#*%$@ Nailing! - PeachParts Mercedes-Benz Forum

sasquatchgeoff · #1 07-16-2009, 10:03 PM

Here is the story:
My 201 sat up on jacks for about 7 months straight with 3/4 tank of #2 diesel mixed with a small amount of B100 while I completely refurbished the top end of the OM602.911. I did nothing to the IP - it was working great when I dismantled the head - I simply laid a rag on top of it to prevent a lot of trash from getting into the connections that receive the injector lines.

Upon first crank after rebuilding the head and face of the engine I had some serious nailing. Siphoned all but about 1/8 tank and refreshed with straight B5 (the only #2 diesel available in Portland) and that seemed to help a tiny bit. At least that got it to start relatively smooth, but the nailing was close to unbearable.

Took it to the indie thinking the IP timing was off due to the timing chain replacement, but the IP timing was less than 1/2 degree off - the indie left it alone. He says I still have 1500 miles or so to "break in" the chain. In the process of the indie setting up to check timing via the light instrument method, the #1 delivery valve was removed to receive the fitting for the timing light. When he replaced the o-ring and reattached the injector line to the pump, the nailing disappeared! I thought maybe some gunk, water or something else clogging, or otherwise inhibiting proper delivery.

For a while after that, it ran smooth as silk with no nailing. I have topped off a couple of times with somewhat dependably fresh #2 and even took a 350 mile trip yesterday with wonderful performance. Took it out today and the nailing is back, although not as intense as before. It is annoying.

I have put about 750 miles on the car since re-assembly and changed the engine oil to 15-40 Rotella at 500 miles. I keep thinking that it is the fuel. The bottom end of the engine is fine, and the miraculous recovery brought on by the timing check by the indie leads me to think that it is a fuel or IP issue as opposed to pre-detonation brought on by engine oil in the cylinders.

Today I put in some Lucas top cylinder treatment along with a 4 gallon top-off of B99 hoping to maybe get the gunk or water or whatever that was in the fuel. Drove about 100 miles and the nailing is still there. It is 95 degrees in Portland today and I haven't rebuilt the A/C yet.

Thanks in advance for any and all comments/help/advice

- geoff

H-townbenzoboy · #2 07-16-2009, 10:06 PM

I would have the injectors pulled and pop tested to see if they're the culprit.

sasquatchgeoff · #3 07-16-2009, 10:11 PM

They were rebuilt by a certified Bosch service. They should be perfect. I guess I should have mentioned that in my initial post.

H-townbenzoboy · #4 07-16-2009, 10:14 PM

How long ago were they rebuilt?

sasquatchgeoff · #5 07-16-2009, 10:20 PM

I had them rebuilt while the head was in the machine shop. About 6 weeks ago.

jt20 · #6 07-17-2009, 04:18 AM

I know no one wants to hear my gasser allegory... but,

I had a Fiero for a few years and nearly fixed everything to get it back to its 98hp peak performance level (yeah, its a go-kart). It still ran like a 3-legged horse.. I just thought that was how Pontiacs ran from the mid to late 80's. Finally found a cracked exh manifold... fixed that and performance improved. Thought I was done and congratulated myself.

Finally, someone said, when are you gunna get that car of yours car fixed?

- "what are you talking about, its a Pontiac Fiero?"

-is that so?...check your egr valve

-[to myself]: "whatever dumb@#$"

replaced the egr the next day... and drove that car until I crashed it against a brand new BMW... and then some more.....- fiberglass is strong, P.S.

anyhow, egr valves can fail and effect performance severely. Take a look at the locknut and adjusting nut on the top of yours and try to remove any slack by turning it out.

I am also partial to the injector theory, fuel can only absorb so much water in so little time - it does not 'go bad' its millions of years old!

sasquatchgeoff · #7 07-17-2009, 11:42 AM

Loosened the nut and backed off the set screw about a full turn - it was all I could muster - seems to be the max. Tightened locknut back down. The threads were marked with the blue factory seal, so I doubt if it had ever been adjusted. I will test drive on a trip to Eugene today and report results.

jt20 · #8 07-17-2009, 12:52 PM

mr. Sasquatch,

I believe I led you astray w/ the EGR disable. You want to tighten / turn in the set screw as far as possible. This will prevent the valve from opening even if vacuum is applied to it.

Terribly sorry.