Huge Oil Leak due to Cold Temp?

amatow · 01-02-2002, 12:50 PM

I purchased my 87 with 60k miles in August from a person in Texas. It had a very minor oil leak from the oil line that feeds the tensioner on the left hand side of the engine. This was reported during the inspection. The leak never resulted in any dripping on the ground. I planned on fixing it this winter after a valve adjustment. I put the car away for the winter after Thanksgiving, a few days later a bunch of oil was on the ground under the engine. I had not even started it yet. I moved the car back into the drive and cleaned up the floor. It had gotten well below freezing a few nights earlier but was now about 40 degrees outside. I put cardboard under the engine and inspected it every few days. Nothing dripped.

After a few weeks when it got below freezing again, it leaked again. It leaked even though I did not start it.

The leaks appear to be coming from the oil return tubes, possibly the valve covers, and possibly the covers over the chain tensioners.

1. Does it seem reasonable that the warm weather car now is loosing its seal during cold temp?
2. The oil return tubes seem very loose. I can spin them by hand and wiggle them back and forth. I expected much more compression on the seals than this. How tight or loose are they supposed to be?

Any similar experience or advice?

lukeh · lukeh's Garage

I had the same problem with my 83SC cab. It would drip a little now and again. Come winter, I would put the car away. Our average winters highs are in the 20's and lows in the teens. The oil would drip so bad that I had to change the cardboard every few weeks. I ended up selling the car but always figured it had to be the effects of the cold.

Bill Douglas · 01-02-2002, 12:58 PM

I wouldn't go wiggling or turning them.

I'd leave them alone and just get some new cardboard

Like you suggest the problem may go away once the weather warms up a bit. If you really want to fix the problem you can replace the oil return tubes with new expanding ones from Pelican Parts.

Bill '79SC.

Iggy · 01-02-2002, 01:40 PM

Bill:

Forgive my intrusion on the 911 board, but my 928 has the same symptoms.... a very minor leak during warm weather turns into pools of power steering (ATF) beneath my car. Also, where no oil leaks at all during warm periods, a small leak develops during the cold (which it is now). It figures that the largest leak occurs in my unheated garage overnight, but my enclosed garage at work (unheated but still much warmer than the outside air) only gets a few drops per day on the floor.

My P-car mechanic told me that as long as I was careful and added fluids to maintain the right levels, my only problems would be a dirty (very) garage floor.

Fix it when you have the time. Just don't forget to make sure you have enough oil.

P.S. Has anyone encountered leaks after an oil change to synthetic oil?

Bill Douglas · 01-02-2002, 01:53 PM

Iggy, your mechanic seems to think it's ok so I'd go with his recommendation. I'm a beliver in not fixing things unless you really have to incase you make things worse or are wasting time and money when you don't need to.

There have been a few postings with the pro's and con's of switching to synthetic on this BBS, maybe do a search.

Have fun, Bill.

amatow · 01-03-2002, 05:18 AM

Since I'm going to do a valve adjustment, I will be replacing the valve cover gaskets anyway. I owned a VW beetle for 10 years and had to replace a pushrod tube occasionally due to a leak. These were springloaded and were seemed to be more tightly sealed. I think I can do the same on the 911.

It is strange to hear about cold temperature causing a leak. You might think that the oil being thick in the cold would be less likely to leak.

My oil level gauge works fine and I keep it well filled. I'm not worried about loss of oil but rather the mess in the garage and all over the engine when I drive it.

Still wondering how tight the oil return tubes normally when sealed properly. Anyone have some experience?

Rot 911 · 01-03-2002, 06:28 AM

Having changed more than a few oil return tubes I can almost guarantee that is what it is. Do you still have the original tubes? You can tell by looking. If the tube is one solid piece they are original. They leak more when cold because you already have 15 year old o-rings that have already shrunk due to age and the added cold just makes for more clearance for oil to leak out. Just buy a new set and change them while you are doing your valve adjustment.

amatow · 01-03-2002, 07:06 AM

I think this a great idea. The ones on the vehicle are original. It doesn't look like too much trouble to replace them.

Rot 911 · 01-03-2002, 07:12 AM

Amatow, this thread might be helpful to you: http://www.pelicanparts.com/cgi-bin/vb/showthread.php?s=&threadid=52131&highlight=oil+return+tubes

Joeaksa · 01-03-2002, 07:29 AM

Had the same thing on my 72 911 years ago. Everytime it got cold I would come down and find a puddle about 3-4 feet around on the ground. Got tired of this and swaped all four of the oil return tubes with new ones with the better "O" rings and never had the problem again.

Seems that the "O" rings contract with temp and the cold seems to strike the oil return tube most often. Would look here first.

JoeA

amatow · 01-03-2002, 08:58 AM

I'll be ordering a set of tubes soon. I think I saw Wayne's book available on Amazon for 25% less than it costs here. That stinks. I was thinking of ordering the book and the tubes together. Kind of a Christmas present.

T Bird · 01-03-2002, 10:44 AM

Anybody remember the space shuttle Challenger? Cold weather played deadly havoc with the rubber O rings on that ride.

amatow · 01-31-2002, 10:32 AM

I replaced the tubes the other day. It was quite easy. The tips on this sight were very helpful. I didn't remove any other parts. The hose clamp provided enough leverage to push the tubes in. It took about 2 hours without rushing at all. After the first one each one takes only about 10 minutes.

No oil on the floor even when its cold.

Thanks

Planter91C2 · 01-31-2002, 10:41 AM

this happens to my car when i store it and i was always puzzled. i thought the oil would be thicker when colder and not leak as much.

marcesq · marcesq's Garage

I just replaced my original type with expandables in conjunction with the annual valve adjustment.

As indicated above, it is not a difficult process, however, read the tech article. Be aware that the tubes can be seated fully against the block/sump, and not be entirely seated in the cam tower when the c-clip is installed. I know this because I had the valve covers off when I installed the tubes.

Make sure you position the hose clamp as near to the end of the tube as possible on the large end or the tension of the clamp will make expansion of the tube impossible

Rot 911 · 01-31-2002, 11:10 AM

Congratulations and welcome to the ranks of the home mechanic!

Britwrench · 01-31-2002, 11:12 AM

I believe the reason the oil leaks are more noticable during the winter is nothing to do with the temperature.

When you store the car the oil level in the engine rises due to drain back from the oil tank. As the level rises the oil is above the oil return tubes. If the o-rings are even slightly old and hard the oil will leak.

If you drive the car every day or so the oil level in the engine remains low and....no leaks.

amatow · 01-31-2002, 01:12 PM

I believe that the tempurature pushes the system over the edge. I believe that leaks would have started to occur at higher temps in a few months/years. The o-rings were compressed such that the sealing surfaces were completely flat. This likely happened due to the 13 years since new. When it got cold the rubber in the o-ring likely stiffened and possibly contracted to cause the seal to leak. With the old o-rings, I could easily slide the tubes back and forth and spin them. There was not much compression of the o-ring. With the new o-rings, the tubes fit nice and tight and it is difficult to move the tubes. I kept one of the o-rings and cut it. The cross section was nearly square not round as it should be.

I am confident that the fix is good for 10 years or more. It was amazing how much oil could come out so quickly.