Series 1 oil pressure higher than usual

[Vonkie]

Dear friends and boffins!

I have been absent from this forum for so many moons.I suppose that's an indication of the absence of frustrations and no need for solutions! My Lady Devorguilla '63 Series 1 3.8 is running so nicely. I am heading towards 20,000 miles since I took delivery in October 2017. Other classics vie for attention, but she still does her bit.

For the last 3 years or so, she has been very, very consistent with oil pressure. When the engine is hot, she would idle at 20 psi and drive at 40 psi. Lately, the oil pressure was suddenly higher than this. At high speeds, between 80 - 100mph (the latter not done very often!!), she would go to 55 psi. At least the pressure does not creep continually upwards - after a long stint at speed (say a consistent 85-90 mph), she would calm down and coast at 40 psi or so at 50 mph, and idle anywhere between 20 and 30 psi.

I had the oil changed for the first time in over 2 years, oil filter replaced - it's the cannister type as on page B.46 of the manual, pressure relief cleaned, sensor checked, and all was apparently in order. After all of this, the pressure was perhaps slightly lower, but still higher than before - i.e. 55 psi at speed, rather than 40.

She also uses more oil than she should (some spotting but no obvious leaks).

I use Castrol Classic 20w50 and try to keep the level above halfway up the gnarled bit on the dipstick.

Should I be concerned? Bear in mind I don't do any of the work myself.

[christopher storey]

Nothing to worry about there, I think. The oil pressure senders are notorious for inaccuracy, and in any event the pressures you report are not atypical for an engine in good condition

What is your oil consumption? "too much" for any XK engine is anything worse than perhaps 150 miles per pint , 200 being entirely typical although some people do report figures significantly better than this . The usage is also definitely performance related i.e. the harder you drive it, the more it will use

[phoenix]

I fitted a capillary fed oil gauge and used the normal voltage type as a warning light . (different switch)
I think they give a better and more reliable reading.

[chrisfell]

What Christopher Storey said.

I have had four senders, only one reads consistently and where it should. My car uses around 1 - 1.5 litres of oil between 3,000 mile oil changes, and most of that falls on the ground. Only a small amount gets burned, there is a slight hint of blue smoke on the overrun.

[Vonkie]

What is your oil consumption? "too much" for any XK engine is anything worse than perhaps 150 miles per pint , 200 being entirely typical although some people do report figures significantly better than this . The usage is also definitely performance related i.e. the harder you drive it, the more it will use

Well, I check the oil cold before any journey. Usually a week or two between journeys, and a journey is usually about 100 miles or so. The breakfast runs tend to entail a stretch of road of about 10 miles where she can stretch her legs at over 90 mph, and at times even around 100mph. I seem to need about a pint per journey to keep the level at just over half the gnarled bit on the dipstick. So, call it a pint per 100 miles, but also with standing around a week or so every time. That's a bit much. She's always been oil thirsty. Fuel use not bad - between 12 and 15 litres per 100 km depending on town or open road. In Britspeak, last few tanks have been 19,67 mpg, 21,78 mpg and 24,9 mpg (mainly open road mind)

[christopher storey]

I would not worry ( yet ) about 100 miles per pint . First thing to ensure is that you are not overfilling it, because this will lead to excessive consumption as surely as night follows day . Like the oil pressure senders, the dipsticks are notorious for inaccuracy, and the only sure way to deal with this is to drain and refill with no more than 8.5 litres and mark your dipstick with the level which is then shown

[Vonkie]

Ok, thanks for the warning - I know gauges can be misleading, but did not think a dipstick can be far off from right.

I'll wait until it gets to on or below the start of the gnarled bit.

[mtnjag]

I have found on my car it makes a significant difference to the level as to when you check the oil level.
If I check it after sitting for an hour it is lower than if I check the following day.

I think the method to follow is if you are following the level closely check it within the same period each time or you may not be comparing apples to apples.

I would assume all the oil has drained back within an hour, perhaps the higher level the following day is due to oil filter drainback. I have a spin on filter.

Regarding oil usage, I have thought 100 miles a pint very excessive. Assume this is a English pint but even if a US pint that's 200miles per US quart which is a lot of oil. I complained about usage better than this in another thread on this forum entitled "Huge Engine Oil Consumption" and was advised on correcting the unfortunate problem.

[abowie]

I have thought 100 miles a pint very excessive.

I have 4 cars with XK engines; 2 3.8s and 2 4.2s.

All have less than 2000 miles since rebuild. None of them use any oil at all.

[Robbiee]

My engine has done 14,000 in 5 years and never seems to use oil either

[Vonkie]

The pics are of the spray pattern accumulating on the garage floor (over several months), and spotting under the car (also accumulated over months). The missus is thrilled. No smoke while driving.

Drove her 120 miles today and left the oil alone, despite showing 1/3rd into gnarled bit cold on dipstick.

Let's see.

[christopher storey]

That black deposit is very likely just to be carbon washed from the exhaust system when the engine is cold . Having just looked up Sandton and seen that it is 1600 metres = 5250 feet above sea level, I do wonder whether you are over rich , and that is leading to excess oil consumption . I think at your altitude, a weaker needle than UM would be justified

[mtnjag]

If that's months accumulation of oil I would not be concerned at all, IMO you are doing good! And it actually looks like more than it is. Put a little absorbent tray down.

I think you will spit carbon. Since that is over several months it really may not be too excessive, but you are using quite a bit of oil and that will contribute so not a surprise. Clean it and see what it looks like after a start up or two.

You have downturn pipes so it goes to the floor. My 62 has the pipes straight out, don't want park close behind on startup.

[malcolm]

I get the same carbon deposits, even though engine is excellent. I have cardboard sheets behind my (straight) pipes to stop the black going onto the shelving behind it.

[Vonkie]

That black deposit is very likely just to be carbon washed from the exhaust system when the engine is cold . Having just looked up Sandton and seen that it is 1600 metres = 5250 feet above sea level, I do wonder whether you are over rich , and that is leading to excess oil consumption . I think at your altitude, a weaker needle than UM would be justified

Thanks guys; I am comforted.

After the first about a year and a half of gradually getting teething problems smoothed out, I had adopted a very strong 'ain't broke don't fix' policy on the basis of a devil I know, and if she's been running for many months on end with no serious issues, I regard this as such a blessing that I have them mess with settings and the like only when something goes wrong. I'll bear in mind the potential for a slightly leaner setting for next time. The clock is coincidentally with someone who does one of these modern fixes on the back of the clock - I had a proper watchmaker attend to the cute technology of the original clock a few times, but she always stopped running after a while, so I am now opting for an acceptable cheat here.

I'll report back - especially when I hit 20,000 miles since delivery (I am at about 19,200).