Crazy oil pressure problem. Rises, drops then rises at WOT. WTF???
04-08-2010, 08:47 PM
#1
Crazy oil pressure problem. Rises, drops then rises at WOT. WTF??? Guys I have got a really friggin weird oil pressure problem.
Some background information.
Melling 10554 standard volume pump w/ white spring
Stock pan and windage tray
Two weeks ago the oil pickup fell off of the pump. It is possible that I had nearly 200 miles and 6 dyno pulls with the pickup off. The pickup was replaced and the engine believe it or no seems fine. I only noted the pressure falling when braking which lit the dash light. Never saw an ill effect accelerating or cruising but I think its safe to say that I might not have seen the idiot light occasionally coming on to indicate split second no oil pressure.
Cold idle oil pressure is 60#.
Cold rev makes 80#.
Hot idle oil pressure is 20#.
Cruising at 2K RPM is 30#.
Cruising at 4K RPM is 50#.
Here is where it all goes to Hell.
When at WOT, pressure climbs and is consistent with having 10# per thousand RPM until around 5K RPM.
When you hit 5.5K, the pressure drops instantly to around 30# then shoots back up to around 60# at around 6K RPM in the blink of an eye. I can slowly accelerate and the same thing happens.
I have tested with 1 quart oil under filled, oil level full and 1/2 quart overfilled. The problem remains. I have replaced the filter, problem remains. I have not yet tried thicker oil but I have noticed the pressure drop still occurs with cold oil and a WOT blast.
The oil pump pickup is between 3/8" and 1/2" from the oil pan floor. The relief valve is not seized up. At a glance, the pump showed nothing unusual but I did not look very close at it. Also I can not say for certain that the oil pressure drop issue was occurring prior to the pickup falling off. I do find it difficult to believe that I would never have noticed the gauge behavior when blasting on it for nearly two years.
I am confident in the following:
The pickup height is not out of spec
The pickup is still attached because I welded the Hell out of it
I called Melling and they had nothing to contribute other than to say they have never heard of this problem. I don't think its bearing clearance related because if it was, I would have lower oil pressures across the board. Also when I recently drained the oil to replace the pickup, the oil was very clean with no signs of bearing fragment or other junk. I asked the folks at Melling to blame either the pump or the motor. They blamed the pump. Could it have gotten damaged as a result of the pickup being off?
Can someone provide some insight into this problem. I really want this fixed ASAP.
Thanks.
Bill
Some background information.
Melling 10554 standard volume pump w/ white spring
Stock pan and windage tray
Two weeks ago the oil pickup fell off of the pump. It is possible that I had nearly 200 miles and 6 dyno pulls with the pickup off. The pickup was replaced and the engine believe it or no seems fine. I only noted the pressure falling when braking which lit the dash light. Never saw an ill effect accelerating or cruising but I think its safe to say that I might not have seen the idiot light occasionally coming on to indicate split second no oil pressure.
Cold idle oil pressure is 60#.
Cold rev makes 80#.
Hot idle oil pressure is 20#.
Cruising at 2K RPM is 30#.
Cruising at 4K RPM is 50#.
Here is where it all goes to Hell.
When at WOT, pressure climbs and is consistent with having 10# per thousand RPM until around 5K RPM.
When you hit 5.5K, the pressure drops instantly to around 30# then shoots back up to around 60# at around 6K RPM in the blink of an eye. I can slowly accelerate and the same thing happens.
I have tested with 1 quart oil under filled, oil level full and 1/2 quart overfilled. The problem remains. I have replaced the filter, problem remains. I have not yet tried thicker oil but I have noticed the pressure drop still occurs with cold oil and a WOT blast.
The oil pump pickup is between 3/8" and 1/2" from the oil pan floor. The relief valve is not seized up. At a glance, the pump showed nothing unusual but I did not look very close at it. Also I can not say for certain that the oil pressure drop issue was occurring prior to the pickup falling off. I do find it difficult to believe that I would never have noticed the gauge behavior when blasting on it for nearly two years.
I am confident in the following:
The pickup height is not out of spec
The pickup is still attached because I welded the Hell out of it
I called Melling and they had nothing to contribute other than to say they have never heard of this problem. I don't think its bearing clearance related because if it was, I would have lower oil pressures across the board. Also when I recently drained the oil to replace the pickup, the oil was very clean with no signs of bearing fragment or other junk. I asked the folks at Melling to blame either the pump or the motor. They blamed the pump. Could it have gotten damaged as a result of the pickup being off?
