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Old 21-08-2007, 14:36   #1
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oil filters and by-pass valve question

Have been doing some research into finding a good quality oil filter at a reasonable price versus the slightly inflated price from Universal. I can get Baldwin heavy duty filters for about $10 and I'm told they are good units. They have two units that are identical dimensions to what I need except one has the bypass valve set at 8 psi and the other at 20 psi.

Can anyone tell me why this might be and what the risks/rewards are with either of these settings?
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Old 21-08-2007, 20:02   #2
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All this work over for 3-4 dollars.
Universal doesn't spec the bypass pressure.
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Old 21-08-2007, 20:04   #3
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I assume this is an oil filter system????

A bypass on a fuel system, the filter has to be between the pump and outlet (nozzle).

For a diesel, I'd go with the higher bypass due to the blackening of oil which may cause some resistance........................_/)
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Old 22-08-2007, 00:21   #4
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8 psi for a bypass pressure setting seems very low for a diesel. Your engine manual should have specifications for this value.

Absent specifications, the best thing to do (assumeing you have an oil pressure gauge) is to compare your normal cruising speed oil pressure with these values. I suspect it is a lot closer to 20 than to 8.

I have a 30 year old Westerbeke 4-154 and the bypass pressure is 40psi.

Bill
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Old 22-08-2007, 06:11   #5
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If it was 3 or 4 dollars I wouldn't care. Universal filters for this thing cost $26 EACH plus shipping of $25 for every 4 I buy. I like to change oil every 40 to 50 hours so it adds up. Fuel filters same thing. Kinda tough when the oil filter is supposedly a rebranded Champ that sells for $6 in most places and the fuel filter is a rebranded Baldwin that I can buy for $10.
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Old 22-08-2007, 06:24   #6
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Quote:
Originally Posted by jdope71
If it was 3 or 4 dollars I wouldn't care. Universal filters for this thing cost $26 EACH plus shipping of $25 for every 4 I buy. I like to change oil every 40 to 50 hours so it adds up. Fuel filters same thing. Kinda tough when the oil filter is supposedly a rebranded Champ that sells for $6 in most places and the fuel filter is a rebranded Baldwin that I can buy for $10.
Not knowing which Universal you have, I can say that the most common oil filter has an MSPR of $14.60 USD for part number 300209. I went back and checked all of the filters hav an MSRP of less than $15.00 USD.
As an added bonus using OE parts also gets the OE parts warranty. And, yes I have had oil filters fail.

40-50hrs is half of the recommended oil change interval specified by Universal. Unless this engine runs 24/7 I don't see an advantage to anyone but your parts providers.
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Old 22-08-2007, 06:41   #7
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Correct part number. But by the time the local distributor adds his slice, pays duties, import brokerage fees, customs and excise, converts from US dollars and pays his shipping cost, then repacks and ships them to me it costs me $26 per filter plus shipping. My Universal book says 75 hours for oil change. The stuff is so black by 30 to 40 hours I just think it's better to change it. Maybe I'm just not used to what diesels do to oil this being my first one in a boat. The engine runs great and seems to be in very good shape, hoping this will help keep it that way. Thanks for your input though, I appreciate it.
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Old 22-08-2007, 06:59   #8
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Diesel will turn the oil black in a short time. This is normal.

Please fill out your profile with atleast a general location on the globe. It would have minimized this conversation if I'd known you were somewhere other than the US.
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Old 22-08-2007, 11:11   #9
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Exclamation Just a note

If your oil is blackening soon after an oil change, you maybe having a compression problem. The cylinders could be glazed or the rings are worn.

How many hours are on the motor???

30 - 40 hours is only a couple weekends for a sports fisherman. That's a lot of oil changes!
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Old 22-08-2007, 13:57   #10
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Unless you totaly pull the engine apart and parts wash each component, the oil will turn black imediatly as soon as it has mixed with old residue around the engine. That is normal and you won't solve the issue. The difference with Diesel oil from Gasoline engie oil is that it has a high detergent level in it, to do eactly that. Wash the Carbon from the engine parts and hold those carbon particles in a state of suspension. If the oil does not turn black quickly, you have a problem because the oil is not doing the job.
Use a good quality oil and good quality filter and change every 100hrs. Sooner is good practice, but not essential, providing you use top qualtiy disposibles.
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Old 22-08-2007, 14:21   #11
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Thank you all for the info. I don't believe the engine has any issues, it has 436 hours on it and runs fine, no smoking under heavy load so I don't think it's a glazing problem. I think it's an owner problem, I'm not used to how diesels interact with oil. I'm obviously on the wrong track with changing oil more frequently and how that might keep it cleaner. Sorry for the confusion resulting from lack of location info. The lower price of the Baldwin filter is only part of its attraction, I think it is possibly a better filter than the OEM part.

