Oil Pressure Fluctuations

Hello fellow HAMB’ers.

Recently I treated my 1962 Ranchero to a freshly rebuilt 200ci inline six. I built the motor myself.

Below you can see the before pics.






After pics.







I had the machine work done at a local machine shop which has a great rep. They did a wonderful job.

BACKGROUND:
The motor build went fine. I followed all the steps a person should take in building a motor. Cam lube, platigage bearings, torqud bolts in the correct order, primed the oil pump before install, primed the motor before breakin, used Brad Penn 30W break in oil & Schneider racing cam additive (cause I have a Schneider cam)…the whole deal. I used new parts or rebuilt parts when new units could not be found.

The motor break in went fine and I currently have 500 miles on the motor. Most of the miles are just back and forth to work.

A month ago took the Ranch on a longer drive. As I drove along a flat country road I noticed my oil pressure was down at about 20psi with motor rpm’s at around 1500. The motor was at operating temp. and my valve train was not making any unusual noise. As I watched the gauge, keeping the motor at a steady rpm, I saw the needle climb back to 40psi then down to 35, down to 20, back up to 35...and it danced around like this. I quickly pulled over and checked the oil level. Dip stick said FULL. I looked the motor over for leaks and found none.

After that I began to eagle eye the oil pressure gauge on my trips to work. Oil pressure is normal (40-45psi @ 1500-2000rpm) for about 5 miles, but after that the pressure begins to drop, sometimes getting as low as 5psi while coming to a stop at a street light. The needle will dance up and down sometimes, but not as wildly as the first time I noticed it. Most of the time the pressure is within specks, 20psi while at a stop light 35 while taking off from a light. But then other times there seems to be no change what so ever or a drastic dip and gradual clime.

WHAT I’VE DONE SO FAR:
In an effort to find the source of the oil pressure fluctuations I’ve done the following.

1. Replaced the mechanical oil gauge for a new mechanical oil gauge = same reading.
2. Checked the PCV valve = operates fine
3. Checked the oil fill breather = free and clear, breaths fine
4. Swapped valve covers = Someone suggested the valve cover on my motor was wrong and had the pcv valve at the wrong end of the cover. This did not change a thing.
5. Double checked accuracy of dip stick. = it is the proper length
6. Added oil. First added ½ quart to motor - no difference, oil pressure still dropped within the 5 mile mark. Added an additional ½ quart. - motor began to blow smoke. Obviously too much oil. Dumped the extra quart to return level to proper volume.
7. Checked dip stick while motor was running. At first it read halfway between FILL and the end of the stick, later it had nothing on it but some spray.
8. Changed oil filter to a different brand = no change in psi drop
9. Installed a topless valve cover (cut the top off) and watched motor oiling for 30 minutes of idling and goosing it. Oil pressure dropped but oiling of valves and rockers remained constant. No sign of oil pooling on my head, all seemed to drain back to lifter gallery like normal.
10. Dropped oil pan to inspect pick up screen, pump and bearings.
--A. pick up screen was securely bolted to pump, had the gasket, and screen was clean.
--B. Oil pump was securely fastened to block, no gasket used.
--C. Checked a few main bearings and they are not scored, just look polished. Didn’t bother looking at connecting rod bearings, but could if someone suggests it.
11. Measured the oil pump & pick up tube, and measured oil pan depth = measurements lead me to believe that the pick up screen is hovering just above the bottom of the pan, not much room.
12. Took the oil pump apart to inspect the pressure regulator spring.

Below are some photos of the pump.














I used a feeler gauge in between the pump housing and pump gear. Book says 0.006-0.012“. I could only fit a 0.007 in there. The spring is fine and springy.

QUESTION:
What do I do now!?!

To my untrained eyes my oil pump looks fine. It was brand new at install, manufactured by Sealed Power (P/N M65B). The motor has just over 500 miles on it. Should the pump look like this? Do these few scratch marks mean the pump is toast?

