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2.0 LNF Engine: How-To: Repair LNF cylinder head oil leaks

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2.0 LNF Engine: How-To: Repair LNF cylinder head oil leaks

Old 09-17-2009, 12:16 AM
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How-To: Repair LNF cylinder head oil leaks

Is your LNF powered Cobalt SS leaking oil from the drivers side of the cylinder head? Has your local GM dealership been less than helpful on the matter? Well fret no more! In this how-to I'll attempt to guide you though fixing this once and for all. My car has been leak free now for a thousand miles and about a month, so I feel comfortable posting my method.

All of this originally came out of a 15+ page thread found here:

https://www.cobaltss.net/forums/2-0l-lnf-performance-tech-153/intake-camshaft-sensor-issue-153670/

And then a analysis thread of my leaky Cobalt here:

https://www.cobaltss.net/forums/2-0l-lnf-performance-tech-153/oil-leak-analysis-my-09-tc-186430/

Chances are your car is leaking from all 3 places too, and if its not now.... it might soon. I'd recommend just doing all 3, but if you want to cherry pick your specific issues be my guest. Also please note some of the pictures might seem out of order. Now that I've done this job, I would've taken the car apart differently. When I started I had no idea that my car was leaking from 3 places either.

A set of metric gear wrenches makes this job a snap, but any small metric tool kit should do.

1.) Remove the low pressure fuel pump relay, and start the car to relieve fuel pressure. The car will die on its own. Try to start it a couple more times to be sure the pressure is relieved. Consult your owners manual on the exact location of this relay, but its located in the engine bay fuse box. Once the car won't start, remove the negative battery terminal in the trunk. We're working with fuel and electronics here, best to be safe.

2.) Loosen t-bolt clamp on hot charge pipe from turbo, loosen & remove T30 torx on the hot charge pipe about midway (where it bolts to the bracket on the cylinder head) and then finally pull it off of the turbocharger. Carefully maneuver this pipe out of the way as you're working on the car. The lower rubber section will give you the freedom of movement you need without totally removing the pipe.

Should look something like this:

http://www.ecimulti.org/gallery2/mai...serialNumber=1

3.) Now, remove the bracket the hot pipe was bolted to via the T30. There are three 10MM holding this bracket to the cylinder head. You also need to disconnect the large wiring loom on the side. Use a flat blade and carefully undo the plastic wire loom holder from the bottom. You'll also need to remove what I believe is the evap purge line that runs over top of this bracket. Just simply disconnect it from the solenoid on the intake manifold and maneuver it out of your way. Also disconnect the harness from the high pressure fuel pump.

Once the bracket is removed, go ahead and also remove the sound isolator off the high pressure fuel pump too. You may also want to remove the larger vacuum hose that runs above the oil filter housing and goes to the front of the intake manifold and route it out of the way for now. Remove any wiring that looks like it might get in the way of the next steps, I can't remember everything I disconnected. Just mentally note what you did so the car will run again.

Should look something like these:

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=1

4.) Using a 17mm flare wrench, remove the feed line and pump output line from the high pressure fuel pump. You do NOT need to remove the pump output -> rail line, just loosen at the rail and it'll pivot out of the way. Have a rag ready to catch the fuel, you will spill some. Remove the two 10MM bolts that hold the round (I think this is a pulse dampner? but not sure) silver disc to the intake manifold and then the feed will move right out of the way. Remove the two 10MM bolts holding the fuel pump to the cyliner head and stow the pump in a safe place for now. I'd advice having a rag ready and under the pump to catch oil. Do NOT damage the gasket or o-ring on removal.

Should look something like these:

http://www.ecimulti.org/gallery2/mai...serialNumber=2

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=2

http://www.ecimulti.org/gallery2/mai...serialNumber=2

5.) Remove the 3 10MM bolts holding the intake cam end cap to the cylinder head. Not much to say about this one. Note which position the end cap was in, although it doesn’t appear to matter what orientation its installed from my eyeballing. Have your rag ready to catch oil from this too.

Should look something like these:

http://www.ecimulti.org/gallery2/mai...serialNumber=2

http://www.ecimulti.org/gallery2/mai...serialNumber=2

http://www.ecimulti.org/gallery2/mai...serialNumber=2

6.) Last but not least, remove the cam position sensor from below the high pressure fuel pump. It's held in with a 10MM bolt which you should remove. Then, CAREFULLY nudge the sensor out with a flat blade screw driver. Do NOT damage the o-ring upon removal.

