Excessive blue smoke and oil consumption

[Merlin_V12]

Dear All,

I have just joined the members website after being a JEC member for some five years and already I have seen a lot of useful stuff on here.

My reason for writing is that I have a 1967 Series 1 2 + 2 auto which I have had for around five years it has always emitted quite a bit of blue smoke when starting up and uses quite a lot of oil. It is currently on 110,000 miles and had a rebuild by the previous owner the extent of which is uncertain. I have done a compression test and all six cylinders read in the 160's. The car drives very well indeed and pulls like a train including up hill. Whilst oil pressure reads around 50 on cold tick over after driving for about 20 mins this drops off to less than 10 on the smiths gauge. The previous owner in his wisdom fitted another oil pressure gauge in the oil line under the bonnet which reads normal oil pressure at all times.

Research I have done to explain excessive smoke and oil consumption suggests many things including:-

Worn valve stem seals / guides
Blocked breather gauze
Worn oil control rings (although as mentioned above I have good compression on all six cylinders)
Poorly tuned triple SU carbs
The poor reading on the smiths gauge when hot has been suggested to be a faulty oil pressure sender

I should mention that I don't have any oil leaks as the front oil seal which did leak was replaced some time ago and the rear one which one might have expected to leak does not!

I would really like to get to the bottom of this problem once and for all so would like to seek your advice.

Many thanks in advance.

David.

[piman]

Hello David,

an indication of cylinder head oil consumption is to accelerate hard after being on the over run, that generates most smoke if that is the problem. If that is not the case then it is probably piston related, of course it can be a bit of both?

It is worth checking/cleaning the breather system anyway, and as you say it runs well then the carburettors are probably fairly OK. I would certainly favour the reading of a mechanical gauge over the electric one fitted by Jaguar.

Alec

[Merlin_V12]

Dear Alec,

Thanks for getting back to me.

You dont think that oil is coming down into the cylinders when the car is at rest from worn valve stems / guides then? As when I start up after its been standing for a few weeks there is literally clouds of blue smoke. However, for example I used the car yesterday and took it for a good long run and started it again this morning and the blue smoke is minimal.

I've been advised to try Millers 20W50 engine oil and engine oil stop leak (although i dont have any leaks). I'll also get the breather system cleaned and see what happens.

I will also try and get a new oil pressure sender unit to see if this improves the oil pressure reading on the smiths clock.

I would appreciate any advice on this plan of action.

Thanks

David

[piman]

Hello David,

there is not likely to be any oil passing down the valve guides at rest, it is the engine vacuum that draws oil down the stems when running, which is why it shows up most after the over run when the manifold depression is greatest.
I don't really know why you have a lot of smoke after being standing for a while, and as you say after a long run then start the effect is minimal. I suspect it depends on what sort of running the car has had prior to it being stopped, e.g. if it was just started and left idling for some time then stopped, this could draw oil into the engine?

If you are running a thinner oil than a 20/50 then changing to a good brand of 20/50 is a good idea. I wouldn't bother with the stop leak.

Alec

[Merlin_V12]

Dear Alec,

Thanks once again for your reply.

I am currently using a 20W50 Motorway Comma mineral oil.

it has been suggested that after I clean the breather system that i try Millers 20W50 engine oil.

I appreciate what you said about the vacuum effect of drawing oil but as for the blue smoke after standing for a few weeks it seem to me that it must be being burnt in the cylinders hence the blue smoke?? but then if there was excessive oil getting into the cylinders then it wouldn't run very well and the plugs would get gunked up right? Truth is it runs very well and pulls like a train. I just want to know how to stop it and reduce oil consumption. i guess i just need to know how / why this is happening. Do you think new valve stem guides and seals might cure it if the cleaning of the breather system and change of oil does not?

Any thoughts on that?

Regards,

David

[piman]

Hello David,

a personal opinion is that I wouldn't chose Miller's over what you are running now, I doubt it would make any significant difference and as you are using oil will add to the running costs.
Yes, too much oil would get on to the plugs. It's difficult to diagnose problems without physically looking at them so there is some room for error.
I would say that your engine may well need valve guides, (there are no seals) but once you start where do you stop and it may get expensive. As the car is running well it's your decision as to whether you want to go to what may turn out to be a full engine rebuild.

Is there anyone local to you who is familiar with this engine who could advise, possibly from the local regional group?

[Merlin_V12]

Hello Alec,

Thanks again for your reply.

I just cant think of what else would cause so much oil consumption (top up 2 litres in 100 miles!) and excessive blue smoke on start up after a period of rest when there are no obvious oil leaks.

Yes I am more than happy with her performance always a thrill to drive my e type and puts a smile on my face every time but i would like to venture out further from home without the constant worry about oil level and consumption.

I appreciate what you are suggesting about mission creep here but do you think the valve guides could be done in isolation if the rest of the engine seems oil tight? I have a quote to do the job from a garage near Bridgewater that specialises in classic cars.

