Melling Oil Pump ... Low Pressure
05-23-2011, 11:08 AM
#1
427 Low Oil Pressure ... Solved I recently installed a Melling Oil pump (10295) on my new ERL 427 shortblock. The pressure was really low using 5w30 and ERL said to go to a straight 40 weight. (The clearances on the engine are a little loose IMO) Even with this my hot idle pressure was only 14-15. So I upped the oil to 50 weight Valvoline racing oil. With 50 weight the pressure is reading 50 at cold start and 28-30 at hot idle. I would have thought that my cold start pressure would be way more then 50 with this heavy of an oil.
So I'm thinking that either the sending unit isn't giving me the right numbers or the pump has an issue...installation or otherwise. The pump I'm using is the stock volume/higher pressure model so the low pressure that I've read that's associated with higher volume pumps emptying the stock size pan shouldn't apply. This is supposed to be a higher then stock pressure pump ... but I don't see it.
We're going to use another gauge to test the sending unit first because as I've been told a bad ground can cause the sender to give misleading readings. The engine was built on a stand and the oil pump gasket check and recheck so I'm fairly confident that If we go back in that's not going to be the problem.
So I'm thinking that either the sending unit isn't giving me the right numbers or the pump has an issue...installation or otherwise. The pump I'm using is the stock volume/higher pressure model so the low pressure that I've read that's associated with higher volume pumps emptying the stock size pan shouldn't apply. This is supposed to be a higher then stock pressure pump ... but I don't see it.
We're going to use another gauge to test the sending unit first because as I've been told a bad ground can cause the sender to give misleading readings. The engine was built on a stand and the oil pump gasket check and recheck so I'm fairly confident that If we go back in that's not going to be the problem.
Last edited by GTO1_OHIO; 08-08-2012 at 09:56 PM.
05-24-2011, 12:48 AM
#3
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Just to chime in here, but one time when installing a melling pump (the high volume, but same idea) I accidentally partially pinched the O-ring. I had similar results, oil pressure was lower then expected. The pump had already been run before so I knew where it should be on my build so that helped in my case and I tore it down once I saw the oil pressures ~15-18 psi below expected.
I too checked and re-checked when I had pinched it. Unfortunately, a partial pinch is hard to detect. With the angles that the oil pump and line work at you could get it to mate up pretty well and still end up pinching it.
I too checked and re-checked when I had pinched it. Unfortunately, a partial pinch is hard to detect. With the angles that the oil pump and line work at you could get it to mate up pretty well and still end up pinching it.
05-24-2011, 01:46 AM
#4
05-28-2011, 01:51 PM
#5
Found out that the oil pressure is actually 7 lbs more then the gauge is showing ... but still lower then we think it should be. A friend of mine who also has a GTO says his was the same way when he tested with a mechnical gauge. Since I'm still not good with this I bought a SLP pump to replace the melling so we'll see if it is the pump itself.
Last edited by GTO1_OHIO; 05-28-2011 at 07:25 PM.
06-03-2011, 07:31 PM
#6
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ERL Block Found out that the oil pressure is actually 7 lbs more then the gauge is showing ... but still lower then we think it should be. A friend of mine who also has a GTO says his was the same way when he tested with a mechnical gauge. Since I'm still not good with this I bought a SLP pump to replace the melling so we'll see if it is the pump itself.
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06-07-2011, 08:26 PM
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08-08-2012, 08:25 PM
#10
...so last September after changing to the SLP oil pump it helped a little but once the coolant was up to 200+ degrees the pressure would drop to 10 psi and the bells and whistles on the dash would go off and say to check oil. Basically you could watch the pressure dropping as the coolant temp went up. This was on straight 50W.
In October ERL agreed to take the block back to see if it had a problem. They did a pressure/leak test on the block, heating the block to 225 degrees to see if a hair line crack opened at operating temps. ...still nothing, everything checked out.
So ERL plugged the D.O. D. passages, tighten the main bearing clearances to .017 - .018 and installed a new barbell plunger to rule out any damage to the existing one. I'll give ERL this, they have gave me their best effort to try and figure this out. Everything was done under warranty except shipping.
In April I was told the pressure looked better and went to pick up the ... but unfortunately after driving it for only 15 minutes the pressure was down in the low teens.
... so we decieded to go with a Katech Oil Pump ... 23% more volume then stock. https://ls1tech.com/forums/generatio...-oil-pump.html
I just picked the car up this weekend and things look good. At hot idle ... up to 205 degrees I'm seeing 26-30 psi while in drive at 800 RPM. At 1200 RPM I'm seeing low 40 psi which it jumps to if put into park. This weekend I raced at Pontiac Nationals with temperatures in the 90s and a track temperature in the mid 140s. The oil pressure stayed in the 30s - 40s. This is now on 20w50.
Now it's time to put some miles on her to see if the problem is really solved.
In October ERL agreed to take the block back to see if it had a problem. They did a pressure/leak test on the block, heating the block to 225 degrees to see if a hair line crack opened at operating temps. ...still nothing, everything checked out.