At first I assumed that the oil must be pooling up some where and not returning to my pan. Why else would my oil pressure drop to near zero when coming to a stop. If the pan had enough oil in it, the pump should not be starving for oil. And the pressure gradually dropping to 20psi while rpms remain constant then jump back up to where we expect the pressure to be, tells me the regulator is wacky, or there is something in my system which is plugging a hole from time to time. Yet I can bet a years salary (don’t get your hopes up, it aint much) that within 5 miles from my house my pressure will drop while maintaining 1500 rpm.

I’m stumped.

I’ll be taking my oil pump into a trusted shop to get their pro opinion. But thought that I’d put this out there and grasp at some straws in hope that some wise person will have some crazy rad suggestion.

If anyone has experienced an issue like this, please share your experience and solution, if you found one.
Thanks to all in advance.
Cheers.

 

Last wacky oil pressure thread turned out to be a spark plug wire separater stuck in the pickup tube - small block Chevy motor.

 

have you used another pressure guage just to be sure on your readings,and have you checked the mains

 

You said your oil pickup tube is just barely above the bottom of your pan. How much is it? You don't want it almost touching. I perfer about a 1/2 to 3/4 of an inch. Also after the machine work did you make sure all your oil gallery plugs were in place?

 

Any scratches I see on the oil pump parts look like normal machining marks from the factory. I would get another pump for it if you have any doubts about it, they're relatively inexpensive.

If you had a systemic engine problem (bad bearing, etc) the oil pressure would be consistently bad. I would be more inclined to put another gauge on it and drive it around. You may also want to get another oil filter than a Fram, they have a general bad reputation to them and have been known to do odd things to oil pressure.

Bob

 

I watched a video from Melling. They suggested taping a 3/8" drill bit to the base of the pick up screen. Apply a thin coat of white lithium grease. Then put your oil pan on, remove your oil pan and see if there is any white grease on the bottom of your pan.

If the pan wont even go on, or teater-totters back and forth, then you know that there is less than 3/8th inch.

My pan went on. When I removed it I had a stripe of white grease. So I know that my pan is 3/8th of an inch below the pick up tube.

I spoke with Majohr Murry (a well respected garage in Portland) They like to have 1/2" clearance.

I spoke with Summit Racing tech line and they suggest 1/2" as well.

My pan is some what concaved. I also didnt noticed how many dents and dings the old thing has. It's obvious that I need a new pan too.

I'll post more in a bit.

I just got a presurized oil tank, which connects to my block at the oil pressure gauge fitting. I'll use this tank to pump oil through my block and wathc each part of my motor for big leaks.

More detail later this weekend, I promis.

 

Try another gague,or sending unit. If it's really doing what you say, i'd think that the pressure would be more uniformly low, if something was truly out of whack on the mechanical side. Also you might try shimming your pressure spring a bit.
Good Luck!

 

You have tried everything I would have, guage filter, inspection ect....

The only thing I can even surmise being the culprit, it a faulty spring in the pump....

There is a chance, a main bearing started to turn, partially blocking a passage, but I really think thats pushin it....

My first guess was the filter seeing a fram, but you changed that right away.... You may, after completing your inspection and restarting the engine, simply try something like sea foam, incase by some slim chance, you got some silicone trapped in an oil passage????

Either way its a flook... I would change out the spring in the pump before reassembly...I cant remember whether you said you did the pump or are doing it..... Its a ghost for sure....

And you microed the crank and the journals are true right?? the slightest egging will do this..

 

Since you have the pan off, you can blow air into the oil pump mount. It will push the oil out of the filter and you can see if you have a large amount of oil flowing somewhere. Once it empties the oil you can hear a large volume of air if there is an oil galley plug leaking. This procedure is messy!

 

I'd surely try a NEW oil pressure sending unit...affordable enough. A "flakey" unit COULD absolutely cause your symptoms. Make sure wiring is good and tight at connections, also. DD

 

Mechanical gauge and he has tried another one.

 

Duh...I sure blew that one. DD

 

You said you plastiguaged the bearings, but you didn't post the numbers.. You also stated you used 30w breakin oil.. If your clearances are on the loose side and you're now using a "low weight" multiweight oil, such as 10W30, 5W20, etc) the oil could be thinning enough to cause the low pressure..

