Who knows the oil pressure in the engine Oil Cooler? - Page 2 - PeachParts Mercedes-Benz Forum

Diesel911 · #16 11-15-2007, 12:39 AM

Quote:

Originally Posted by tangofox007

How many gauges does your injection pump have?

I have been a member for about 1.5 months and when I have read IP in other threads it has always ment Injection Pump. When I get conflicting information I ask questions. Now the next time I see IP I know that some people mean instrument panel.
You can hook up a fuel pressure gauge to your fuel injection pump if you want to. It would tell you the pressure between the fuel supply pump and the relief valve that controls the pressure on the side of the fuel injection pump.
When I worked in a fuel injection shop an ran these types of pumps on the test stand I always have a gauge on it. The relief vlave springs can weaken and the valves on the supply pump can ware out and the gauge would indicat.
On the a vehicle it could indicate when you need your fuel filter changed.

#17 11-15-2007, 05:50 AM

Quote:

Originally Posted by Diesel911

Is there anyone out there who knows the oil pressure in the engine Oil Cooler or the hoses that go in and out of it?

Up to 101.5psi continuous, up to 110psi surge.

Diesel911 · #18 11-18-2007, 02:12 AM

I think I have found an answer; In the MB service manual (18.8-005/2) it states the relief valve in the oil filter housing is set at 3.5 bars (on my 84 300D). Since the oil returning from the oil cooler goes back to the oil filter housing and through the oil filter part goes to the engine bearings and part goes back to the oil pan.
This indicates to me that as long as everything is functioning correctly (especially the oil filter relief valve) the oil pressure in the oil cooler and oil cooler hoses should not be more than 3.5 bars.

300SD81 · #19 11-18-2007, 03:08 AM

Quote:

Originally Posted by Diesel911

I think I have found an answer; In the MB service manual (18.8-005/2) it states the relief valve in the oil filter housing is set at 3.5 bars (on my 84 300D). Since the oil returning from the oil cooler goes back to the oil filter housing and through the oil filter part goes to the engine bearings and part goes back to the oil pan.
This indicates to me that as long as everything is functioning correctly (especially the oil filter relief valve) the oil pressure in the oil cooler and oil cooler hoses should not be more than 3.5 bars.

Is that 3.5 bars compared to atmospheric, or 3.5 bars from one side of the filter to the other? The gauge reads 3 bars, and is usually pegged by 2000rpm or less, which should mean that it will easily exceed 3.5 bars...

omegabenz · #20 11-18-2007, 03:38 AM

What sort of upgrades have you done to your MB?

i bet there is an AN connector with a port for a gauge. I could possibly hook it up if someone can source this above connector

#21 11-18-2007, 08:41 AM

Quote:

Originally Posted by Diesel911

I think I have found an answer; In the MB service manual (18.8-005/2) it states the relief valve in the oil filter housing is set at 3.5 bars (on my 84 300D). Since the oil returning from the oil cooler goes back to the oil filter housing and through the oil filter part goes to the engine bearings and part goes back to the oil pan.
This indicates to me that as long as everything is functioning correctly (especially the oil filter relief valve) the oil pressure in the oil cooler and oil cooler hoses should not be more than 3.5 bars.

Incorrect, the oil cooler operates at system pressure of up to 7bar. The bypass valve is for the pressure across the oil filter. In the event the oil filter becomes clogged the bypass will open and allow dirty oil to enter the oil system. Dirty oil is better than no oil.

funola · #22 11-18-2007, 10:54 AM

Quote:

Originally Posted by omegabenz

What sort of upgrades have you done to your MB?

i bet there is an AN connector with a port for a gauge. I could possibly hook it up if someone can source this above connector

I am sure you can get a AN tee fitting to plumb in a gauge. Not sure if there is enough room to do so. Maybe at the upper oil cooler fitting?

What size AN did you use? My guess would be #10?

mobetta · #23 11-18-2007, 11:19 AM

OK- so now we know the pressure can get slightly over 100psi. if you look around hydraulic shops, even at shop-pressure air lines, you will see many clamps that can withstand this pressure.

I am not going to jump on the wagon saying that it is a bad idea to change out your oil lines w/ new hoses- quiet the opposite-

what is the ID of the hose you got, and what are the best style clamps...I have been dreading changing out my oil lines, because the job has only been made harder by the extra WVO stuff I have in the way. I would be interested in doing this the easy way- replace the hose. no worries on stripping the cooler, either.

Diesel911 · #24 11-18-2007, 12:07 PM

Quote:

Originally Posted by mobetta

OK- so now we know the pressure can get slightly over 100psi. if you look around hydraulic shops, even at shop-pressure air lines, you will see many clamps that can withstand this pressure.

I am not going to jump on the wagon saying that it is a bad idea to change out your oil lines w/ new hoses- quiet the opposite-

what is the ID of the hose you got, and what are the best style clamps...I have been dreading changing out my oil lines, because the job has only been made harder by the extra WVO stuff I have in the way. I would be interested in doing this the easy way- replace the hose. no worries on stripping the cooler, either.

1/2 inch ID is too small so I used 5/8 inch hose. The 5/8 inch hose slips with very little tightness over the hose barbe. The clamps were shielded hose clamps made in the USA. T-bolt type clamps would have been a better choice but I could not get any locally and it is difficult to find any on the internet that are small enough.
You have to use hose that can take the heat of the hot oil going through it. It is not just a matter of hose that can take the pressure.

KAdams4458 · #25 11-18-2007, 12:07 PM

A little warning: On my '77 300D, the two hoses are different diameters for the upper and lower lines. I have no idea why. Don't be like me. Make one trip to the parts store, not two.

