200ci Low oil press at higher speed

[dawnovsky]

Hi guys.
It s been a while not being here. Hope you are all good.
It was a while too I haven’t rube the mustang . A baby , a new job and a moving hundreds miles from home makes difficult to find time to ride the 66 mustang . She was waiting in my parents garage since 2022 being run once in 2023 by my brother.

Eventually had an opportunity to drive it down to my new place .
New oil and filter (20w50 and motor craft filter)
New trans oil and filter
New coolant .
New brakes fluid
Fully charged battery
A One hour test run and we were good to hit the road for 800km

After several hours of driving the engine develop a ticking noise (from lifter I guess).
Release the throttle, and ticking vanished after few seconds . Hard to stop on the side of the highway in France. So I push to the next gas station . Have few coffee to Let her cool down .

Sign of oil spillage on the engine bay (not much). Most of it from valve cover gasket but also a bit from the breather .
Oil level correct (still at MAX when not cold yet)
Add a bit of extra oil for good mesure. Wipe the excess oil and went back on the road.

Over the last 2 remaining hours of driving had the ticking noises twice for few seconds before vanishing when releasing the throttle a bit . Noticed it was associated with a low indicated oil pressure .
Oil press was going up and down 1/5 of the scale may be.
Engine temp lower third of scale
Oil pump relaxe a few years ago. Not tons of miles on it.
Solid 3/4 oil pressure when cold .

What do you think??
Please say Engine slug


Many thanks in advance

 

[aussie7mains]

First off, check the oil pressure with a gauge, dont relie on the Ford factory one.

 

[Frank]

Oil is accumulating in the valve cover and not returning to the pan quickly enough. If it does it again, pull over and check the oil at once, I predict it will be very low on the stick.

 

[drag-200stang]

That thick oil is not helping.

 

[dawnovsky]

I have been using 20w59 since 15 years on the mustang. It was in South Pacific tropical region with a lousy radiator so it kind make sens. Now in France with brand new copper rad (but still a 160F thermostat).
Would you recommend lighter oil and a hotter thermostat ?

 

[dawnovsky]

First off, check the oil pressure with a gauge, dont relie on the Ford factory one.

This I understand . However when lifter noise happens needle is low .
When noises stops , needle is higher.
In old fashioned aviation abition we used to say when it comes to oil pressure absolut values doesn t mean much . It s more like “is there oil pressure or is there not ? “.
But you are right all the way . I ll try to get a mechanical gauge handy

 

[dawnovsky]

Oil is accumulating in the valve cover and not returning to the pan quickly enough. If it does it again, pull over and check the oil at once, I predict it will be very low on the stick.

Make sens . So the question is why oil Is accumulating on to and not returning fast enough. ? And how to improve it?
I was about to put a piece of cardboard on over a portion of the Radiator to increase temp.

 

[Frank]

Make sens . So the question is why oil Is accumulating on to and not returning fast enough. ? And how to improve it?
I was about to put a piece of cardboard on over a portion of the Radiator to increase temp.

When it happened to a friend (with me in the car) on a 250 Ford 6 (long ago) it was mostly due to a worn engine. The cylinder blow by was pushing up thru the oil drain holes to escape, combined with too-old thickened oil. In your case, you say the engine is not overly worn. Reducing oil viscosity should solve it, will help regardless. And yes, increasing engine temp will also help.
If there's no mechanical issue with the engine I'd start there. 10w-30 or 10w-40 + 180* thermostat.

 

[427John]

If this is an original not rebuilt engine the first thing I would do in this scenario would be pull the valve cover and side cover and verify that the oil drainbacks aren't restricted at all. An engine that has had miles put on it with the oils they had back then is sure to have a buildup of sludge and deposits and then when it gets run with todays oil that keeps the engine much cleaner a lot of that stuff gets broke loose and tends to collect at the most restrictive areas which is typically the oil drainbacks. My dad once bought an older rig that had a 351W in it and it was smoking and exhibited occasional low oil pressure, he pulled the valve covers and found the oil drainbacks nearly completely plugged with a combination of sludge,varnish, and chunks of valve stem seals, he cleaned all of it out and put it back together without putting new stem seals in it and it ran great with no smoke and good oil pressure. I had told him that he should at least put new stem seals on it but him being the frugal old dude he was he just laughed and said probably but I got away with it.

