Oil Pressure Emergency???

vristang

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Oct 12, 2005

#1

• Oct 12, 2005

• #1

Oil Pressure Emergency??? (Problem Solved)

Since the rebuild oil pressure has been rock steady at 50-55psi. When warming up this morning the oil pressure sat low at about 35psi. Once warmed up the pressure came up.
On the drive home this afternoon it did the same thing during warmup. After the motor was warmed up (coolant about 200 and oil about 180), I tried hitting the throttle. The oil pressure dropped to zero until I came off the throttle. Tried it three times. Pressure returns to 50 very quickly.

The motor is in the sig.
I am using a Melling HV pump and running 20w50 Mobil 1 (was planning to go to 5w30 this weekend), and the oil level is good. I have correctly marked my dipstick for my pan.

Is this a sign of a bad pump? Hopefully a bad sending unit or connector?

Thanks in advance for the advice.
jason

 

M

meshow99

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Apr 19, 2004

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Oct 12, 2005

#2

• Oct 12, 2005

• #2

I had the exact opposite problem. I had zero pressure at idle and good pressure upon throttle. Keep us informed. I am rebuilding my motor now and would like ot know what the problem is should I run into it. good luck

 

vristang

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Oct 12, 2005

#3

• Oct 12, 2005

• #3

meshow99 said:

I had the exact opposite problem. I had zero pressure at idle and good pressure upon throttle. Keep us informed. I am rebuilding my motor now and would like ot know what the problem is should I run into it. good luck

Click to expand...

thanks for the response.
low pressure at idle and good pressure off idle is what I would expect for a failing pump. Good luck with your build.

Maybe the pressure valve is faulty?
Maybe the high viscosity oil is the problem?

I just checked the connector at the sending unit, and it wasn't corroded or otherwise contaminated.

I am starting to get scared.

 

8

88FoxSaleen

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Oct 12, 2005

#4

• Oct 12, 2005

• #4

i have a fairly new Melling HV oil pump in my car & since day 1 i have had somewhat low oil pressure at idle but great pressure while driving & all has been well. it must be getting a little cold in Seattle. i think that 20/50 oil is a little too thick for a cool temp if this is the case. i was certified in oil viscosities years ago. i had a buddy blow an engine running 20/50 oil in cold weather (too thick to pump, H.V oil pump or not). for years i have always run 10/30 in my v8 mustang year round because i live in NH & the oil is a good compromise for the rapidly changing weather hear (hot to cold & back to hot). give it a try. should be a little less trying on the oil pump.

Jay

 

The Shape

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Oct 12, 2005

#5

• Oct 12, 2005

• #5

Stock Gauge?

 

srothfuss

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Oct 17, 2004

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Oct 12, 2005

#6

• Oct 12, 2005

• #6

Two things come to mind:

1) Your probably sucking all of the oil out of the pan if you have a HV oil pump...

2) Your oil is too thick for the cold(er) climate of Seatle. and this is causing your motor to starve when you are "in the throttle"

 

302RollinHard

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Oct 12, 2005

#7

• Oct 12, 2005

• #7

I think they got it nailed........

If it is colder than say 60F up there you are pusing it with the 20W50 until the motor gets warm. Hence the problems in the morning and perhaps after sitting for a while (temperature dependant) Also those high volume oil pumps may 'outrun' themselves meaning the return to the pan is slower than the pump. Running 20wt I wouldn't be surprised to see that.

 

vristang

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Oct 13, 2005

#8

• Oct 13, 2005

• #8

Thanks for all the replies!

I will drive out and change the oil tomorrow. 10w30 or 5w30 Mobil 1. If it is just the viscosity though I don't see how I would have any problems (all of a sudden) when the motor was hot.

I hope you guys are right.

And yes I am still stuck with the stock gauge. There very well could be no problem at all. I have yet to hear any noise associated with oil deprivation.

Thanks again
jason

 

jrichker

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Oct 13, 2005

#9

• Oct 13, 2005

• #9

To help diagnose my oil pressure concerns, I added a tee, short hose and a cheap gauge from Home Depot under the hood. It is ty-wraped into the bundle of wires for the computer self test. Not real obvious, but easy enough to see if I need it while I am under the hood. Total cost was less that $10.

 

The Shape

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#10

• Oct 13, 2005

• #10

Got a picture of that J ?? Sounds like a great idea. I hated how the autometer gauges looked in my otherwise stock intereior so I got rid of them, but I would love to see a visual of your setup I may give that a try.

 

HISSIN50

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#11

• Oct 13, 2005

• #11

If running M1 15W-50, it has very nice pour point numbers (to about -40*F as I recall) and good viscosity readings in colder temps..........

Good luck Jason.

 

vristang

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#12

• Oct 13, 2005

• #12

HISSIN50 said:

If running M1 15W-50, it has very nice pour point numbers (to about -40*F as I recall) and good viscosity readings in colder temps..........

Good luck Jason.

Click to expand...

Yeah, I remember seeing something to that effect, which is why I did not worry about running such high viscosity. Suposedly the synthetic fluids would allow using higher viscosities. Then again, maybe not.

I did switch over to 5w20 with a fresh K&N filter. The problem is now gone. Oil pressure is very steady around 50psi. Not sure if it is related or not but I also changed the filler cap because the threads had been damaged, and replaced the vac line from the pcv to the seperator. The vac line was kinda soft and looked like it was collapsing, so I replaced it with high pressure fuel line. Since I made more than one change I can't say for sure that it was just a problem with viscosity selection.

Oil viscosity too high?
Plugged oil filter?
Collapsing pcv/seperator vac line?
Loose filler cap?

I had about 2,500 miles on that oil change when the problem started.

Many thanks to all who provided their input.

jrichker; I like your suggestion for an engine mounted pressure gauge. It will happen when I get the time.

jason

 

HISSIN50

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Oct 13, 2005

#13

• Oct 13, 2005

• #13

Jason, glad to hear your pressure went back up. The K&N does flow very well (at perhaps the expense of very good filtration - great flow and great filtration dont go hand in hand).

If you find your separator hose collapses again, I recommend hydraulic line (that is what I used). It is actually very stiff (I did not want the line to be able to collapse or kink, since it routes tightly around my strut tower brace). It was 89 cents/foot.

JR: in what section of the home store do you get your gauges (and is it the same one used for fuel pressure that I have seen you talk about)? You have piqued our interest