Help! Wierd oiling issue...

[Tspringer]

When parking my '69 911S with 2.7RS MFI engine the other day at home, I noticed a very strong oil burning smell. After shutting off, I peeked in the engine bay and there was oil all over the top of the engine and blown all over the place.

I de-greased everything and completely cleaned the engine bay. I discovered oil was passing through the filter assembly. It was clearly leaking some out the bottom drain plug onto the top of the engine.

I then attached a hose to this drain pipe and ran it to a clear coke bottle before attaching it with duct tape. Then I drove around until the engine was fully warmed up. Sure enough, when I got back the coke bottle had about 4 ounces of oil in it. However the top of the engine also had more oil splattered about again, like its leading past the gasket at the breather assembly perhaps?

The breather hose that runs from the top of the engine to the oil tank is very wet with oil. When I checked the oil, it also showed the car to be over-filled by a good bit. Clearly the car is pushing oil out the breather to the oil tank, which is filling up to the point that oil is being forced into the air cleaner and then dripping all over the engine.

Now comes the tricky and confusing part:

Its been over 2 months and 1000 miles of driving since the oil was last changed. The car has been to full operating temp many times. The car does not currently have a front oil cooler. I have not added any oil since the last oil change, when 9 quarts were put in. Until yesterday, the car has not exhibited this problem at all!

Why is the car suddenly acting like its overfilled with oil? If that is the problem, why would it not show up right after the oil was changed?

I have also had oil pressure concerns with this engine. It was built by Supertec in CA and installed in Sept. of 2001. When I got it, the oil pressure was showing about 10lb per 1000rpm at 190 degrees temp average. It was indicating zero at idle, and about 50lb at 5000rpm. At 6000rpm it would show 65lb or so. At 7000rpm it showed 75lb. I installed the newer oil fittings with the smaller orifices at the heads to try and increase pressure. It is better now: at 5000 rpm I get 60lb. Under hard acceleration at 6000rpm I show 75lb - 80lb. However, if I just cruise on the highway at a constant 5000rpm, I will only show about 50lb or so. Cruising constant at 3000rpm gives me only 30lb. The pressure definitly jumps when the engine is revved. The engine was fully rebuilt in Sept '01 with a 3.0 oil pump. I have always thought it should show more pressure than this. The car never runs over about 205 degrees.

Could there be a problem with the scavenge pump? Perhaps the scavenge pump has had something go wrong, the engine is filling with oil and now blowing through the breather to the oil tank which is filling with oil and allowing overflow to the air filter? Could this also be related to a possible oil pressure problem?

IS it possible one of the pressure release springs is messed up somehow?

This is perplexing to say the least. The engine runs great. It has tons of power and revs like a demon. It throws a bit of white smoke on startup sometimes, and a tiny bit of black smoke when you rev it hard when standing at the engine bay... but nothing at all out of the ordinary. I have not done a compression test but cant imagine its leaking by the rings and pressurizing the crankcase when it runs so well and is giving so much power.

If there is a problem, I need to figure it out and get it fixed while its still winter. I plan on tracking this car a lot come warm weather. Im worried that when its hot outside and the temp goes up even more... Ill have even less pressure and a bigger problem. (I am installing a front cooler this winter).

Thanks for any ideas and help!

Terry

[Jim Sims]

Your oil pressure is about right; 10 psi per 1000 rpm at operating temperature. The pressure pump is a fixed displacement per revolution pump; output and hence pressure for a given system (engine and pressure relief valves) depends on the pump speed. It doesn't matter how much oil one puts in but how much came out versus how much is put in. If one doesn't drain the oil tank, engine sump and change the oil filter 9 quarts could be too much. The oil level should be mid-way between the two marks on the dipstick at operating temperature. If one has the level at the top mark, hard turns to the rignt can throw oil left through the breather hose to the air cleaner housing or airbox. There is a drain line from the bottom of the housing or airbox which originally was set up to drain oil or other liquids ingested by the air cleaner out a rubber duckbill type valve to the front right of the engine sheet metal near the starter. Another source of leaks is an old hard breather hose which can no longer effect a good seal to the nozzle on the engine breather housing. The breather housing to engine case gasket is a source of leaks especially if the breather housing or cover wasn't checked for flatness (they can warp with time) before installation. Also, oil will pickup water and gradually increase in volume unless there are extended periods of time that take the oil above the boiling point of water (212 degrees F at sea level). Owners are often perplexed by a car that normally doesn't appear to be using oil and then all of a sudden burns a lot during an extended trip. The oil was being burned daily but during the day to day driving it's volume was being made up by entrained water. Then the water was boiled off during a long hot drive and the oil level dropped. Check your oil level with the dipstick and maybe some more hot driving will solve your problem. Cheers, Jim

[pwd72s]

Good thoughts from Jim. My '72 has the factory front cooler...and I thought they were standard on the '69S??? But I've found that draining tank & sump, plus changing filter, 8.5 quarts puts me between the lines of the dipstick. The later engines take more oil than our early S's...

