2.0 oil leaking out of breather

teachkenpo · 02-20-2010, 04:12 PM

Hi, I have a 66 911 with a 2.0. It has been sitting for the winter and decided to start it up today. Drove it half a mile and pulled it back into the garage. I noticed a 2 cup size puddle of oil and found that the car was blowing a good deal of oil out the oil breather. What could be the cause? Thanks in advance.
John

304065 · 02-20-2010, 04:22 PM

The factory oil breather vented from the case to the oil tank, where the vapor condensed on the tank walls, and then the hot air vented to the base of the aircleaner. That is an aftermarket setup you have there, so I don't know whether what you are seeing is normal or not.

I had the same issues with my '66 2,0 in the winter, and it turned out to be excessive blowby caused by 45% leakdown in a few of the jugs. Tore it down and found FIVE broken compression rings. Ultimately, excessive crankcase pressure is the cause of blowby. What are your compression and leakdown results?

Kudos for starting in the winter.

EarlyPorsche · 02-20-2010, 04:40 PM

You just need a catch-can breather. Look it up online.

teachkenpo · 02-20-2010, 04:43 PM

Hi John. Thank you for your reply. I will do a compression test tomorrow, but I don't have a leakdown tester yet. Lets see how the compression looks first.
I just started tearing down a 2.2 so I would prefer not to have to deal with this at the same time, but better now than in the summer.
On a positive note, I thought my tranny was bad, but after replacing all the shifter and linkage bushings today it really shifted nicely. That is of course until I saw the smoke from the oil cooking on my exhaust.

John

kidrock · 02-20-2010, 05:46 PM

+1, excessive blowby is usually due to bad rings...a compression test is in order to confirm. BTDT

teachkenpo · 02-21-2010, 10:15 AM

Here are my compression numbers.
130
121
118
110
111
120
Would these explain the oil blow-by? I was expecting the compression to be lower.
Thoughts?
John

teachkenpo · 02-21-2010, 05:13 PM

I forgot to mention that the car did not leak oil while I warmed it up at idle before driving it the first time, or when warming it up before the compression test. It only leaked when it was driven. Considering the above compression numbers, does it still look like a ring issue?
Thanks,
John

kidrock · 02-22-2010, 11:37 AM

John,

I'm responding only to give you a bump on this. I'm not an expert, but I had similar problems with other vehicles in the past. I had an American V8 with the exact same problem you described, and the local wrench described it as bad/broken piston ring. Similar problem with a Harley-Davidson aircooled V-twin...oil blowing by through the crankcase vent. I tore it apart and found the rings were good, but the cylinder went "out-of-round". I doubt this is the case with your vehicle. However, in both cases, I wound up tearing the motors apart, boring cylinders, installing rings, re-working heads etc.

From what I see, your numbers look pretty low, particularly in #4 & #5...but again, I'm not an expert in these cars. But I like to tinker.

304065 recommended a leakdown, which is probably a good recommendation...it'll give you a better idea of the numbers you posted.

Hopefully, someone more experienced than me will give you some better feedback. But I still believe that a ring job is in order, at the least.

teachkenpo · 02-22-2010, 12:40 PM

Hi Kidrock. Thanks for the comments. While it is destined to be rebuilt, I would like to postpone it until next winter if possible. An off-line friend wondered if it could be the oil thermostat not opening up, or possibly a blocked oil cooler that is causing the oil to overheat and vent out. I will post a question on the rebuild forum while waiting for input here.
Thank You,
John

304065 · 02-22-2010, 12:46 PM

Those don't look catastrophic, although 140/150 is more what I would expect to see. I don't generally rely on compression tests on their own, and would recommend a leakdown in addition.

You can put a latex glove over the breather hose from the crank to actually observe whether it's inflating or not.

Can you post another pic of oil filter and filler neck area? It looks like the hose from the case breather is pointing at an unnatural angle. Remember, hose from breather to the tank, hose from filler neck to the aircleaner (or in your case, the aftermarket filter).

teachkenpo · 02-22-2010, 01:51 PM

Hi John,
Thank you for your input. Here is the picture you requested. I don't have a leakdown tester yet, but I am trying to borrow one this week. Also, do you think there is any merit in the idea that it could be the oil thermostat?
Thanks,
John

304065 · 02-22-2010, 02:10 PM

I don't think it is either the thermostat or the oil cooler- those would be identified by the telltale ten foot puddle of oil under the car

If the thermostat doesn't open to send oil to the cooler, the oil temperature will rapidly redline. If the oil cooler is blocked, well, if the internal passages are blocked, the engine will stroke out pretty rapidly. If the fins are blocked, you will see the oil temp rapidly redline.

2,0 heads are known to be detonation prone and the factory revised the combustion chamber design and valve angle in 1970. Has your engine ever been rebuilt?

teachkenpo · 02-22-2010, 04:47 PM

Quote:

Originally Posted by 304065

I don't think it is either the thermostat or the oil cooler- those would be identified by the telltale ten foot puddle of oil under the car

If the thermostat doesn't open to send oil to the cooler, the oil temperature will rapidly redline. If the oil cooler is blocked, well, if the internal passages are blocked, the engine will stroke out pretty rapidly. If the fins are blocked, you will see the oil temp rapidly redline.

