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E36/7 Z3 (1996-2002)
E36/7 Z3 Roadster, Z3 coupe, Z3 M Roadster and Z3 M Coupe talk with our gurus here.

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  #1  
Old 04-24-2012, 07:13 PM
DaveBZ3 DaveBZ3 is offline
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Z3 Hot Oil Smell

This is an ongoing problem since I purchased the 2001 Z3 2.5 a few months ago. After driving the car I have the hot smell outside the car. I can raise the hood and even see smoke rising from around the catalytic converters, but it's hard to see the exact location of the smoke.

Twice I have degreased and pressure washed the area and the cats do not appear to oil on them. The previous owner claimed he just changed the valve cover gasket, but maybe he missed something and oil is dripping onto the manifold and burning off.

At this point I thought I would replace the valve cover gasket again. Are there any other parts or seals I should be purchasing...or can you think of other parts that could be leaking? Thanks.
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  #2  
Old 04-24-2012, 09:37 PM
Blacklane Blacklane is offline
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Sounds like the classic symptoms of a failed Crankcase Ventilation (CCV) valve. It's a common failure every 80k miles or so.

One check is to remove the oil filler cap with the engine running and feel for a solid vacuum there. If not, suspect the CCV.

It could also be the oil drain from the CCV to the dipstick. That can get plugged and cause an oil-burning smell.

Then you could also be burning the rubber hose between the exhaust manifold and the Secondary Air Pump (SAP). That would be caused by a faulty SAP valve allowing hot exhaust to back flow into the hose.

Of course if you are actually seeing oil seeping from the valve cover gasket, that's a no-brainer. Replacing that is not too hard, but be sure to replace the valve cover gasket, two spark-plug gaskets, fifteen valve-cover-bolt rubber washers, plus a bit of RTV sealant at each end of the cover at the corners of the cam shaft half-moon places.

Last edited by Blacklane; 04-25-2012 at 06:06 AM. Reason: Additional Info
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  #3  
Old 04-25-2012, 05:49 PM
DaveBZ3 DaveBZ3 is offline
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Blacklane, thanks for the reply.

I warmed up the car, let it idle and removed the oil filler cap. I put some thin paper over it (a Home Depot receipt) and it's getting sucked in a little...indicating a vacuum of course.

I'm not sure how this translates to oil leaks. Seems like a vacuum would want to draw air in, not push oil out. Maybe it's drawn in at one point and pushing out at another.

Anyway, I suppose I'll be replacing the PCV value. From what I've seen it appears to be a PITA...any tips. I should probably redo the valve cover gasket as well and replace the rubber cover washers you mentioned.

My SAP is fine. The hose was burned through when I bought the car and I replaced. It appears to be running approx. one minute when cold, then turning off. I assume it's OK.
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  #4  
Old 04-25-2012, 08:56 PM
Blacklane Blacklane is offline
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If the SAP hose burned through before, then the SAP valve is bad, allowing hot exhaust gas into the hose. The replacement hose won't last long. That seems like a likely source of your smell.

By the way, a bad CCV or clogged CCV drain (into the dipstick pipe) will force engine oil into the intake and result in a burning oil smell and increased oil consumption. It's worse at the tailpipe, but the whole car will sort of smell like a refinery.
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  #5  
Old 04-26-2012, 07:48 PM
DaveBZ3 DaveBZ3 is offline
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When I replaced the SAP hose I pulled off the valve and ran some cleaner through it. I then reinstalled and checked the vacuum hose with a gauge...pull vacuum for around a minute, then stopped. After the engine cooled I checked the valve. It appeared to close after a minute.

The smell and smoke is rising up from the back where the cats are. I guess I'll replace the PCV valve and valve cover gasket, etc an see what happens. Thanks for the advice.
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  #6  
Old 04-26-2012, 08:29 PM
Blacklane Blacklane is offline
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Obviously if the smoke is coming from the catalytic converter, your problem is not the SAP system, however, a vacuum test of the SAP valve is not a complete test. You should remove the hose between the valve and the Secondary Air Pump and feel for an exhaust leak through the valve. A common failure mode of the pump is to have exhaust blowing back into it and causing condensation inside the pump.
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  #7  
Old 04-27-2012, 08:59 AM
wifesauto wifesauto is offline
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take it to a mechanic with a lift so he can look for an oil leak/seepage. changing things that may not be bad can make things worse.
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  #8  
Old 04-27-2012, 06:32 PM
DaveBZ3 DaveBZ3 is offline
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I took a closer look and I can see fresh oil seepage around the rear pre-cat ox sensor. It was probably dripping there into the manifold. I ordered a valve cover gasket and the 15 rubber washers. For now I'll assume the PCV valve is OK since I'm not getting any other symtoms that it's bad.

I also pulled off the hose off the SAP valve and cranked the car. It appears to be operating as it should. It closes after a minute and I can't fee any exhaust coming out. The inside of the new hose is still very clean. I would think if I was getting some back flow it would have some soot.

I'll update next weekend. Thanks for all the advice.
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  #9  
Old 04-27-2012, 07:01 PM
Blacklane Blacklane is offline
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One of the best descriptions of how to replace the valve cover gaskets is under the "Procedures" tab on the Beisan website: http://www.beisansystems.com/index.html. Their instructions are for replacing the VANOS seals (something else you may want to consider), and part of that is to remove and replace the valve cover. Their instructions include photographs, what tools to use, torque specs, and exactly where to put the RTV sealant.
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  #10  
Old 04-28-2012, 05:40 AM
DaveBZ3 DaveBZ3 is offline
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Excellent pics! Much more detailed than the Bentley manual. The manual is almost a waste of money, but that's a whole new post...