Kind regards,

David

[oldtimer]

Two litres per 100 miles

um, what's that, 4.5 litres to the gallon , that's near enough 1/2 gallon per 100 miles, cor Bennett , that's an awful lot of oil.

A compression check might be a good starting point !

Engine to normal running temperature
Ensure ignition is dead
All Sparking plugs out
Fit compression gauge
Fully charged Battery
Crank engine over with Throttle fully open
Record pressure reading -- 9:1 = 180lbs per sq. in.
Repeat on other cylinders

Oldtimer

[piman]

Hello David,

yes you can do the valve guides in isolation and that will also give a guide to the bore wear, if any, when the cylinder head is off. That is really heavy oil consumption and it would be interesting to see what all of the plugs look like? If it is guides, all the plugs should be fairly similar in appearance.

Is the garage you are contemplating familiar with XK engines? Whilst it's not rocket science it is better to use someone who does regular work on them. E.g., Jaguar heated the heads up to fit the valve guides, that takes a fair sized oven to put an XK head in.

Many years ago I had a local garage (Claimed to be performance engine specialists) do some work on my cylinder head and they made a real mess of it, I ended up sending it to Forward Engineering to have it done properly.

Alec

[Merlin_V12]

Hello Alec / Old timer,

Thanks for your respective replies

A compression test has been done and all six cylinders were in the 160s

Alec: the garage I had in mind would be sending the head away to do the valve guides and then refitting.

Who do you have in mind? Can you recommend anyone in Somerset where I'm based?

regards,

David

[piman]

Hello David,

Somerset is a long way from me so I can't help there, sorry.

Incidentally it's worth putting where you live on your posts, you can do it easily from your account control panel. That way you might find someone close by?

Alec

[Merlin_V12]

Thanks Alec.

I've just updated my profile

David

[stuarthardy]

Hi David

That level of oil consumption is exceedingly high and, if there are no major leaks, can only be the result of burning oil during normal running.

Compression tests are a fairly crude method of determining wear and differences in pressure readings between cylinders is usually what you look for, rather than the absolute reading.

Blue smoke on start up does suggest that the oil is seeping past the stem seals and worn valve guides when the engine is stopped. I have known this to happen on other types of engines. The rate of oil consumption, however, seems to suggest something more serious than valve seal/stem wear and I would be looking at cylinder bore/piston wear.

Valve seal wear is usually the culprit if you notice a cloud of smoke behind the car when you lift off the throttle after a brief period of brisk acceleration.

Have you tried a 'wet' compression test where you repeat the test after introducing a little engine oil into the cylinder through the spark plug hole? If the compression increases noticeably during the wet test then it suggests there is a problem with bore or piston ring wear. Otherwise the problem lies with the head. Also, was the compression test work done on a hot engine as this would give lower readings?

There is also the possibility that the head gasket has failed and an oil gallery is feeding oil into one or more cylinders although this would most likely be accompanied by a drop in compression.

Are all the spark plugs a nice nutmeg colour or do some have oily or sooty deposits.

Finally, are you using a good mineral oil rather than a synthetic oil?

Regards

[Merlin_V12]

Dear Stuart,

Thank you very much for such a comprehensive reply to my post. I may not be absolutely correct with the stated oil consumption but it is a lot.

I did not seem to get the same amount of smoke when I was using the car every day the week before last when we had that lovely sunny weather which makes me wonder if it is the valve guides in that instance not having the time to drop a lot of oil into the cylinders to be burnt off as blue smoke (just a thought).

I will certainly look into the other things you have mentioned and report back when I have done so.

Thanks again.

David

[Art1012]

Hi David, did you resolve this issue of excessive oil consumption yet?
My 1967 2+2also suffers from oil draining into one of the cylinders when the car has been standing for a couple of weeks. The same cloud of smoke on starting, but after that running perfectly. Ken Jenkins advised that the late S1 cars, including the 2+2 models did not have valve stem seals fitted. Some drain down is expected on S1 cars. You could have later S2 4.2 valve guides installed, which do have stem seals.
The level of oil consumption you report indicates that oil is being lost rather than burnt. I thought my front oil seal was good. But after inspecting the underside of the car after a long hard run I found oil on the chassis the seal looked fine, but was losing oil past it when the engine was revving and under internal pressure. It was burning off on the exhaust system, so there was no obvious leak. Again at the recommendation of Ken Jenkins I fitted a later XJ6 front crankshaft seal kit which is a Viton seal and comes with a new crankshaft Boss with an internal O_ring.
I am still living with the oil drain down issue, but with the later crankshaft seal, I am getting around 750 miles per pint. I am running on Miller Classic 20/50, but intend to go to a semi synthetic on my next oil change now that my engine has covered 4,000 miles since rebuild.
Hope this helps
Art