Which one, engine or transmission, is leaking oil?
 

Hi all,

Once again, I've come here to ask for your wisdom in determining which one, engine or transmission, is leaking oil. The car is a 2001 Boxster with Tiptronics.

I can see several wet spots. One noticeable spot is right between the transmission and the oil pan. I will take pictures and post here if necessary. I already poured the UV dye into the engine oil and the result is inconclusive. I said that because under UV light, the leaked oil looks similar to other non-dyed oil as well as the engine oil. Is the UV dye not working as advertised? The dye is made by NAPA. I have several questions to ask:

1) Is there a way to do the same procedure (UV dye) with the transmission oil?
2) If it's leaking transmission oil, how can I keep refill it easily and quickly (I already removed the transmission underbody pan)
3) A indie shop looked at it and told me they can't fixed it since they think the leak is right where the transmission connected to the engine, hence dealer fix item only.

Thank you.

most likely rms leak?

The most common leak that would be in between the engine and transmission is the IMS bearing or the RMS (rear main seal) both located on the back of the engine were it meeting the clutch and transmission. The IMS bearing is serious and the RMS is an annoyance. Both require dropping the transmission to confirm and repair.

Posting some good pictures may help forum members help you diagnose the issue.

I've never hear of a good Porsche shop say "the leak is right where the transmission connected to the engine so it's dealer fix item only". You may want to find a good independent Porsche shop. There are plenty in the L.A.

I would never put a dye into the engine oil. While it may help with finding a leak who knows what it is doing to your engine.

Actually, the quality dyes from companies like Uview are completely harmless to engine's or other component's, assuming you use the correct dye in the correct place.

I'll take some pictures of the leaks and post it tonight.

FYI, many years ago (when the car was still under warranty), the dealer fixed the RMS leak once before.

How do I know if it's an IMS or RMS leak? Quite frankly, I'm a bit tight with $$$ right now. I'm willing to get my knuckle dirty and I'm just your average DIY. Definitely I can't afford to take it out to a shop. What are my options here? What risks are there if I continue to drive the car while monitoring the oil level? I assume the both IMS & RMS leaks engine oil? Now that I know it could be IMS related, my main concerns are IMS and transmission leak (which I can't really refill/monitor easily).

The final RMS seal which works well came out in 2005, so assuming you had yours replaced before 2005 there's a good chance yours is leaking now, BUT The IMS could be leaking also.

You may be able to get an orthoscope through the CPS access hole. You will, of course, need to remove the CPS (Crank Position Sensor). If you are able to maneuver the orthoscope between the flywheel and the engine you can try to see if its the RMS, which is at the center of the engine case, or the IMS, which is at the bottom of the engine case. The orthoscope may also be able to reach front transmission bearing.

The usual process is to remove the transmission. Whether the orthoscope method is even possible, I don't know. But if it isn't the only method is to drop the transmission.

First, is it a seep, a drip, a leak, or a puddle?

A seep is oil on the housing but rarely or only occasionally drips onto the ground.
A drip is several small spots or a small accumulation on the ground.
A leak is 50 cent size spots every time you park.
A puddle is the size of a coffee can.

I'd ignore a seep, just wipe it off occasionally.
A drip can go either way but I'd probably ignore it also mainly because removing the transmission is a big job. Just put a piece of cardboard under the car when you park at home.
A leak is worrisome enough to warrant serious intervention.
A puddle means you waited too long and should have fixed it when it was a drip or a leak.

Second, make sure that the fluid is actually coming from inside where the engine and transmission mate. It is well known for oil to leak in one location and then seep along for quite a distance and then accumulate/drip at a place that isn't actually leaking. I had oil dripping from the bottom of the valve covers and two shops said that I needed to have the valve covers re-sealed, but the oil was actually coming from the spark plug tubes. Check and double check to be sure of the exact location of the source.

Third, the options are pretty straightforward;
(1) Remove the transmission to see what is actually leaking and then repair/replace whatever is leaking. If you're a handy DIY'er, this is a bit time consuming but not technically difficult.
(2) Try and get an orthoscope in to see what is leaking without removing the transmission
(3) Drive it as-is and monitor the oil and/or trans fluid levels religiously (the only way to check the trans fluid level is to remove the fill plug on the side of the trans)

And last, I don't mean to sound harsh, but you might want to find a new indie shop.

I had a similar 'leak'. Turned out to be the AOL dumping a lot of oil in the inlet which made its way in between engine and transmission. Went away after replacing the AOL and cleaning the inlet.

The only way to know if the RMS or IMS seals have failed is to pull the gear box, clutch and flywheel and then take a look. There is no other way.

There is absolutely no way to get any type of otoscope behind the flywheel to see the IMS or RMS, believe me, we have tried several of the smallest and most expensive on the market, and none of them worked. You have to take the car apart.

Again, many thanks to those who have responded. It's priceless to get different perspectives from those who are knowledgeable and have no motives to empty your wallet.

@thstone, the leak is more like a 'leak' ie., several spots of 50cents on the ground. I can see several spots where oil is standing.
@BYprodriver, yes the warranty work to fix previous leak was before 2005 (2003 to be exact)
@nieuwhzn, I too have just spent $1400 to replace the AOS and the water pump.

Last weekend, thinking that it was a transmission leak, I tried to top off the transmission oil. FYI, I just changed the transmission oil & filter a few months ago. However, with the transmission oil at the correct temperature and the engine is running, when I removed the filler plug the hot oil gushing out quite a bit. So I put the plug back in. I'm 100% sure I did NOT put in as much transmission oil as the amount that came out when I change the oil few months ago. Is this because I only jacked up the rear wheel instead of raised all 4 wheels at level?

Highly doubt it's tranny oil and most likely IMS\RMS. Tranny fluid has a pretty rank smell to it much worse than engine oil and tend to be thicker.

Yes needs to be level when replacing fluid to get proper level. I would think you could tell fresh fluid stain from engine oil.

I know that you say that the oil spots are at the junction of the engine and tranny but....

Given that any leaking fluid loves to travel to take you off its path, have you looked at other typical potential sources? Do you smell hot oil when or after driving your car? What about spark plug tubes and O-rings?

Finally figured out where the leak is coming from
 

I just want to update this thread so it can be closed and hopefully help someone else in the future should they have similar problem.

After reading all replies and some thinking, I decided to replace the engine oil & filter with new fluids. Afterward, I was able to compare the fluid leaking on the floor with the fluid from the transmission. It was obvious the oil leak must come from the engine since it's very light & clean (compare to the darker transmission fluid).

Many thanks to those who responded. The wisdom of this forum is priceless and comes with no string attached, unlike some of the repair shops out there.