Gimpster

This is a continuation of the 16 page long thread about the cam position sensor leaking. I will eventually (unless someone else beats me to it) do a complete how-to on repairing these with photos. I realize that some of you have fixed this with RTV, but I’d like to understand this issue more. I think GM might like to as well. I’d not seen many detailed pictures on what’s going on, so thought this might help some people too.

I’m not going to speculate too much on what I think is causing this. I think it’s a combination of a few things, but would prefer the input of an engineer.

My back story: I purchased this car 3/5/2009 w/160 miles. Pretty much right after I bought this car, I started seeing threads on this. I didn’t bother to check my car until I did an oil change around 8/2/2009. At this point the car had 5000ish miles on it. I observed a good amount of fresh and old oil residue in the general vicinity of the cam position sensor. As of tonight the car has 52xx miles on it. My car is 100% bone stock, has never had a wrench, intake or tune on it.

At this point I took the vehicle to two of the local GM dealers and the SA eyeballed it and said it was “normal”. One SA referred me to the TSB about acceptable oil consumption for new GM vehicles. The people who have been able to get a dealer to service this reported the sensor was swapped, but the leak persists. I decided to fix this myself as many of you have, but I’ll be going about it a bit differently. I’m also cognizant to the fact many people out there don’t like working on cars, so being armed with all of the data they need to get these leaks fixed once and for all will be useful.

Tonight I got a chance to finish taking apart my car, and document it carefully with photos. I discovered my car has the trifecta (sorry Vince!) of oil leaks in this general area. To be honest it’s a bit daunting to even tell what’s going on 100% with the amount of oil and grime down there.

My car was leaking pretty darn bad IMO. There was even pretty fresh oil on top of the transmission bell that was running down towards the front transmission mount. There was also a large amount of oil on the side of the cylinder head that looked pretty fresh. Here are some general pictures of the mess I had.

http://www.ecimulti.org/gallery2/mai...serialNumber=1
http://www.ecimulti.org/gallery2/mai...serialNumber=2

1. Cam position sensor – After getting everything out of the way, it became much more obvious just how much leaking/seeping has been going on here. This thing was gross to handle. These pictures speak for themselves. Note no oil inside the connector of the sensor itself, so definitely the o-ring.

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

2. High pressure fuel pump – I noticed a fine layer of oil and grime around the bottom half (from bolt to bolt) of the fuel pump. I removed the fuel pump to find the gasket between the housing extension and the pump was saturated heavily with oil. It became pretty y obvious to me that oil has been pushing past the o-ring where the pump enters the housing for awhile.

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

3. Intake cam end cap – I then observed a fine layer of oil and grime on say the bottom 3rd of the end cap where it meets the head. I removed the end cap and it was pretty clear that oil has been likewise pushing past this shaped o-ring. I think this might be a case of poorly installed o-ring from the factory. If you look close at some of the pictures, you can see the o-ring was twisted up pretty bad in there. I’m going to order a new one and see if that doesn’t stop this particular leak.

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

So leak 3 I might be able to pass off as a twisted o-ring, but the likelihood of GM going under spec on 2 or possibly 3 o-rings seems somewhat unlikely to me. I didn’t want to speculate too much, but I’m wondering if this engine has a possible crank case pressure problem causing oil to push by? This could be pretty easily checked on a dyno and some pressure testing equipment.

I’m going to just stop right now and quit speculating publicly.

I welcome any and all constructive input.

007G5GT

Nice writeup man, it is SO refreshing to see an intelligent and well written post here. Kudos.

I'm leaking in 2 out of the 3 spots you are, no leak from my cam end cap and I'm at 7200 miles so it wouldn't surprise me if replacing that seal takes care of that one for you.

My dealer has replaced the o-ring at the cam sensor AND the seal on the fuel pump at my request, they didn't even hesitate, I told them what was leaking and they ordered the parts while I was standing there. I checked everything 500 miles later and it was (and still is) leaking just as bad in both locations.

