VictorTL

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Disclaimer; I've never broken open the top of a J-Series motor. That said, I have broken open the top end of many V type engines over the years; it seems as often as not, one head is more coated with dark varnish than the other. Another observation is on engines which have used almost exclusively synthetic oil, the difference in color is far less apparent.

Why does this happen? My theories:

• On some engines, the oiling to one head is more plentiful than the others; hence the oil in/on the head with the lower amount of flow gets hotter.
• On some engines, the coolant flows first to one head then to the other; one head is hotter than the other.
• On some engines, the coolant comes from a different source or location in the block for each head; one head is hotter than the other.

Regarding synthetic oil versus non; given the generally higher (sometimes much higher) volatility of non-synthetic oil (i.e. it evaporates at a lower temperature), it isn't surprising some surfaces are more varnished than others.

There may be a few other causes, however, in the end, varnish in and of itself, doesn't typically cause an issue for many hundreds of thousands of miles.

VictorTL

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Hmmm, never actually looked at the PCV on either of my J-Series engines. That said, typically the PCV is located on the side of the engine which would naturally run higher pressure from the blow-by gases. Thinking about this, I don't remember ever seen a pattern as to which side the PCV is located, I can literally think of instances of it being on either side.

Thinking about this a bit further, there will typically be a breather tube of fresh filtered air on the valve cover opposite the PCV valve; that may well be another reason why one head becomes more varnished that the other; the side with the fresh air will typically be a bit cooler than the side used to collect the blow-by gases.

VictorTL

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Basically, more pollution, a lot more. Then there is the issue of a non-vacuum assisted CVS (Crankcase Ventilation System) which generally result in high water and fuel dilution of the oil, excess sludge formation in the engine, and accelerated engine wear. Back in the bad old days, an open CVS system would use a tube mounted in a high, and relatively oil free location (say the top of a valve cover with a baffle, and then the tube would run down under the car into the under-car airflow. As the vehicle would move down the road, a small vacuum would be formed (much like how wind helps pull smoke up a chimney) which aided the evacuation of the blow-by gases and helped fresh air to enter the engine on the breather side.

If you simply disconnect the PCV, there will be no vacuum to aid CVS, and your engine will suffer the consequences.

VictorTL

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A properly designed catch can shouldn't restrict the flow to any significant degree. Are you having an oil blow by issue which is mucking up your intake manifold?

VictorTL

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I'm assuming the tube which collapsed was the tube from the Catch Can to the Intake Manifold. Assuming that's the case, then toss that Catch Can in the trash; it's worthless.

VictorTL

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I'm thinking the tube may not be the issue, the Catch Can is causing too much restriction between the PCV and the manifold. A more robust tube may be worth a try, but I'm concerned about the can itself.

VictorTL

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I don't have any actual experience with automotive Catch Cans; just theoretical knowledge of the subject. My concern with yours is if the downstream tube collapsed, there must be quite a bit of restriction.

97'CL2.2

ill answer this here bc apparently my answer on the other forum wasn't good enough? the rear bank is the fresh air inlet side of the pcv system, meaning all the fresh air enters this side and draws the vapor AWAY from the rear bank, concurrently the front bank with the pcv valve is under vacuum from the attachment to the manifold. these two forces create a flow from the rear bank to the front bank. this means ALL of the oil vapor passes through the front bank under vacuum conditions (anytime other than WOT basically) which causes staining over time compared to the clean filtered air which gets drawn in through the intake tube at the rear bank.

VictorTL

VictorTL

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I guess before any of us can answer your question, another question needs to be asked; what are your goals?

VictorTL

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Okay, here's my take on that issue after having torn down many-many engines over the years. As a general rule, I can tell within the first few minutes of engine disassembly whether an engine has been lubricated on a steady diet of synthetic oil. Why? THe vacuum lines and the intake manifold/plenum down stream of the PCV feed are much cleaner. Many folks correctly state an engine lubricated with conventional oil will last just as long as one lubricated with synthetic, assuming frequent enough oil changes, however, there are other intangibles which make me favor synthetic. The cleanliness of the intake systems on engines with synthetic oil in the crank case is one of the most important (to me) among them.

So, why the lower amount of buildup with synthetic oil? One word, "volatility". Conventional oil, even the very best conventional in the world (whatever that happens to be), has a much higher NOACK value than the lowest quality synthetic oil (the lower the value the better). Long story short, as with virtually all liquids, when oil gets hot it tends to evaporate, the hotter it is, the faster it evaporates; a huge percentage of the deposits in the intake system are those from evaporated oil mixed with combustion blow-by gases. In engines lubricated with synthetic oil, the relative lack of oil fog in the stream coming out of the PCV system means a much higher percentage of those blow-by gases make their way into the combustion chamber and are summarily dealt with when the intake mixture burns.

I know lots of folks are concerned about keeping the internals of their engines as pristine as possible, hence the fact catch cans are even on the market, but in the grand scheme of things, it is doubtful a catch can will add even a single mile of life to an engine or prevent even a single item of maintenance from being required.

97'CL2.2

this last part is the real take away. bottom line is honda designed a system to deal with a normal amount of blowby gasses the engine will produce, if you are getting oil consumption a catch can will be a diagnostic tool at best, indicating weather you have excessive blowby or not. if you have no consumption, id leave it be the way honda designed it.

VictorTL