Can someone provide some insight into this problem. I really want this fixed ASAP.
Thanks.
Bill
Last edited by wrd1972; 07-06-2013 at 03:38 PM.
04-08-2010, 09:21 PM
#2
Launching!
Join Date: Jan 2010
Location: Winter Haven, Florida
Posts: 281
Likes: 0
Received 0 Likes
on
0 Posts
I would like to see what is said on this one thats for sure. I know two people that this is happening to, but when oil pressure starts dropping they stop holding the peddle down.
04-08-2010, 11:41 PM
#5
Forgot to mention that I have a mechanical gauge hooked up. The day I saw this problem, I right then tee'd it in along with the OEM sending unit. I can loop it back and under the windshield wiper and watch it as I drive. Also replaced the OEM sending unit too.
The new sending unit very closely matches what the mechanical gauge reads. The older one clearly read higher by about 5# across the board.
This is not a faulty reading. It is real and badly pissing me off.
The new sending unit very closely matches what the mechanical gauge reads. The older one clearly read higher by about 5# across the board.
This is not a faulty reading. It is real and badly pissing me off.
Trending Topics
04-09-2010, 12:45 AM
#8
Banned
iTrader: (2)
Join Date: Mar 2010
Location: SOCAL1320
Posts: 367
Likes: 0
Received 0 Likes
on
0 Posts
Guys I have got a really friggin weird oil pressure problem.
Some background information.
Melling 10554 standard volume pump w/ white spring
Stock pan and windage tray
Two weeks ago the oil pickup fell off of the pump. It is possible that I had nearly 200 miles and 6 dyno pulls with the pickup off. The pickup was replaced and the engine believe it or no seems fine. I only noted the pressure falling when braking which lit the dash light. Never saw an ill effect accelerating or cruising but I think its safe to say that I might not have seen the idiot light occasionally coming on to indicate split second no oil pressure.
Cold idle oil pressure is 60#.
Cold rev makes 70#.
Hot idle oil pressure is 20#.
Cruising at 2K RPM is 30#.
Cruising at 4K RPM is 50K#.
Here is where it all goes to Hell.
When at WOT, pressure climbs and is consistent with having 10# per thousand RPM until around 5K RPM.
When you hit 5K, the pressure drops instantly to around 30# then shoots back up to around 60# at around 6K RPM. I can slowly accelerate and the same thing happens.
I have tested with 1 quart oil under filled, oil level full and 1/2 quart overfilled. The problem remains. I have replaced the filter, problem remains. I have not yet tried thicker oil but I have noticed the pressure drop still occurs with cold oil and a WOT blast.
The oil pump pickup is between 3/8" and 1/2" from the oil pan floor. The relief valve is not seized up. At a glance, the pump showed nothing unusual but I did not look very close at it. Also I can not say for certain that the oil pressure drop issue was occurring prior to the pickup falling off. I do find it difficult to believe that I would never have noticed the gauge behavior when blasting on it for nearly two years.
I am confident in the following:
It is not g-force related
The pan is not being sucked dry
The pickup height is not out of spec
The pickup is still attached because I welded the Hell out of it
I called Melling and they had nothing to contribute other than to say they have never heard of this problem. I don't think its bearing clearance related because if it was, I would have lower oil pressures across the board. Also when I recently drained the oil to replace the pickup, the oil was very clean with no signs of bearing fragment or other junk. I asked the folks at Melling to blame either the pump or the motor. They blamed the pump. Could it have gotten damaged as a result of the pickup being off?
Can someone provide some insight into this problem. I really want this fixed ASAP.
Thanks.
Bill
Some background information.
Melling 10554 standard volume pump w/ white spring
Stock pan and windage tray
Two weeks ago the oil pickup fell off of the pump. It is possible that I had nearly 200 miles and 6 dyno pulls with the pickup off. The pickup was replaced and the engine believe it or no seems fine. I only noted the pressure falling when braking which lit the dash light. Never saw an ill effect accelerating or cruising but I think its safe to say that I might not have seen the idiot light occasionally coming on to indicate split second no oil pressure.
Cold idle oil pressure is 60#.
Cold rev makes 70#.
Hot idle oil pressure is 20#.
Cruising at 2K RPM is 30#.
Cruising at 4K RPM is 50K#.
Here is where it all goes to Hell.
When at WOT, pressure climbs and is consistent with having 10# per thousand RPM until around 5K RPM.
