924Board.org

[gml]

TL;DR:
- exhaust smoke from my 924 NA, not clear why
- Is it valve stem seals?
- Should I do a head rebuild, should I try additives?

I changed my oil, and the first drive afterwards, I suddenly noticed my 924 NA puffing smoke out of the exhaust. It was whitish-greyish-blueish and smelled kind of like burning rubber. So I'm thinking I have an oil burning issue. The oil level is now halfway in between the dipstick lines even though I just filled it to the max.

Drove it about 5 times since the first time, every time it starts smoking just as I pull into the driveway. I drive it gently around the neighbourhood and its fine, but as soon as I pull back into the driveway it starts smoking. Its a pretty steep incline so I thought it could be somehow related?

But today it didn't smoke at all, even after I parked on the incline...

Just after this all started, someone local with some 924 experience advised me that its likely valve stem seals. To test this I tried downshifting and revving (increase manifold vacuum advice from here). Today it didn't cause any smoking; the other day it did, but I parked in the driveway immediately afterwards so I can't disentangle those two causes...

So it's not clear whether its valve stem seals. Any other causes I can test?

I did a compression test in May and the numbers were good: 152, 160, 146, 161 psi. At the time it was not road worthy and had not driven for a few years — since then I've put about 300km on the engine.

I am thinking this winter I'll do a head rebuild with head gasket, valve stem seals, etc etc. Any advice on parts I should order, tools, things to not forget about doing while the head is off?

In the meantime are there any recommended additives that can let me safely enjoy driving until winter comes around? Should I avoid additives entirely (as the manual suggests), or should I use them and then definitely do the head rebuild?
_________________
George

1982 924 NA 5-speed

[Cedric]

Until winter Enjoy it and fill it up with oil if it isn't too bad, oil is cheap . Could possibly be valve stem seats, in my turbo they were very brittle and one had started to fall into pieces though you might possibly need guides aswell, and remachining of the seats. If you have a shop nearby they can measure if the valves are sealing properly or not.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/

[kondzi]

The other option is... Remains of unburnt oil / fuel in exhaust that burns in the exhausts when it gets hot. Got such issue with two cars that sat way to long before I bought them and started resurrecting. In the end it was few times getting the exhaust warmed up a lot and then if disappeared. Just an idea.
_________________
---
Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)

[gml]

Possible, but there was no burning for about 300 km of driving and then when it happened it was quite intense smoking (shut the engine off immediately).

Is there a crankcase vent or an oil separator on my 82 NA that may be the cause? Seeing stuff about the turbo but not clear about the NA.
_________________
George

1982 924 NA 5-speed

[gml]

Had a nice drive today with no smoke, until I reached a red light on an incline where the front of the car was pointed down about 5-10 degrees. I didn’t turn the engine off and drove straight through the intersection. It stopped smoking once I went forward (and on level ground)

Similar downward incline to my driveway, which is where I also noticed the smoking. So the only times I have seen the engine smoking are when the front of the car is on a 5-10 degree downward incline.

Is there any explanation for this?
_________________
George

1982 924 NA 5-speed

[Mike9311]

Maybe the front valve guide seals are the ones that are bad. Your car is angled down and all your oil must pool and drain in that direction?

Once accelerating the oil moves to the back. Level ground gives more options for head oil drainage.

At least those seals are easiest to change on the car if you want to experiment

I had a thread a while back were I asked what mysterious pieces were found in my oil pick up. Everyone here pointed to valve guide seals and that's exactly what the they were.
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car

[safe]

Probably valve stem seals.

Is it a big problem for you? Its not like the engine will implode because it burns some oil...
If you start adding oil and checking fuel at the station instead of the reverse its another thing.
_________________
/Magnus, Stockholm Sweden
=======================
Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe

[Cedric]

The valve stem seals in my turbo were really hard and brittle, so much that i found half of one seal in the bottom on the oil pan, it had just snapped of. But a track driven turbo car ages them more quickly of course. In theory they are interchangable with the head still in the car, assuming everything comes apart easily, which is not always the case.
_________________
1980 924 Turbo
www.instagram.com/garagecedric/

[Mike9311]

This was the thread where I was asking advice myself. Valve guide seal bits in oil pick up in pan

https://www.924board.org/viewtopic.php?t=44588&highlight=oil+pick
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car

[924RACR]

Yeah, I've found seal bits in the oil pan too, most recently in the motor I took apart to build my latest Prod motor. Nasty, crunchy things!

PS: and that wasn't even a Turbo!
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[gml]

Thanks all. I will aim to replace the valve stem seals and head gasket for good measure over the winter. The smoking problem is less scary now I know it stops pretty quickly, but it’s still embarrassing and I check the oil before I start the car.
_________________
George

1982 924 NA 5-speed