Oil Pressure Frustration

I have an incredibly frustrating problem and I have done everything imaginable to resolve it. New here, this is my very first posting.

A few years ago I did a complete rebuild to my 1965 200 CID. Bored cylinders, new pistons rings, all new bearings, new camshaft, valve guides, new valves, hardened exhaust seats, machined crank shaft with oversized bearings, just about everything. It started very nicely and ran well.

But I didn't drive it much for a few years as I lived overseas until recently, was in 'States only 6-7 weeks per year. Since coming back permanently I have encountered a consistent, infuriating problem with oil pressure.

It's fine after a cold start, up to 50-55, then drops to about 40 once hot (lower at about 800 RPM). So far perfectly normal.

But on the highway, after the engine gets hot, the pressure gauge begins to fluctuate, needle jumps suddenly back and forth between 20 and 40. This is at constant RPM and speed. If I come to a stop while this is happening the pressure drops to a frightening 5-10, and at this moment I get lots of smoke from the exhaust. I am getting oil fouling on the spark plugs.

While the plugs are clean it runs beautifully! But it gradually worsens as the plugs become more fouled.

This is a very consistent pattern, it happens exactly the same way each time. I have done everything conceivable, talked to a number of people, and there is no solution. It happens as much as ever.

I am incredibly frustrated. I have talked to a number of people about this, and I have yet to hear anything that I haven't tried. Nothing has made any difference.

So, here is my list:


It is not the gauge. Installed a mechanical after-market gauge quite a few years ago. Before the rebuild it always read a rock-steady 35-40 when at highway speeds. Took it to a shop and we compared my gauge to theirs, again at highway speeds, and the exact same fluctuation occurred. Got the same exhaust smoke and lifter rattle. It is not a faulty gauge, it really is low oil pressure.

It is not low oil level. This was the very first thing I checked when the problem first appeared, I pulled over as soon as it was safe and checked the level. Perfectly fine.

It is not the oil pump. When this first appeared, I was using an old rebuilt pump that I first installed in 1998. My first attempted solution was to get a new pump. Melling, completely new manufacture, not a rebuild. Stock specifications, not high volume. Made no difference at all. Again, I had no such problems when the engine was worn, using the old pump, with low cylinder compression and what later turned out to be broken top piston rings. Why did this fluctuation suddenly appear, with new everything?

It is not a gap between oil pump and engine block. Checked it thoroughly, even replaced the bolts and ground down the end of one of them to ensure it did not bottom-out in the blind hole. Gasket is good, oil pick-up tube and screen good also. It is mounted at exactly the same height as before the rebuild, back when I never saw this fluctuation and the plugs stayed much cleaner.

It is not an obstructed oil port. If this were the case, wouldn't I see pressure problems all the time? Again, the pressure is perfect until the engine gets hot. This is not a normal pressure drop with heat. This fluctuation is at a constant RPM at highway speeds (60-65 mph), only after the engine gets hot. This happens EXACTLY THE SAME every time! And, while underneath looking at the pump mounting, I blew air through the oil ports, had a nice mess everywhere. The problem continued as before

It is not a spun bearing. While underneath I looked at both rod and main bearings, all are fine. A spun bearing would have been destroyed by now, and I would see lots of other nasty symptoms like metal fragments in the pan and unpleasant rattling of piston rod against crankshaft. When the plugs are clean it runs beautifully, and quiet.

It is not the piston rings. Had a look, all were perfectly clean and intact. Replaced them anyway, didn't want to risk damage by re-installing them. Besides, compression is good, 165-170, very little variance between cylinders.

It is not the oil filter. Thought of this simple solution early on, installed a new Wix 51515, right off the shelf. No change whatever, fluctuation continued.

It is not valve guides. Had them replaced by a reputable shop, along with valves.

It is not valve stem seals. Installed new ones with the head rebuild. In desperation I replaced them a few weeks ago. Made no difference at all.

