[crunk04gtp]

Hi all,

Brought my car into an indy to have them blow smoke through the system as I was now pretty sure my ongoing lean condition was caused by some sort of vacuum leak. They tell me there is a leak coming from under the intake manifold but wanted 5 hours labor to take it off and look closer. There is also a misfire on cylinder 1. Not too much experience with these folks so I told them to hold off.

Are there any common problems with vacuum leaks under the intake manifold on M113s that this might likely be or am I in less charted territory?

Does anyone have any suggestions on how I should proceed with fixing this on my own, or ideas on the difficulty of such a venture?

Warren, is it cool if I cross post this in another sub-forum that has the M113 engine to see if they have any ideas?

Thanks,
Bill

*note: misfire on #1 is not occurring enough to throw a DTC

 

[Check Codes]

The only real candidate (short of a crack in the manifold or something) is the little vacuum hose at the front bottom of the manifold that supplies vacuum for the changeover system. This is common to ALL M112 and M113 engines, AMG included.

You can easily see the hose (at least where it disappears into the manifold) if you remove the secondary air injection pump.

And if that's it, then yes, the manifold does have to come off. Depending on your mileage there are a host of other PM-related tasks you can accomplish simultaneously.

How are your DIY skills? It's not that rough to R&R the manifold.

 

[crunk04gtp]

I'd give myself a 7 or 8 on a 1-10 scale in terms of shadetree mechanic abilities. For reference, replacing an injector pump on an OM617 is something I wouldn't hesitate to do. The biggest thing that puts me through a loop is working in tight spaces, other than that I'm pretty proficient.

I spoke to the tech a second ago and he said he thinks it is the manifold itself and that if I take it off a visual inspection should let me know if that's the case. I'm leaning towards DIY on this one. What sort of preventative maintenance should I do while the manifold is off? Are there any specialized tools I should get for this?

Few updates on the symptoms:
-One thing I forgot to include is that I've noticed a pronounced high pitched whine coming from the front of the engine which has gotten worse recently. That sounds more like the hose you're referring to than the manifold itself?

- lean condition has always been only when the car is at idle

-They said it was smoking BAD (like, "hey guys come and check this out" bad)

-Car is idling way worse than when I brought it in a few hours ago. Thinking the smoke might have made the leak worse.

-Apparently it is throwing a code for the #1 misfire and I misunderstood.

Thanks again for the advice. It's really appreciated.

 

[crunk04gtp]

I ended up farming it out as there's a tenuous situation at my job and taking a day off to take care of this seemed like a bad idea. Problem was a diverter valve was damn near sheered off at the flange. Seemed like the sort of thing that could have been remedied w/o removing the manifold but I wouldn't have caught it before doing so and neither did three other mechanics who have looked at the car. C'est la vie.

From what I can see car is no longer running lean Still a little rough though. My understanding is that working properly the idle should be glass smooth inside the car. Since it's probably been lean for 15k miles or more I'm thinking good chance plugs are fouled. I didn't want to bother with them until the lean condition had been resolved. Hoping cats are fine, but I feel like the car would throw a DTC if they went bad?

 

[eric242340]

I ended up farming it out as there's a tenuous situation at my job and taking a day off to take care of this seemed like a bad idea. Problem was a diverter valve was damn near sheered off at the flange. Seemed like the sort of thing that could have been remedied w/o removing the manifold but I wouldn't have caught it before doing so and neither did three other mechanics who have looked at the car. C'est la vie.

From what I can see car is no longer running lean Still a little rough though. My understanding is that working properly the idle should be glass smooth inside the car. Since it's probably been lean for 15k miles or more I'm thinking good chance plugs are fouled. I didn't want to bother with them until the lean condition had been resolved. Hoping cats are fine, but I feel like the car would throw a DTC if they went bad?

Give it a good blast down the freeway to clear out the carbon build up and see if this helps before getting in any deeper.