Should look something like these:

Here is the sensor, its the black thing covered in grime

http://www.ecimulti.org/gallery2/mai...serialNumber=2

http://www.ecimulti.org/gallery2/mai...serialNumber=2

http://www.ecimulti.org/gallery2/mai...serialNumber=2

7.) CLEAN EVERYTHING UP. Use your favorite cleaning agents (mine was brake cleaner) and clean ALL components thoroughly. I mean down to the wiring, sensor, end plate, fuel pump and all mounting surfaces. Make sure you get the bore where the orings rest clean too. There was also a large amount of oil and gunk on my cylinder head and the top of my transmission. I would advise highly against getting any brake cleaner on the fuel pump gasket OR any of the o-rings. Carefully remove the o-rings with a tooth pick and set them aside. Just wipe those off with shop towels and don't lose them.

Now to stop these leaks we must use RTV. On my car I used Toyota FIPG (Form In Place Gasket) which has a work time of 15 minutes and run time of 1-2 hours. I don't advocate which RTV you use, just telling you what I used. Any quality RTV that is made to resist oil will do. ThreeBond comes highly recommended and Yamabond & Hondabond might also be good alternative. I would skip the el cheapo brands at the auto parts store and go with a high quality OEM approved sealer in general.

Here is a picture of a FIPG tube with the Toyota P/N on top. This P/N is specifically for oil usage on oil pans (Toyotas don’t use oil pan gaskets, just RTV bead), cam caps and other places where oil seepage must be stopped.

http://www.ecimulti.org/gallery2/mai...serialNumber=1

9.) Reassemble in the order we took it apart.

Run a nice small bead of RTV into the grove the o-ring rests in on the cam position sensor. Then slide the cleaned o-ring over the sensor and into this groove. I would then run another small bead of RTV over the o-ring. Reinsert the sensor into the cylinder head and torque the bolt to 10 ft lbs. If you don't have a torque wrench, snug it down but don't KILL it. 10 ft lbs isn’t a whole lot of torque

The pictures I took of this didn't come out, sorry about that.

10.) On the cam end plate, I chose to ditch the formed o-ring GM used from the factory. Take your cleaned end plate and insert the 3 bolts just about 5-10mm into it. There are nylon holders that will make reinstallation much easier this way. Otherwise you're bumbling around trying to center it. Run a bead of RTV into where the formed o-ring once was, and then compress this INTO that valley. Run another bead on top of that to form a nice 5mm bump. Reinstall the end cap onto the cylinder head and evenly torque the bolts to 10 ft lbs of torque.

After this sucker drys, I can promise you it'll never leak again.

Here are some pictures to make that procedure a little more clear:

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=1

11.) Now on to the fuel pump, we're getting close! First run a bead around the circular base of the fuel pump where it mates to the head. Look at the pump and you'll know exactly what I mean. Slide the cleaned or new gasket (note the orientation, the gasket says which side goes out/in) and compress it against that RTV. Then run another bead of RTV around that same circumference. This will make a nice RTV sandwich. Then, just like the cam position sensor, run a small bead of RTV into the groove where the o-ring rides. Gently slide on the cleaned o-ring and like before run a light bead on the o-ring. Gently insert the fuel pump into the cylinder head and tighten the two bolts to 10 ft lbs.

I forgot to take pictures before laying down the gasket, but hopefully these will help some:

http://www.ecimulti.org/gallery2/mai...serialNumber=1

http://www.ecimulti.org/gallery2/mai...serialNumber=1

12.) Now its time to put everything else back together. I'm not going to write much on this except to note the fuel lines going to the pump can be a bit tricky. Make sure you align them straight as possible before tightening the compression nuts. Technically, those lines are supposed to be replaced after being used just ONCE. I and others haven’t had any issues though, but don't blame me if your car bursts into flames. If I ever took them off again I'd likely replace them.

I would highly recommend letting the RTV dry for at LEAST 12 hours before driving, 24 if you can. Most say run in 1-2 hours, but why take the chance? Not worth having to do this job again.

I hope this how-to helps some of you, and if anyone thinks I missed something please PM or post and I'll edit the how-to. Until next time...


Last edited by Gimpster; 10-02-2009 at 12:48 AM.
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Old 10-02-2009, 12:31 AM
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BUMP!

