Running in - Oil Pressures

[l10tus]

The Sprint has done about 250 miles since its full rebuild, engine is running well enough, but quite rough until warm.

'Running in' steadily, with no prolonged large throttle openings or labouring.

I'm using 'Millers Classicrunning in oil'.

Oil pressure has been 40PSI when cold at tick over, reducing to 20PSI when warm.
Settling around 35 - 40 over 200Rpm when driving (warm).

I took it on a longer run yesterday afternoon _ about 35 miles, but found the oil pressure dropped to 25 - 30 after a period (very brief) at higher revs. (Approx 4K RPM) - with tick over dropping towards 5PSI or zero.

It did recover whilst being driven over 2K, but worried me somewhat !

No nasty noises when I parked up, water temp 74 degrees, tick over fine, with no signs of over heating.

I will run it tonight to check the startup/cold pressure, but wonder if this Millers running in oil is characteristically thin when warm??

It's fitted with a standard oil pump and filter.

Any ideas to make me feel better ??

Replies great fully received !

Thanks,

Phil.

[gjz30075]

What's the weight/viscosity of the Miller's oil?

[englishmaninwales]

I'm using Millers Classic running in oil at present (SAE 30) following a rebuild and I'm up to 500 miles, and about to oil/filter change. Your fall in oil pressures look low to me, I'm getting hot pressures of 45 psi on the road and 25 psi at idle. New standard oil pump, crank not reground but new bearing shells, cylinders honed and new rings only.
I used the 2-5k RPM 3rd gear repeated acceleration running in process as described on here by Rohan:

"1. Use a specific running in oil that will have high zddp levels or any cheap mineral oil with a zddp additive
2. Start and warm up the engine and check for leaks and noises and setup the carbs . Dont run it for more than 20 to 30 minutes and dont let it idle for to long during this period
3. Take the car on a quiet road with no traffic and an appropriate speed limit and do third gear acceleration cycles at full throttle from approx 2500 rpm to 5000 rpm and then slow down again and repeat. Do this 40 or 50 times over maybe 100 km's. This will fully bed in the rings
4. Change the oil to the long term oil your going to use and filter and your done ( assuming the engine was built right in the first place with correct tolerances and machining / honing of the bores etc)

The rings bed rapdily because of the combustion gas pressure behind them pushing them against the cylinder walls. You have maximum combustion gas pressure between 2500 and 5000 rom with the throttle wide open. Under no load with throttles mainly closed you have much lower combustion pressures and thus lower forces seating the rings against the bore walls.

I do it in third gear as a compromise - in second you go through this rev range too quickly in 4th you end up at to high a speed on most quiet back roads."

[oldchieft]

Any smell of petrol on the dip stick?

Jon the Chief

[TroonSprint]

I am also running-in a Sprint engine using Millers Running-In Oil. This is not a multigrade, but a straight SAE30 mineral oil. I have a 20 thou rebore but standard crank with new shells and a new oil pump. After about 300 miles my hot idle pressure is around 20 - 25 psi, and it runs at 40 or slightly above when driving. Hope that helps.

Mike

[l10tus]

Well tonight the situation got worse!

I started the car as normal - but no oil pressure after 20 seconds ! ( it normally delivers 40 PSI within 2 seconds of start up).

Switched off and checked again - no pressure !

Undid the Oil Gauge connection at the block - started the car briefly - no oil coming out of the block !

What next ?

Pump to be replaced - only done 250 miles from new?

Filter failure of some sort??

Pick up pipe dislodged - sump off ??

What a start to running in!

Is it possible for a Pump to just fail so quickly?

More thoughts please?

Regards,

Phil.

[gjz30075]

Unlikely the pump is bad. Who did the rebuild? I'd start there and advise them of the situation.

[prezoom]

Could be a stuck pressure relief valve. If it gets stuck in an open or operated position, it can allow the oil to drain back out of the pump and makes it near impossible to create enough suction to pick up oil out of the sump.

[rgh0]

Running in oils are usually a single grade mineral oil with loads of anti-scuff additives ( eg high zinc levels) but low detergent / anti acid additives and no viscosity improvers. They are not intended for extended use due to the low detergent and anti acid levels as they dont hold impurities in suspension or help prevent corrosion. Without viscosity improvers they thin out at higher temperatures hence the lower idle pressures and hot running pressure below 40 psi. They are designed to assist the controlled wear that running in is all about.

Having said all that 20 psi at idle is still ok - I would not get worried unless its under 10 psi. 30 psi for hot running at revs is also OK when using a running in oil especially if your not pushing the redline during running in.

I would normally only use running in oil for the first 100km of my normal running in procedure and then change to a good quality group 4 or 5 synthetic oil.

cheers
Rohan

[bill308]

Peter Marcovicci of Marcovicci-Wenz Engineering, recommended and used Brad Penn1 to break in my new, dry sump engine on the dyno.

After a few minutes at a high idle and adjustment of balance and mixture, we started short, controlled pulls and quickly worked up to wide open throttle operation and 7500 rpm yielding 165 bhp and called it a day.

We suspected timing was incorrect, but had no way of checking it as the available timing lights were not working at the time. I'm using a programmable, Electromotive xdi-2, crank fired ignition system. A week later the timing was sorted and we moved on with the break in and full power pulls, again to 7500 rpm. After about an hour of total running we consistently saw above 190 bhp and 165 lb ft of torque. The engine was now considered fully broken in with a 9000 rpm limit, due to valve train constraints.

Peter recommended and used Brad Penn 1, 15W40 synthetic oil because of the relatively high ZDDP content.

Bill

[joe7]

Try changing your oil filter.

[cusword]

If an oil is too thin, much of it can run back and leave the pump dry and unable to create pressure to pump. Take the end plate off the pump and fill it with Vaseline. This should prime the pump..........worth a try.......

dwc

[l10tus]

Jon,

sorry for delay in replying - no, no smell of fuel on the dipstick.

All,
Thanks for the thoughts!

I'm in the process of removing the Oil Pump and Sump, I removed the oil filter, that was full.( not sure if that proves the suction or pump is working? - which way does the oil flow through the filter? - Centre outwards through the element or vide versa ??)

I've loosened the pump from the mating face on the block, can't fully remove it yet - but the spiral gear still seems to be attached securely at present. - Can't be the pump can it????

Perhaps when the sump is off I'll get more of a clue?

At present I'm thinking:-

Pickup pipe has become loose / blocked (300 miles??)

Oil that thin that it has caused it to cavitate and pump be air locked?

Outlet oil way for the Oil Gauge, blocked due to extra revs applied (sucked something up??)

Pump broken?

Jack shaft gear stripped?

I'll keep you posted!

Regards,

Phil.

[theelanman]

erm....probably a silly suggestion but have you re torqued the head bolts?.....
if they were new, there could have been a little give in them which a couple of heat cycles at the correct torque might have 'stretched' out.......
just a thought.....

[l10tus]

Thanks for the replies,

Not sure about the head bolts ?

I removed the pump and sump last night - pump seems to be capable of pumping ok - the spiral gear isn't loose and it makes sqelching noises when turned by hand?

The pickup pipe is still installed correctly, the gauze pickup filter is in place and the filter was full of oil.

Everything looks intact bearings - wise - so I'm really struggling to explain the sudden drop of pressure, the partial recovery, then no pressure at all at next day start up?

Any more ideas or suggestions.?

Regards,

Phil.