Excessive oil consumption

[Jagman1950]

I've had my 1963 OTS for 54 years so I do know most of its history. However, I do think it was run hard the 7 years previous to my ownership (as evidenced by the trailer hitch that came with the car). Had to put in a 1966 synchronized transmission just after I got it as it was ticking in first pretty bad. Anyway, always did use a fair amount of oil, about a quart per 300-400 miles.

I decided to overhaul the engine in 1990 and surprisingly the engine didn't look too bad, but I did put in new rings, ground the valves, put in new valve guides, timing chain, etc. But didn't drive it much after that, maybe 1000 miles then put it into storage for 15 years. Got it out of storage, and the oil consumption didn't get any better. Last year sent it to a vintage Jag shop to replace the rear main seal and carb refurbishment and they had a terrible time setting the timing, but we eventually got it. They put in 10w30 synthetic, then replaced with 20w50 synthetic, and was really showing about 40 miles to the quart. Had them do a compression check (all cylinders at 180 lbs except one at 175) and also a leak down test (all at 100/96 except one at 100/68) so it appears OK. Have changed to oil to non-synthetic 20-50 with not much difference. Engine sounds good, I think the oil smoke has been reduced but can still see some on acceleration, I'm at my wits end..... any suggestions on what to look for?

[Gfhug]

Wayne, sorry to hear of your problem. The choice of oil can be a contentious issue with many using “classic” 20w50 such as:
https://www.morrislubricantsonline.co.u ... r-oil.html
A read of their technical data might be interesting to compare with what you’ve got.

Some feel there is no need to put in classic oils and happily use modern synthetics. You pays your money …

Just something to consider is there glazing of the bores? Your compression figures suggest not. Except for that one leak down number. Was there any indication of where that was from? Valves? Rings?
From my involvement with aircraft, that isn’t a good figure. Most people don’t do leak down tests on car engines just the compression tests like you’ve done.
But glazing can be a problem with aircraft piston engines after overhaul and a straight oil is generally used for the first hours. Say the equivalent of 1000 miles.

Could it be worth removing the head and checking over the one cylinder in particular? With the head upside down fill each cylinder head section with petrol (ok, gas ) and leave to see if the valves leak at all.

You might even get a helpful response from contacting Rob Beere http://www.rob-beere-racing.co.uk/
As the title suggests he’s very much into rebuilding XK engines and the V12s for racing. You could always admit that it was suggested on this forum and ask for any thoughts even though you won’t be shipping the engine to him.

Good luck with your endeavours and hopefully others will have their own ideas.

Geoff

[abowie]

40 miles to the quart is a LOT of oil. If that was all going through your engine I'd expect a LOT of blue smoke, not just a bit on acceleration. Your good compression and ok leak down numbers also would make me question that.

A puff on acceleration could be caused by lack of functioning valve stem seals, but are we dead sure that oil isn't leaking out somewhere? If not the rear main, maybe the oil over pressure bypass hose or oil filter housing?

Will be interesting to see what others say.

[paydase]

There should be oil traces on the floor of your garage and also visible dripping when you maneuver the car.

[malcolm]

As above, it surely must be a leak. You'd be driving down the road in an impenetrable blue cloud otherwise.

[mgcjag]

Check your dipstick.....is it straight and does it just slid in place easy......its not unusual for it to catch the baffle as you push it in and then gives a false reading....Steve

[Fuel.inj]

Steve have made a very valid point regarding the dipstick. It’s easily misread if it not positioned correctly.

[Jagman1950]

I don't think the dipstick is a problem. But I will take another look at it.

May just need to be driven....

[2Bobone@gmail.com]

Shortly after acquiring my '62 XKE I became aware of what I considered to be excessive oil consumption. It was in the neighborhood of a quart every 400 miles. I consulted the local Jag expert and still remember his take on the issue. He said [delivered with a Cockney accent], "Sir, Jaguars fairly weep oil" ! I pursued the issue no further with the Jaguar but when it occurred with a different car I was able to trace it to a clogged crankcase breather. Possible ?

[abowie]

Do have a good look at the OP valve bypass hose.

They are a common source of leakage and you might not see it until the valve actuates at 60psi or so when the car is running.

[Jagman1950]

The OP bypass hose is just a hose by the oil filter, correct? Does it get clogged up or something. I really don't see any oil coming from it or around it getting on anything. But I will take another look at itl

Thanks for your suggestion.

[abowie]

They can split, and notoriously leak because the sump fitting and the housing fitting are different diameter.

[Jagman1950]

I've cleaned the screen and made sure everything was open on the Cylinder head breathing components, but I don't see anything else to look for. The hose is attached to the air breather box as it appears it should be. I would very much like to find something wrong with the breathing system as that really sounds like issue.

Thanks for all your help. Any ideas?

[Jagman1950]

They can split, and notoriously leak because the sump fitting and the housing fitting are different diameter.

I'll certainly look at it again, but don't remember seeing any oil coming directly from that.

[abowie]

Fair enough. Just a thought.