal diameter than the stock breather pipes and with few bends. Any restrictions and at the very least you will push the dipstick out sooner or later ( I have seen stock cars with no catch can fitted push the dipstick up straight after an oil change)

2. These pipes must not be silicone or normal rubber, they must be fuel safe. Those nice red or blue silicone tubes and bends you can buy rot when exposed to diesel and oil mist, The same goes for normal rubber hose. This will eventually cause the pipes to collapse and reduce flow

3. Catch can should be placed low in the engine bay

At least lower than the return fitting to the engine. this will stop oil/water/cude  condencing out of suspension and returning to the engine when the car is turned off and cooling down

4. A sealed can or one not fitted with a safety valve should only be fitted below the level of the oil level in the sump. This will prevent the oil/water/cude being syphoned back ito the engine should the can become full

5. Safety valves are a must, to stop any possitive pressure in the system building up, if the crankcase pressure rises or the can becomes full

6, Catch can must be large. Cans designed for petrol, are not big enough for a heavy breathing diesel I'd go for 1 litre minimuim

7. Cans should be baffled or contain material to aid the condencing out of the mist. Its no good venting the gasses to an empty can the back to the engine, very little will be caught (a couple of bits of gauze is not good enough

 

If you are still considering fitted one........have a look on the internet and see whats on offer for Catch Cans designed for diesels, please don't fit a chinese can with small plastic pipes no vent and no baffles

8. Do not remove the PCV valve, its a one way valve there to stop air etc getting forced back into the enginefrom the intake

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PCV valve

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The Provent range of catch cans desighed for diesels

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Silicone hose rotting when exposed to dise/oil (hose had turned black inside

Back to 300C Workshop w2

The Inside of a standard rubber pipe used with fuel/oil