I'll cure male baldness before this misfire. - Page 4 - PeachParts Mercedes-Benz Forum

sethza · #46 01-21-2012, 01:41 PM

With the hood open in the morning, I obsessively watch my engine idle before work or school for a few minutes to see if I have a Doc Brown moment and realize there is something obvious and apparent that would cause a bad idle. Just as I'm about to shut the hood, EUREKA! I catch a wiff of raw diesel. I take off my specs and bring my face as close as I can to check every fuel related hose and component under the hood. I put a finger under the lift pump(which I checked, it is working at the very least) and pull it up slightly moist.

Lets rehash, if I haven't scared away everybody yet:

I have a bad idle when the engine is warm.
New injector nozzles hit off 25% of the problem(and vastly improved power at higher speeds)
Delivery valve seals knocked off another 25%
Transmission mount took away another 25% of the physical 'shake'.
There is still a little Thumpy thump thump at warm idle, audible at the tailpipe and can be felt in the body of the car, the engine rocks side to side.

Could a seeping lift pump or primer pump(which is new, but could be the copper ring..) cause a drivability issue that is only present at idle when the engine is at full operating temperature? Is there anywhere where I could just buy the copper seals, since a new lift pump is so expensive and the primer pump is only a couple of years old?

Stretch · #47 01-22-2012, 03:41 AM

Well there are plenty of places you can buy the copper ring seals - any place that sells air / oil filters should stock them. If not they should know who does...

whunter · #48 01-22-2012, 05:48 AM

Quote:

Originally Posted by sethza

With the hood open in the morning, I obsessively watch my engine idle before work or school for a few minutes to see if I have a Doc Brown moment and realize there is something obvious and apparent that would cause a bad idle. Just as I'm about to shut the hood, EUREKA! I catch a wiff of raw diesel. I take off my specs and bring my face as close as I can to check every fuel related hose and component under the hood. I put a finger under the lift pump(which I checked, it is working at the very least) and pull it up slightly moist.

Lets rehash, if I haven't scared away everybody yet:

I have a bad idle when the engine is warm.
New injector nozzles hit off 25% of the problem(and vastly improved power at higher speeds)
Delivery valve seals knocked off another 25%
Transmission mount took away another 25% of the physical 'shake'.
There is still a little Thumpy thump thump at warm idle, audible at the tailpipe and can be felt in the body of the car, the engine rocks side to side.

Could a seeping lift pump or primer pump(which is new, but could be the copper ring..) cause a driveability issue that is only present at idle when the engine is at full operating temperature? Is there anywhere where I could just buy the copper seals, since a new lift pump is so expensive and the primer pump is only a couple of years old?

Yes, it could be a temperature variable leak, sucking random air into the fuel system.

.

sethza · #49 05-16-2014, 10:30 PM

Completely Nuts. This thread is actually better than the first one, I'm bringing closure to both.

Finally got the idle smoothed out on this car. I had gotten frustrated with it and parking it for about a year and started driving my boring honda everyday. However, I got tired of looking at my failure *every single time* I stepped out of my house and decided to give the Benz another shot. Figuring I had nothing to lose, I did what every single person on this forum basically would tell me not to do and ordered a junkyard injector pump from ebay, which was like 80 bucks(not a HUGE risk..) I threw it on this morning and after reinstalling it about 3 times(installed it with the timing 180 degrees off the first time and folded the gasket the second time) it started up and (gasp) idled A LOT smoother even after it reached full operating temperature. I've lost some power acceleration-wise but iIve got to double check the precise timing with the drip tube as I don't think I remembered to adjust it with the throttle all the way open today. More on the results from that next week. INSANE how many things I tried before replacing the IP. Only my luck. At least the rest of my ENTIRE fuel system is brand new. Anyone with a similar problem should at least go through this thread, this is one for the medical textbooks.

whunter · #50 05-24-2014, 10:33 AM

Glad it is resolved.

Persistence does pay off..

.

barry12345 · #51 05-25-2014, 03:09 PM

Hind sight is great. The milli volt method used properly may have reduced the frustration in this case. I was not going to suggest it because of fears of improper application. Done properly it is fairly conclusive and saves time and effort. People tend to take shortcuts with the method. This can invalidate the usage of it.

I still feel it is the best method in cases like this. The injection pump is suspect but hard to prove bad otherwise . Other than by substitution as you have done.

Sometimes temporarily running the car on vegetable oil may indicate it is possibly the problem. The thicker viscosity of it can keep the elements pumping well enough. Basically as the injection pumps temperature increases and the fuel in it. The fuel oil thins down much further than the vegetable oil.

It is my thought that a person should at least read up on the milli volt method it in the archives as once understood it is another tool to keep in the back of your mind to locate problems. When indicated it might be useful it is worth doing usually. In my experience it can save a lot of grief.

You were right though. Had you cured male baldness would have been a better outcome.

barry12345 · #52 05-25-2014, 03:30 PM

Quote:

Originally Posted by whunter

Glad it is resolved.

Persistence does pay off..

.

Glad to see you around. Was becoming a little concerned.

whunter · #53 05-26-2014, 02:08 AM

Quote:

Originally Posted by barry12345

Glad to see you around. Was becoming a little concerned.

I still moderate/scan the forum, answer e-mail / calls from members / customers, as possible.

Currently working prototype research and development instrumentation.
Anything from 30 to 400 channels per vehicle.
The schedule is heavy, fast paced, and exhausting.
Getting enough sleep is critical.

.

barry12345 · #54 05-26-2014, 07:49 AM

Workloads and priorities vary and this is well understood. Personally I was concerned that perhaps something unfortunate like sickness, accident or a family emergency may have been the cause.

I am not a pessimistic person but get concerned when someone seems to drop away from the site for awhile. Especially you as you are generally so active on site. Things do happen though and life has many variations and priorities.

I could only wish in your case that you had won a major lotto for example and where still in shock.

Anyways all sounds good. Hope the project goes well.

You are still much younger than myself. I always thought that as we age more free time is available. Especially in so called retirement as is my case. This is not my situation.

.Nobody forewarned me that this could be the case. Self inflicted or otherwise it is what it is. I have to force free time from my still growing list of things to so.

As I sit here this morning at the keyboard I should be out there on a materials acquisition run by now for example . I can defer this for an hour or so though. An extra coffee is good.

What really concerns me in this area is so many young people seem to have so little to do. Not even jobs in many cases. If a simple person like myself can be busy and productive pretty much all his life. Something is really wrong out there now for many.

A part of my life was always learning in one way or another. Too many of the young seem to not have developed this passion. This to me this is a sad situation. Somehow or other our basic educational system or society seems to have failed for too many of them. .

That North America seems to have undergone fundamental changes may be one cause. Or the concept of implementing family values has broken down. External influences seem to be growing that displace them in too many cases. The still rapidly growing drug culture is a horrific example I notice.

I know I am wandering a little or a lot if you wish with this second coffee. That too is just what it is. I just basically wish everyone well. I better get going though or those heat pumps will not get installed today.