P38A Valve stem oil seals.

swac · Aug 25, 2020

Advice please. I had the heads done on my Thor engined P38 last year and she hasn't used any water since but the oil consumption is rather high.
Despite the oil consumption problem I'm still using it as a daily driver. Anyway last weekend we had a 100 mile round trip up and down the motorway to see my mother, the average speed was rather high. When we got back late Sunday afternoon I noticed small oil deposits over the tailgate and rear bumper, these deposits were not black sooty specks but rather like a light misting of clean oil.
I have thought long and hard about this and think that it coming out of the exhaust due to one or more failed or failing exhaust valve stem oil seals, I thinking specifically exhaust valve stem oil seals because the engine doesn't smoke at all and the plugs are clean.
My question is how easy is it to change the valve stem oil seals without having to take the heads off?

Thanks in anticpation.

myfirstl322 · Aug 25, 2020

https://www.v8forum.co.uk/forum/viewtopic.php?t=3703

brianp38dse · Aug 25, 2020

Have you looked at the underside of the car for oil as surely the cats would burn off the oil and it would also upset the O2 sensors, if it'd clean oil I don't think it's going through the exhaust.

Mark Piercy · Aug 25, 2020

If the plugs are clean and you've got misting at the rear I would also check underneath. Maybe a sump seal or crank seal gone? Check the crank case breathers as well. They could be blocked and pushing oil out somewhere?

swac · Aug 25, 2020

brianp38dse said:
Have you looked at the underside of the car for oil as surely the cats would burn off the oil and it would also upset the O2 sensors, if it'd clean oil I don't think it's going through the exhaust.

The underside of the car is clean Brian. I had not noticed the oil there before but I can't think where else that it could have come from. Through the week doing about ten miles each way to and from work I hardly notice it using any but at sustained high speeds she does seem to drink a bit.

Henry_b · Aug 25, 2020

If you do indeed change the stem seals, a good way to keep the valve in the cylinder is to attach a compressor to the adaptor you use for a compression tester

I'd do a compression test though, if that mush oil is making it into the cylinders.

I't would cloud out the back end like a MOFO too.

swac · Aug 25, 2020

Mark Piercy said:
If the plugs are clean and you've got misting at the rear I would also check underneath. Maybe a sump seal or crank seal gone? Check the crank case breathers as well. They could be blocked and pushing oil out somewhere?

Hi Mark, I've only recently fitted a new oil separator insert in the short stubby pipe on the drivers side rocker cover, as the local independents who did the heads and head gaskets for me hadn't fitted one. I thought that fitting the separator insert might reduce the consumption and it probably has a bit but it still drinks it if you start driving enthusiastically.

Ratae · Aug 25, 2020

Having used it on several cars (not a P38 though) over the years I can confirm that the rope down the plughole trick works.

Mark Piercy · Aug 25, 2020

What mileage have you on your bus?
You. Can use string in the bore and wind the piston up to help compress the valves into place.
That would be my last resort. What oil also are you using!?

Mark Piercy · Aug 25, 2020

Ratae said:
Having used it on several cars (not a P38 though) over the years I can confirm that the rope down the plughole trick works.

Pipped me to the post

swac · Aug 25, 2020

Henry_b said:
If you do indeed change the stem seals, a good way to keep the valve in the cylinder is to attach a compressor to the adaptor you use for a compression tester

I'd do a compression test though, if that mush oil is making it into the cylinders.

I't would cloud out the back end like a MOFO too.

Henry, the plugs are clean and it doesn't smoke so I don't think that the oil is getting into the cylinder, I think that it's running down the stem of the exhaust vave and just being pulled out with the exhaust gases?

Mark Piercy · Aug 25, 2020

swac said:
Henry, the plugs are clean and it doesn't smoke so I don't think that the oil is getting into the cylinder, I think that it's running down the stem of the exhaust vave and just being pulled out with the exhaust gases?

It would still burn in the cylinder or in the manifold.

Mark Piercy · Aug 25, 2020

Is the engine exterior clean as well?

Henry_b · Aug 25, 2020

swac said:
Henry, the plugs are clean and it doesn't smoke so I don't think that the oil is getting into the cylinder, I think that it's running down the stem of the exhaust vave and just being pulled out with the exhaust gases?

If it doesn't smoke then it isn't burning it..

An exhaust does get extremely hot, far too hot not to show off a bad oil consumption issue

It would also still be burnt off if that was the case..

If it isn't burning it or leaking it, where is it going?

What grade oil you running?

pwood999 · Aug 25, 2020

Bought this kit many years ago for changing valve-stem oil seals with heads in place. Actually only ever used it on 4 cylinder Fords, but should work equally well on RV8.

https://www.ebay.co.uk/i/1834935789...MIoeCk1o626wIViKztCh0OMgR-EAQYBiABEgLTrvD_BwE

swac · Aug 25, 2020

Mark Piercy said:
What mileage have you on your bus?
You. Can use string in the bore and wind the piston up to help compress the valves into place.
That would be my last resort. What oil also are you using!?

Almost 140K now. I was using 10W/40 semi synthetic but following the advice of the good people on this forum I've been topping up with 20W/50 mineral oil, to be honest though I've only put about 1.5 litres of the heavy stuff in to date.

Henry_b · Aug 25, 2020

swac said:
Almost 140K now. I was using 10W/40 semi synthetic but following the advice of the good people on this forum I've been topping up with 20W/50 mineral oil, to be honest though I've only put about 1.5 litres of the heavy stuff in to date.

20w50 is what it should be running, that or 10w60

swac · Aug 25, 2020

Henry_b said:
If it doesn't smoke then it isn't burning it..

An exhaust does get extremely hot, far too hot not to show off a bad oil consumption issue

It would also still be burnt off if that was the case..

If it isn't burning it or leaking it, where is it going?

What grade oil you running?

I was running 10W/40 which I now realise was totally wrong. Following the advice of the good people on this forum, for the last 3 weeks I have been topping up with a 20W/50, but to date I've only put about 1.5 litres in it. I did think that the consumption had reduced markedly but after the high speed run at the weekend I'm not so sure.

Mark Piercy · Aug 25, 2020

swac said:
Almost 140K now. I was using 10W/40 semi synthetic but following the advice of the good people on this forum I've been topping up with 20W/50 mineral oil, to be honest though I've only put about 1.5 litres of the heavy stuff in to date.

How long is to date @swac

Henry_b · Aug 25, 2020

swac said:
I was running 10W/40 which I now realise was totally wrong. Following the advice of the good people on this forum, for the last 3 weeks I have been topping up with a 20W/50, but to date I've only put about 1.5 litres in it. I did think that the consumption had reduced markedly but after the high speed run at the weekend I'm not so sure.

Change the oil in it with a good 20w50 VR1 Valvoline and give her a good run..

P38A Valve stem oil seals.

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