2011 328ix has melted a second valve cover enough to leak oil!!

[Elka]

My 2011 328i xdrive (2/2011 build date) began to melt a second valve cover where it meets the head (see pic) and produced a leak according to a smoke test (smoke coming out between metal bracket and plastic vc under the valve cover bolt just behind the secondary air valve). No smoke anywhere else from smoke test (although it smokes from oil on the cat when I start it).
IMG_1046 (1).jpg

Question: What might be causing enough excessive heat at the base of the secondary air valve that could begin to melt the vc and brand new OE vcg.
I have spent hours looking and it doesn't seem that anyone else has had vc melt. It has happened on two valve covers now.
I realize that exhaust gases are held just under that bolt by the check valve.
Secondary air check valve seems to be working (could only blow through it in direction from air pump to head.
VC installed with engine out of car so I am pretty sure the vcg didn't roll.
Crankcase "pressure" is -39 millibars. I have read that it should be -30ish mb.
I don't want to replace the valve cover until I remedy the excess heat issue? Can't afford to melt another one.
The new OE vcg didn't leak the first 900 miles, and then it did.
Could a restricted catalytic converter cause this heat?
Thanks in advance for any insight!

[drewusmaximus]

Is there a leak somewhere at the exhaust manifold? Have you done an engine flush?

[Elka]

Is there a leak somewhere at the exhaust manifold? Have you done an engine flush?

Thanks for replying.
I replaced the connecting rod bearings and every seal on the engine (except valve seals). Upon install of engine, I reused exhaust manifold seals (they were brand new, but had been installed once before and had to remove exhaust manifold). I don't hear an exhaust leak.
I haven't done an engine flush but am about to change the oil with 1000 miles on the rebuild. I am curious what makes you ask that question? I bought this engine from a shop. 110,000 miles on it.
pulled the pan to do the gasket, and it had this in the oil pickup. (see pic)
IMG_0719.jpg
So the engine had eaten the serpentine belt and digested some vanos adjuster bolt heads and one front/aluminium head bolt head. So someone had replaced the vanos adjusters and the front crank seal but didn't want to drop the subframe to pull and clean the pan. I replaced the aluminium head bolt. I also pulled the connecting rod bearings and they looked amazing. Replaced anyway for good measure.
Oil pump was clean as was the rest of the engine as much as I could see. So that's the history of the engine. It runs well, idles smoothly. Does that help?

[drewusmaximus]

I was wondering if the heat from the exhaust manifold was travelling up to that point where the VCG is melting or there might be an internal blockage, causing the oil buildup at that section and if there's a blockage, the oil isn't circulating and generating more heat. I also wonder if some pieces of the belt are in the pan, limiting oil flow to the top of the engine.

[Elka]

I have pulled the pan and cleaned it out. I pulled the pump when I did the connecting rod bearings, it was clean. Belt could have gotten lodged somewhere in the head on its way down to the pan, but I don't think any would have made it into the oil galleries since it would have had to pass through the filter first, and I don't see how that would be possible. Maybe it is though. I will reply when I have drained the oil to see if any pieces of belt drain out of the pan.
I am beginning to think that a failing secondary air injection valve gasket allowed hot exhaust to leak and a stream hit the valve cover right there by it. The gasket was new, and it was rightly torqued, but it still leaked. I just don't know if the gasket leaked because it got too hot, or if it was faulty from the begininning and it leaking make the cover melt.
I haven't ruled out exhaust leak elsewhere. I can't hear it, but the fact that it smokes within 15 seconds after starting it makes me think that smoke is exhaust, not oil burining off the cat. Could that cat even we hot enough to smoke oil 15 seconds after cold start?
Anyway, I will keep you updated and thanks so much for your suggestions and for helping me think through this.

[drewusmaximus]

Since you pulled the pan and cleaned everything out, it's unlikely there's belt remanence in there. I think you're right about the secondary air injection valve gasket. I can't see anything else in that vicinity that would melt the VCG. Keep us updated. I definitely would like to know what you find.

[marvinstockman]

Get yourself a cheap infrared themometer, drive the car hard on the highway, pull over and explore the engine for hotspots.

https://www.amazon.com/s?k=infrared+...s_ts-doa-p_1_8

[drewusmaximus]

I hate to say this, but maybe warped head? Two new VCs and still leaking? Have you checked the surface of the head while the VC was off to see if it's leveled?

[Elka]

Marvin, thanks for the infrared thermometer idea. Don't know why I didn't think of that. I am leaning toward it being an exhaust leak. I read two forums regarding installing Active Autowerks headers that said to retorque the exaust manifold nuts around 1000 miles. This smelly leak didn't manifest until 900 miles after installing the engine. I plan to try to see if any of the nuts have backed off (hoping they have because that would explain the leak). If they are tight, I am going to install 6 new exhaust manifold seals.
Drew, I reallly hope it isn't the head warped. I hasn't overheated since I have been driving it, and the stinky smoke is only in the last 100 miles. I replaced the water pump, thermostat, hoses, etc. upon installing the engine. But I will keep that in mind as a possibility. After I check the manifold nuts, I plan to check exhaust backpressure to make sure cats are flowing. I have read that if it's under 1.25psi at idle or 3psi at 2500rpm, it is fine. I would think excessive backpressure could cause exhaust leaks or excessive heat. Off topic, Drew, I saw in your bio that you have a 95 525i. Very cool. I have a 92 525it. Love it. So simple to work on. Anyway, I will update this thread tomorrow after I tinker a bit. Thanks for helping me think through this.

