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I'm not I understanding the problem with keeping the bypass. Why wouldn't I want bypass? If my IMS bearing fails, the bits from it will only get into the engine if the pressure differential is greater than 8 pounds when it happens the filter goes into bypass. If the filter isn't in bypass, the bits won't pass through. Is it a given that when the IMS bearing fails, the filter will go to bypass?
And wouldn't the bits from the IMS already have gone through some of the engine on their way to the filter?
Normally you want a bypass to counter oil-starvation; this is only an issue with cold start at extremely low ambient temps or a severely clogged oil-filter. If your engine had an IMSB failure, like mine, there will be leftover metallic debris in the sump and oil pump. Until those are fully washed out with several oil changes, you might want to opt disabling the bypass to be absolutely sure no debris passes by.
A small percentage of valves apparently have a faulty spring, which allows the valve to open prematurely (thus at higher ambient temperatures). If this is the case, you also may want to disable the valve with this mod.
If your engine had a properly working valve you should be safe however, even if you had IMSB failure.
Bypass mechanisms also exist to prevent the oil pump from destroying itself. Liquid are practically not compressible, so if there is a blockage in the delivery side of the pump, without a bypass, something will blow up or come apart, including any pressure lines, pump housings, shafts, etc. I believe most oil pumps have a bypass (pressure relief valve) to solve this problem. In the 996’s case, I’m not sure where the oil pump bypass exists. Does it divert oil back into the sump? Oil filter bypass exists for a similar reason. If the filter becomes blocked, something has to give, including the filter media, filter housing, lines, whatever is in the way. The 996 oil filter bypass is routed to the engine, not the sump. “It’s better to deliver some oil to the engine, even if contaminated, rather than run it dry”, the Porsche engineers decided.
The better approach would be to have sensors on both bypass mechanisms to have the ECU turn on the oil light on the dash. That would have driven up the price/complexity.
Oil pump bypass sits at the front of the engine, basically a piston with a spring. It limits maximum oil pressure at the filter to 5 bar. Anything over that gets rerouted to the sump.
Bypass mechanisms also exist to prevent the oil pump from destroying itself. Liquid are practically not compressible, so if there is a blockage in the delivery side of the pump, without a bypass, something will blow up or come apart, including any pressure lines, pump housings, shafts, etc. I believe most oil pumps have a bypass (pressure relief valve) to solve this problem. In the 996’s case, I’m not sure where the oil pump bypass exists. Does it divert oil back into the sump? Oil filter bypass exists for a similar reason. If the filter becomes blocked, something has to give, including the filter media, filter housing, lines, whatever is in the way. The 996 oil filter bypass is routed to the engine, not the sump. “It’s better to deliver some oil to the engine, even if contaminated, rather than run it dry”, the Porsche engineers decided.
The better approach would be to have sensors on both bypass mechanisms to have the ECU turn on the oil light on the dash. That would have driven up the price/complexity.
The main oil pump has a bypass valve to limit max pressure to 5 bar as Boxman suggests, but the return is not to the sump, but rather back to inlet side of the pump.
As Murphyslaw correctly suggests, Porsche (as well as most manufactures) assume "dirty oil is better than no oil" and more problems would arise from customers not properly maintaining there engines and running oil and filters too long causing filters to become "low flow" and a by-pass would be beneficial. IMOP our engines are more likely to be endangered by debris by-passing the filter under cold start conditions, than it would be by "low or no flow" due to filter blockage/dirt from long term useage.. I suggest not using a by-pass on the filter, change oil and filter at low intervals, and install lots of high strength/temp magnets in the sump pan to collect any ferrous debris, and check/clean sump with each oil change, it is easy to do..
Why would multi-weight oil be a problem when it's cold? If you're running 0W-40 weight, isn't the cold weight 0 and hot weight 40? Once the engine warms up, the oil is 40W weight but at start up on a cold day it's 0W.
Anyway, did my first oil change on the C4S yesterday. Seems pretty straight forward. I like the canister too. No need to cut open a filter case. Is there any advantage to the spin on adapter?
Dave
Originally Posted by Porschetech3
The main oil pump has a bypass valve to limit max pressure to 5 bar as Boxman suggests, but the return is not to the sump, but rather back to inlet side of the pump.
As Murphyslaw correctly suggests, Porsche (as well as most manufactures) assume "dirty oil is better than no oil" and more problems would arise from customers not properly maintaining there engines and running oil and filters too long causing filters to become "low flow" and a by-pass would be beneficial. IMOP our engines are more likely to be endangered by debris by-passing the filter under cold start conditions, than it would be by "low or no flow" due to filter blockage/dirt from long term useage.. I suggest not using a by-pass on the filter, change oil and filter at low intervals, and install lots of high strength/temp magnets in the sump pan to collect any ferrous debris, and check/clean sump with each oil change, it is easy to do..
