mnmasotto

I have a 1987 3.2 carrera with 75K original miles. The car has been extremely well cared for and never had any engine work. The car has been driven appropriately(no short trips) it whole life. The car has always had Valvoline 20-50W, changed every 3000 miles, until 50K when the preferred oil was swiched to Mobile 1 15-50W.

Recently the car has been using about one quart of oil every 750-800 miles. The car never, every smokes, even on start up!!!!!!!!! The car has no oil leaks. My mechanic (very well respected local air cooled Porsche specialist) said the plugs always look great!!! The car runs absolutely fantastic. The car has never been abused, raced or tracked. A recent leak down test was between 2-4% on all cylinders. A second opinion said that he was not sure what the culprit was? valve seals, ring?? He recommended a valve job and new rings (assuming the P & C's measure within tolerances)

Question number 1) Do I need to do anything? I do not mind spending the money on a new engine if it is really needed, but is it needed or is this normal for a 3.2 with 75K?

Question number 2) What could happed if I just drive it until is gets worse?

Question number 3) If I refer to the factory Porsche manual this is within normal limits??? However, others with recently rebuilt engines use much less oil. Who do I trust?? A local mechanic has looked at the data and says just drive it!!!

psychoideas

I'd switch back to Valvoline 20-50W at your next oil change and see if that cures the problem.

Amber Gramps

my first thought was viscosity. the lower the number, the thinner the oil, the quicker it will sneak past the rings and burn up.

I also think more engines burn at that rate than owners want to admit.

If you want to spend money on an engine, mine is available during the week.

Steve Weiner-Rennsport Systems

Nice car,..

Thats a fair amount of oil consumption and I'd not ignore that. Piston deposits from such a thing will increase the propensity for detonation and that amount of oil makes the rings stick in their grooves.

That said, these are fantastic cars and will run for a very long time as long as everything is healthy. I'd bet that your valve guides have the normal wear issues and a good valve job will enable you to get many more years of service before a rebuild is necessary.

Drew Theodore

Not to highjack the thread, but will changing back to dino oil slow the leaks down instantly or does it take a while.

g-50cab

It will take a little while -

Mine - at 60K miles also had similiar oil consumption - Mine was a valve guide issues - the plugs looked fine - but if you revved it up to 6000 rpms and let the engine brake the car - it would smoke a little - very little with the catlytic converter - a little more without.

After a few times on the track - my oil consumption went from 800 to 400 miles to the qt - that's when I decided to jump into a top end (which turned into a total rebuild and performance).

My mechanic theorizes that on the 3.2 - low miles can be the culprit and lead to valve guide issues. You don't want the miles to get to low per quart- the last thing you want to risk is dropping a valve into the combustion chamber - then your "top end" gets lots more expensive.

Amber Gramps

when is someone just going to come out and say "some valve guides on '87's are bad" that is all I got when I was shopping. when I got mine home and started driving it arround everyone asked if it was an '87 with bad valve guides....nobody here wants to talk about it. I got an '88 and don't yet have the milage history to say exactly what mine is consuming but it is in the 1,000+ mile range. I've added 6,000 miles and 3 quarts, so I'm just getting started.

theiceman

some 993s have bad valve guides causing SAI issues, some SCs have bad valve guides.. causing high oil consumption..... you know what most caravans have bad valve guides causing James bond type smoke when you pull away .... and yes my Audi ( mosquito killer ) has bad valve guides ....

I think it is just a car thing in general , and we have so many cars that have been around so long , this type of thing can and will happen ... I don't think you can be too paranoid about it ...

The problem lies in that I think the only way to truely tell before purchase is to drive a car for 1000 miles and see how much oil it uses ,,,,, like that will happen ...

unless you have a really honest seller ....

Peter Zimmermann

Although Steve's points are valid, very much so, I used a somewhat different criteria for when it was time to do the valve job. Our benchmark was 300 miles/qt, or when the customer got sick of adding oil (usually in the 400 - 500 mile range), whichever occurred first. We never had a valve failure in a 3.2, and we always collected data by measuring disassembled engines that had "x" consumption, "y" consumption, or "z" consumption rates. It is probably valve guide wear (no accel smoke, great leakdown numbers = good pistons/rings/valves) that is causing your consumption, and like Steve said, stay on top of it - don't ignore it and hope that it goes away. Regarding when you switched oil, how long after did the consumption rate start to get worse? I think that I'll agree with your mechanic, for now, and that is to drive it. But start a consumption chart, that will force you to track it! Do not add oil until the dipstick reading is right on the minimum line. Add one quart, record your mileage, and keep track of the oil level until the level is once again at minimum. Add one quart and record your mileage. This will give you a really accurate number, and you will know immediately if consumption has a dramatic change for the worse.

theiceman

300 miles per quart Pete? that is like a quart every fill up ? holly cow .... the back of your car would be filthy ...

Amber Gramps

most things that are fun to do require a little clean up when your done.

Peter Zimmermann

OK, Douglas, keep it clean...

ice: LOL! Believe it or not, the cars with whale tails could actually drip a little from under the spoiler! Not much would show up on regular cars, but that's why most of my customers got sick of adding oil (at every fill-up) and brought the car in for repair sooner.

VNTGSPD

This is a timely discussion for me as I have a similar issue except that I do see smoke. I've had great feedback on the Pelican forum including from Steve W. himself (thanks Steve ) and I know the correct solution is a teardown and assessment of heads, cylinders, pistons & rings. However, I am trying to buy time until I can afford to do this and that means driving the car about 2K miles as is or parking it for a year.

Mine is a 2.4 with about 40K miles on the p/c and 35K on the heads with 5% of that track miles. It acts like valve guides except that I see more pronounced smoke in the 3-4K rpm range when cruising in 3rd, 4th, or 5th gear at very light throttle which may or may not be guide related - I don't know. No smoke on acceleration except for the initial puff from idle at a stoplight.

IF guides are worn, would I see any short term benefit from replacing the seals until I can afford the time and money for the proper teardown? This would be a pretty non-invasive job that I can do myself in a day or so and I already have a new set of valve guide seals in my spare parts bin. So, I'd really only be out a days worth of labor and some misc. parts.

Oh yeah, a little early to know for sure but it appears that oil consumption is 200-300 miles/qt. but I'm still tracking.

Opinions???

Cheers!

David

theiceman

Actually this I know as my 944S used to use a quart about every 500 miles .... i got it fixed because I got sick of washing it, under the little tail at the back would be filthy all the time and you would get dirty opening the hatch and if you leaned in ...
I can't imagine it was any fun for that brand new white car behind me either under hard acceleration on the high way .... fortunately the oil on my 911 tail is only what I keep putting off from leaking out ..

Peter Zimmermann

David: Unfortunately there is no absolute way to analyze your car's condition, unlike the 3.2 car that's discussed above, which is much more of a classic condition/problem. Your car, on the other hand, has engine repair history that might play a role in why it has the high consumption problem. Let's start by asking why the engine was apart for pistons/cylinders, and only 5K miles later for head work. Next, let's learn if you have MFI or carbs. If the heads were done properly (new guides, valve stems within allowable wear tolerance, etc.) they shouldn't even be close to being worn out. Same goes for the p/cyl set, provided that they were new Mahles when installed. One thing to know is when the high consumption started, and how quickly it happened. Has the car had a leakdown test recently, if yes, what were the numbers?