Crankcase Breather

Post by **Longdog** » Sun Apr 19, 2009 6:32 pm

Hi does any body have a good solution to crankcase breathing that is a;not into the engine to spoil the charge, and b;wont clog every 10 miles and send oil back through the rear of the crank.I currently have a small k&n on top of a standard (1275) timing cover breather but this keeps clogging with oil vapour.Is there any body out there with a catch tank or similar with a good term of reliability?

Post by **bmcecosse** » Sun Apr 19, 2009 7:44 pm

The only solution is to suck it into the engine - and burn it! The amount is miniscule - it really won't 'spoil the charge' in any detectible way - and it solves all the oil leak problems - and saves you breathing in the carcinogenic oil fumes. The 1275 inline engine is poorly served for breathers (Mini has an additional one on the trans case) - either add one on the rocker cover and take it to the carb (or directly into the inlet manifold via a 1/8" restrictor) - or pipe the timing cover breather to the carb. I prefer the rocker cover option - this allows some air to flow through the engine from the timing cover breather, and helps to minimise mayo formation!

Post by **bigginger** » Sun Apr 19, 2009 8:26 pm

bmcecosse wrote:The only solution is to suck it into the engine - and burn it! !

No, it's not. One solution is to suck it into the engine - and burn it, another is to vent to air, as some of the 1098s (among other engines) did. I've no strong opinion either way, but "The only solution" seems a little odd.

Post by **Longdog** » Sun Apr 19, 2009 8:51 pm

I'll give it a go as it is the most cost effective option and see if there are any probs.It does make sense to put the crankcase under lower/possibly negative pressure.

Post by **Longdog** » Sun Apr 19, 2009 8:53 pm

Thanks for replies btw.

Post by **bmcecosse** » Sun Apr 19, 2009 10:09 pm

Andrew - LD has tried venting the fume - it's not working for him! As I explained above - the 1275 inline unit has only one breather - it's not enough when there is any blow-by. Yes - you can add another on the rocker cover - that will help to vent fume - but my expereience is that the only successful (maybe I should have put that)

solution is to burn the fume. I had a 1340 Mini engine that had only thin rings on the pistons - it had v good compressions, and ran v well - but it had some crankcase pressure, was smelly (oil fume smell - actually made eyes water after a bit) ) and leaked oil - and after a period of idling had an impressive plume of blue smoke. Connected the rocker breather to the manifold (via the 1/8" restrictor) and the blue smoke stopped - and so did the leaking. Yes - the idle was slightly upset - but it was a 544 cam anyway, so it was never going to be smooth. it worked well for my engine !

Post by **bigginger** » Mon Apr 20, 2009 12:08 am

As I said, no strong opinion - just seems a little short sighted to claim your way's the ONLY way. Maybe his problems are with the filter - I have had none running just the factory one with a length of tube venting to underside - but understand what you're saying, just don't much like the absolute certainty that it's THE RIGHT ANSWER.

Post by **bmcecosse** » Mon Apr 20, 2009 10:50 am

I believe it is ! Works for me - and seemed to work for BMC too - they provided the rocker cover connection, the linking pipe and the inlet on the SU for that very purpose!

Post by **bigginger** » Mon Apr 20, 2009 1:46 pm

On some engines, they did, yes, but not on all - which kinda reinforces the point that there is NOT just one way as you maintained in the original post, and the only thing that I'm pointing out.
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