While talking to a tech rep at Summit Racing (I live just a few miles away!), he showed me an article from the Bronco Busters section that describes a similar problem. It was no help at all, this guy's problem turned out to be a faulty oil pump relief valve. I can't believe that both my old re-manufactured pump from 1998 (which worked fine before the engine rebuild) would have the exact same defect as the newly manufactured Melling I installed the very day after this problem first appeared.


Here's my theory:

Somehow I am getting excessive oil on top of the cylinder head. The resultant deficit in the oil pan results in the pump sucking air, hence the fluctuation. After a few seconds enough oil drips to the pan, pressure is restored. Before dripping down some of this oil gets sucked into the cylinders through the intake valve stems, hence the fouled plugs and smoke out the exhaust. While I had the head off a few weeks ago I saw clear evidence of oil fouling on the intake valves, but much less on the exhausts. As an experiment I added (temporarily) an extra quart of oil, and the problem reduced dramatically, which gives this theory some credence. But this is no long-term solution. It wouldn't stop the plug fouling.

All the evidence points to this, but I can't imagine how it could be happening. When I first thought of this possibility I looked at the rocker arm assembly, thinking that perhaps the shaft was worn and excessive oil was squirting past the rocker arms. I found a "new" rocker assembly from a '63 Falcon. Got a new shaft, new springs, cleaned and reassembled all the parts. The "new" shaft mounting pedestals are in much better shape than the previous ones, they mount very tightly against the cylinder head. I ran it for a while with the valve cover off, saw no oil leakage between the mounting pedestals and the shaft, nor excessive oil elsewhere, it drips from the rocker arm ports very normally (I suppose this could change with heat and RPM). None of this made any change at all, the fluctuation, lifter clatter, and fouled spark plugs continue as much as ever.

I am incredibly frustrated. Can't imagine anything that I have not tried. My one final thought is that perhaps a cam shaft bearing was installed improperly (I didn't install them myself). Could this result in a strange restriction that re-directs oil where it's not supposed to go, such as accumulating on top of the head? This means removing the entire engine, but that's likely to be my next step anyway.

Can anyone think of something that I have not tried? At my wit's end.

Yes I think your theory could have some merit as far as the oil pump sucking air at times and if that happens yes the oil is somewhere else like up in the valve cover. The Ford 200 oil pans stock have no balfeling to help keep the oil around the pick up tube so low and occasional no oil pressure can often happen with high performance or high speed use. What Melling oil pump part number did you install? Have you checked that the heads oil returns are clean as well as all the way down through the block so the oil can return to the oil pan? What type rings did you install? What weight oil are you using? Lastly do you rember what Main and Rod bearing clearances did you have during the engine rebuild? Good luck

@Arlene,

It does sound to me like too much oil is accumulating in the head, not draining back into the oil pan quickly enough, and eventually the oil pump is starved for oil, sucks air and thus the fluctuation.

You might try finding an old valve cover, cutting the top off of it with an angle grinder or similar, then installing it on your engine with gasket and sealer. Start the engine, allow it to come up to operating temperature, and put the engine through some RPM changes. Do it long enough to simulate the drives during which this issue is occurring. If oil is accumulating in the head, you should see this. The valve cover will moderate the amount of oil that is splashed everywhere.

If oil doesn't accumulate in the head, it's real "head scratcher".

Good luck,
Bob

Have you ever changed the break-in oil out of the engine since you rebuilt it? I would cut the oil filter open, stretch out the paper element and inspect it. It can tell you a lot about what is happening inside the engine.

Thank you all for your interest.

To answer a few things, Summit Racing lists my oil pump (Melling) as MEL M65B, that's where I bought it. All specifications are stock.

The oil passages are clear, had the head off recently and took a look. New oil added through valve cover drains right down very quickly. And, I have replaced the oil since initial start up. Though I did not inspect in as much detail as was mentioned here, I have never seen any metal fragments. The current oil filter is a new one I installed after this problem first appeared.

After several hundred miles I put in 10w30 synthetic.

