Well I ran a buddy's boroscope into my intake manifold over the weekend and just as I suspected there was significant build up of carbon on the intake valves. I have been having drivability issues that have worsened over the summer. I strongly suspect one or more of the valves is sticking open intermittently.

I took the car to two different dealers and one dealer was downright hostile and accusatory while the other simply blamed my aftermarket parts for the problem. The first dealer stated that I had blown a piston because I had low compression on one of the cylinders (any mechanic worth his salt can tell you that a leaky intake valve will cause the same problem).

I have put a bandaid on the problem my fixing a miniscule boost leak and replacing the upper tmap sensor. The car runs (mostly) but my friend the engine machinist tells me that he feels like the head needs rebuilt at this point as there continues to be at least one valve that is not seating properly. Not sure what to do since the dealers want to say my parts are the problem. I have some valvetrain chatter at 2000 rpm and the car sounds wrong when downshifting and letting off the accellerator at 3000 rpm. There are currently no codes being thrown but I think that's because of the cooler weather. It is very frustrating.

 

Have you tried to seafoam your engine? It may help.

 

Seafoam wont help on a DI motor. Ive seen guys doing walnut shell blasts on the valves to clean them up with fairly good success.

 

Yeah I seafoamed earlier this summer but it had no real effect that I could discern. From what I have read about seafoam, it doesn't really help with severe deposits and may do nothing with mild deposits. Severe hard coking of the stems seems to have been unimproved in my case.

 

I have heard about using a low ash euro blend oil. Not sure if its available in stores but I know i can get it through amsoil.

 

I too am worried about this....considering I just bought my LNF SS. It has 17k miles.

Anyone tried removing the intake manifold...and tried brushing off the gue with some gasoline?

 

John over at Powell suggests that and a few other things in this thread.

https://www.cobaltss.net/forums/2-0l...e-gunk-282355/

 

People have removed it and used a toothbrush to clean them manually with some success

 

The pics at the beginning of that thread show deposits that are mild compared to the ones in mine. I may see if I can get a good one to post this evening. There would be clearance issues between the carbon deposit and the wall of the port in mine. It's very bad.

 

Walnut shells or a c02 blaster would work the best in my mind.

 

CO2 blaster? I am not familiar with this.

BMW dealerships do the walnut shell treatment. I don't know of anyone that might do that within 500 miles of me and I loathe the thought of taking my car to a high end import shop that might have the tools required. $$$$$$$$

 

c02 blaster is a machine that sprays little dry ice pellets. Once they hit the material they evaporate right away and it leaves zero fluid behind so all the **** will come off the valves really easy. Not cheap though.

 

No I wouldn't imagine anything regarding this repair is going to be cheap. I would love for GM to honor the warranty and fix this but that doesn't seem to be in the cards at this point. It's annoying as hell. Really annoying when I see Fiat ads that seem to encourage people to mod their 500's and Abarths.

 

That makes sense seeing as how this is in the LNF section, my bad.

 

^This.

Its by far the best solution ($$$$). This method is used in all types of cleaning because of how it leaves no additional mess behind, is great for delicate surfaces and truly does a phenomenal cleaning job.

 

The machines are far from cheap though.

 

Rentals for dry ice blasters run $700/day as far as the research I was able to do today. Even at half or a third of that it's still pretty damn high.

I will do the walnut shell treatment. Was on some of the BMW. Audi, VW forums today and it's pretty straight forward. I have more than enough mechanical experience to do this job. (Replaced the rings and bearings in my old LeBaron). It's mostly a matter of time to do it and I have already pissed away too much time with dealerships.

My Dad's shop has a media blaster and big froggin compressor so I just gotta buy walnut shell media and an intake gasket. Maybe a drop-cloth so this **** doesn't get everywhere. I will take some pics and post them up. Car guys love that ****. LOL.

 

Do it!!!!

 

anyone ever think of trying egr delete to help with the issue?

or just buy a new head every few years

 

or is it true that we dont have an egr valve

 

We do not have an EGR valve.

 

Ya I read that after I posted

 

That 700 dollars is just ridiculous, you would pay for the machine after a week of rentals. If your ever in Ontario you can come use my partners haha. I'm yet to try it out (busy/lazy) but all this talk makes me want to drive over there and start shooting stuff.

 

If I'm in Ontario I'll take you up on that. Hell I wouldn't even worry about the valves. I would just like a chance to blast some **** with dry ice. We could remove the labels from our empties with it. LMAO!!!

 

I feel like buying a new head would be a better idea, then cleaning your old one and when your new head gets dirty you swap that one on haha