72T smokes help!

I've got a 72T rebuilt as to Especs. Recently it started smoking gobs of smoke when it warms up to 180 degrees. The smoke comes out the tailpipe. After the motor cools down the smoke goes away.The motor was rebuilt less than 10k miles ago.It doesn't drip any oil.I read that the oil cooler circuit opens at 178 degrees so it seems there is a connection.But how could this cause smoke out of the tailpipe?

I have serious doubts that the smoke is directly related to thermostat operation.

Could your oil tank be overfilled? Oil expands as it heats up. Many of the newer cars with CIS experience oil getting blown into the air filter assembly when the oil tank is overfilled.

There is a breather line into your air cleaner from the oil tank, although it would have to be an extreme case for the oil to go 'uphill' to get to the injection stacks! I suggest removing the air filter housing from the engine, inspecting both the injection stacks, and the housing where the filter cartridge resides for oil blown in from the oil tank ... both areas should be dry, not oily, if there is not an overflow situation with the oil trank!

Just in case you recently added oil to the tank based on a 'low' reading on the oil level gauge, it should be noted that the only accurate measure of oil tank level is the dipstick, read when the oil is warmed up above 176 degrees F (80 C,) engine idling at 900 rpm, on level ground! And, refilling the oil tank after an oil change is a two-step process. An initial refill of 9 or 10 quarts, followed by topping-up after the engine has been warmed-up. The level in the tank should never be above the middle level between the high and low marks on the dipstick when the engine is 'warm' at the 180 degree F level, because the oil will expand even more as the temperature gets up to the 220-230 degree F (or higher) level at high speeds, or waiting in line at the bank with the Air Conditioning on!

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Warren Hall
1973 911S Targa

How does the motor go (aside from the smoke) following the rebuild to E specs Bobboloo?

What did you change and was it worth it??


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'72 911 TE

Thanks Warren, I checked the intake. No oil.To bad it would have been an easy fix. I recently did a clutch job and when I refilled it I only put in 8 qts of oil. I didn't think to recheck it after the engine warmed up. The oil level indicator showed in the middle of the gage. About 6.5 qts when cold. As the engine would warm the oil would read up to 8qts. The gage appears a little wacky. After reading your reply I went and checked the level in the tank. It didn't even register on the stick. Although I can see oil in the tank. I'm a dummy I think maybe I robbed the valve guides of oil. The motor however runs fine and doesn't make any weird noises. I'll try topping it off and see what happens.


[This message has been edited by Bobboloo (edited 08-07-2000).]

Oops, I meant the previous reply to go to Warren. Matt regarding the rebuild to E specs.I don't have the specifics because it was done before I bought the car. The previous owner told me the cams were replaced with E cams and the distrbutor was also replaced. He didn't have any paper work on the car. I don't know if the MFI pump was done. The car runs great. However this is my 1st 911. I owned a 912 before so I don't have anything to compare it to. The E cams seem to really start to pull strong in the 4500 to 5500 range. I haven't taken it above 5500 rpm's because I really haven't had a chance to drive the car yet. I'm still in the process of sorting the car out.

Bobboloo, you do know that you have to check the oil level when the engine is warm and at idle, right? I made the mistake when I first bought my car of checking the oil level when the car was off and according to the dipstick, it was 2 or 3 qts too low. I added a couple and took off for a drive. When the motor warmed up it blew white smoke out the pipe like crazy. Beginners stupidity...

Yes, those oil sender gauges seem a bit wild don't they. Best just to trust the dipstick and use the gauge for visual amusement should you be unfortunate enough to be stuck in traffic.
I'm certainly no expert on dry sumping, but I have a feeling that low oil in the tank isn't critical. Obviously the factory says that the level they set is optimum and it's inadvisable to let it dip too low.
But.....My reckoning is that the great quantity of oil is there for cooling purposes, and it also sits in that big tank to give the air bubbles a chance to come out of suspension.
If it works like a reservoir for extreme circumstances, eg high cornering forces or sustained high speed running then it probably has an element of Porsche Overkill designed into the system (a good thing..)

Surely even if there was a small ammount only of oil in that tank surplus to the requirements of the scavenging pumps and oilways etc you would still get a constant oil pressure. Not ideal by any stretch of the imagination, but perhaps ideal enough to discount starving your engine of oil as you are worried about?

Thanks for confusing me for Warren by the way, great compliment!

Feel free to tear my arguement to pieces anyone, I'm just as curious myself!


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'72 911 TE

I think it is time for me to jump in in defence of fully functioning oil level gauges - mine seems to work perfectly.

Call me a showoff for boasting about it, but when the tank is half full by dipstick, it is half full by my gauge. And the low and high indicators seem to be accurate too. Am I the only one with this unusual "feature"? (I suppose I have to have something that works perfectly on the car, there is plenty wrong with it!)

Of course, I still only use it as a guide - In reckon oil level is too important to trust a potentially faulty unit - who knows when the sender might be failing.

Cam

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Cameron Baudinet
1975 911S

I too doubt the low oil level has caused any damage.

