Carbon buildup and fuel injectors

**Grizzlie** · 05-27-2006, 12:59 PM

I have a 2004 Sprinter. When it was newer the engine made a 'popping' sound when accelerating. This sound was accompanied by a deifinite drop in engine rpms. The mechanic at the dealership 'said' he couldn't hear it and therefore never made any notes of it.
Fast forward 2 years and 178,000 miles: I am getting exhaust fumes in the passenger cabin. Same mechanic pulled the top cover off the engine and discovered massive carbon buildup over the fuel injectors. Injectors 4 & 5 are not even visible. They are buried under a large 'lump' of carbon. #3 is only partially visible.
Mechanic said he could clean the carbon out for $750.00. He said new injectors are $400.00 each. Total estimate to fix: $4,000.00!
I can't afford to repair this vehicle and therefore have parked it. I'm losing money every day it's down however.
I think if I clean the carbon out and replace the copper seals on the injectors I might be all right. It should eliminate the exhaust leaks in the cab. Believe it or not, the engine runs aboslutely fine with no misses or anything.
Has anyone ever heard of this problem? Does anyone have a remedy? Is this repair possible for a 'backyard mechanic'?
Please Advise,
Grizzlie

P.S. - I purchased a new 2006 Sprinter around the first of April. I've not experienced the 'popping' noise with it. Could the popping noise be related to the exhaust leaks and carbon buildup?

**BestSprinterTech** · 11-10-2006, 02:08 AM

Not too comon of a problem but I have seen it. The brass o rings are leaking compression, which in turn makes that carbon build up. It takes for ever to get all that carbon out. Replace the injectors and brass o rings, there is no saving them. Plus the injectos are held in by torx bolts the carbon has worked its way into that torx head and you have no way to grab onto that bolt to get it out. Then good luck getting the injectors out they will be stuck in there pretty good. We use a special tool at work. Even with that tool its a pain in the ass. Sometimes you can get all that carbon out and everyting goes ok, sometimes they cylinder head needs replaced. Depends on if any bolts break off, etc.

**Grizzlie** · 11-10-2006, 08:58 AM

Thanks for the info. It's pretty much as I suspected. Unfortunately the company won't even discuss the problem with me because of the age and mileage of the vehicle. I believe the 'popping' sound I heard coming from the engine compartment when the truck was brand new (and under warranty) was caused by the leaking injector seals. So this problem came straight from the factory. Daimler Chrysler refuses to even consider this as a warranty problem. I faithfully took my vehicle to the dealer for every service appointment during the warranty period. The mechanic remembers me bringing it in for the popping noise, and now agrees that the problem was there when it was new. DC, on the other hand, doesn't even want to discuss the possibility of covering the repair.
In the meantime the truck continues to run well, though with a slightly decreased fuel economy, about 2 mpg less than my other one. I need to get serious about repairing it and get to it. But by keeping the windows down about a 1/2" the exhaust smell inside the cab is minimal and we're making some money with the vehicle.
Thanks for your reply and the repair tips!