Maybe GM should have went with cork gaskets in these locations as that seems to have stopped the leak for Term2 and a few others. Who knows if that's only a temp fix because the cork absorbs some of the oil or if it will actually permanently take care of the problem.

I agree that it would be nice to have an engineer from GM chime in on this "acceptable oil usage". It's both ridiculous and laughable that GM would even consider this remotely OK, let alone standard procedure for this engine. Buck up and fix the issue instead of pretending it doesn't exist. If I wrote a piece of software with a reproducible bug or memory leak I would man up and fix it instead of telling my users "Deal with it, that's how it was designed."

Not to get off on a rant here but this is one of SEVERAL reasons why I'm kind of unhappy I bought my SS...don't get me wrong, it certainly puts a smile on my face when I'm pushing it to 11/10ths but I've had WAY to many issues for a car less than a year old. Not to mention the god-awful interior rattles. It's embarrassing.

Gimpster

While I think the fixes Terminator2 and others have used on the fuel pump stopped the leak, I believe its treating a symptom and not the problem. Not sure if you've had the pump off... but in addition to the gasket between the head and pump there is an o-ring where it enters the head.

If that o-ring was doing its job, in my mind, oil should never even reach that gasket.

I could be totally offbase on that.

Picture of the oring on the pump in question:

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

About the interior rattles: get used to them I've owned a bunch of GM products and thats just old hack for them. No offense to any GM interior engineers who might read this. The best cure is to own a good sound system to drown them out. Thankfully the Cobalt SS comes with one!

007G5GT

Yea I was kind of a dick in my first post...sorry for that, had just got off work, haha. The interior rattles bug me but I know it's an econobox and I have to deal with them.

I haven't had the pump off myself yet but the o-ring thing makes sense. Maybe an extremely small amount of oil is supposed to be able to slip past the o-ring but not the amount that actually does and the outer gasket can't stop all of the excess.

SSlobalt

Awesome post. Thank you so much for taking the time to write that up.

Gyrocon

yeah gimpster, great post! with 25k Kms on my car now, its interesting that I had the cam sensor oil leak. but strangely, after I passed about the 15K mark on the odometer, the leak has sealed itself. not sure how or why, but it did. I"m not complaining about it that's for sure! hopefully I don't develop any of the other two you mentioned.

More_Torque_More_HP

I am forwarding this post to the proper engineer, I am sure it will help generate a permanent fix.

Permafried-

Permanent would be good; if it goes again outside of warranty I would fight tooth and nail to have GM replace it all over again. Unfortunately there has been no TSB released, no "notes" for dealers that it's a known issue, etc. Long story short, it's costing GM more than it should when it's a known fault with the LNF as techs in the shop will typically run a dye test, etc to confirm that is in fact where the leak is originating .

As for the original post:

Very nice write-up. As for repair at the dealer, mine replaced the part and sealed it (I'd have to get my work order out to recall exactly what they used) to prevent it from happening again. Guess it all comes down to how willing your dealership is to help; sounds like the ones you went to were basically uselss (normal and "TSB" on oil consumption on a new vehicle...please).

Gyrocon, keep an eye on it, if yours "sealed" I'd be more concerned with "why" it did that without any form of servicing. Mine was blasting blasting out oil like synthetic was free (which we all know it is not ). It got progressively worse and by the time it went in they estimated I was losing a tablespoon or so a week. Might not sound like much, but over a 6 month period for example it quickly adds up!

northvibe

iTrader: (1)

sub'ed I will check this when I get home.... Thank you for the post gimpster! And thank you Bill for forwarding this on to gm engineers.

So did Term2 just replace those 2 gaskets with cork ones?

Gimpster

Well, theres only one gasket to make (fuel pump mounting flange). I'm not sure what Terminator2 used... but I'd recommend avoiding pure cork. This comes from many years of replacing cork oil pan gaskets on old GM trucks

I planned on using this material:

http://www.garlock.com/ViewProduct?product=224&region=1

Garlock only sells in bulk, but usually you can find material with similar properties at the auto store. Once again, I really don't think that gasket was designed to stop oil.

