Oil Light On Under Acceleration

[Corpulent Tosser]

My Speed 6 Cerbera gives a large belch of blue smoke on start up if left for a while, this could be weeks or hours it still happens. Also oil consumption is high, it varies but probably around 400 to 500miles/litre, sometimes higher. Mileage is around 27,000 and the engine has never been rebuilt, the car was laid up for a few years before being recommissioned around three years ago.

There appears to be no loss of performance and I am thinking valve guides rather than piston rings but I don't know and hope someone might have a more informed opinion.

A new development though is that the oil light has come on a couple of times during hard acceleration, but the oil pressure gauge maintains >50psi, the oil level is OK, in fact a little high as I must have over filled last time I topped up.

What would be causing the oil light to come on when the gauge still shows healthy pressure ?
Should I be concerned that something is about to fail in a big way ?

Thanks
Murray

[m4tti]

Hard with out being able to look under the bonnet. The oil light might be poor wiring to the pressure sender, they do occasionally die have replaced one.

The smoke on start up is likely to be valve seals/worn guides. If you look at the link in my profile you'll see what's going on. Basically to solve that the engines coming out with a minimum of a top end rebuild.

Edited by m4tti on Thursday 2nd June 09:42

[Sagi Badger]

ummhhh.

Left standing for a few years. I have found these with valve guide oil seals popped up off the stems, esp. where left standing as the seal sticks to the valve stem, the oil dries up and when it is keyed over the seals get dragged off the stems. Cam cover off and take a look.
The two pics show the oil seal with and without valve spring. The oil light coming on may be triggered by the high engine speed low oil pressure warning, think..., wait to be corrected, it triggers at 35PSI or below over 4K.
What oil, is it fresh, is the oil pressure relief valve clear of debris, is the filter clogged (should default to bypass if clogged)... lots of options and of course is the ECU earth, the sensor earth and sensor itself OK?

Keep us posted

J

[Corpulent Tosser]

Many thanks

Oil is fresh and good quality (Fuchs) new filter a few weeks ago.
Gauge is still showing around 55psi when light comes on.

Valve guides/seals are my guess for the smoke and oïl consumption, particularly knowing the car was unused for a few years.

As a head rebuild requires removing the engine I guess this is a good time to get a full rebuild done, I suspected I would need to do this at some time but expected it to be when the finger followers did there thing, but it is budgeted for anyway.
The question will be when to get it done, who to get to do it and what rebuild to get done.

Thanks again for the replies.
Murray

[330p4]

Murray sounds like valve guides/seals first try a compression test if the figures a low remove the tester pour a capful of oil through the plug hole and test again if the compression returns temporarily then it is rings if little difference it is valve guides are worn and valves not seating properly. If compression OK you may be lucky and it is just valve stem oil seals but with the oil consumption you state guess it is guides also good luck
Ian

[330p4]

Murray sounds like valve guides/seals first try a compression test if the figures a low remove the tester pour a capful of oil through the plug hole and test again if the compression returns temporarily then it is rings if little difference it is valve guides are worn and valves not seating properly. If compression OK you may be lucky and it is just valve stem oil seals but with the oil consumption you state guess it is guides also good luck
Ian

[Firing order]

Have you carried out a valve clearance check while doing this you can check the valve stem seals condition
This only involves removal of rocker cover .

[Firing order]

Have you carried out a valve clearance check while doing this you can check the valve stem seals condition
This only involves removal of rocker cover .

[Corpulent Tosser]

Thanks guys.

I am at work in Africa at the moment so cant do anything to the car right now but get home in a couple of weeks and will have a look then.

My understanding is that to do the seals the head has to come off and that means taking the engine out, if so I am inclined to get a full rebuild done as the incremental cost is not huge and as the car has never had a rebuild it is something that is budgeted for.

If the seals can be done with the head in situ that would be a different story.

[Whitey]

Does long periods without starting the engine make the valve stem seals dry out due to lack of lubrication?

[m4tti]

They should have residual oil on them, which by its nature won't dry out. It could drop off over a long period due to gravity. More importantly the guides and seals were of a budget nature.

[Firing order]

Yeh would agree with m4atti .
However check for elongated valve guides and holes that guides sit in ,excessive movement
Can break up seals.