4L V8: excessive oil consumption?

[phuma]

My disco 4L V8 is using too much oil to my liking :-/

Background:
. 1999 Disco 2 4L V8, 196000km
. running BP Vanellus C6 Classic 15w40 (this is a multifleet oil used by an independent locally)
. recently (200km ago) replaced thermostat - old one was stuck open
. at same time also replaced HT leads; was misfiring
. oil currently in engine for about 2000km
. had a near overheat situation after new thermostat was fitted (temp guage went up, and I shut off the engine as the needle went into red, and the red light came on). The overheat was because some idiot previously blocked off the pipe from the engine to the thermostat; radiator cleaned and everything fine now.
. is not losing water at all - never has, and has not since the thermostat incident
. seems to smoke a lot after overrun (only easily seen at night?)
. little bit (puff) of smoke if you floor it while standing
. no drops, nothing!, where it is parked
. smells a bit oily if you've driven it hard, and coasts to a halt

I would guess my consumption is about 1 to 2 litres per 1000km; yesterday the dipstick dropped by 5mm after a 100km run at speeds of about 120km/h, aircon on. I have not really watched it as closely since the near overheat incident, so cannot really say if the overheat has damaged something :-( I have also not really kept that good records of when I filled up with oil before, but I have had to top up (would guess at least 1 litre) between 5000km services before.

1. What is the oil consumption I should be expecting from this vehicle?
2. How much oil can worn valve stem seals "lose"? Can it explain this consumption?
3. There's a bit of oil sweating between the gearbox (R380) and the engine - is there a drain plug that I can check what's going on there?
4. Can one change the valve stem seals on this engine with the heads still on? Or is it marginally more effort just to take the heads off, do the head gaskets and everything you can do with the heads off?
5. Lots of people on 4x4community.co.za recommend running Caltex (Chevron) Delo 400 multigrade 15/40. Comments?
6. Would it maybe be a good idea to do a leakdown / compression test to isolate the possible problem? Any other tests that I could do myself?

I have sent off some oil for oil anaylys; will hopefully have the results later this week, but don't know if that will tell me anything.

[RoverP6B]

Hello phuma,

My engine is a 4.6 with about 35,000km up. The heads have K-lined valve guides, and stem oil seals have not been fitted.

As my engine is not a regular 4.6, it runs a distributor with camshaft driven oil pump, engine oil is Penrite HPR 30...20W-60.

Oil consumption is always very stable over both city and country driving, being 400 to 500ml per 1600km.

Ae your engine breathers clear,..no blockages?

Ron.

[Pedro_The_Swift]

smoke on overrun is oil passing the rings,,
(at least you know the oil pump is ok,,,)

I ran my D1 on RX till it started using some between 5k changes, then switched to HPR30,, so from around 150K to 280K it never used any oil.

sometimes fleet oils just aint enough,,

[PhilipA]

I would guess my consumption is about 1 to 2 litres per 1000km

My 3.9 with 190KK on it uses about 500-700Ml of valvoline 15-40 in 5000Km, and I think that would be typical of an average 3.9-4.0.

To me there is something seriously wrong with your car. Maybe the oil control rings have lost tension. I would have a compression test and leak down first to see what condition the rings are in.

It looks to me like a new short engine may be required, or at the very least new rings but this usually involves a rebore and new pistons.

I would be very surprised if it was just guides as usually the V8 is pretty gentle on guides even though most of my consumption is via the guides ( and yours has teflon seals).
Regards Philip A

[phuma]

Haven't replied yet because Philip's post scared me too much!

I'll check the breathers first ;-) Any chance it's just because the previous owner did not do enough changes, and the oil is now "cleaning" it and therefore using more? Please? :-)

Pedro - I always thought smoke on (after) overrun is oil going past the valve stems?

This is a weekend, and overland, vehicle. I don't expect miracles from it, some oil consumption would be ok - so if there is some cheaper ways to make it less consumptious :-) I'm all ears.

I will check back with the oil analysis results as soon as I have it.

[phuma]

Can I have a blown head gasket with the only symptom being oil lost?

[Psimpson7]

Im not familiar with the layout of the oilways etc in the head of a V8, but one of my cars suffered a head gasket failure where it leaked oil from the oil return area of the head gasket from the head to the block, so its probably possible.

[PhilipA]

My assessment is based on the amount of oil. 2 litres per 1000Km is 200CCs per 100Km , or 20CCs per 10. It is just the sheer volume of oil used that leads me to rings as the most likely explanation.

If leaking the underside of the car would be coated in oil and drop 6 inch pools every time it stopped so surely it would be noticed.

Mine had a small leak at the pressure relief valve that caused it to use 1 litre total per 5000Km and it coated the sump and crossmember with oil .

Regards Philip A

[PLR]

Can I have a blown head gasket with the only symptom being oil lost?

G`day ,

no not really , the oil only passes through on its way to the overhead gear .
There are only 2 small holes one at either end and far from any compression so would need to be a very unusual failure .

If it a manual gearbox , when stationary and running temp , give it a rev at around 3000rpms for 5 or 8 seconds if it blows some smoke the rings are possibly at fault .
If it`s an auto it can still be done but the auto may not like it .

Give it a leak down or dry/wet compression test anyway , give an idea of what it`s like .

If the oil your using now is a first use go back to what it was using .
If the consumption reduces that`s all it is and would be the first place i`d be looking .

With any engine it seem to be there are oils they like and oils they don`t , it`s not uncommon to change brands of oil and fine an increase in consumption or more leaks or the other way .

Cheers

[phuma]

Pulled the plugs tonight (they were the complete wrong kind; Champion RN11YCC - for the 3.9). Here are some plug porn for you guys... only plug 5 looks *really* oily. I had misfiring before, and also changed the leads about two weeks ago. Could a misfire make a plug look like that? The other plugs?
(next four pictures in next post)

I fitted Champion EON 2 on instructions from my independent... he does not like the NGK BPR6ES :-/

Oh, and by the way - photographically this was a challenge :-)