Oil pipe and pressure issues

[Karlos99]

Evening all.

Been have an on going issue of oil pipes failing on my 2110 bus motor. It's running a 30mm berg pump, remote filter head, Fram HP1 filter with a sandwich plate that feeds an external oil cooler and I use 20/50 mineral oil.

Since March I've had 1 by 1 all the full flow pipes fail so 4 in total. I thought I may have a stuck relief valve but on removal they are both free. The motor first run in June 2014 so my thinking is if the pump was to mighty it would have started bursting hoses from the beginning? Didn't start having trouble till March this year when 1 went, then again in July when the other 3 failed 1 by 1.

I've since had all new hoses made by a local hydraulic company, my pressures at idle are: 40 psi cold and 15psi hot. Any advice or ideas welcome, I'm stumped 

[Martin S.]

I suppose you could try a lighter oil as 20w50 would be a 20w on startup when it's cold. I use 5w40 synthetic which is quite a bit lighter when cold especially. Berg cautioned about the startup pressure thru the filter which he said could cause cheap filters to burst. I haven't had that happen, but my bro in law did and ended up getting the Berg relief valve oil pump cover and he said that cured his problem so you could try that. I've never had a hose fail and I've used some that a local hydraulic shop made up using rubber hose and swedged-on ends they did at their shop, and I've also used Berg's teflon hoses. I did have a failure that stumped us for a while when trying out a home made aluminum cooler. It was a flex metal hose the type used in natural gas hookups for a stove or gas dryer. It worked good and then started leaking and it turned out in that case that the balanced 2332 engine had such crazy vibration that it pulsed thru the hose and fractured it. You can feel that by hand even idling on the hose - try it yourself and you will be shocked. When I bought a Setrab cooler the info with it cautioned about that problem saying those pulses would crack their aluminum cooler so make sure to secure the lines to a solid part before hooking to the cooler. Lesson learned.

[Bruce]

I think you can cure all your problems by doing an oil change.  Put in some 5W-30.

Everyone has a gauge that they say reads the pressure.  I think this is the wrong terminology.  Your gauge is actually reading back pressure. 
Your main bearings and cam are where the oil has to be delivered.  The source is the pump.  Your gauge is placed between them so that it reads the pressure that feeds back to the pump.  If you change to thinner oil, it flows easier through and into the bearings, causing less back pressure to the pump.

So many guys are fixated with seeing a high number on their oil pressure gauge.  To me this is wrong.  A high reading on the gauge is bad because it tells me that your oil cannot get into the bearings.  At extreme pressures, the plunger gets compressed all the way down, allowing the oil to go out the relief port straight back into the sump.  What good is that doing?  Wouldn't it be better if that oil went into the bearings?

Your back pressure gauge is lying to you.  The burst lines are telling you your pressure is too high.
Using thinner oil will also make your oil temps run lower.

[JS]

Could it possibly be that the hoses were not good enough quality?

[Karlos99]

Could it possibly be that the hoses were not good enough quality?

They were from speedflow with anodised torques fittings. The new pipes I've had made are from a mate at Pirtek rated at 4500psi

[Lids]

Are you using the Berg pressure relief pump?

[andy198712]

I think you can cure all your problems by doing an oil change.  Put in some 5W-30.

Everyone has a gauge that they say reads the pressure.  I think this is the wrong terminology.  Your gauge is actually reading back pressure. 
Your main bearings and cam are where the oil has to be delivered.  The source is the pump.  Your gauge is placed between them so that it reads the pressure that feeds back to the pump.  If you change to thinner oil, it flows easier through and into the bearings, causing less back pressure to the pump.

So many guys are fixated with seeing a high number on their oil pressure gauge.  To me this is wrong.  A high reading on the gauge is bad because it tells me that your oil cannot get into the bearings.  At extreme pressures, the plunger gets compressed all the way down, allowing the oil to go out the relief port straight back into the sump.  What good is that doing?  Wouldn't it be better if that oil went into the bearings?

Your back pressure gauge is lying to you.  The burst lines are telling you your pressure is too high.
Using thinner oil will also make your oil temps run lower.

As said here, PSI is a measurement of restriction. think about it, your pump pumping down a open pipe with a gauge inline, just pumping it out into the air, no PSI but a lot of flow, if you blocked off the end, and put a 1mm hole in there, a lot of pressure but not much flow.

BUT

 you need X amount of pressure to keep that cushion or film of oil to separate the bearing from the right? and i don't know how you work out what you would need as it would vary dependant on load...?

bit off track i know! 

[Steve D.]

Check the easy stuff first- make sure that your oil lines are in the correct ports in the filter head.  Oil will flow the wrong way through and oil filter's anti-drainback valve, but it isn't happy about it.

[andy198712]

i was reading a local (i think) site about some filter heads being marked up wrong in the IN and OUT department...

does anyone know the correct way?

[Roope]

[Bruce]

As said here, PSI is a measurement of restriction. think about it, your pump pumping down a open pipe with a gauge inline, just pumping it out into the air, no PSI but a lot of flow, if you blocked off the end, and put a 1mm hole in there, a lot of pressure but not much flow.