Thank you all for trying to come up with something new. I have spoken to a number of professionals and it's a bit aggravating explaining everything I have done to address this while they suggest the same things over and over. I am glad you agree that it seems likely that there is too much oil going where it's not supposed to.

Could oil be welling up from the lifter gallery somehow? I don't think it's dripping down from the rocker assembly, as that's supposed to be the only source of oil up there. As with everything else I can't imagine how this could happen, but SOMETHING is happening and I am running out of ideas. Something wrong with the lifters (hydraulic)? I got them from Classic Inlines with one of their camshaft packages.

I like the idea of cutting a window into an old valve cover and taking a good look. May try that as soon as I find one.

i wouldnt be so quick to dismiss the relief valve being faulty. its possible that the spring was defective from mellings supplier. so until such time as you actually pull it apart and test the spring itself, you really cant reject the idea that it might be bad.

i have seen too many parts fail in race engines that were new, and should be perfect to not seriously consider it might be the problem. to give you an idea, we had a friend that bought a set of brand new valve springs for his race engine, and he tested them himself, and set the spring height, etc. everything tested out perfect, but the first run his motor started missing badly, and had no power. he checked everything in the ignition and fuel system for problems. he rejected the idea that a valve spring was broken, until we pulled a valve cover and found a broken valve spring.

lesson learned, never reject the possibility that something might be wrong even if it is new. defects happen all the time.

I must admit that a faulty oil pump could remain a possibility, but I have tended to doubt it because the problem first appeared when using an older pump, a rebuild I first got in 1998. I would be more willing to consider this possibility if the problem had appeared only with the new pump. There were no oil pressures problems at all before the engine rebuild, and the plugs, though sometimes dirty, where nowhere close as fouled as now. I have a hard time accepting that this older pump, which worked perfectly for years, right up to the rebuild, suddenly developed a problem overnight. Installing a new pump was the first thing I did when the fluctuation appeared (the very next day actually). In that the pressure fluctuation remains exactly the same with a new pump as with the older, I have a hard time believing that the problem is here.

I am more and more convinced that the problem is somewhere in the block. The head itself has only one source of oil, the final rear rocker assembly mounting pedestal has an oil port underneath. This in turn connects to the after end of the lifter gallery.

That's what it's supposed to be. I am wondering if oil is getting in from somewhere else, however much I can't imagine how. Hard to observe, it only happens at higher speeds and with a hot engine, and that's hard to replicate in the garage.

what would happen if all the rings were lined up @ assembly (rather than clocked away frm @ other)?
Unrelated?

Chad It could possibly have more blow by.

Arlene1965":17tk4xkg said:

I must admit that a faulty oil pump could remain a possibility, but I have tended to doubt it because the problem first appeared when using an older pump, a rebuild I first got in 1998. I would be more willing to consider this possibility if the problem had appeared only with the new pump. There were no oil pressures problems at all before the engine rebuild, and the plugs, though sometimes dirty, where nowhere close as fouled as now. I have a hard time accepting that this older pump, which worked perfectly for years, right up to the rebuild, suddenly developed a problem overnight. Installing a new pump was the first thing I did when the fluctuation appeared (the very next day actually). In that the pressure fluctuation remains exactly the same with a new pump as with the older, I have a hard time believing that the problem is here.

I am more and more convinced that the problem is somewhere in the block. The head itself has only one source of oil, the final rear rocker assembly mounting pedestal has an oil port underneath. This in turn connects to the after end of the lifter gallery.

That's what it's supposed to be. I am wondering if oil is getting in from somewhere else, however much I can't imagine how. Hard to observe, it only happens at higher speeds and with a hot engine, and that's hard to replicate in the garage.

Click to expand...

The cutout top of the valve cover is a good plan or You could remove the valve cover, and side cover, and then pull the distributor so you can use a drill to turn the oil pump. Then watch how everything oils to see if there is a problem. But after that if you still can't see the cause I think If it were me I would probally pull the engine out, disassemble it and inspect everthing carefully to find the cause. Good luck

Just putting this out there, have you checked your engine breather system? Sometimes when you get a build up of crankcase pressure
it can stop the oil returning to the sump.

