Oil Pressure Loss

[bowen71]

Well I am pulling the engine and having it gone through.  As of right now I am only getting about 38-40 PSI at a cruise.  I know its still within specs with the 10psi-1K but, I used to have about 50-55psi at cruise.  I just got 20k on a 2110 and I have done regular oil changes using 20w-50 Castrol and adjusted the valves every 3rd oil change or when needed.  I run a 2110 with a 72 plate oil cooler and a 10in fan along with the stock oil cooler and a GEERS filter.  What can I do to ensure that this thing lasts more than 20K next time.  

Here are the specs:

71 Super

DPR 82mm crank
Mahle 90.5 pistons
DRD R294 Cam, 294 duration, .512 lift
1.4:1 rockers
C/R 8.2:1
Heads DRD L6 42x37.5
26mm shadek oil pump (blue printed)
12lb flywheel
Stage 1 with 200mm Cush Lock Disk
2.5 qt sump
44 IDF's 36 vents, 135 mains, 195 airs, 55 idles , f7 tubes
009 Dizzy w/pertronix
MSD 6A
NGK PB6ES .050 gap
Taylor 8mm wire
German Blue Bosch Coil

Trans is a KCR pro street trans, 4.12 RP stock 71 Gearing
25.5 inch tall tire

Now this is a daily driver.  I put at least 60 miles a day on this car.  What can I do different to ensure it lasts longer.  BTW it never sees a track it is completely a driver maybe a Honda/Mustang eater every now and then and it never sees above 6k never.

[65bug]

Bowen,
 Was the case brand new on this build?

[bowen71]

New AS41 case everything was new.

[Bruce Tweddle]

You don't have a problem to fix.  Leave it alone.
Drain that tar and put in the correct viscosity of oil.

[bowen71]

There has to be a reason the pressure has dropped I can change to a 10W-30 and see what happens but, with a drop of oil pressure and an increase in temp of the oil dont that seem like there is a problem?

This all started after an oil change and a valve adjustment well about 200 miles after and it is steadly dropping.  pressure at an idle also dropped to 12-15 psi from 20-25 psi

What causes it?

[Ohio Tom (DdK)]

Stuck or not seating properly oil relief plungers.
Worn out oil pump.
Worn out main/rod bearings (althouh not likely).

[Dougy Dee]

I'd check for a failing gauge or sender first.

[bowen71]

I thought maybe the gauge was bad but the temp is going up also so unless I have a both gauges bad I dont think that is the issue.

Also it reads normal when cold why would it change when warm? I will see if I can get a mechanical gauge on it and check to see what it has.  This weekend will be pulling the pump cover and checking for wear and flushing the system.

[marty hiskey]

if your oil temps are going up your pressure is going to drop. what is your oil temp after a run on the highway. maybe like mentioned above you have something hanging up one of your relief valves or you have something in the fan shroud housing blocking the airflow over your oil cooler. have you made any modifications to your setup like timing, carb jetting, etc. those things will cause head temps to go up which also will increase oil temps.

[David Ward]

Stuck or not seating properly oil relief plungers.
Worn out oil pump.

These were my first two thoughts until the mention of higher oil temps.  It may be related to the oil cooler.  Many, many years ago I put together a "smog engine" using mostly used parts.  The engine had high oil temps and oil pressure dropped when fully warmed up.  Turned out to be a clogged oil cooler.

Isn't it possible that if there are issues with the oil relief springs and plungers it might cause temp problems?  Oil could be bypassing the cooler, or is restricting flow to the cooler.

[bowen71]

I havent changed anything to the engine in about a year this is something that started out of the blue.  I am running the stock cooler and a 72 plate cooler with a fan. 

The only thing that happened lately is a clogged idle jet but I solved that.  I am going to go through it on Sunday.  Yesterday I put a can of Seafoam in the oil and let it run for about 30 min and until the oil temp got to 180* and oil pressure dropped down.  It was at 180* and 15 psi of pressure at an idle. 

As for what the oil temp is on a run on the highway.  With a 3 mile run at 75-80 the oil temp climbed to 200* and pressure was 38-40 psi. 

[Mike Lawless]

Like the others said, I think I would first find out why the temps are rising. Could be a lot of things causing that, even though "nothing has changed."
When you drain the oil, has there been any flakes of metal? Did you take the filter apart to check it for debris? If there are no physical signs of failure, there's no reason to go to extreme measures yet.

