1998 S70 Non-Turbo Oil leak and rough idle.

Nigel347 · Post by **Nigel347** » 01 Oct 2014, 17:13

Was given this car about 6 months ago, and its never did me wrong, but has always had a small oil leak and a weird rough idle. So this past weekend i decided to put her up on stands and do a FULL tune up. After reading up on similar oil leaks i was almost positive that my pcv system was the problem. So new water pump, timing belt, pcv system, spark plugs, wires, distributor rotor and cap, fuel filter, air filter, and an oil change done. (S/O to the guys over st IPD and their End of Summer Sale) started her up and still idling a little rough and smoke coming from the back of the engine due to oil dripping onto the heatshield. About the rough idle if i Turn the wheel to the left or right the idle smooths out and it sounds fine, its only when the wheel is straitened that it idles roughly. Anybody else have or heard of this problem. I ordered the cam seals today but i doubt that's the problem due to the oil dripping from the rear of the engine and not off the side. Thanks for any info you can come up with.

Post by **Ozark Lee** » 01 Oct 2014, 19:43

If the rear cam seals are leaking then oil is likely getting into the distributor cap which can cause the car to run rough. The engine gets loaded a bit when you turn the wheel but I don't have a good explanation as to why that would cause the idle to smooth out.

...Lee

Nigel347 · Post by **Nigel347** » 01 Oct 2014, 21:08

Well when I took the old distributor out there wasn't any oil in it, but when I took the spark plug cover off there was a significant amount of oil underneath.

Nigel347 · Post by **Nigel347** » 03 Oct 2014, 12:52

My dads saying that i might need a valve job and that might be whats causing the rough idle, which doesn't make since to me because it wouldn't smooth out when i turn the wheel. Any other suggestions?!?!

Post by **Ozark Lee** » 03 Oct 2014, 13:38

When you did the full tune up what did you use for parts and did you gap the spark plugs? After my first tune up my first 850 ran like crap and the mileage dropped about 30%. I used the some seriously wrong parts including the Bosch Platinum +2 spark plugs that you can't properly gap. The gap is critical and it needs to be 0.028 - error on the tight side.

All of the oil under the spark plug cover could be from a bad gasket on the oil filler cap. That is often a clogged PCV but you indicate that you serviced yours. The gaskets are cheap and I replace mine about every third oil change as a matter of course. With my fleet I buy them by the dozen like I do new crush washers for the oil drain plug.

I still don't have an answer for you on why turning the wheel makes the car run better.

...Lee

Post by **FLXC90** » 03 Oct 2014, 14:16

FWIW- does the engine adjust for the increased load from the steering pump? Also, either dirty valves or other vacuum issues would be my guess, does it have a mild dead spot just off idle?

Nigel347 · Post by **Nigel347** » 03 Oct 2014, 16:45

Lee- I used NGK spark plugs, and i dont think the gapping is the problem, unless the original spark plugs were gapped incorrectly, ive heard about the oil filler cap also, guess thats my next thing to try. Also i noticed the oil is dripping off the top of the valve cover on the rear left side of the engine.

FLXC90- Don't really understand what your reffering to when you say "dead spot"

Post by **FLXC90** » 03 Oct 2014, 17:39

if you rev the engine from idle, does it hesitate and the accelerate? kinda like a stumble before it gets going?
Try hooking up a vacuum gauge, not just for a direct reading, but to look at how the engine behaves. It's old tech, but the basics still apply, may narrow your troubleshooting.

Before you look at a valve job, try a seafoam treatment to clean carbon deposits from the valves etc... it's only about 10 bucks!

I just replaced my rear cam seals (in the last 15 minutes) is it bad if the seal falls out when you remove the plate behind the distributor rotor

, mine did! Mine has 223k on it, I didn't see a mileage for yours.

Post by **FLXC90** » 03 Oct 2014, 17:52

Also, have you checked the air cleaner thermostat flapper assembly in the air box? Don't know if that would cause rough idle unless it was already warmed up. Also the Idle Air Control might be dying or dirty.?

Azik09 · Post by **Azik09** » 04 Oct 2014, 06:47

Rough idle is the first symptom of problems in vacuum system. Did you tried to disconnect MAF sensor? If idle will stabilize in this case, so vacuum leak is the most likely reason.
P.S. You did not specified the model of your engine. If it is B5252 or B5202, it has MAP sensor but not MAF. MAP-based systems are less sensitive to vacuum leaks than MAF-based.