My OT Ford requirement is 5w20.. That stuff is thinner than water.. How it lubes the engine is beyond me..

RustyPile

 

Several friends have had oil pump issues on recent builds too. If you are sure the bearing clearances are correct, it's most likely the oil pump. You mentioned checking rotor to body clearance, how about rotor to impeller clearance and rotor end gap? A weak pressure relief spring could also be the culprit. I would suggest replacing the pump with one from Ford or a NOS parts vendor, IMHO the quality is much better than aftermarket replacement parts. Also, lose the FRAM filter...

 

Replace the oil pump as the grooves in that end cover are not good,those rotor pumps sometimes have issues. Run 20-50 or 15-40 oil,for sure stay away 5 anything.

 

Yeah I read that one before posting this one. That was first thing I looked for when I poped the oil pan.

 

YEP, listed above.
"WHAT I’VE DONE SO FAR:
In an effort to find the source of the oil pressure fluctuations I’ve done the following.

1. Replaced the mechanical oil gauge for a new mechanical oil gauge = same reading...."

 

After speaking with the head mechanic at Majhor & Murray Limitied (Portland Or.) He said to NEVER shim the spring. He's seen two filters burst like mellons and their springs were only shimmed a fraction.

Both my gauges are brand new. The first one was a cheap-oh. But the second I purchased is a Datcon. They are both mecnanical. I trust the Datcon.

 

I took a close look at the crank. The machine shop align bored (or honed...I cant recall now) and balanced the crank too. I feel that it and the bearings are fine. I did pull three main cap bearings and they look fantastic. The wear on the bearings is only evident because it's a bit shinner than the rest.

I think the ghost is in the distance of the pick up tube being too close and causing cavitations, and the pump spring.

 

FRAM IS GONE! As I looked into this mystery I thought OIL FILTER?? So I read up on them. I nearly turned green when I read ALL of the bad stories about FRAMS GONE BAD.

I sprinted to the local parts house and picked up two WIX filters. Just holding an empty WIX in my hand I feel the difference.

I'm sorry I ever put one on my new motor, but up to this point I'd never ever had a prob. but who wants to push their luck.

Thanks for the concern and the suggestion on going NOS. I have a feeling that this pump is the bad guy and it's because todays parts are not as carefully made.

I'll look into that.

 

Sorry Rusty Pile I dont have the numbers. I did the plastigage when I was assymbling the motor early this winter.

Currently I'm still running 30W oil. I've been running the GREEN OIL by Bradd Penn. It is supose to have lots of ZDDP and I was informed that todays API rated oil has almost ZERO zddp.

Thanks

 

UPDATE: I took my pump down to Majhor & Murray LTD in Portland Ore.
http://www.majhormurray.com (Great garage and great guys, for any of you locals)

I spoke with their head mechanic. We discussed several things. He did not feel that my pump was bad, but he was concerned about the marks on the regulator valve bore. He stressed that I < DO NOT > shim my pressure regulator spring. He heard of such a thing and it blew two oil filters like a grenade.

We also talked about pick up screen clearance. I let him know that I barely have 3/8&#8221; clearance. He suggested ½&#8221; of clearance. If a pick up screen is too close to the bottom of the pan the suction can actually cause cavitations and suck air. I was honest and said that my pan was a bit concaved and my clearance could be a bit less than 3/8&#8221; in places.

He educated me on oil pumps, oil pressure and oil volume. Turns out that an oil pump does not create oil pressure. An oil pump simply provides volume. The pressure is at any place the oil can escape back to the pan. To ensure that your motor is tight you need to see where oil is escaping and how quickly it is escaping. To do this I would need to pump oil back into my motor @ 40psi and watch my main caps, connecting rods and other places that oil is needed.

They lent me a tool which is a can that can be filled with oil, pressurized (equipped with a pressure gauge) and it has a hose to connect to the oil pressure outlet on my block.

Melling has made some good videos to check out.

