M Fig

My 86 carrera, that I just bought, seems to smoke a little when sitting at idle (stop lights etc.). It is usually after the engine is warm. Nothing major, but I can see a puff in my rear view mirror. Before I purchased the car, I had a PPI that came back very positive. Engine was said to be "very strong" and "Dry". It does not leak any oil. They did not do a compression check. The mechanic said he really didn't think it needed one. Is this something I should be concerned with?

TIA

rfuerst

I think your mechanic is a idiot!!How can he take your money and honestly give you feedback on the car without doing a compression check?It would appear to me that you have a possible problem with valve guides.Good luck and find another mechanic!

Weaver

Always, always get a compression test done, no matter what the previous owner and his (or your) mechanic says.

TheOtherEric

Is a compression test really needed if the car only has like 50,000 miles?

If the answer is YES, well then....oops.

Weaver

Eric, that brings up a good point. Where do you draw the line on comp. tests? If I was looking at a clean 68k miles 3.2ltr I probable wouldn't, but if it was a 71K mile engine, I would. What's 3000 miles? Strange ,huh?

I guess I assumed Fig's 86 probable had some miles on it when he had his ppi. My mistake.

RANDY P

I've heard of pro mechanics who cite whether or not the engine is OK simply by checking the mileage and drivng it - and state their findings that way. IMHO Compression test should always be done, if you're like me you won't sleep without it (nonetheless I wouldn't buy w/o it). But beware, compression and leakdown tests will not tell you about valve guide condition. Go back and state your findings to your wrench (another reason to have the PPI AND service done at the same place) and see what they tell you.

Check to see the color of the smoke next time, light and hazy or is it dark? Maybe someone got oil in the muffler? Anything's possible.

Also, what this really is all about is oil consumption - regardless of any promises the wrench may make this will be the tell - all. Keep really, really good notes. Average it out over 3,000 miles - the bare minimum regardless of mileage should come be at least 600 mi / qt. With reasonably low mileage on car even over 900 - 1000 / qt. should be expected. If you're under that (600) then you'll know it's internal wear.

Good luck

rjp

86Coupe

I also have an 86 Carrera. Before I bought it PO had recently done compression check and it was even in all cylinders. 102K miles. Mechanic who did PPI said the only check it needed was to let up on the gas at about 4,000 rpm in second gear and look for blue smoke. If there is any it means value guide wear.

It passed and I bought it. No regrets, very low oil consumption, leak down was recently 1 - 2%. But it will once in a while puff blue right after start up. I heard this is not an internal wear issue but due to the design of the "flat" engine.

Maybe your puffing was a few minutes after start up?

Try the 4,000 rpm check and see what you find. The 86s weren't notably bad for valve guide wear so I'd be surprised if it need repair if your mileage is below mine.

Pete
86 Carrera Coupe

rich 36

smoke on start up is not uncommon, as i posted in another thread last week, my mate c2 89 smokes a fair bit, and wont idle if he takes off the oil filler cap, just stops, we think this is related.
Mine only puffs out occasionally on start up, or if i park uphill, do'nt know why, uses hardly any oil. and no leaks 82SC.
Richard

JDaniel

Smoking at idle is not "normal". Even though startup smoke is common for 911s, that doesn't make it a good thing.
Your problem sounds like the infamous Premature Valve Guide Wear. This usually appears around 40k-60k miles. So if anyone is looking at a 3.2 with lower miles don't skip the compression/leakdown just becuase they figure low miles= no problems. In addition.. compression/leakdown may not uncover valve guide wear.

Steve Weiner-Rennsport Systems

Hi Gents:

I'd just like to ring in here for a moment on this subject.

First, any PPI must include a compression & leakdown test for the inspection to be of any value. This is not a catch-all for everything, but its a general indicator of engine health and can pinpoint some issues depending upon the test results.

Second, some models were known for premature valve guide wear (including the 3.2 litre engine) and there is a separate, specific test for valve guide wear. The compression/leakdown tests will NOT tell you anything about guide wear.

Although I cannot speak for other shops who do these kinds of things, I'll do a compression and leakdown test as part of ALL PPI's, as well as remove the valve covers to check the guides on everything.

Worn guides can generate excessive valve noise that cannot be "adjusted" away and will contribute to higher-than-normal oil consumption.

Almost all 911's will emit a small puff of smoke on cold startup, especially when left sitting for a while but like everything; its a question of degree.

RichardL

What is the real significance of some Valve Guide Wear? Is it just that the motor will consume more oil than usual? Will it lead to emmission test problems or a significant loss of power?
My gut feeling is that I would "live with it" unless it was really important to sort it out!

RANDY P

If your guides start to fail, excessive oil gets past them and into the combustion chamber, smoke, excessive usage and eventually it'll get to the point when your plugs start to foul. In reallly advanced cases, the valve can't transfer heat to the cylinder head to cool off, and the valve head breaks off. If that happens you're dead in your tracks and pretty much guaranteed a major rebuild with a new head and piston / cylinder.

It's not pretty.

rjp