[drewusmaximus]

I no longer have the 525. I loved that car. Very easy to work on because the entire engine was accessible. I have a feeling it might be the exhaust manifold. How does the bonnet look? Is there a specific dark spot on it? I would definitely retorque the manifold bolts and test. Good luck and keep us posted!

[Elka]

So I got up under the car and although it is leaking oil at the right rear corner of the valve cover and dripping on the cats, it didn't look like any of the smoke was coming from a leak between the head and exhaust manifold. I threw my scan tool on and drove around looking at the short term fuel trims. Bank one is running quite lean (9-11% fuel trim adaptation), and bank two is running a smidge rich (-.8 fuel trim adaptation). I am still getting a Band1sensor 1 O2 sensor is sluggish but I just replaced it with a Bosch.
I rechecked the crankcase pressure and it is -41mb compared to 33mb spec. So a litte to much vacuum. I will replace the valve cover, pvc valve, and a new valve cover seal and see if that reduces the lean condition any. Then I will switch injectors around to see if the bank one lean/bank 2 rich pattern switches too. I will update asap. I fabricated a plate to go over the secondary air injection valve port that is threaded for a 0-5psi gauge. When the gauge gets here, I will confirm there is not excessive exaust backpressure just to rule that out. I'll update when I have more information. Merry Christmas!

[Elka]

So I plugged in an exhaust backpressure gauge in the bank 1 O2 bung and, although it bounced so much that it made it hard to tell, it didn't look like it was over 3psi at 2500 rpm. Idle may have been more than 1.25psi though. I did find that the air injection hose was melted at the air injection valve end (not the pump end) which would imply excessive heat (at least at some point). I removed that hose and started the engine. The valve allowed no exhaust to pass back up toward pump. i could put my hand over the hole in the injection valve and felt no exhaust...that was at idle. Maybe it has a weak spring though and allows a backflow of heat at higher load.
As for catalytic converter temps, I checked with an infrared thermometer and found:
front of bank 1 cat - 399F
Front of bank 2 cat - 333F
Center pipe where down pipe meets center pipe bank 1 - 267F
Center pipe where down opipe meets center pipe bank 2 - 103F
Not sure why the difference is so much there. Does that mean that bank 2 cat is dead and producing no heat through the catalytic process?
These numbers may be flawed somehow.
Here is some live data showing short term fuel trims, long term fuel trims, and cat. temp both at idle and at load.
At idle:
IMG_1195.jpg

At load (going up a hill):
IMG_1187.jpg
So at idle, fuel trims look acceptible. Under a load, bank 1 is too lean and it's having to adapt by increasing injector pulse width 12%. Bank 2 is a bit rich and it's having to adapt by reducing injector pulse width 7%.
The oil is definitely coming from a failed VCG after only 900 miles. I am ready to replace it, but I want to diagnose why it failed before I do.
Oh, I did notice small oil bubbles coming out at the base of the air injection valve. That is what made me wonder if there was backpressure in the exhaust. Should their be oil leaking out of that place? I thought that was just exhaust.
Anyway, I was hoping something popped out to you and you might have an idea of what more to test. I still plan to swap injectors from bank 1 to bank 2 (one at a time) until bank 1 shows rich and bank 2 show lean.
I am now leaning toward a defective injector valve only at high rpm. That will be my next test I think.
Blessings

[drewusmaximus]

The temps for the cats should be around 1000-1200 degrees. 399 degrees is awfully low. At a cold start, the cats can reach 500 degrees within a minute. Might be clogged cats? What is the temp on the exhaust manifold? Start the car, let it idle for a couple of minutes, Then check the temp starting at the manifold and work your way down to the secondary cats. Those cats should be around the 1000 degree range. Keep us posted.

[NHinNC]

The temps for the cats should be around 1000-1200 degrees. 399 degrees is awfully low. At a cold start, the cats can reach 500 degrees within a minute. Might be clogged cats? What is the temp on the exhaust manifold? Start the car, let it idle for a couple of minutes, Then check the temp starting at the manifold and work your way down to the secondary cats. Those cats should be around the 1000 degree range. Keep us posted.

Is that 1K temperature for the substrate or at the outer can?

[drewusmaximus]

If you plug in an OBD reader and check the live data on a cold start, you should see the CAT temps reach 1000 degrees within a minute. The temp is for the cats. Not sure what the temps are at the muffler. Keep us updated d

[1320euro]

I know this is an older thread by 2 months or so. Just wondering if any results?

Running into this on my gfs car. Original valve cover melted right at 2nd air valve. Melted hose too. Replace valve cover, hose and air valve. Lasted not even 1k melted again. No fault codes leading up to it melting.