[maui]

I say change your oil filter again and maybe get a temp gun and check your temp after a hard run and get a good reading to see if your sending unit is correct.

[bowen71]

Well to start off I went to adjust the valves to make sure that I am not creating the problem there and I have way to much side to side play.

I measure about .024 gap on one end of the shaft. It appears that the intake rocker has about .015 on one side and .006 on the other.  Which is way to much.

I know that should not cause pressure loss but I cannot adjust the valves with that much play. 

[IN RANGE inc.]

Remember to measure that with the rockers on the head. It changes a bit when all the holes are lined up on the rocker studs.

[bowen71]

I did measure it before but when I went to shim it the shims were the wrong size not thickness but the inner diameter was off.

[bowen71]

Well today I shimmed the rockers and adjusted the valves.  I also pulled the pump cover and relief and bypass valves.

The pump cover had a little wear so I sanded it down with 600 grit and a piece of glass but I dont think that was the problem I could see the wear but couldnt feel it. 

Also the valves were clean and so were the springs all seems good.

But it still drops to 10psi when the temp gets to 180*

When I pulled the valve near the flywheel the oil came out cool at first then hot.  Now I know the oil was at least 150* if not more because I had the car running just prior to that. Why did it come out cool?

[Dominick Luppino]

At what RPM is your engine idling at? The rule is, 10psi per every 1000 RPM’s.

I would also drain out the light weight oil, for street driving I recommend 20/50

[bowen71]

Idle is at 900rpm and is at 10psi and the pressure is at its max at 40psi no matter how high you rev it.

[Bruce Tweddle]

Idle is at 900rpm and is at 10psi and the pressure is at its max at 40psi no matter how high you rev it.

You don't have a problem.

[Dominick Luppino]

You don't have a problem.

X2

[bowen71]

I understand that the oil pressure is good but why did it drop? I am trying to figure out what is failing.

The oil pressure is just a sign of something gone wrong.  The engine has 20k on it.  I want to figure out what is failing so I can fix it and go on.  Did the bearings go? Is it just a spring in the control valve? Did my oil pump start to eat its self? 

I have a good amount of money in it and I dont have the money to redo it.  Just trying to find the what is failing.

[Dominick Luppino]

I understand that the oil pressure is good but why did it drop? I am trying to figure out what is failing.

The oil pressure is just a sign of something gone wrong.  The engine has 20k on it.  I want to figure out what is failing so I can fix it and go on.  Did the bearings go? Is it just a spring in the control valve? Did my oil pump start to eat its self? 

I have a good amount of money in it and I dont have the money to redo it.  Just trying to find the what is failing.

Then just take it apart...

[bowen71]

So an update, I went out and drove the car last night and it ran great oil temp stayed at around 190ish @ 75mph on the freeway for 13 miles. Oil pressure at around 40 psi and 10 at an idle.

So this morning with a cold engine and not running I metered the oil pressure sender and it read 10.2 ohms (10-180 ohm switch) then I started it and warmed it up.  Checked it again like before but warm it read 8 ohms. It's out of tolerance when warm. Found my oil pressure drop I think. I will have to buy a new sender and try again.

[gkeeton@zbzoom.net]

I've taken apart engines with new mag cases that have chewed up the lifter bores in as little as 5000 miles with cams as small as W100's. If you are still worried, and truely want to take things apart, pull one side of the pushrod tubes to check the lifters. You can then stick your finger in the lifters, through the holes in the case, and see if you can wiggle them side to side. If there's no play, put on a good set of spring tubes, and run it.

[David Ward]

So an update, I went out and drove the car last night and it ran great oil temp stayed at around 190ish @ 75mph on the freeway for 13 miles. Oil pressure at around 40 psi and 10 at an idle.

So this morning with a cold engine and not running I metered the oil pressure sender and it read 10.2 ohms (10-180 ohm switch) then I started it and warmed it up.  Checked it again like before but warm it read 8 ohms. It's out of tolerance when warm. Found my oil pressure drop I think. I will have to buy a new sender and try again.

I think you found the problem.  No need to do a teardown of your engine.  After market gauges and senders aren't always 100% accurate, especially as they age.