Why would multi-weight oil be a problem when it's cold? If you're running 0W-40 weight, isn't the cold weight 0 and hot weight 40? Once the engine warms up, the oil is 40W weight but at start up on a cold day it's 0W.
Anyway, did my first oil change on the C4S yesterday. Seems pretty straight forward. I like the canister too. No need to cut open a filter case. Is there any advantage to the spin on adapter?
Dave
Because 0w oil is still thick when cold. Not as thick as 5w or 10w, etc., but still very slow moving in terms of hot vs cold.
Murph,
I thought the 0W-40 would stay at about a 0 weight down to well be 0C. Here's a chart I found of 10W-30. It shows that it stays at 10 weight down to -20C. If it can flow to every part of your engine that it needs to get to, why would it blow off the bypass at the filter?
Dave
Originally Posted by murphyslaw1978
Because 0w oil is still thick when cold. Not as thick as 5w or 10w, etc., but still very slow moving in terms of hot vs cold.
If you apply the mod described above? No, except the spin-on costs about 199$ more. The spin-on also has a smaller filter medium and thus a reduced flow capacity, which under normal circumstances is not a problem at all; in extreme cold, however, the spin-on will starve your engine for oil sooner than the bypass-less canister.
So if you're worried about the bypass letting unfiltered oil by AND you want to start your engine in arctic conditions such as a true Nordic winter, you're even better off with the modified canister than the spin-on, in terms of oil starvation.
I thought the 0W-40 would stay at about a 0 weight down to well be 0C.
It does, however a 0W oil doesn't have the same viscosity throughout it's temperature range either. Just like any other oil, colder = thicker. A 30W at 0 deg C is thicker than 0W at 0 deg C, but a 0W at 0 deg C is a hell of a lot thicker than 30W at 100c
If you apply the mod described above? No, except the spin-on costs about 199$ more. The spin-on also has a smaller filter medium and thus a reduced flow capacity, which under normal circumstances is not a problem at all; in extreme cold, however, the spin-on will starve your engine for oil sooner than the bypass-less canister.
So if you're worried about the bypass letting unfiltered oil by AND you want to start your engine in arctic conditions such as a true Nordic winter, you're even better off with the modified canister than the spin-on, in terms of oil starvation.
It does, however a 0W oil doesn't have the same viscosity throughout it's temperature range either. Just like any other oil, colder = thicker. A 30W at 0 deg C is thicker than 0W at 0 deg C, but a 0W at 0 deg C is a hell of a lot thicker than 30W at 100c
The napa 1348 (not 1042) filter also has a bypass mechanism. Two aspects different than the stock filter though:
1) It has a much stronger spring (also you get a new spring for every filter change so no chance for the spring to go weak)
2) During bypass, the debria will tend to stay at the bottom of the canister so a little bit safer
The napa filter also has a bypass mechanism. Two aspects different than the stock filter though:
1) It has a much stronger spring (also you get a new spring for every filter change so no chance for the spring to go weak)
2) During bypass, the debria will tend to stay at the bottom of the canister so a little bit safer
I had made the exact error in the past, however their construction vid is a 'general' filter - individual differences apply. I've dissected a 1042 and it doesn't have the bypass as depicted in that picture.
Originally Posted by Charles Navarro
The filter we use is a 1042 and is from a 97-04 Corvette and flows 9-11 gallons per minute:
I specifically said it flows fine under normal conditions. Would you argue it flows more than the original cartridge? The filter medium inside is significantly smaller in terms of surface area, a factor two almost.
I'm talking about differences in an extreme case; extreme cold. If one flows more than the other, the one that flows most is the safest when starting up in extreme cold ambient conditions.
Hi Charles, the ones I took apart are constructed exactly like the in the diagram, including the "up-front safety by-pass valve". I believe the spring allows the filter element to drop down in case of extreme pressure so oil could escape from the silicon anti-drain valve and by-pass valve in the diagram.
Edit: sorry I was referring to NAPA 1348, not 1042. The 1348 does have a by-pass valve inside.
I had made the exact error in the past, however their construction vid is a 'general' filter - individual differences apply. I've dissected a 1042 and it doesn't have the bypass as depicted in that picture.
I specifically said it flows fine under normal conditions. Would you argue it flows more than the original cartridge? The filter medium inside is significantly smaller in terms of surface area, a factor two almost.
I'm talking about differences in an extreme case; extreme cold. If one flows more than the other, the one that flows most is the safest when starting up in extreme cold ambient conditions.
Perhaps the design has changed since you took one apart? I just took one apart a few days ago and it has the by-pass valve as shown in the diagram.
12-07-2018, 11:46 AM