[drewusmaximus]

I know this is an older thread by 2 months or so. Just wondering if any results?

Running into this on my gfs car. Original valve cover melted right at 2nd air valve. Melted hose too. Replace valve cover, hose and air valve. Lasted not even 1k melted again. No fault codes leading up to it melting.

Two months, 7 months, who cares... That's what the forums are for.. To help each other regardless of time.. Do you have an OBD reader? If so, plug it in at cold start, watch the live CAT data and see if the CAT temps goes over 1000 degrees. If the CATs go above 1000 degrees within a minute, the CATS are not clogged. If the CATs don't go above 1000 or take a while to reach 1000 degrees, it's possible the CAT(s) might be clogged and the exhaust gases are not escaping as fast as they should, thus building up by the secondary air pump connection. From my understanding, the secondary air injection pump is connected to the exhaust to help during start up. If the exhaust gases don't flow as they should, I assume those gases will build up by the secondary air pump connection. If this issue occurred on other models that don't have the secondary air pump, then I would focus elsewhere, but it seems to occur on models with the secondary air pump. If the CATs are clogged, that's probably due to oil consumption, which points me to the CCV sucking oil. I would replace the CCV along with the VC, then clean the oil build up on the piston heads, intake and throttle body. Since you're going to replace the VC, you might as well replace the CCV and clean stuff up. It might seem intimidating to do that work, but it's rather straight forward. Have the right tools, pick a nice weekend, keep the parts you take off together and organized and take pictures so you know how to put things back. But, if the CATs are clogged, I don't know how to clean them. I've read people gutting out the CATs, which also gives them a bit more umph, but I don't know how to clean clogged CATs. Keep us updated..

[Elka]

Two months, 7 months, who cares... That's what the forums are for.. To help each other regardless of time.. Do you have an OBD reader? If so, plug it in at cold start, watch the live CAT data and see if the CAT temps goes over 1000 degrees. If the CATs go above 1000 degrees within a minute, the CATS are not clogged. If the CATs don't go above 1000 or take a while to reach 1000 degrees, it's possible the CAT(s) might be clogged and the exhaust gases are not escaping as fast as they should, thus building up by the secondary air pump connection. From my understanding, the secondary air injection pump is connected to the exhaust to help during start up. If the exhaust gases don't flow as they should, I assume those gases will build up by the secondary air pump connection. If this issue occurred on other models that don't have the secondary air pump, then I would focus elsewhere, but it seems to occur on models with the secondary air pump. If the CATs are clogged, that's probably due to oil consumption, which points me to the CCV sucking oil. I would replace the CCV along with the VC, then clean the oil build up on the piston heads, intake and throttle body. Since you're going to replace the VC, you might as well replace the CCV and clean stuff up. It might seem intimidating to do that work, but it's rather straight forward. Have the right tools, pick a nice weekend, keep the parts you take off together and organized and take pictures so you know how to put things back. But, if the CATs are clogged, I don't know how to clean them. I've read people gutting out the CATs, which also gives them a bit more umph, but I don't know how to clean clogged CATs. Keep us updated..

Ok, so I made an exhaust back-pressure tester. I had purchased one, but the rubber hose melted on the first use. So I bought an oil-filled 0-10psi gauge, got an 02 sensor hole adaptor and flared some 1/4" copper tubing so nothing would melt. So bank one was between 0-1.4psi at idle and about 2 at 3000 rpm. Bank 2 was about 1.75 at idle but would undulate between 3-8psi at 2000rpm and if I blip the throttle, it would peg at 10psi briefly. So there was certainly a blockage in the bank 2 exhaust line. So I disconnected the pipe right at the downpipe (before the second cat) to see if the blockage was in the first cat (on the intake manifold) or the second cat (under the car). When I rechecked the back-pressure in bank 2 after disconnecting it there, there was zero backpressure at idle and .5psi at 3000rpm. So the blockage was in the second cat. Rock auto had a wholesale close-out (last one in stock) on a Bosal cat, so I installed it and there is zero back pressure on bank 2 now. The elusive exhaust leak sound is gone. It revs smoother and more readily. I am going to replace the VCC and secondary air injection check-valve seal. They both failed after a long trip of 2600rpm driving. It would have caused sustained higher backpressure, and heated up the check-valve seal. As for the VCC, I think the blockage prevented exhaust from evauating the bank 2 cylinders as well, which meant less air was drawn into those cylinders, which decreased vacuum in the intake and crankcase at higher rpms. The positive crankcase pressure caused the CVV failure prematurely (or the added heat in the head in bank 2). Anyway, oil seems to have stopped leaking at cylinder 6 (I assume due to lower crankcase pressure) and I will monitor it for a few days. Power is increased at higher rpms. Just wanted to update you all to let you know that if you have high heat at the secondary air injection check-valve or a leaking VCC that is newish, do an exhaust backpressure test.

[drewusmaximus]

Awesome! Glad you figured it out. Thanks for the update! Another one for the books...