2,0 heads are known to be detonation prone and the factory revised the combustion chamber design and valve angle in 1970. Has your engine ever been rebuilt?

Hi John,
You refer to a puddle of oil under the car if the thermostat doesn't work. I had that. Not a 10 foot puddle, but a puddle. Or are you referring to something more than oil spitting out?

In reference to your question about being rebuilt, yes it was. Twice over it's history. Both times many years before I came to own it. I have all the paperwork. The cam towers were "updated to late model oiling" The heads were rebuilt with new valve guides about 1990.
John

304065 · 02-23-2010, 12:53 PM

Quote:

Originally Posted by teachkenpo

Hi John,
You refer to a puddle of oil under the car if the thermostat doesn't work. I had that. Not a 10 foot puddle, but a puddle. Or are you referring to something more than oil spitting out?

In reference to your question about being rebuilt, yes it was. Twice over it's history. Both times many years before I came to own it. I have all the paperwork. The cam towers were "updated to late model oiling" The heads were rebuilt with new valve guides about 1990.
John

John,

My comment about the 10 foot puddle was a joke- I mean if the pressure built up due to a blocked thermostat or oil cooler, you would soon have a very serious external leak, probably from the cooler fins themselves which would rupture. The geared oil pump is a positive displacement pump, which means the oil has to go somewhere. . . somethin's gotta give!

Here's the thing about rebuilds-- do any of your receipts show replacement pistons or pistons and cylinders? Over time, the ring groove wears due to microwelding between the groove and the rings-- the ring sticks to the groove and then breaks off, which over time can widen the groove out. If new rings are installed in a worn groove, they will very quickly break, resulting in low compression. This is precisely what happened when the engine in 304065 was rebuilt in 1982-- receipt for rings but no pistons, and I found the original long skirt pistons in the cylinders when I tore it down.

These days you can borrow one of those LCD borescopes, pull off the sump cover and actually look inside, at the back of the pistons, to see if you recognize the telltale long tang. That would indicate original pistons, which more likely than not have a worn out groove after 44 years.

"Updated" oiling LOL, I get it now, that's because the first Spraybar engine was 903070, from approximately November, 1965. I wonder whether you still have spraybar cams with the oiling holes in the cam base circle.

Anyway, a leakdown will allow you to pinpoint the issue and resolve any uncertainty. If you need to tear it down, there are many of us who have been there before to help. (I still have to time my cams, though, and bolt the manifolds on!)

Good luck!

kidrock · 02-23-2010, 05:16 PM

hey John,

FWIW, I know you stated that you wish not to rebuild until next winter. Unfortunately, you have an issue that won't disappear. You'll be driving her sparingly until you get her fixed...it will most definitely start blowing more and more oil, which in turn will inevitably spill onto hot parts, making your Porsche resemble a Bob Marley concert.

teachkenpo · 02-23-2010, 05:25 PM

Hi John,
I have decided to just finish the rebuild of the 2.2 and get that in the car. That way I can do the right thing and just pull the 2.0 apart and stop wishing it didn't need at least a partial rebuild. At the least, new rings will be better than the old ones. Thanks for your advice and encouragement. Would love to see your 66 sometime.
John

teachkenpo · 02-23-2010, 05:31 PM

Hi Stone,
I thought that my neighbors came running over when I pulled in because they figured I was having a barbecue! It is possible that some of them where here for the potential "concert" instead. Regardless, all future events have been cancelled due to the rebuild commitment as stated above.
John

Fleming · 02-24-2010, 02:11 PM

John, did you check the oil level with the engine running?

There is a story of a local guy that was having terrible, terrible, troubles with oil everywhere in the engine compartment. Comes out that the local oil change place drained the engine oil and "tried" to refilled with 9 quarts....but didn't drain the oil tank... couldn't get all the oil back into the tank - massive over fill.
_______________

I had blow by so bad on a drive to California (from MN) I was stopped for a possible engine fire (and pointed to by fellow drivers way too many times). The fix was a platform made from a coke can hose clamped over the heat exchanger to drip the over flow away from the offending heat source. (Yes it worked a little). Fresh Valve cover gaskets and a drip tank (Clear plastic water bottle with the breather hose poked in to it) helped for quite a while. The blow by was a problem - the BIG problem was burning oil on the heat exchanger.

Try a temp fix and see if it helps. If nothing else it's great conversation for the neighbors. Here in the land of giant mosquitoes a little smoke spray is considered good....(EPA, no I did not say that.)

teenerted1 · 02-24-2010, 02:36 PM

isnt that vent hose supposed to go to an overflow tank and the tank is vented through a filter like that?

teachkenpo · 02-24-2010, 02:37 PM

Hi, I did check the oil. It was certainly not high

. I did experience that once though. My son has an 87 and I told him he should check the oil and that it might need a quart or two. His reaction was to add two quarts without confirming that it needed them. He figured more was better. I got a phone call telling me his car was smoking really bad. When I checked, it was 2 quart high.

Your mosquito reference reminded me of when I was a kid. I used to see the neighbors kids ride behind the mosquito spraying truck on their bikes when it came through the neighborhood. I can remember the thick oily smoke floating through the house if we didn't close the windows in time. It never seemed to do any good with the mosquitos, but I wonder how many brain cells it killed.

Thanks for reminding me why I can't ever remember where I put my keys.
John