What I highlighted is not true in the case of our oil cct.  The VW oil pump is a positive displacement pump.  That means it pushes the same volume of oil, regardless of the viscosity or back pressure.  But your thinking is not completely wrong.  With your 1mm hole, less flow will get through it since we have another path in the oil cct called a pressure relief valve to drain off the excess flow.

you need X amount of pressure to keep that cushion or film of oil to separate the bearing from the right? and i don't know how you work out what you would need as it would vary dependant on load...?

What you are about to learn will amaze you.
Pressure = load divided by area.  
What is the load on a connecting rod at peak cylinder pressure?  Then what is the area of the rod bearing?
Now do the math.

Karlos, IMO the Berg pressure relief cover is the wrong way to solve this problem.

[Fiatdude]

I would not be worried about the high pressures -- I would be up grading to high end Hydraulic hose that is rated far higher than anything you will ever need -- that is what I've done on my engine as I see pressures over 100 psi at cold startup with my very large oil pump -- I've also started using hard line and steel braided hose everywhere

 

[Karlos99]

I can't help but think though, why was it ok for 7000 miles prior to this problem. If the pressure was to much it would be doing over stuff too? Like bursting oil coolers and filters? I've had hydraulic pipes made by pirtek, just need to try them.

Karl

[Fiatdude]

Karl --

Nobody says it, but hoses are subject to a lot of stresses and they will 'wear out', fatigue and burst -- they are experiencing a lot of heat and pressure cycles from your engine -- and you have just found the life expectancy of that brand/style of hose, 7000 miles of starts and stops, warm-ups and cool downs -- I've had steel braided lines fail too (mainly the rubber/nylon inside starts separating) -- you need to buy the best stuff and keep an eye on it by inspecting the hose for it getting hard, brittle or cracking. -- AND be prepared to replace them on occasion !!!!! I believe by having some very good lines made, you will have put this issue behind you....
 
You wouldn't think that connecting rods would never wear out from fatigue, but my friend has to replace his rods in his engine every 9 miles at a cost of $1500 -- they are under extreme stress in a top fuel funny car, but I'm just trying to make a point.... everything has a life expectancy and some things last longer than others... good luck in the future !!!!!!!

[Karlos99]

Thanks for your help mate, I've had some pipes made up by my friend at the local hydraulic pipe company. The new pipes are PTFE lines with braided top layer and stainless steel unions. Rated at 4500 psi so should be ample for a VW motor 

Karl

[Martin S.]

What kind of hoses were the ones that burst? Do you think the hoses were at fault? I figured that if there was excessive oil pressure, the filter would have failed before the hoses, or at least started bulging. The hand made al cooler we were trying out ended up ballooning and closing up completely so with a trouble light behind it you could not see any light come through with obviously high oil pressure (not using 20w50). There were the heavy-duty oil relief valve springs in the engine so we put the OE ones back in and went with the Setrab cooler. Through all that the Berg teflon SS hoses were fine.

[Karlos99]

What kind of hoses were the ones that burst? Do you think the hoses were at fault? I figured that if there was excessive oil pressure, the filter would have failed before the hoses, or at least started bulging. The hand made al cooler we were trying out ended up ballooning and closing up completely so with a trouble light behind it you could not see any light come through with obviously high oil pressure (not using 20w50). There were the heavy-duty oil relief valve springs in the engine so we put the OE ones back in and went with the Setrab cooler. Through all that the Berg teflon SS hoses were fine.

They were -8 hoses from speedflow. My thoughts exactly about the pressure. I would have said a filter or cooler would have gone, pipes didn't balloon or swell, they just seemed to seep oil.

[Martin S.]

The only thing I can think of would be a run of defective hoses or an inexperienced operator who assembled them. The teflon SS hoses should never be a problem no matter what oil you use. The City of Winnipeg retrofitted their entire transit fleet of buses with the SS teflon hoses after some failures with the original rubber ones and completely eliminated their downtime. Well worth the upgrade cost. I did run a car for 14 years with rubber ones done at a local shop and they are still good now though.

[nlvtinman]

I am going to share my own forgetfulness and/or overall stupidity. From the oil pump cover to the filter adapter, that is to which side of the adapter-In or Out side?

[Martin S.]

What kind of hoses were the ones that burst? Do you think the hoses were at fault? I figured that if there was excessive oil pressure, the filter would have failed before the hoses, or at least started bulging. The hand made al cooler we were trying out ended up ballooning and closing up completely so with a trouble light behind it you could not see any light come through with obviously high oil pressure (not using 20w50). There were the heavy-duty oil relief valve springs in the engine so we put the OE ones back in and went with the Setrab cooler. Through all that the Berg teflon SS hoses were fine.

They were -8 hoses from speedflow. My thoughts exactly about the pressure. I would have said a filter or cooler would have gone, pipes didn't balloon or swell, they just seemed to seep oil.

Since you say the pipes didn't balloon or swell don't blame the hoses themselves, the problem was more likely the way the fittings were installed onto the hoses. If you look at a youtube of how it is done, you will see it is not that simple and needs someone doing it who is good. https://youtu.be/HK5kFcP81cE