On the fuel pump o-ring and cam position sensor o-ring, I'm ordering slightly thicker Viton o-rings from McMaster Carr. If those o-rings work out I'll be happy to post the p/n's. Using my caliper/micrometer I measured the ID of those flanges and the sensor/pump and did some research to find o-rings that might help seal a little better.

Gimpster

Wow, sometimes this site pisses me off. I typed a long post and it ate it with a "database error".

---

I got my trusty calipers out tonight and took some measurements. ID = the diameter of the component itself and OD = the diameter of the orfice it goes into.

Fuel pump ID = 32mm
Fuel pump OD = 34.75mm

Cam position sensor ID = 15.85mm
Cam position sensor OD = 18.50mm

The orginal o-rings could spin freely on the components and were 2mm thick. The components kinda just flop in, seem a shade loose to me from experience.

I'm going to order some Viton o-rings here in a few minutes in varying sizes, and I'm thinking I might step up the thickness a little bit too.

Mindrot

iTrader: (1)

Sticky IMO. Great write up

More_Torque_More_HP

Here is what I have found out so far about the oil leak at the fuel pump. It seems that there is a problem with the Loctite sealer used in production where it is not curing properly. The problem is not with the gasket. The repair is to clean all sealant off the surface and apply 3Bond RTV to the surface and reinstall. MAKE SURE YOU USE 3BOND, I have seen many problem with other RTV sealers.

A dealer bulletin has not been issued yet but it is forth coming.

Hope that helps

Gimpster

Bill,

I don't recall seeing any sealing product (of any sort) when I took it apart. It all just looked like bare aluminum to me. Do they mean to apply the 3bond RTV to the o-ring area, the gasket or both?

CudaJoe

iTrader: (1)

problem found lol.

julius41282

iTrader: (1)

When I first noticed this, I thought maybe it was just oil from the oil filter being removed! I sometimes kinda feel like my car was slapped together by a little kid...

More_Torque_More_HP

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

This picture looks like the RTV coating on the gasket is not sufficient and has an oil leak path. Make sure you clean all the oil off the gasket, the head and the pump.

I would apply the 3Bond RTV and only the 3Bond brand no one elses, to the head and to the back of the pump so that the gasket is making an 3bond sandwich.

Permafried-

Excellent news, thanks for the update! In case anyone is interested, my dealer ran a dye test on mine and replaced the following part; it also mentioned sealant was used (on our provincial forums mine is the only dealer that has ) but I can't recall the name off the top of my head:

Part Number: 12589459
Description: PLANTE N 002930 AR

As best I can tell there is no longer an issue with oil leaking from the general vicinity.

Gimpster

I looked on gmpartsdirect and that P/N just lists as "plate". I'm wondering if that is the end plate?

I sure wish gmpartsdirect had drawings/illustrations of all the parts. Unless I'm really stupid and they DO have a secton for this.

Permafried-

End plate is my guess; I'll post up the work order for replacement when I get home I THINK it mentioned exactly what part was changed but end-plate rings a bell .

jerrodmann

Just looked at this on my car... I got the oil leak... pics to follow. ****.

Tomtwtwtw

Just to confirm, this is by the passenger side of the engine, near the motor mount? (I think that's what I saw in the first picture). I will take a close look at mine this weekend.

Permafried-

Mine was leaking on the driver side. If facing the engine bay it was to the left and behind the fuel pump. Running my finger along it resulted in some pretty greased up hands

Gimpster

This particular post is in reference to the drivers side, but I have seen other posts of peoples valve cover (I guess that would be the timing chain compartment over there) leaking too.

I'm lucky in that it APPEARS my valve cover isn't leaking, but a lot of other people are dealing with that in addition to these leaks I've posted.

oopsitouchedmyself

iTrader: (2)

i've seen tons of that multiswell gasket stuff at my work, lots of piping systems use that as a gasket by me it seems. maybe i could get some if needed.