So ERL plugged the D.O. D. passages, tighten the main bearing clearances to .017 - .018 and installed a new barbell plunger to rule out any damage to the existing one. I'll give ERL this, they have gave me their best effort to try and figure this out. Everything was done under warranty except shipping.
In April I was told the pressure looked better and went to pick up the ... but unfortunately after driving it for only 15 minutes the pressure was down in the low teens.
... so we decieded to go with a Katech Oil Pump ... 23% more volume then stock. https://ls1tech.com/forums/generatio...-oil-pump.html
I just picked the car up this weekend and things look good. At hot idle ... up to 205 degrees I'm seeing 26-30 psi while in drive at 800 RPM. At 1200 RPM I'm seeing low 40 psi which it jumps to if put into park. This weekend I raced at Pontiac Nationals with temperatures in the 90s and a track temperature in the mid 140s. The oil pressure stayed in the 30s - 40s. This is now on 20w50.
Now it's time to put some miles on her to see if the problem is really solved.
08-09-2012, 03:54 PM
#11
Tim at the Car Shop Inc has a line of pumps that have fixed the issues you were experiencing.
My car with .002 mains and .0025 rods 220 oil 5-30 I see 25 idle and 55-60 by 1800 and about 80 at 7000. Cold idle is 72 psi
This pump has been tested on NHRA SS cars. Texas mile and street car apps and has eliminated oil delivery issues
I have been running this pump for a year and had great performance from it.
Best thing to do is talk with Tim they are doing some things that no one else is doing and they are working great. My dads car has his pump also and has 11,000 miles with perfect performance.
Tim
My car with .002 mains and .0025 rods 220 oil 5-30 I see 25 idle and 55-60 by 1800 and about 80 at 7000. Cold idle is 72 psi
This pump has been tested on NHRA SS cars. Texas mile and street car apps and has eliminated oil delivery issues
I have been running this pump for a year and had great performance from it.
Best thing to do is talk with Tim they are doing some things that no one else is doing and they are working great. My dads car has his pump also and has 11,000 miles with perfect performance.
Tim
08-15-2012, 06:52 PM
#12
Id ditch that pump, we had a melling fail while tuning right after the re build on a friends car. it smoked the crank berrings.
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08-15-2012, 08:50 PM
#14
The drive gear from the get go before we installed it seemed way to sloopy and tolerances had to be way to loose but he wanted it put in anyways cuz it was cheaper and he paid the price for it...
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08-15-2012, 08:58 PM
#15
Tim at the Car Shop Inc has a line of pumps that have fixed the issues you were experiencing.
My car with .002 mains and .0025 rods 220 oil 5-30 I see 25 idle and 55-60 by 1800 and about 80 at 7000. Cold idle is 72 psi
This pump has been tested on NHRA SS cars. Texas mile and street car apps and has eliminated oil delivery issues
I have been running this pump for a year and had great performance from it.
Best thing to do is talk with Tim they are doing some things that no one else is doing and they are working great. My dads car has his pump also and has 11,000 miles with perfect performance.
Tim
My car with .002 mains and .0025 rods 220 oil 5-30 I see 25 idle and 55-60 by 1800 and about 80 at 7000. Cold idle is 72 psi
This pump has been tested on NHRA SS cars. Texas mile and street car apps and has eliminated oil delivery issues
I have been running this pump for a year and had great performance from it.
Best thing to do is talk with Tim they are doing some things that no one else is doing and they are working great. My dads car has his pump also and has 11,000 miles with perfect performance.
Tim
08-15-2012, 10:13 PM
#16
Maybe this......but who knows if it flows any more than stock.
http://moroso.carshopinc.com/product...id/90969/22120
.
http://moroso.carshopinc.com/product...id/90969/22120
.
08-16-2012, 05:48 AM
#17
We've built 8 Ls Cars in the past few yrs as side jobs and we have always used TSP Ported and shimmed pumps or left the stock ones in the car and never had any issues w oil pressure or failure.
08-17-2012, 08:20 PM
#18
Maybe this......but who knows if it flows any more than stock.
http://moroso.carshopinc.com/product...id/90969/22120
.
http://moroso.carshopinc.com/product...id/90969/22120
.
08-23-2012, 06:43 PM
#19
A little more testing. I drove for an hour, 2 lane highway with a max speed of 55 this weekend and the pressure was 26-30 at idle (800rpm) when I got home. Today I drove into Atlanta for work with max speeds up to 75 and the lowest I saw was 24-26 this evening after a 45 minute ride home with coolant temps reaching 192 degrees. So so far the Katech pump looks like it was the solution but I want to put a 2 hour highway trip under my belt to make sure.
09-06-2012, 01:08 AM
#20
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i got a melling 10296 and at idle im seeing 25 lbs and then when running much more normal numbers. i am concerned and wondering whether to change. wish i had left my previous pump.
