Originally posted by oppy Well thanks Blue - at least now I'm not the only nutcase!
Ummm, Bob, I think you should reread the info - the way I read it the gear-to-housing clearance shown in the table is 0.20 mm MAX. That ain't much!
Oppy, 0.2mm is 7.9 mils (thousands of an inch), this doesn't include the gear to gear clearance!!! In my previous post, I gave
3.9-7.5 mils, which is 0.1-0.191mm.
Originally posted by oppy Not really Bob - if the filter is oriented such that the inlet is down, the column of oil would be under slight pressure. If the inlet is up, you would need to create a vacuum to move the oil. Apples and oranges.
That's exactly my point oppy. A siphon doesn't rely on gravity, rather it works on a vacuum created by differential pressure. I can see though, that it would not work if the filter was not completely packed with fluid because an air gap might break the vacuum. If an oil pump was tight enough to prevent oil from getting through we wouldn't need gaskets on our engines to keep the oil from seeping out, would we?
Your analogy of the fuel transfer pump is a really good point. I see what you are saying. That if the siphon effect I describe were to hold true, once you hand cranked a fuel transfer pump and got the fluid moving you could just stop cranking and let the siphon do the rest of the work. Then you would need a valve at the end of the hose to shut off the fuel flow when you were done. But I think the difference is in this case, is that the fuel transfer pump is at the highest point of the fluid path. So when you stop cranking the pump the fuel runs out of the hose and creates an immediate air gap which prevents a siphon. But what I'm saying is that if the transfer pump were on the very end of the hose and it was lower than the fuel tank, you would start a siphon.
Like I said, I never really thought about this before. This is a very thought stimulating subject. You guy's are great! You've shown me the correct way to spell "siphon" too!
I’m not convinced of the siphon effect but I will say that if it does exist there is still a difference. The filter opening that is pointing down would drain out and the one pointing up would only siphon to a point.
Originally posted by BlueRanger94 I’m not convinced of the siphon effect but I will say that if it does exist there is still a difference. The filter opening that is pointing down would drain out and the one pointing up would only siphon to a point.
I think we are in agreement. The original statement was a filter that is mounted upright does not need an anti-drainback valve,
which I said was not true do to siphon action.....
i just replaced my oil pump that had over200000 miles on it it was still holding oil back,i ran a qt of engine flush through it before i drained it. the oil pump had abourt 2 hours to drain back.when i took the pan off their was no oil coming from the oil pump back to the pan.So when i unbolted the oil pump oil ran out all over me.so this wore out oil pump was holding oil back.Plus the anti drain valve on the motor craft filter didnt do its job either.I didnt take it off untill i had the new pump in and the engine bolted down
I seems to me that if the siphon effect were real, the dipstick reading would indicate an oil level beyond the MAX mark assuming the correct amount of oil was added to the engine.
Originally posted by Houckster I seems to me that if the siphon effect were real, the dipstick reading would indicate an oil level beyond the MAX mark assuming the correct amount of oil was added to the engine.
That's the reason for the oil filter anti-drainback valve!!!
It is a well-known trick in PSD circles to punch a hole in the filter to drain the 2 qts of oil that it holds out of the filter before removing the filter. Makes the filter much lighter and easier to handle.
I've done it several times. 2 qts. in, 2 qts. out.
Not doubting your siphoning theory, but in the PSD, it doesn't hold water (or oil).
The oil pump does not let oil flow back so it does not siphon
The pump i just took off was holding oil back.This oil was thinned out like water and the pump still kept it from draining back(the oil was not coming out of the pump when i took it off it was running out the block where the pump mounted)(300 sixs)
This pump was old and had over 200000 miles on it
Also if the pump didnt hold oil back then everybody that used fram oil filters(since it seems nobody here likes them) their dipstick would read overfull all the time.because that oil in it would siphone back to the pan
Originally posted by redv92c The oil pump does not let oil flow back so it does not siphon
The pump i just took off was holding oil back.This oil was thinned out like water and the pump still kept it from draining back(the oil was not coming out of the pump when i took it off it was running out the block where the pump mounted)(300 sixs)
This pump was old and had over 200000 miles on it
Also if the pump didnt hold oil back then everybody that used fram oil filters(since it seems nobody here likes them) their dipstick would read overfull all the time.because that oil in it would siphone back to the pan
Well, I'll use your same example, if oil didn't drain back, why do
people have valve train noise on start up with Fram filters?? If
the oil pump held the oil back, there shouldn't be any noise on
startup...
Originally posted by oppy I'll answer that one Bob - you'd actually have to believe that Frams cause valvetrain noise, which I don't.
Hi Oppy, it's good to hear from you!!
Well, if you do a search on it, you will find a lot of people that have had valve train noise on start up with Frams, and the noise
stops when they switch to a different brand of filter...
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Siphon effect