Finally got approved, hope folks with oil leaks get some use out of this.
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Old 10-02-2009, 04:28 AM
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Awesome! Thanks! If I can't get my dealership to fix this, I'm going to have to do it myself.
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Old 10-02-2009, 11:22 AM
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click
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Old 10-02-2009, 11:42 AM
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good write up !!!!!
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Old 10-02-2009, 01:30 PM
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excelent how to! I would note, the cleaner the application of the silicone bead is, the more effective it is
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Old 10-02-2009, 02:44 PM
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Excellent!
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Old 10-03-2009, 04:28 AM
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I dont know about you guys but i removed my sensor and the cam end plate and replaced the sensor with o ring and the end plate gasket under warranty and i didnt remove the fuel pump or anything else for that matter. Im a gm tech so i do all my own warranty work which is a bonus. No leak now.. Great How To tho
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Old 10-03-2009, 12:46 PM
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Many people have just had orings swapped by dealers and the leaks came back. In my case the local dealerships didn't even want to fix it, period. In the analysis thread we were advised by the resident GMPP engineer to fix the car using this method. Before that in the bigger thread other people had also used the rtv method. This is how I managed to stop my leaks and thought I'd share.

Every car is different. My car was pissing oil out of the end plate, the fuel pump and the cam position sensor. The pictures don't do it justice, there was oil EVERYWHERE and leaking down the front side of the bell housing all over the transmission mount.

I can tell you this much, its still squeeky clean down there.
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Old 10-08-2009, 05:24 AM
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thanks for the write up. i will fix my small leaks this weekend, yay.
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Old 10-17-2009, 03:58 AM
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its been 1 week, and its bone dry. i'm so glad theres one less defect in my car now.
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Old 10-22-2009, 04:32 PM
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How long does this whole project take?
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Old 10-22-2009, 05:02 PM
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Excellent write-up Gimpster!! I've linked to this from our provincial Cobalt club's site in case anyone over there wants to take a crack at resolving this themselves .
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Old 10-23-2009, 12:36 AM
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Hmmm, maybe 1-2 hours depending on your mechanical ability. However you should really let the RTV cure all the way.

Originally Posted by Psytocrophic View Post
How long does this whole project take?
Hey, glad some of you found it useful.
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Old 10-24-2009, 08:26 PM
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Great write up man, helped me out ALOT it really was a breeze to do.

I left out the Cam end plate also but after i put it on and everything i felt i should have left it in. I mean put some RTV where the gasket was and then some more on top of it. I really dont see how it could of hurt.
Im a little worried that the rtv wont hold on the end plate but your saying yours is holding up just fine.

Whatever ill keep a close eye on it, if it leaks i have the gasket and that really is the easies leak to get to. If it hold...then great!

Thanks alot gimpster!
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Old 10-25-2009, 12:05 AM
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update: mine is still dry till today
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Old 10-25-2009, 04:25 AM
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till today? Meaning it leaked today?
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Old 10-25-2009, 10:53 PM
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i meant still no leak still this day, haha.
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Old 10-26-2009, 02:09 PM
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Originally Posted by fakameanrepresent View Post
i meant still no leak still this day, haha.
haha ok!
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Old 10-27-2009, 12:50 PM
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i am going to go to my dealer after i take all of my dam parts off. i dont have the time and the place to work on something like that.

would it be a bad idea to print this off and bring it in to the dealer. not say the website or anything just bring in the picks of where the oil is coming from and tell them what it is.

i also have to figure out if that is what is actually leaking on my car. mine looks like that but also my oil is gettting caught in the 2 slots behind the oil filter cap.
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Old 10-27-2009, 02:58 PM
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More Torque More HP on here claims there is a TSB out for this now, but I've not seen anyone post it. The TSB would likely be motivate them more than this article, but who knows.
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Old 10-27-2009, 04:03 PM
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Originally Posted by Gimpster View Post
More Torque More HP on here claims there is a TSB out for this now, but I've not seen anyone post it. The TSB would likely be motivate them more than this article, but who knows.
they are going to look at me like im retarded. i am going to tell them that there is alot of ppl out there that are having problems. then they are going to ask me where i got my info. i have heard of ppl bringing a print out from here with them and the dealer changed alot of **** on there car.
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Old 10-27-2009, 04:31 PM
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I haven’t noticed any leaks on mine, but this is good to know in case it does start.
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Old 10-28-2009, 01:20 AM
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how many miles have you guys put on since doing this
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Old 10-28-2009, 03:45 AM
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I tried to get my dealership to fix this but they were less than helpful. Infact they denied that i even had an oil leak and said it was just build up?? Even when i put my finger in there and pulled out with oil my finger and stuck it in his face he still said it was normal.

I looked at him called him a douche bag and went on my way. Fixed it myself, **** the warranty ill fix the **** myself unless its a pricey part.
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