- Joined
- Oct 21, 2023
- Messages
- 3
I think catch cans are a great idea because they can prevent a sticky valve situation with oil squishing out of the lifter, with the subsequent annoying sound, partial opening of one or more valves, engine imbalance and foaming oil as PCV system was never a mature design with no changes since implementation in the 70s.
However if not designed and implemented the right way they can create more problems than they solve. While satisfactory quality catch cans are not expensive or hard to find, the connectors are a problem. PCV oil resistant hoses seem to be the right choice but they tend to collapse under manifold vacuum and are not thermally conductive and do not promote condensation of the blow by gas before it reaches the catch can itself that may not have enough volume and low enough temperature to promote condensation for most of the gas which means some will pass into the intake that may be colder than the can, condensate and trickle up to the valves.
PVC clear tubing seem to cool a bit better but collapse even more, especially during hot summer days.
For that reason i tried to use a corrugated copper connector instead. However, after a couple of months i found small amounts of green stuff inside the can that comes from the condensed gas corroding copper, besides mostly water mixed with oil and probably corrosive stuff from oil additives and also chemicals from partially burnt fuel. Which puzzle me since i saw cars with copper lines for EGR valves. However those handle (return) exhaust which may have a different composition (less unburnt fuel) than blow by gas and also coat selves on the inside with protective soot.
Ok so next experiment was with a water heater connector made of probably 304 stainless steel (the kind a magnet does not attach much to) again for water heaters bought on Amazon. I looked in the can after about a few hundred miles and did not see nothing. And BTW i think i get water in the can if the gasoline has some in it. (or temperature outside is lower?).
So i did not look again for a couple of months or a few thousands miles when i started to feel oil smell or better said, fuel mercaptan marker smell that the oil from blow by catches from the unburnt fuel coming from a not so perfect rubber adapter. So i looked again in the can and this time i saw again a teaspoon of something similar with the green stuff before, but yellow-white, like solid butter underneath a couple of ounces of the known water/oil emulsion. Is that wax from oil or corrosion from the stainless steel connector?
It doesn't seem to have passed the can, as i can't see any in the evacuation line towards the intake where is nothing but oil but it looks like i'm up for an emergency oil and filter change (Mobile one 5W20 for 20k miles). My question is if a different kind of oil will be less corrosive. Or any ideas at all (thinking now of using this). Going without it is not an option as the engine imbalance and subsequent vibration promote driveability issues at high speed and not so perfect roads.
However if not designed and implemented the right way they can create more problems than they solve. While satisfactory quality catch cans are not expensive or hard to find, the connectors are a problem. PCV oil resistant hoses seem to be the right choice but they tend to collapse under manifold vacuum and are not thermally conductive and do not promote condensation of the blow by gas before it reaches the catch can itself that may not have enough volume and low enough temperature to promote condensation for most of the gas which means some will pass into the intake that may be colder than the can, condensate and trickle up to the valves.
PVC clear tubing seem to cool a bit better but collapse even more, especially during hot summer days.
For that reason i tried to use a corrugated copper connector instead. However, after a couple of months i found small amounts of green stuff inside the can that comes from the condensed gas corroding copper, besides mostly water mixed with oil and probably corrosive stuff from oil additives and also chemicals from partially burnt fuel. Which puzzle me since i saw cars with copper lines for EGR valves. However those handle (return) exhaust which may have a different composition (less unburnt fuel) than blow by gas and also coat selves on the inside with protective soot.
Ok so next experiment was with a water heater connector made of probably 304 stainless steel (the kind a magnet does not attach much to) again for water heaters bought on Amazon. I looked in the can after about a few hundred miles and did not see nothing. And BTW i think i get water in the can if the gasoline has some in it. (or temperature outside is lower?).
So i did not look again for a couple of months or a few thousands miles when i started to feel oil smell or better said, fuel mercaptan marker smell that the oil from blow by catches from the unburnt fuel coming from a not so perfect rubber adapter. So i looked again in the can and this time i saw again a teaspoon of something similar with the green stuff before, but yellow-white, like solid butter underneath a couple of ounces of the known water/oil emulsion. Is that wax from oil or corrosion from the stainless steel connector?
It doesn't seem to have passed the can, as i can't see any in the evacuation line towards the intake where is nothing but oil but it looks like i'm up for an emergency oil and filter change (Mobile one 5W20 for 20k miles). My question is if a different kind of oil will be less corrosive. Or any ideas at all (thinking now of using this). Going without it is not an option as the engine imbalance and subsequent vibration promote driveability issues at high speed and not so perfect roads.
Last edited: