Burning oil. Rebuild time close?

[RPV911]

1989 3.2

So I’ve heard around 800 miles between quarts is normal. I’m averaging 500-600. Should I be prepared for a top end in the near future? Puffs of whitish smoke on startup but only if I haven’t driven it in a week. I try to drive it 3 days a week. Each drive is to work which is 80 miles round trip.

Thanks for any feedback.

[Reiver]

How many miles on it...… I don't think 800 miles between quarts is normal actually regardless of the manual unless you are racing full time.
Cruising should be your least demanding oil usage.
A puff on start up can be normal...gravity taking oil past open valves when stopped. 5-600 is high consumption and a pita.
I'd say yes....I do not add any oil between 3k oil changes generally but had a top end 42k ago on an '83. I use about 8-10 ounces in 3 k.
BTW, I have no engine leaks....that can contribute too you know.

[gregwils]

500-600 miles per quart is in spec....barely. I don't know if there is a 'normal' since there are people that get 500 miles per quart and others that get 2,000. It's really a function of consumption and you consumption is pretty high. It's quite possible your issue is only valve guides and seals, but while you are in there....https://www.google.com/imgres?imgurl=https%3A%2F%2Fbanner2.kisspng.com%2F 20180716%2Fpao%2Fkisspng-emoticon-smiley-emoji-heart-wink-emojis-tristes-5b4c7152241a77.7391262815317364021479.jpg&imgrefurl=https%3A%2F%2Fwww.kisspng.com%2Fpng-emoticon-smiley-emoji-heart-wink-emojis-tristes-5502905%2F&docid=i0MDbZICmUSCaM&tbnid=8CwThnYoZnPy8M%3A&vet=1&w=900&h=800&bih=593&biw=1185&ved=2ahUKEwijyez3y_njAhWkmuAKHaJpAL0QxiAoBXoECAEQI Q&iact=c&ictx=1

[RPV911]

127k and no leaks.

[bpu699]

Oil is cheap. Rebuilds are expensive. Keep driving it. A quart every 500 miles is nothing... when you are putting in a quart every fill up...wellllll, that’s different

[RPV911]

Originally Posted by bpu699

Oil is cheap. Rebuilds are expensive. Keep driving it. A quart every 500 miles is nothing... when you are putting in a quart every fill up...wellllll, that’s different

Ok thanks. Good point!

[darrin]

Originally Posted by bpu699

Oil is cheap. Rebuilds are expensive. Keep driving it. A quart every 500 miles is nothing... when you are putting in a quart every fill up...wellllll, that’s different

disagree here -- if your valve guides are shot and allowing that much oil to flow through, they're also no longer transforming heat off of the valves as effectively. An overheated valve that breaks off while driving is going to make your engine rebuild a LOT more expensive.

At 127k miles and 500 miles per quart of oil, it's likely time to dig in.

[RPV911]

Originally Posted by darrin

disagree here -- if your valve guides are shot and allowing that much oil to flow through, they're also no longer transforming heat off of the valves as effectively. An overheated valve that breaks off while driving is going to make your engine rebuild a LOT more expensive.

At 127k miles and 500 miles per quart of oil, it's likely time to dig in.

Also a note, everything runs pretty cool. I mean it barely gets past the second hash mark on the oil temp. Does that matter at all?

[evilfij]

Oil is cheap.

This is one of my favorite notes I have read about oil consumption (not a Porsche, but a radial aircraft engine).

On the Wright 3350 [Connie fame] normal oil consumption could be 1 US gal per hour with a max allowable of 5 US gals an hour so the external oil tank had to be large and on the 749 was 55 US gals for each engine.

[Reiver]

127 k is not really high miles....I was getting 5-600 mpq at 230k on a 3.0.

I know the early 3.2's had issues with valve guides wearing out prematurely... but I suspect that may have been addressed by '89 but am not sure.

How do your plugs look?

BTW, it is hard to get a 3.2 to overheat with the oil cooler set up you have....they are excellent.

[GaryR]

Originally Posted by RPV911

1989 3.2

So I’ve heard around 800 miles between quarts is normal. I’m averaging 500-600. Should I be prepared for a top end in the near future? Puffs of whitish smoke on startup but only if I haven’t driven it in a week. I try to drive it 3 days a week. Each drive is to work which is 80 miles round trip.

Thanks for any feedback.

I had an 89 that, if it sat for more than an hour, could be used to cover a city to prevent accurate bombing.. Now THAT was time for a top end rebuild. Little puff at startup after sitting a week? Pfffft!

[MrBonus]

I know it’s a long shot but make sure you don’t have any hidden oil leaks that aren’t making their way to the pavement.

[darrin]

Originally Posted by RPV911

Also a note, everything runs pretty cool. I mean it barely gets past the second hash mark on the oil temp. Does that matter at all?

Don't believe so -- the heat issue I referenced ONLY affects the valve itself (the increased separation between the worn valve guide and the valve itself reduces heat transfer from the valve - which is exposed to exploding fuel in the cylinder - and lets the valve get hotter than it otherwise should)

Things you should be looking for are:
a) fouled plug(s) (pull all you spark plugs and post a picture of them -- note which cylinders each plug comes from using the firing order diagram sticker isn your trunk)

b) oil smoke in exhaust during deceleration -- worn valve guides will allow oil to be sucked between the valve and the guide by the vacuum produced during deceleration. Unfortunately, a well functioning catalytic converter will burn most of this oil smoke away, making this hard to detect

c) valve noise after adjustment -- while 911 valves can get noisy, they should be pretty quiet after being adjusted to spec - when properly adjusted valves are noisy, its a good sign that the valve guides are worn. Per Porsche guru Bruce Anderson, "If the valves are noisy you should have your mechanic check the valves for valve guide wear. You can check the valve guide wear by pushing the valves from side to side with a screw driver with the valve just lifted off of the seat a few millimeters (about 10 mm). You can actually judge how worn the guides are with this method."