They claim the vanos seal start to go out at 20K miles. However, I don't see much written in the forums about this being a problem. I suppose folks could be getting a code like "camshaft positioner" and not realizing its a vanos seal problem.
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  #11  
Old 04-28-2012, 06:42 AM
Blacklane Blacklane is offline
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I don't think the engine diagnostics can detect bad VANOS seals. I suppose there is no point, since they always fail and they fail at a predicable rate. Mostly the complaint is the list of performance problems on the Beisan website: low-end torque, hesitation, etc. There are also a few YouTube videos on VANOS rattle, if you want to hear what that sounds like.

Last edited by Blacklane; 04-28-2012 at 06:51 AM.
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  #12  
Old 04-29-2012, 04:30 PM
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amancuso amancuso is offline
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I had that oil smell in my '00 Z3 2.3 Problem was an incorrectly installed valve cover gasket. Oil was dripping down the engine/exhaust into the bend where the exhaust comes down then under the body. I changed the gasket and pressure washed behind the engine/exhaust pipe in the area and the smell was gone within 2-3 days of regular driving.
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  #13  
Old 04-29-2012, 06:37 PM
DaveBZ3 DaveBZ3 is offline
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Amancuso,

I think I have the exact same problem. The previous owner claims he just installed a new gasket, but I appear to have oil dripping on to the exhaust manafold. I just ordered a new gasket and rubber washers from Bavarian Auto. If you have any tips on the installation let me know. I'll post next weekend once I finish the job.
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  #14  
Old 04-29-2012, 07:39 PM
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amancuso amancuso is offline
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Quote:
Originally Posted by DaveBZ3 View Post
Amancuso,

I think I have the exact same problem. The previous owner claims he just installed a new gasket, but I appear to have oil dripping on to the exhaust manafold. I just ordered a new gasket and rubber washers from Bavarian Auto. If you have any tips on the installation let me know. I'll post next weekend once I finish the job.
Just take care when positioning the gasket at the rear.
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  #15  
Old 04-29-2012, 08:10 PM
BlackjackM BlackjackM is offline
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From what I've read, those washers that blacklane mentioned are different sizes for certain spots on the valve cover and if you install them in the wrong spots you will get a leak. Sounds like that may be the case here.
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  #16  
Old 04-29-2012, 08:54 PM
Blacklane Blacklane is offline
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I only know of one part number for the bolt washer seals: 11-12-1-437-395. There are 11 around the outside and 4 in the middle. That's for the M52 and M52TU engines.

There could be different part numbers for other models. Be sure to check RealOEM.com for your particular model.
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  #17  
Old 04-30-2012, 10:15 PM
rudyrov rudyrov is offline
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Regarding the SAP valve, (witch I assume is a cold air injection system utilized when the engine is cold and the fuel mixture is rich)
In my car when I start the engine from a cold condition, I could swear that the exhaust is louder for maybe a minute. From the drivers seat it sounds louder over towards the location of the air pump. I was considering that the valve may be failing. After a minute or more the exhaust sound seems to quiet down and "switch" to the rear of the car.
I also am guessing that the SAP valve has not only a vacuum control system but perhaps a one way flow control, so exhaust doesn't go up to the air pump?
My question.... Do you think I am correct and this is indeed a bad valve?
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  #18  
Old 05-01-2012, 09:42 AM
Blacklane Blacklane is offline
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The job of the Secondary Air Pump (SAP) is to force additional oxygen into the catalytic converter during times of rich fuel, or for about a minute after cold start-up.
The SAP valve should open when the SAP turns on, then close when the SAP is off. It is activated using vacuum power through a solenoid mounted on the other side of the valve cover. There is no one-way valve to protect the SAP. If the SAP valve leaks, exhaust flows into the SAP. In fact, thatís the best test for a leaking SAP valve: pull off the hose and see if exhaust leaks out. The valve can be removed and cleaned with MAF sensor cleaner, EGR Valve cleaner, or similar products.
If youíre hearing exhaust sound only during cold start-up, I would suspect a bad pump, since the valve is supposed to be open during that time.
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  #19  
Old 05-01-2012, 01:39 PM
rudyrov rudyrov is offline
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My SAP is working, I just checked it. And My SAP Valve seems to work just fine staying open for a minute or so then closing, along with the pump shutting down.
I didn't realize that the SAP valve didn't contain a one way valve. That would explain why I can hear the exhaust sound when the system is on.
I didn't realize that there is no one way valve in the SAP valve, that would explain the extra exhaust sound that I hear.

RR
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  #20  
Old 05-06-2012, 02:59 AM
DaveBZ3 DaveBZ3 is offline
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Today I installed the new gasket. I could tell it was leaking around cylinder's 4-5 by the amount of oil in the alumium heat shield. BMW could of ramped the heat shield away from the engine so the oil runoff goes away from the manifold...but then I guess they would not sell as many gasket replacements.

Anyway it was fairly easy to do. I used some gasket sealer (RTV) along the lower edge.

As advice for anyone doing this: install a small rag into each spark plug hole. If you dropped a nut in one of thise holes it would be tough to get out. Those 8mm nuts for the grounds are really small.

I've only driven around 10 miles with the new gasket and engine oil cleaned up, so I may need a few more miles to determine if I was successful.

Two follow-ups:
1). My first pre-cat ox sensor is loose. I don't think it can unscrew since it would have to twist the wire 15-20 times (once per thread revolution) What is the best way to tighted the ox sensors?

2). Does anyone know why the intake cam is housed in a plastic box?
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