Also, terribly rich mixtures will make engines smoke. I believe the 'rich mixture' smoke is darker than the 'oil burning' smoke.

Chokes that don't turn off are the usual culprit which, in a CIS car, is the infamous Warm Up Regulator.

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'83 SC

Hi Matt thanks for the encouragement. It still smokes when it gets up to 180 degrees. I added 3 qts of oil to bring the level in the tank to the proper level with the engine running at the above temp. It doesn't seem quite as bad. It mainly smokes at idle which makes me suspect the valve guides. Thanks again for your input. Bobby

The smoke is diffenently oil. I can tell by the smell and the bluish color. By the way the oil I put in is Valvoline 20/50w. Thanks

Bobbolo,

Hey everybody knows Valvoline oil smokes like crazy. Surprised you didn't know that!!! Just kidding. I too experienced the "Elected a new Pope" white smoke caused by checking oil while cold. Learned that from years of having water cooled cars. Boy did I feel like a true dummy when I called my guru and he asked ...."Did you check the oil with the engine running and warmed up??" Compounding my ignorance I said "Hell no...I know how to check oil...I've been doing it for a long time". Thank god he has patience with an idiot!!!

Bobby,

One more suggestion in the quest for knowledge about the source of your smoke ... pull all six sparkplugs and examine for evidence of black, oily deposits on one or more plugs.

There is a possibility that the oil is coming from valve guides, perhaps because of a 'missing' or defective valve guide seal. To determine whether it is an intake or exhaust valve, you need to know whether the plugs are fouled or not! Let us know what you find ...

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Warren Hall
1973 911S Targa

Hi Warren,I checked all the plugs.They were clean as a whistle.The electrode and tips had no sign of fouling.The only plug that showed any kind of obnomally was the #4 plug which had a very, very slight blackish fog on the ceramic part of the electrode.I might add that these plugs have only been in the car for about 100 miles. They are Autolite Platinum gapped to the spec book info. Once again thanks so much for your help. Is it time to pull off the valve covers? Bobby P.S. I noticed that the oil has actually dripped from inside the tail pipe. I don't know if that has to do with the high volume of the burning oil or if it could suggest something else. Thanks

[This message has been edited by Bobboloo (edited 08-08-2000).]

Wow, it sure sounds like the oils is not burning in the combustion chamber, but rather is ignited by the hot exhaust pieces. I am not familiar with how this might happen, but is there any way for oil to get into your exhaust system without going through the combustion chamber?

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'83 SC

Bobby,

I would suggest pulling off the muffler to see if there is evidence of oil on the inside of both heat exchanger (header) outlets, or just one. That #4 cylinder may be a little suspect, but not clearly a problem, yet.

It seems to me that the oil is getting into the exhaust downstream of the combustion chamber, since the plugs are clean. That pretty much leaves the exhaust valve guide seal(s) as the culprit ... whether there is more than one cylinder involved or not, is yet to be determined.

How long, mileage-wise, was it after the rebuild, did the smoking begin? Does the engine blow a large cloud of smoke upon startup every time, or a majority of the time when started from sitting overnight?

Did you have the rebuild done, or was it a previous owner? If you know who did the work, there may be a good reason to contact them, soon. If my suspicions are confirmed, you may be the victim of a missing valve guide seal that they left off, or installed incorrectly.


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Warren Hall
1973 911S Targa

Problem solved. I switched mufflers. I had recently installed a stock muffler that I bought used off of Ebay. It came all the way from Conn. to Cali. with oil in it. It however didn't smell or show any signs of this when I unpacked it. A good deal that turned out to be not so good of deal. When I got my car it had a sport muffler which is a little loud for my tastes. So I bought this muffler that only had "minor surface rust","many more good miles in it". When I got it the left side input pipe was crimped partially shut. It also had the wield broken around that pipe. My choices were ship it back, inccuring shipping costs totalling more than what I paid, when added with the costs of getting it. Or repair it. Which I opted to do. Evidently the previous car this muffler was on dumped oil into it. Or he accidently spilled oil into it. I don't fault him for the oil incedent. he probably didn' know this would happen. I do fault him for the misrepresentation of the condition of the muffler. All said and done, I should of bought a new one from Pelican Parts. They are 5 min. from where I live. I "saved", and I use that word loosely, about $80 over the cost of a new Dansk repro and am the proud owner of smokin,butt ugly wielded muffler. Thanks again for your input on this one. Especially Warren for his methodical troubleshooting.Thanks Bobby

Bobby,

You are quite welcome! Glad the mystery was solved without bringing up 'issues' with the rebuild!

One thing I recommend for both computers and cars you are going to be keeping a long time and making changes to is to keep a logbook ... and everything maintenance related goes into the logbook: everything changed, added on, removed, etc. goes into the records! Any changes in performance, problems, etc. get noted, too! It makes backtracking when troubleshooting a lot simpler! Aircraft and most race cars usually have one, too, and it gets passed on to subsequent owners or operators.

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Warren Hall
1973 911S Targa