THE BIG R56 COOPER S ( N14 ENGINE) ‘BODGE UP’ CURE FOR STOPPING THE INLET VALVES COKING UP + PROPER CURE.
…………. IF YOU HAVE THIS MODEL READ THIS !
We have recently read through 10 years of threads regarding the problems of the inlet valves coking up, with the associated problems and how people ( Main Peugeot Dealers include I believe) have addressed the problem. I am amazed that so few people understand the importance of the PCV circuit to the inlet manifold, but in particular its importance with a turbocharged engine.
THINGS YOU PROBABLY DO KNOW
-The direct injection system causes much carboning up of the inlet valves
-The engines have pinking/knocking issues ….. The oil re- entering the inlet charge massively reduces the octane causing this. If ignored it can, put holes in pistons.
-An Oil Catch Can (or 2) is a good idea.
THINGS YOU THINK OR HAVE BEEN TOLD ARE THE SOLUTION……that are not!
-Fit an OCC on the boost side circuit (So far so good)
-Block off the PCV valve circuit back to the inlet manifold…….NO !
It looks to me that even Peugeot have resorted to blanking off this port ( Or at least selling the parts to allow the customer to do it). Here’s the plus sides AND the longer term problems from things you probably didn’t know:-
– Reduces the carbon build up. ( If used with 1x OCC on the boost circuit).
– Cheap to do.
– A short term fix but the problems are lurking just around the corner.
SO NOW HERE’S WHAT YOU DIDN’T KNOW & THE LONGER TERM PROBLEMS THAT CAN OCCUR.
1) The conventional ‘journal bearing’ turbocharger requires a small negative pressure in the sump/crankcase to assist the gravity oil return back to the sump. Remove the PCV inlet manifold ‘suck’ and the turbochargers oil return rate to the sump slows down, raising the level of oil inside the bearing housing, resulting in the oil internally spilling over and leaking directly into the hot exhaust side (turbine) of the turbocharger. This burns under the ‘almost red hot’ heat of the turbine and exits out of the exhaust pipe as smoke yet is often not easily visible. Normally it is more apparent at idle, overrun or very light throttle. Note in this instance the oil doesn’t burn through the engine internals…It goes straight from the turbo oil feed into the exhaust ….THAT’S THE OILY SMELL YOU GET, WHEN BLOCKING OFF THE PCV TO INLET MANIFOLD.. Very few people even know where the smell is coming from let alone be able to explain why it happens. It won’t happen all the time btw, usually it will be very intermittent…Not great for the Cat either!
2) Blanking off this circuit means ALL the ‘piston blowby’ now vents out the end connection of the rocker cover and back in the turbo inlet pipe. This is where many have put an OCC. This is a good thing, as it catches a good amount of oil/water/fuel contaminants. But here’s where the good bits end . Firstly in putting ALL the breathing /oil separation tasks through one poor little OCC invariably much more will ‘bridge it’ and go into the turbo. The problem is all this oil entering the turbo is very bad for the turbo in more ways than one. Even worse it now goes on from there through the intercooler and coats all the internal cooling fins and tubes with oil reducing its charge air cooling efficiency. Finally, the bulk of this oil and fuel leftovers just collects and stays in the base of the intercooler. This has in effect become your new undesirable ‘Supersize OCC’ ! One other problem being the inlet temps go up and pinking/knock returns.
3) More sludge build up over time in the engine. Put simply you’ve got no venting ‘helping hand’ vacuum suck as you’ve blocked it off
4) Other seals and gaskets more likely to weep/leak over time from increased crankcase pressure.( i.e. No negative pressure situation under normal driving)
5) Throttle angle increases at idle, so possibly codes /dash lights etc. could occur.
OK SO WHATS THE PROPER FIX HERE ?
– The only proper fix is 2 x Oil Catch Cans on independent circuits AND retention of the inlet manifold ‘suck’ to the vacuum OCC circuit.
– Also use ONLY super unleaded fuel, but that’s more to do with the pinking/ piston destruction.
– Change those Spark Plugs once a year or so.
– Fit GTT PowerMist . The Water Methanol mix blasts the oil off the back of the inlet valves like no other. It also increase the octane value by a huge amount and lowers intake temps big time .More expensive this one, but very effective so I thought I would mention it.
WHAT IF I WANT TO RUN JUST ONE OCC TO SAVE COST ETC?
– In short it can never be as good.
– Also fills up twice as fast as 2 cans.
– As stated if you do, just don’t block off that inlet manifold suck.
OK BUT IF I RUN JUST ONE OCC AND DON’T BLOCK THE INLET MANIFOLD OFF, SURELY THE OIL STILL GETS SUCKED IN ON LIGHT THROTTLE VACUUM ?
-Yes it does, you are resolving the problem when on boost though with the one can, so still much better than nothing.
The BRAND NEW GTT R56 OIL CATCH CANS, will be available very soon as a set of 2 for ultimate fix, or just a single ‘Boost Circuit’ OCC + GTT special mod to reduce oil getting in on the other circuit during those vacuum situations. In summary with these turbocharged engines we don’t recommend any blocking off as it removes one problem and introduces a whole new set of them.
PS. N18 is different, it uses Valvetronic not closed throttle to control air in to the engine,…So please don’t compare the one PCV hose you see on these to the two you see on the N14 version.