I think one of the rear head bolts is specific to it's location, and has a shank.
I couldn't find the original info but there is a reference to it in the stickies.
/viewtopic.php?t=29111
I have no idea if it's related, just throwing it out for speculation.

PCV valve?

You might have put synthetic oil in it to soon. I usaly run a few thousand miles before switching to it. It can cause the rings not to seal properly if used too soon.

Arlene 1965.

ll good advice and . Auxab. I think hit very closely on your problem. 200 oil pans are shallow and sloped on each end. I question why.

Add to this, capacity is only 4 to 4.5 ouarts of oil.


If you have much blow-by, a pcv system is not enough to aid drainback to oilpan. Sometimes a hard stop or launch will turn the

idiot light on.

I experienced this on more than one 200. You need a good open breather on valve cover and maybe fashion another one (as I did)
off the fuel pump mtg. boss.

You may have pump pickup screen restriction or cracks to allow air entrance. You shouldn't have plug fouling unless oil is flooding
down v alve guides or up past rings. Which you already know.


Good luck on your search and keep us posted.

Gary

Ausxb,sorry to have misspelled your user name.

Gary

Replacing PCV valve was one of the early things I did. And, I had well over 2000 miles on the new engine before going with the synthetic oil. Was that insufficient?

But I am intrigued by some of the things mentioned here. . . particularly engine ventilation. Is perhaps the standard PCV system inadequate for my now a bit more hopped-up engine? Compression is a bit higher that before, and I added a higher-performance camshaft (Clay Smith 264/264 112), part of a camshaft/lifter/spring package that Mike from Classic Inlines recommended. Installed dual exhaust headers quite a while ago, the first performance mod I made, well before this rebuild (seemed a good place to start).

Could all of this have added up to some unusual internal air flow?

I have noticed (but not given much attention) that my PCV valve rattles when at lower RPM (>1000). Had this with an earlier PCV valve, so I replaced it (some time ago). But new one rattles as much as the old, and I didn't give it much more thought.

What to do about this? Should I remove the PCV valve temporarily as an experiment?

Thank you for the input! I appreciate hearing some new ideas.

Witch way is the rod oil spurt hole facing ,cam or major thrust side" passenger side"? I do not think this would cause this ,but it would not help.

I can't say that the PCV is the culprit. But I do know that my previous setup was bad. Was forcing oil up into the distributor. The problem disappeared when I installed the adjustable one. I was amazed at how well the car idled after installing that as well.

From your description it certainly sounds like oil is being pumped to the rocker cover and not returning to the sump.
If the engine has excessive blowby this will cause a high pressure in the sump and not allow the oil to return. The Blowby
Usually occurs with the engine under load. ie cruising at the speed you describe
When I was Working as a Mechanic we would use a Cylinder leak down tester to determine where leakage was occurring
whether it was past valves or rings. This tester put compressed air into the cylinder at TDC Compression stroke.
If it was leaking past the valves you could listen to the exhaust for air escaping(if it was an exhaust valve)
or open the throttle (if it was an Inlet valve) or remove the oil filler cap and listen or feel air escaping past the rings.
This maybe another way of diagnosing your problem.

On another note is your rocker cover the standard unit or after market as the standard covers have a baffle plate under the PCV
valve to stop oil being sucked into the intake. Some aftermarket units don't have this baffle. But still doesn't explain the noisey
lifters. So would be looking as described above.

Cheers, Hope this helps.

I'm curious to know what it ends up being also. My one-cent thoughts:
1) since it is oil pressure AND plug fouling, the theories about pcv and crankcase ventilation seem plausible. I actually run a pcv valve PLUS the original road draft tube just for overkill, easy enough to test-remove pcv and plug line to manifold
2) crankshaft end play is a possibility with oil-hole line-up
3) A solid-lifter cam in a hydraulic engine (or a solid lifter block with hydraulic tappets) could be an issue.
....just throwing stuff against the wall!