Diesel911 · #26 11-18-2007, 12:15 PM

Quote:

Originally Posted by funola

I am sure you can get a AN tee fitting to plumb in a gauge. Not sure if there is enough room to do so. Maybe at the upper oil cooler fitting?

What size AN did you use? My guess would be #10?

It looks to me like the only way to settle oil pressure issue is to T in a gauge. I don't want to do this as my system is doing fine with no leaks. If I was going to T in a gauge I would just take off one end of the hose get two 5/8 inch hose nipples and a pipe T and install it that way and add anothe length of hose to the end and assemble it. This would be ok for testing but the weight of it hanging down from the oil cooler would not be a good thing as the hose nipples are often made of brass.

funola · #27 11-18-2007, 12:19 PM

On my 83 300DT, both lines are the same diameter. It is a metric size and from memory, I measured the metal lines at 15 mm dia. A 5/8 hose is a bit on the loose side so is not ideal but with 2 good clamps it should be ok IMO. I'd use one worrm type clamp and the other a constant pressure spring type clamp which will self adjust as the hose ages.

Diesel911 · #28 11-18-2007, 05:33 PM

Quote:

Originally Posted by ForcedInduction

Incorrect, the oil cooler operates at system pressure of up to 7bar. The bypass valve is for the pressure across the oil filter. In the event the oil filter becomes clogged the bypass will open and allow dirty oil to enter the oil system. Dirty oil is better than no oil.

I can't agree with this.

#29 11-18-2007, 05:40 PM

Quote:

Originally Posted by Diesel911

I can't agree with this.

How can you not? Its the truth and how it works.

The bypass valve exists to prevent oil starvation to the engine and oil filter collapse from a large pressure differential across the media. All oil filters have it. Some like ours don't have one in the filter itself but have it built into the filter base while other types of filters (Mostly spin-on) have the valve inside the filter.

http://www.synlube.com/oilfilters.htm

Quote:

If blockage occurs in the filter, bypass valves open. This allows oil to go around the filter and back to the engine. In this situation, lubrication with unfiltered oil is better than none at all.

http://minimopar.knizefamily.net/oilfilters.html

Quote:

They also have a pressure relief or bypass valve that will allow oil to bypass the filter element in the event that it becomes too plugged to pass enough oil. This prevents engine oil starvation and the possibility of destroying the element, possibly causing pieces of it and the junk it filtered to enter the engine. Also, when the oil is cold and very thick, it will tend to bypass the filter through the pressure relief valve because it cannot pass through the element until it thins out somewhat. If it did not do this, the filter element media would tear open.

http://www.machinerylubrication.com/article_detail.asp?articleid=398

Quote:

Most engines incorporate a bypass valve across the inlet and outlet of the full flow oil filter within the lube oil system. The valve is designed to open and bypass oil around the filter and/or element when the restriction reaches its opening pressure (Figure 2).

The bypass flow circuit ensures oil flow to the engine when there is a significant restriction across the filter due to element plugging or cold start conditions. Typically, engine manufacturers design bypass valves to open at a pressure differential of approximately 10 to 30 psid with some as low as 4 psid (28 kPad), and others opening as high as 75 psid (500 kPad). Some engine manufacturers locate the bypass valve in the filter mounting base on the engine, while others locate the valve within the filter. Either way, the same purpose is served.

Oil filters are designed to withstand differential pressures significantly greater than those experienced under normal operating conditions. Therefore, when a center tube or element has collapsed, it is usually the result of a sticking or otherwise malfunctioning bypass valve.

In some instances, a sticky filter bypass valve alone is not enough to collapse the center tube or element. The oil pump pressure regulating valve may also stick in the closed position, which results in increased pressure and oil flow through the filter. Although this condition may be only momentary, it can quickly collapse the center tube if the bypass valve fails to, or is unable to, relieve the excessive differential pressure.

A collapsed center tube or element can lead to a loss of filtration and oil flow to the engine. There is the possibility that interior parts of the filter or filter media may be physically displaced and could migrate into the system interfering with the oil flow. Additionally, debris and contaminants that are held by the filter may be released.

From WIX http://www.wixfilters.com/productinformation/gff_oilfilters.html

Quote:

If a WIX full-flow filter becomes "clogged", or excessively restrictive to oil flow, the filter by-pass valve ensures continued engine lubrication by allowing the oil to by-pass the filter. Some vehicle manufacturers have the by-pass valve built into the oil filter mounting unit (located on the engine).

Other vehicle manufacturers require full-flow filters have the by-pass valve built into the filter itself. All Wix oil filter types recommended for these particular applications include the by-pass valve assembly in the filter.

By-pass Valve Assembly -- spring loaded valve assembly that allows oil to by-pass the element under high-differential pressure conditions such as cold oil and/or excessively contaminated media. This allows lubrication of the engine, but without full-flow filtration.

funola · #30 11-18-2007, 05:50 PM

Probably easier and better to make up a 100 to 150 psi gauge to mate up to the oil line going to the OEM oil pressure gauge.

Quote:

Originally Posted by Diesel911

It looks to me like the only way to settle oil pressure issue is to T in a gauge. I don't want to do this as my system is doing fine with no leaks. If I was going to T in a gauge I would just take off one end of the hose get two 5/8 inch hose nipples and a pipe T and install it that way and add anothe length of hose to the end and assemble it. This would be ok for testing but the weight of it hanging down from the oil cooler would not be a good thing as the hose nipples are often made of brass.