Intermittent smoking - Carrera motor

[Dan J.]

Hi,

I'm interested in some input on this issue, and I've done some searching on this board already. My car's symptoms seem to be a little different from what I've read so far, so maybe someone has dealt with the same problem.

Condition: '86 Carrera with 180k miles. I am missing the records from previous owner between 55k through 130k miles, so it is unknown whether it has had a top end rebuild during that time.

It uses around 1 Qt of Kendall 20/50 per 1,000 miles. I'm not sure how much of that oil the car is burning as there's a small leak from the engine oil cooler (I'll be fixing this during the next tune-up) and it had a small leak from one of the cam covers (I put on new cam cover seals a couple weeks ago, which stopped that leak). The current oil cooler leak is pretty minor, a drop on the garage floor every couple days, and the bottom of the motor has a little oil gunk at the cooler and bottom oil hose connection. The top of the motor (oil therm, breather) is dry.

My shop always does a compression test as part of their tune-up service and the results are always very consistent. The last was performed at 169k miles and resulted in 170lbs in all 6 cyl. From what I know, the motor is all stock except a SW chip and GHL exhaust and seems to run very strong. I run both a cat and cat bypass (for DE use) and that doesn't really influence the amount or density of the smoke.

The car never smokes on startup when cold. Beginning last summer, the car would occaisionally (1 instance every 1k miles or so) emit oil smoke when warmed up. This was noticable when sitting still, although it's likely to have smoked when moving as well, just not easily noticed from the driver's seat. This smoking happened in isolated circumstances, independent of oil level and only when the engine oil temp was above the bottom white level on the gauge in around town stop/go driving.

A year later, the car now smokes more often, although not consistently under the equal conditions (temp, oil level, type of driving).

This leads me to think that it's an oil leak somewhere that might be getting into or on the heat exchangers, or somehow the car is ingesting oil from the tank. Would worn valve guides or piston ring issues result in inconsistent smoke?

The only consistent factors I have been able to measure is that it only happens when the car is somewhat warmed up, and I only notice it when at idle. I drive the car every day to work 14 miles each way, almost all highway. The car almost never smokes at idle after driving that 14 miles to/from work.

I just pulled all the plugs to look for clues, and they are all dry and a consistent gray/tan color with no obvious signs of oil burning.

I'm about to do the next 15k service (cap, rotor, plugs, fuel filter, valve adj.) a along with an oil change (I change at 3k miles), new plug wires and I'll also pull the oil cooler and replace those 3 seals. I'll also do another compression check.

What else should I be looking for? Many thanks in advance for input.

Dan J.

[Dan J.]

Another question on this, thanks in advance for any input.

While I have the valve covers off this weekend for the valve adjustment, I'll want to check for broken studs. Is it a matter of putting a torque wrench on each head stud to see if it rotates?

If so, what torque setting should I use?

Many thanks,
Dan J.

[johnnyo]

OK you have an 86 carerra, 1 qt every 1,000 miles is acceptable, as far as the intrmittant smoking at idle two pooibilities, upon hard cornering the oil may work its way through the breather hose into the airbox also as you probably already know if oil level is above halfway mark when fully warm can also work its way into the airbox, check the airbox for any clues as to oil. as far as headstuds you will more than likely not have any pulled studs (aluminum case) as were the issue with mag cases, but you very well may discover when pulling the bottom valve covers that bolts will just fall out (broken studs) especially because Dilivar was used in the exhaust heads and over time are suseptable to the elements, you may be lucky enough if the PO did a rebuild and knew of the headstud issues replaced the lowers with steel studs as are on the top, I have ever heard of the steel studs breaking, others may chime in their experience with steel, by the way get waynes rebuild book, very interesting and informative reading, good luck and let us know what you find as far as lower studs,

By the way Dilivar studs are notmagnetic incaseyou wanted to determine what you have, Johnny O

[Dan J.]

Thanks for the reply.

I'll post the results after getting in there. I'll pull the air box and look. It will likely have to go in order to access the top oil cooler nuts anyway. Last time I had the airbox open, it did have some grime, especially in the 90deg rubber boot that leads down into the plenum.

I have the 101 projects and Engine rebuild books, the pages are already somewhat dog ear'd.

Thanks again,
Dan.

[mca]

I will bet you anything that there is oil dripping on your exhaust. I have that problem b/c oil is leaking through my valve cover bolts onto the exhaust below.

Sometimes when stopped at idle, my car will show no signs of smoke. Then, when the oil hits the exhaust ... kaboom ... crazy smoke that looks like my car is on fire.

Keep us all posted.