[Tspringer]

My car did originally have a front cooler, but its not currently installed. I do plan on installing one before spring as I plan doing alot of track days and I know it will get too hot i nthe summer on track without one.

I am going to drain some oil out of the engine sump, about a quart. Then I will see if it has the same problem.

The really perplexing thing about this is that until this issue popped up 2 days ago, I had no oil leaks or in the breather at all. None. Many times prior I had run the engine to hotter temps than I got when this happened. All of a sudden its not just a small amount of oil coming through the breather... but lots. I got over 4 ounces from the air cleaner drain in less than 5 miles of driving, plus another 4 ounces leaking from somewhere else all over the engine.... this after I had fully degreased the entire engine bay and cleaned it.

[michigan]

I wonder if a stuck oil cooler thermostat would have any bearing on this sudden leak/blow back condition? I personally would be inclined to look in that direction first.

[Jim Sims]

A stuck engine mounted oil thermostat would result either in a car that takes a long time to get to temperature or one that overheats (since this car currently doesn't have an external oil cooler) and this car apparently doesn't have temperature problems. I would guess the thermostat is okay. Even if it's stuck there is a bypass. There is also a pressure relief valve that should open at around 77 PSI (if it's OEM) and dump oil back to the pressure pump inlet. This pressure release is also consistent with the reported max oil pressure of 75 to 80 psi. The o-ring on the engine mounted thermostat could be leaking and putting oil on the top of the engine (along with several other possible leaking items) but it will not put oil inside the air cleaner housing. That has to come through a breather hose. I still suspect there is too much oil in the engine/oil tank. Cheers, Jim

[pwd72s]

Jim, any thoughts that this could be oil filter related????

[Jim Sims]

I don't think so. If the oil filter clogs there is a pressure actuated bypass. If the bypass doesn't work the scavenge pump would have difficulty putting oil into the tank and it would pool in the case. However, the only feed to the pressure pump is from the oil tank so if the tank ran dry (due to oil pooling in the case) the oil pressure should drop as there would be no oil available for the pressure pump. This car doesn't appear to show oil pressure problems. This also shows how important that rubber "S-hose" between the oil tank and engine is. If that fails one doesn't have oil pressure. Since this hose is also "cooked" by it's proximity to the exhaust it is a regular replacement item IMO. Cheers, .Jim

[pwd72s]

My thinking was based on 2.4's and up taking a different filter than the 2.2's and 2.0's...since the car is a '69, it should still be running the '69 external oil plumbing....so a filter change a cheap thing to try? If not a fix, not a lot of money or time invested, and just maybe....

[Tspringer]

Today I did drain about a quart of oil out. I drove it around, hard for about 30 minutes to get it up to temp. It did not spit any oil out the breather.... and when I checked the oil it had dropped to right at the top of the dipstick max mark.

I am still perplexed by how the oil level apparently went up suddenly resulting in the blowout through the breather. Its been 3 months since the oil was changed, and I have added ZERO in that time. I did put in 9 quarts when I changed it... which considering the front oil cooler is not hooked up at all is perhaps too much. But why would the problem only show up now?

Is there any way fuel could be getting into the oil, and that dilution cause the level to increase suddenly? Its an MFI engine and does run very strong.

Terry
'69 911S w/ 2.7RS MFI engine
'77 Ferrari 308 GTB

[pwd72s]

A puzzle to me...but glad to hear things work better now..

[Jim Sims]

Entrained water from fuel combustion, not fuel dilution (unless your oil smells stongly of gasoline) likely caused the volume increase. If you're at the max level mark, idling with the engine hot, you still have too much oil in the system. Drain out another 3/4 of a quart. When the oil was changed were both the engine sump and tank drained? Was the filter replaced? Cheers, Jim

[Dan Owens]

You mentioned that your car originally had a front cooler but doesn't now. Are the lines still in place and cap at the front of the car? If so is the thermistat still in line?

I'd also agree if your at the top mark on your dip stick your still too heavy on oil. I think if it were me I'd drain all the oil from the engine and tank and start over. That way you aren't guessing at how much is there and also if there are contaminates in the oil they're gone. I would venture to guess (ask me how I know this) that the cost of a fresh oil change aren't anywhere near the frustration and work to clean the engine again.