<iframe width="480" height="360" src="http://www.youtube.com/embed/tjCIuJwnVqU?rel=0" frameborder="0" allowfullscreen></iframe>

http://www.youtube.com/watch?v=tjCIuJwnVqU

I did as they suggested and it was frickin cool!!.
Best news is that my motor is performing properly. All of my bearing points on the crank dripped. Oil flowing down my timming chain was slow and steady. Oil draining from my head was constant as I&#8217;d expect (I&#8217;d just rand my motor without a valve cover and knew how much volume to expect from up there.)
So I think I&#8217;ve really narrowed this down.

I&#8217;ll get a new pump (hopefully NOS) which I hope will have a free moving regulator valve and I&#8217;ll buy a new oil pan. I&#8217;ll do the 3/8&#8221; dowel test with the new pan and if it is still not ½&#8221; clearance I&#8217;ll gently alter my pick up screen.

That&#8217;s it so far.

Any more news and I'll post it to this thread.

Thanks HAMB'ers for all the feed back.

 

Well it's good that you've found the problem.. I kinda doubted that you had a bearing clearance problem.. Most automotive machine shops know how to properly clearance a crankshaft.. I was suspecting either that Fram/junk or the regulator valve in the pump...

My son TxRat, recently tore down a Chevy 327 race engine that I built in the 70s. It had 2 hard seasons of racing on it plus several years of driving on the street. All the bearings were worn into the copper.. The engine still had 40# of oil pressure at idle and around 60# mid RPM range, and the engine had nary a knock.. I built it using a Melling high volume oil pump. If melling makes a high volume pump (doubtful) for your engine, that might be a better choice.. As someone has already noted, stay far away from any multiviscosity oil 5W/anything.. Straight 30W, or for winter time operation, 20w40/50 should work just fine.. And don't forget the zppd..

RustyPile

 

The machine shop (Portland Engine Rebuilders, Portland Oregon) suggested I use Brad Penn oil. It is green. It has quite a lot of ZDDP natually. I'd never heard of ZDDP before this build. Learning about this was great timming because the modern oils had just removed all of ZDDP from the oil. Any oil with an API rating of SM or SN has virtually no ZDDP, as I understand it.

The only other oils out there which have ZDDP in the oil are Valvoline Race oil and .... my mind is drawing a blank, but I know there is one more.

I believe that Lucas has an oil modifier with ZDDP in it. Once I finish this oil pressure issue I'll be down to my last few bottles of Brad Penn and will switch over to regular oil & Lucas or Valvoline racing oil.

What oil & oil modifiers do you guys use in your vintage motors? Is there a good thread on this topic?

 

UPDATE:

I poped in a new pump, pump shaft, pick up screen & oil pan. So far all looks good. I'll get a chance to take it for some longer test drives tomarrow.

I dont know who designed the 4 part oil pan gasket, but they are a real @!$% to put in and keep everything aligned properly. And that new pan I purchased looked fantastic, but when I tried to bolt it up I realized that its side rails were a bit bowed out.

But the suckers back to gether and running. Cant complain at all.
Cheers.

 

UPDATE:

Good news! I drove the motor around my block for 40 miles and the oil pressure never danced around.

At start-up the gauge read 50psi. Once the motor was warmed and chugging down the street the oil pressure never dropped below 40psi, even while anchoring the brakes (as a test).

Looks like my pan gasket didnt quite seat properly at the back, I have one minor oil leak.

But I'm stoked. Ranch is back in action! Just in time for the Rose City Round-Up and Billetproof.

 

See you at rose city round up. That engine came out nice!!

 

Thanks Yeti

 

yeah brad penn is good. its made in PA. I grew up in a town called titusville, where oil was discovered. It is cool to be able to support oil that is made here still. Plus it does have more zddp.

 

re sending units.....Is there thread sealer on yours ? They need a good ground where it screws into the block....sealer interferes with that. Those are "pipe threads" which are designed to not leak due to being tapered...

I didn't see mention of connecting a known good mechanical guage.

Happy Roddin' 4TTRUK