When you hit 5K, the pressure drops instantly to around 30# then shoots back up to around 60# at around 6K RPM. I can slowly accelerate and the same thing happens.
I have tested with 1 quart oil under filled, oil level full and 1/2 quart overfilled. The problem remains. I have replaced the filter, problem remains. I have not yet tried thicker oil but I have noticed the pressure drop still occurs with cold oil and a WOT blast.
The oil pump pickup is between 3/8" and 1/2" from the oil pan floor. The relief valve is not seized up. At a glance, the pump showed nothing unusual but I did not look very close at it. Also I can not say for certain that the oil pressure drop issue was occurring prior to the pickup falling off. I do find it difficult to believe that I would never have noticed the gauge behavior when blasting on it for nearly two years.
I am confident in the following:
It is not g-force related
The pan is not being sucked dry
The pickup height is not out of spec
The pickup is still attached because I welded the Hell out of it
I called Melling and they had nothing to contribute other than to say they have never heard of this problem. I don't think its bearing clearance related because if it was, I would have lower oil pressures across the board. Also when I recently drained the oil to replace the pickup, the oil was very clean with no signs of bearing fragment or other junk. I asked the folks at Melling to blame either the pump or the motor. They blamed the pump. Could it have gotten damaged as a result of the pickup being off?
Can someone provide some insight into this problem. I really want this fixed ASAP.
Thanks.
Bill
04-09-2010, 08:41 AM
#9
I can rule out windage I think. It has the stock windage tray and I have run the oil quart under full and quart over full. I have the stock tray and pickup too. Cant really be a drain back problem. Stock block and heads too. This morning it dropped from around 55# to about 40# during a 2nd gear WOT blast.
Can anyone put a possible finger on anything in the motor excluding the oil pump? My next step is going to drain the M1 5w30 and put standard Penzoil 5w30 back in. I have read where many think the M1 is thinner. I am now grasping at straws.
Whoever figures it out gets all the free Guinness on tap they can drink from my garage Keg-r-ator.
Can anyone put a possible finger on anything in the motor excluding the oil pump? My next step is going to drain the M1 5w30 and put standard Penzoil 5w30 back in. I have read where many think the M1 is thinner. I am now grasping at straws.
Whoever figures it out gets all the free Guinness on tap they can drink from my garage Keg-r-ator.
Last edited by wrd1972; 04-09-2010 at 09:29 AM.
04-09-2010, 09:31 AM
#12
depends on the specific oil. It is possible for a 10w-30 to be thinner at operating temps than a 5w-30 or a 0w-30.
If you want to try a different viscosity try a 40wt, anything multiweight from 0 to15w-40.
The Caprice SS sent to the middleeast got a 15w-40 spec granted it gets warmer in the desert than most of the North American continent BUT it still get cold at night.
The push for thin oils in North America is CAFE driven. I am not saying thin oils are bad, they can work wonderfully. Just saying that the big reason they are pushed is for .01mpg better fuel economy and that the motors will work fine on something thicker in most cases. They are not building different engines for different destinations unless they absolutely have to for some reason.
If you want to try a different viscosity try a 40wt, anything multiweight from 0 to15w-40.
The Caprice SS sent to the middleeast got a 15w-40 spec granted it gets warmer in the desert than most of the North American continent BUT it still get cold at night.
The push for thin oils in North America is CAFE driven. I am not saying thin oils are bad, they can work wonderfully. Just saying that the big reason they are pushed is for .01mpg better fuel economy and that the motors will work fine on something thicker in most cases. They are not building different engines for different destinations unless they absolutely have to for some reason.
04-10-2010, 08:54 PM
#15
11 Second Club
My car does it too. No problems yet. As long as its not 0-psi, I say it's no big deal. If you can fix it let us know what you did to do so. I wouldn't loose sleep over it though...
04-10-2010, 09:56 PM
#17
maybe get a new pan ? high volume with another windage tray. try a 10-40 (unless you have and i didnt catch it) and see what it does. my car has the same setup as you have. i noitced tonight that it drops down atiny ammount under WOT but im running 10-30. my clearances are for atleast 10-40 but i was nervous running it with that thick of an oil in the winter. i might try 15-40
04-11-2010, 09:03 AM
#18
that would make a whole lot of sense. Having the pick up tube up alittle to high would cause a loss in oil pressure. GL with the tear down and finding out exactly whats wrong. Better sooner rather then later. I wouldnt want to blow up my engine either 