Dan O
84' 3.2 Targa

[Tspringer]

Good advice, I will drain another 2/4 quart.

When the oil was changed, the filter was also changed. Its a Mahle filter. The oil was drained from the tank and sump.

The front cooler lines are in place, but not connected to anything. The thermostat housing on a '69 S is inside the engine bay as a part of the oil filler neck. This assembly is missing entirely (I am trying to find one). Thus, there is no thermostat, oil lines or external oil cooler at all.

I am ordering some more filters today and will change it again when they arrive. I agree its better to just get rid of all the contaminants and start over again. The oil does seem to smell a bit like gasoline, but not massivly so. Hard to tell.

Thanks for the tips.

Terry

[pwd72s]

Terry, click here to note the different Mahle filter numbers, depending on the year of the car...
http://www.pelicanparts.com/catalog/shopcart/911E/por_911E_oilsys_main.htm

[speedo]

Jim, I too have a 2.7 mfi motor with this weekend being its first time out this year. I experienced the same oil bypass through the air cleaner problem as Terry and presumed it was also due to "topping off" with excess. My oil pressure was fine until the oil warmed up, and then it read almost no pressure at idle moving up to 40 psi at 4-5k rpms...considerably lower than the 60-65 psi at start-up. I figured that maybe at last oil change I might have used a too light a grade...10-40 vs 20-50 weight....so maybe I need to stay with a heavier weght oil to start with. Then I noticed a small pool of oil immediately after stopping and a steady drip from the area of the line running under the engine trans connection...right near my clutch lever arm. I also notice the short line coming off my oil tank that feeds the line under the motor has a small "kink"/bend in it. This motor was the dryest 2.7 I have ever seen before this!!! Can I easily acces the connection where the line under the motor connects to the left front of the case from under the car and what wrench is this...why would this fitting have suddenly worked loose? Do I need to drain all the oil to replace the short line off the tank?

[Jim Sims]

Speedo,

Change to 20W50; I would recomend a "dino" (made from natural peroleum) oil not knowing about your car's rebuild history. I happen to use Castrol GTX in my '76. The oil pressures and behavior (near zero at idle when warm plus dropping overall as the engine and oil warms) you report are a little low but okay; changing to 20W50 will likely increase the oil pressure.

Drips could be overflow from an oil overfill (look in air filter housing under air filter for oil). The could also be from a leaking temperature switch, thermostat o-ring or breather gasket or hose or an MFI pump oil line on the top of the engine. Clean up the area and look for the origin of the drip.

If I understand correctly (I'm assuming your car doesn't have an external oil cooler up front) the line with the kink is the output of the scavenger pump to the oil tank. On some of the cars (yours may be one of them) the rubber section of the line is a separate section and can be removed while leaving the "hard" metal line in place. I believe the oil line fitting nuts are 36 mm (across the flats) but one may be 27 mm. Yes, you will need to drain the oil tank to remove either line from it. The soft "S" shaped line secured with hose clamps provides oil from the tank to the oil pressure pump.

Cheers, Jim

[speedo]

Thanks Jim...yes I 've got the 2-piece line from the scavenge pump to the tank. Does that line have the tendency to work loose...where it comes off the case? I just disassembled a 2.4 and that line was impossible to get loose! On my air cleaner, I was getting "blow by" , but there is no drain out the bottom of the filter...the oil was just making its way out the bottom edge of the filter. That leak was small, but depositing the oil onto the heat exchangers. The big drips were coming off the line out of the scavenge side...thus my question about wrenches and accesibility. I also noticed my green oil light (center of gauge) flickering but presumed it was a connector issue,...would this have any bearing on the earlier dicussion?

[briankeithsmith]

It sounds like you may possibly have the same problem I just experienced with my 930.

The end result for me was the 5 of 6 cylinders had busted piston rings.

My car ran great also, in fact I was hitting close to 150mph at VIR with this problem.

In addition, my leakdown numbers were excellent.

But if the oil is coming from the crankcase vent, and pumping into the oil tank, or oil overflow, then it could be the piston rings allowing blow-by, which pressurizes the crankcase, which in turn forces oil out of the crankcase vent.

I hope this is not your problem.

Brian

[HawgRyder]

Make sure you only have 1 "o" ring on the filter.
I have seen o-rings stick to the flange and are not easy to see unless you really look.
Also...on my 69S the filter/thermostat housing seems to have fittings on every side....if the front cooler is not connected...are all the openings blocked off?
Bob