Sump oil leak

[daverubberduck]

Thanks guys.

I've just thought of something, but first a little background. This car was rebuilt almost to completion by a restorer and I bought the car off them. The car has never been run since rebuild and there is no guarantee that everything is put together correctly. Now when I was running the engine yesterday I noticed the oil pressure was high, looked to be about 80, and hadn't dropped much after running the engine for about 5 mins. Now in my youth I had an Elan Sprint and I seem to remember oil pressure was about 40 when cold, and when hot 40 under revs and about 20 when idling. So assuming the gauge is working correctly, the oil pressure is way too high. I am using Halfords Classic 20w50. Shouldn't there be a release valve in the pump that prevents too high a pressure? And could this be the cause of the oil leak?
Dave

[rgh0]

Sounds like to relief plunger is jammed in the pump or it has a high pressure pump fitted. It could be a contributor to leaks but I would be surprised if it was the cause given the location indicated

cheers
Rohan

[512BB]

Rubberduck wrote: I had an Elan Sprint and I seem to remember oil pressure was about 40 when cold, and when hot 40 under revs and about 20 when idling. So assuming the gauge is working correctly, the oil pressure is way too high.

Not in my experience Dave. In my everyday Elan, the oil pressure is over 60psi at 2000 rpm when cold, from start, specially in winter. Then runs at 45 psi hot, summer or winter, and that is on a motor that has covered 40k miles since last rebuilt, with a standard pressure oil pump.

A little tip for you as well. Do not run your engine for just 5 minutes. Bring it up to temperature and let everything get nice and hot. Otherwise you will just introduce condensation into the exhaust box and elsewhere.

Leslie

[daverubberduck]

Thanks Rohan, even if it is not the cause I guess I should fix the pressure problem before attempting to fix the leak.

Hi Leslie, well I may have mis-remembered that, or maybe the engine was quite old. The car was 9 years old at that time and the engine had never been rebuilt. Whatever the case, the oil pressure is looking too high now so I need to look into that. Thanks for the tip about letting the engine get hot, I will do that next time (if I don't lose too much oil ).
Dave

[rgh0]

Rubberduck wrote: I had an Elan Sprint and I seem to remember oil pressure was about 40 when cold, and when hot 40 under revs and about 20 when idling. So assuming the gauge is working correctly, the oil pressure is way too high.

Not in my experience Dave. In my everyday Elan, the oil pressure is over 60psi at 2000 rpm when cold, from start, specially in winter. Then runs at 45 psi hot, summer or winter, and that is on a motor that has covered 40k miles since last rebuilt, with a standard pressure oil pump.

A little tip for you as well. Do not run your engine for just 5 minutes. Bring it up to temperature and let everything get nice and hot. Otherwise you will just introduce condensation into the exhaust box and elsewhere.

Leslie

Hi Leslie
it sound like you have a high pressure relief spring fitted to your oil pump which sets the relief pressure at 60 PSI. The standard relief pressure is 40 PSI like Dave remembered in his older car.

cheers
Rohan

[daverubberduck]

Hi Rohan
Maybe my oil pressure is not too high. The gauge in the car doesn't look like what I remember from my old car. The pics below compare the gauge in my car on the left (which looks wrong) with the gauge in another dash I have from a +2S on the right (which looks right to me). I am seeing 80psi but if the needle were in the same position in the other gauge it would be about right. Is it possible I have the wrong gauge or the wrong sender unit?
cheers
Dave

[rgh0]

It is hard to get sender units for the 0-60 psi gauges.
My guess is the gauge was replaced when the sender unit failed as 0-100 psi senders and gauges are easy to get.
But potentially you have an original sender with a 100 psi gauge, not sure what the result would be with that combination.

Before doing anything i would put a mechnical gauge that I know is accurate on the oil pressure tapping to check exactly what is going on.

cheers
Rohan

[daverubberduck]

Thanks Rohan, will do.

[512BB]

Of course you all failed to spot my deliberate mistake, re oil pressures.

I was writing about pressures in my Sprint, where the correct gauge only goes up to 60 psi and it appears after your pictures Dave, that you were writing about a +2 gauge.

So I am entirely happy that there is no fancy relief spring in the oil pump Rohan, as two other roadworthy Sprints that I have with original oil pumps, display exactly the same characteristics, in that on start up, cold, they wizz round to about 60 psi @ about 1500 rpm, then settle at over 40 psi when crusing hot.

And just to mop up a couple of queries that have cropped up over the years on here. It does not matter if your oil pressure shows as low as 10 psi, maybe even lower, when hot, at idle, so long as you have some oil pressure. Writing re STANDARD oil pumps of course.

Leslie

[rgh0]

Hi Leslie

To get 60 psi on start up cold for more than a few seconds says the relief valve set at 40 psi is not relieving the excess oil. This means one of three things

1. Too thick oil - if using old fashioned mineral oil this may be the case when cold
2. Very tight bearing clearances - possible but they are probably to tight if the 60 PSI lasts more than a few seconds
3. A high pressure relief spring set for more than 40 PSI.