 

[dawnovsky]

Side cover ? There s none I am aware of on the 200.
Oil is draining from the top back to the case via the push rod galleries . Probably more than one centimeter wise.
Hard to believe it can be clogged.
I have the car since 2008. I have open the valve cover many time and alway found. Relatively clean engine.
That will be my next move anyway cause I want to have a look at it.

Better order a new gasket first …
The head have been replace couple of year ago . New valves. Still a good idea to have a look at it

 

[drag-200stang]

The oil drains from the head around the 12 pushrod holes to the top of the lifter galley. there is three holes there that the oil drains to the case and pan. like said above pieces of valve seals and what ever can add to the problem with oil competing with blow by with too cold thick oil at that area.
Try thinner oil and get engine temp up to 180.

 

[PSIG]

I would not change oil or thermostat until this issue is resolved, as they should not be the primary source of the problem. One thing at-a-time. After following other ideas, one possibility is oil foaming if overfilled, and 'whipped' by the crankshaft. Oil foaming can cause hydraulic lifter ticking and bearing wear. The dipstick (if the correct one) should read near MAX when cold (overnight), and towards MIN if checked within a couple minutes of warm shutdown. It is a range for this reason. I would verify it is not overfilled after sitting overnight, and drain any excess.

 

[aussie7mains]

This I understand . However when lifter noise happens needle is low .
When noises stops , needle is higher.
In old fashioned aviation abition we used to say when it comes to oil pressure absolut values doesn t mean much . It s more like “is there oil pressure or is there not ? “.
But you are right all the way . I ll try to get a mechanical gauge handy

Just for your information, the ford spec for these engines calls for 10w30 oil, and the oil pressure spec is for it to be 35to55psi (2.5 to 3.5bar for you) with the engine hot at 2000rpm. It can drop very low when idling. It sounds a bit like you engine may have a sticky oil pump relief valve, when the valve is open pressure drops. Unfortunately you need to take the sump off to get to it.

 

[427John]

My bad, I forgot the falcon six didn't have them like just about every other inline six ever.

 

[427John]

Side cover ? There s none I am aware of on the 200.
Oil is draining from the top back to the case via the push rod galleries . Probably more than one centimeter wise.
Hard to believe it can be clogged.
I have the car since 2008. I have open the valve cover many time and alway found. Relatively clean engine.
That will be my next move anyway cause I want to have a look at it.

Better order a new gasket first …
The head have been replace couple of year ago . New valves. Still a good idea to have a look at it

If the head has been off recently then the scenario I described probably doesn't apply, but you would be surprised how tenacious old engine sludge can be. Its not necessarily limited to old engines either, a friend recently had a Dodge Cummins that suffered a lower end failure due to being horrendously sludged up, he asked me what I thought so I asked him if they usually used it when they ran errands and he said yes, knowing how short their errand trips were and how often they did it I explained to him that a big diesel like that under very light load would take forever to warm up and how important it was for that to happen in order to drive the moisture out of the crankcase.

 

[Frank]

I would not change oil or thermostat until this issue is resolved, as they should not be the primary source of the problem. One thing at-a-time. After following other ideas, one possibility is oil foaming if overfilled, and 'whipped' by the crankshaft. Oil foaming can cause hydraulic lifter ticking and bearing wear. The dipstick (if the correct one) should read near MAX when cold (overnight), and towards MIN if checked within a couple minutes of warm shutdown. It is a range for this reason. I would verify it is not overfilled after sitting overnight, and drain any excess.

Foaming may account for air in lifter and lower OP, but not the VC gasket and breathers leaking oil suddenly. The way we knew the oil was all in the VC in my post above was when it got so full the PCV valve inhaled pure oil, and we smoke-screened the entire highway before stalling out completely. . I agree he should find a cause, but I'd wager big the oil was in the top not the bottom. Why is another question.