My main question though was about bypass pressure. I think I understand the function of the bypass valve, if there is a clog or high resistance in the filter then the oil gets bypassed back into the engine without going through the filter element. So what's better, a higher bypass pressure which I assume would force oil through a more clogged filter but probably would lower the pressure the engine sees downstream of the filter, or a lower bypass pressure which would keep the pressure up but send unfiltered oil through the engine. Or am I not understanding what the bypass valve is for?
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Old 22-08-2007, 20:47   #12
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Aloha JD71,

I like your question and would appreciate an answer too. I really didn't realize there were different pressures to different filters whether bypass or not. My engine has an oil filter bypass and would like to know what psi the filter should be rated for too.

There was another thread here which outlined a failed oil filter and the bypass was mentioned but not explained.

Hope someone can answer this one.

Looks like the forum will let me post again. Good deal!!

Kind Regards,

JohnL
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Old 22-08-2007, 21:37   #13
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The filter can also bypass under certain cold weather conditions. Viscosity is high and in order to allow it to circulate while warming up the filter may bypass for a short while.

As others have posted, the engine manual should spec the operating oil pressure range or spec the bypass pressure.

You do not want oil bypassing lower than upper operating range.

Example if the oil pressure range is 10-30 psi you would ideally like a 30 psi bypass. You definitely don't want 8 psi bypass.

I am sure most engines have the bypass valve integrated into the head of the filter housing and is set at overhaul of the engine. This would seem the most common way to do it.
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Old 23-08-2007, 00:01   #14
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John I thought I did explain it in that post you refer to, but oh well, I will again.
Yes there is a bypass valve. This valve can be found in the engine, the assembly that the filter screws onto, or in thr filter itself. It just depends on the maker. Lets go back one step. The Oil pump is a "positive displacement" pump. This means it will continue to build pressure untill something gives. In reality, the most sensitive part to pressure is the filter and the most prone part to blocking is the filter. So the filter can easily be blown apart. Plus, if the filter is blocked, then oil is not getting to the vital components. So a bypass valve is used to "bypass" the oil past the filter if the restriction becomes to great. This ensures the filter is kept safe and the vital components are kept lubricated. It is better to lube them with dirty oil than no oil at all.
The fact that filters have different values of valve lift to bypass the oil, is why the right filter must be chosen for the engine. Just because the filter fits the fitting, does not mean it will work correctly. You don't want oil pressure to be only 8PSI when it should be 40PSI.
In saying that, I know of no Diesel engien that uses only 8PSI. Actually, I know of no engine full stop that uses only 8PSI. For that matter, even 20PSI is very low for a Diesel, but I am not familiar enough with the engine to say if 20 is correct or not.
Are you sure that it is only 8? and not something else or maybe using a different measurement like KPA of Kg/cm of something??
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Old 23-08-2007, 02:17   #15
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Quote:
Originally Posted by Alan Wheeler
The Oil pump is a "positive displacement" pump. This means it will continue to build pressure untill something gives.
Just to explore that a bit.

Let's make sure we are talking about the same things here -

A positive displacement gear pump is designed to deliver oil pressure throughout the engine speed range. It is not a 100% efficient pump either so at idle you will see lower oil pressure than at cruise. Within the system after the gear pump is a bypass valve. It is set at max operating pressure of the engine. When this bypasses oil is dumped straight back into the gear pump inlet. For example and engine with a 10-30 PSI operating range will have this bypass set (by washers and springs) to 30 PSI.

Oil filter bypass is different and when installed it is designed to bypass a clogged or failed filter. Oil that is bypassed is then not filtered but it is still delivered to the engine oil system in the hopes that contaminated oil is better than none.

There should be a way to know if the filter is in bypass - a cockpit light or something.

Now back to the filters - If they are measuring PSID we could be talking about a completely different subject. PSID would measure the Pounds per Square Inch Differential across the inlet and the outlet of the filter. Your 8 PSI filter could be looking for 30 on the inlet and 22 on the outlet and if it sees that, it will bypass.

This could be exactly what you are supposed to have. A 20 psid bypass is huge for small engines...
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