A correctly built engine with right bearing tolerance using a modern synthetic 20W- 50 oil should show 40 PSI when started cold and sit between 30 and 40 psi when running at normal engine speed when hot and around 20 to 30 psi when idling when hot.

cheers
Rohan

[512BB]

Good morning Rohan,

To get 60 psi on start up cold for more than a few seconds says the relief valve set at 40 psi is not relieving the excess oil. 'I only get those pressures for 30 seconds max before the needle starts to drop down'.

1. Too thick oil - if using old fashioned mineral oil this may be the case when cold 'Remember, I am an old fashioned boy, of course {not concourse } I am using old fashioned 20/50 mineral oil, that was what they were designed to run on.'
2. Very tight bearing clearances - possible but they are probably to tight if the 60 PSI lasts more than a few seconds 'Impossible, I built the engines '
3. A high pressure relief spring set for more than 40 PSI. 'What, in 3 engines all displaying exactly the same characteristics, built at different times. Highly unlikely my friend.'

A correctly built engine with right bearing tolerance using a modern synthetic 20W- 50 oil should show 40 PSI when started cold and sit between 30 and 40 psi when running at normal engine speed when hot and around 20 to 30 psi when idling when hot.

If I had built an engine and it ran at only 30 psi when cruising [not down the Kings Rd] I would turn my hand to something else, or find another machine shop. And if it runs at 30 psi at idle, you have your idle speed set to high.

Many years ago, I bought a Colorado Orange Sprint from a garage, cheap. On the way home, I noticed that the oil pressure was dropping and dropping. I never got the car home. I drove it straight to Hendon Way Motors, which was just round the corner from where I lived, and they gave me ?1k over what I had just paid for it. Sweet. I will come back and give the reg no if I can find it, keep watching. Maybe someone on here owns it. No comebacks mind sold as seen

Now Mr Hodges, see if you can convince me of the benefits of synthetic oil over good old mineral. In the meantime, where did I put me bottle of EP90, me trunnions need doing.

Best,

Leslie

[rgh0]

Hi Leslie

By now you should know I love a discussion over a beer or red wine about engine building

I have a nice glass of good Australian red here so lets go !

Why Synthetic versus Mineral oil?

1. The engine does not know the source of the oil or whats on the bottle all it sees is the physical and chemical properties
2. Synthetic oils have a much more uniform and stable molecular structure so their viscosity performance is more stable over a greater temperature range
3. The more stable structure also means they oxidize and evaporate less and maintain their properties longer and don't deposit gum and burnt oils sludge in the engine
4. Mineral oils use "viscosity improvers" to enhance there viscosity performance over the full temperature range due to their inferior molecular structure. These are typically chopped up polyethylene molecules which perform well when new but get destroyed rapidly when exposed to the high shear rate conditions in bearings. Thus the mineral oil looses its viscosity stability quickly.
5. A huge range of lubrication tests consistently demonstrate that synthetic oil is superior in every situation in every test. They also show that polyol ester synthetic oils ( eg Redline) are superior to Poly Alpha Olefin synthetic oils (e.g. Mobil One) which are superior to severe catalytic cracked mineral oils that are allowed to be labeled synthetic oils ( eg Valvoline Synthetic) which are superior to your classic straight mineral oil (e.g. you typical "classic oil")


One downside of poly alpha olefin synthetic oils is that the olefinic molecular structure can react with high olefinic fuel compounds and water to form a sludge foam in engines that do not get hot enough for long enough and build up fuel and water resides in the oil from blow by gases. I used to run a plant that made these high olefinic fuels as a by product and these were blended in as a key component in high octane premium unleaded fuel typically used in high performance BMW and other similar European cars. These car also use synthetic oil as standard. These cars also get driven by wealthy people who have short but slow commutes because they can afford the car and the expensive houses near the city where they work so they never get hot enough. These were the cars that suffered from a grey sludge foam build up in their sumps causing lubrication problems ! The owners blamed the car company, the car company blamed the refinery fuel, the refinery blamed the high octane blend stock we made. The reality was if they just changed to a cheap mineral oil the problem went away

As for why your engines show such high oil pressure when the relief valve is designed to maintain the pressure at no more than 40 PSI is an interesting question. But without a lot more data on engine build and oil used and ambient temperature conditions I cant answer on why it is running at an unnecessarily high pressure for a road engine


As for using oil versus grease in trunnions I only discuss that now with lubrication engineers and even many of them don't understand the fundamental differences and why grease is far superior

cheers
Rohan

[Craven]

Just to add another prospective on the discussion, oil pressure on these Ford engine has been a talking point since the beginning. In response to frightingly low pressure at tickover when hot an explanation given was, don?t worry it?s the flow of oil that is important, high oil pressure does not necessarily mean adequate lubrication. BTW Grease is made up of a carrier usually ?SOAP? and oil.
Watch out for Yellow Metal Corrosion with some EP oils.
Ron.

[john.p.clegg]

....and if you have any oil pressure at all , the centrifugal force in the crank throws this to the big ends

John

[Tom D]

On the subject of sump leaks, what kind of drain plug washer/gasket are people having the best luck with? In searching through past forum discussions I've seen a variety of recommendations, from nylon to copper. Mine came with a crush washer, which is plainly not up to the job. I'd also like to switch to a magnetic drain plug -- anyone know a US source?

Thanks.