Smoke at startup is generally NOT a sign of worn valve guides, instead, it's generally caused by the oil remaining in our cars' dry sump setup leaking past piston rings and into the combustion chamber -- I've found that if, before I shut it off, I let my 86 targa's engine idle until the oil level gauge on the dash rises to register oil level (around 5-10 seconds), I'm giving the oil pump a chance to evacuate the oil from the sump into the oil tank and eliminate/minimize smoke at startup.

Finally, this problem is unique to 3.2 Carrera engines, which throughout their production, used different valve guide material (and different valve guide seals) than other 911 engines. There are a number of theories as to why only some engines are affected, but the only way to resolve a known worn valve guide issue is through a top end rebuild. Did mine at 500 miles per quart with a greasy looking plug when I had 90k on engine. At 180k, I'm still getting around 2k miles per quart.

[Coastr]

I’ve found oil consumption can change depending on how far you fill it. Keeping it at half full on the stick with lots of small topups seems to make the oil go further than dumping in a full quart if it reaches the min mark.

If you’re using 1q/500miles you can get another 5000 miles for $100 or less. Sometimes the temptation to make things perfect gets in the way of just enjoying things as they are. Sure, don’t enter into a 24hr endurance race but it’s probably fine until compression drops badly and it won’t start easy, or starts fouling plugs with oil.

Don’t discount running drips either - you can lose a surprising amount of oil while driving without knowing it. Not all leaks are passive, leaks while sitting- some require oil pressure to show, and you don’t see those as much because they only drip a bit when the engine is stopped and the pressure goes away.

[Catorce]

Let me add some food for thought here. During the time I have been making the reproduction 3.6 engine cases, I got a chance to measure a lot of Porsche cases and we try to measure at least one per month to get a general picture of where the cases are dimensionally. This helps us confirm the accuracy on our cases.

Generally, what I have found is that stock Porsche cases with any kind of mileage at all are usually well out of spec and their tolerances are all over the place. Many engine builders will disagree with this last statement, but many of them are NOT measuring cases with the kind of equipment we have (i.e. 1 micron electronic Renishaw probe on a $275K machine).

This month we measured a 1996 993 case with 65,000 confirmed miles. The case looked almost new, and was one of the nicest I had seen both in and out. I was shocked to find out that after a day of measuring, the main bore was oval and out as high as 2 thou over in many spots.

Remember, the bore spec is 65.000-65.019mm so not a lot of play. On average, this bore was 65.05 and up, and oval in shape.

Also, layshaft center to center of crank bore was also off.

I mention all this because if a low mile late production case is out of spec, then most likely older ones are out of spec as well and many people don't know it.

Out of spec measurements contribute to bearing wear and oil consumption and a host of other problems, and I guarantee you that if your motor is approaching 100K it will be out of spec in at least several places.

The fix for the 993 case we measured is simple - flatten both case halves, rebore the main bore.

Still, it shouldn't be that way and Porsche has, generally speaking, really awful production tolerances on their street cars.

[Superman]

I totally yield to the many who understand these matters far better than I. Respectfully, 911 engines have seven main bearings, according to my recollection. This suggests to me that crankshafts are likely not wobbling much and even if they did, I question how much this would contribute to oil consumption. If oil is burning, then it is entering the combustion chamber. It is getting past the rings or valve guides or both. In the hands of a skilled technician, compression testers and leakdown testers (and the technician's ear) can provide more information about the condition of those rings and guides. In the meantime, like one or more others, I suspect there may be an oil leak. What does the bottom of the engine mounted oil cooler look like?

[Hnichols]

I found that I burn noticeably less oil if I fill closer to the low mark on the dipstick as opposed to the high mark. May or not be relevant info for the 500-600 mi per qt. figure.

If it were me I'd drive it until I need to replace the clutch (or something else that requires an engine drop), at which point I'd plan on a top end. Assuming it doesn't get worse in the meantime.

[996AE]

My 3.2 1988 burned a quart or so every 400-500 with a few oil weeps here and there. At 155k mi ran great but in the end CA SMOG got me. Oil blowing past the rings and guides were failing, finally got bad enough I failed.

25K for engine and a few other mods my White Marina Blue Carrera is back in business.

Could have just done top end but what the heck. Refreshed suspension, interior along with the bottom up engine refresh.

Super happy with the build.

My 3.2 is my driver and its a kick.

[manbridge 74]

Eventually bad guides will show up during leak down test as valve starts to walk over at the seal. Last 3.6 I did had a full half circle where there was no contact at all and valve had a crack about 1/16 inch long. Cylinder number three, it had about 60% leakage. It’s never a bad idea to do leak down and compression tests when wondering about engine condition.

[Reiver]

Originally Posted by manbridge 74

Eventually bad guides will show up during leak down test as valve starts to walk over at the seal. Last 3.6 I did had a full half circle where there was no contact at all and valve had a crack about 1/16 inch long. Cylinder number three, it had about 60% leakage. It’s never a bad idea to do leak down and compression tests when wondering about engine condition.

What he said.....get a good leak down and that will help with your decision on whether to address the oil burning or not.

With what you have indicated and the miles ...coupled with good plug readings and a compression leak down set.....if all looked good I'd drive it until it became a nuisance or had other issues (worse consumption/failed smog).