Is this shudder normal? - PeachParts Mercedes-Benz Forum

macdoe · #1 11-01-2009, 02:37 PM

Hello, I have recently purchased a 1985 300TD.

The problem we have is that at at a certain speed the car seems to shudder under accelaration between 50-60 kms/hr. The face of the speedo has some highlighted orange marks right in between 50-60kms/hr mark and that is where the shudder occurs. That is why I ask if this is a normal instance for this model? My 1980 300TD does not do this. The 1980 also does not seem to have as much power either, though so it is not much to compare to. It has a transplanted turbo motor into it and probably things still missing in the swap. (originaly N/A car )

In the 85,I cleaned the banjo bolt and swithchover valve and lines going to the manifold and to the alda. That seemed to help with the shudder a bit but did not totally cure it. This car also has quite a bit of white smoke when warmed up and when leaving a stop light. When driving for a bit after the stop light the white smoke ceases. It also seems that if I don't give it too much throttle when leaving a light then the white smoke is not so bad.

The guy I got the car from was very honest with me and thought the shudder was because the transmission had problems. The transmission in this shifts great and out of the three diesels I have is by far in the best shape as far as I can tell from driving.( ie. no slipping or flaring)
I don't think this problem has anything to do with the tranny. I think it maybe has something to do with the turbo or the switch over valve-alda? I was also thinking of replacing the nozzles since going through the paperwork that came with the car, it looks like the original injectors and nozzles are still in it. The car starts very easily even in the cold weather. There is no oil in the coolant and no coolant in the oil as I have been keeping an eye on it.

This is the best car in the fleet of MB diesels we have by far in every dept. except for the shudder at that certain speed and white smoke leaving the stop light issues. I also seem to be loosing about a litre of oil every week and a half ( 700kms) This car gets about 500kms per tank of fuel. It has 2:88 rear axle.

My 1980 300TD with transplanted turbo motor gets about 600 kms per tank of fuel. It now has a 3:07 diff. in it. I swapped it in from a 1982 300SD. to put in place of the 3:46 that was original with this car. I have a few things to iron out in this car but it sure seems to get better fuel economy than the 85' which makes no sense to me considering the rear diff ratios and the fact that the 85 has much more guts off the start than the 1980.
Thank you.

kerry · #2 11-01-2009, 02:51 PM

Have you replaced the fuel filters and air filter?

macdoe · #3 11-01-2009, 03:11 PM

Sorry, yes I changed the fuel filters (both, in the engine bay) as well as I drained the tank and cleaned the tank screen. The tank screen was not as bad as I thought it would be, considering the clear plastic filter in the engine bay was totally black when changed.

I did all this at the time I cleaned the banjo bolt to alda and switchover valve deal..... now that I think of it, since I did these three things at the same time I realize I cannot claim cleaning the banjo bolt- alda/ switchover valve as the sole contributor to having a minor effect to the shudder symptom. I would have to consider the new fuel filters as possible factors especially seeing how dirty one of those filters was. The air filter was also changed at this time.
Thanks.

macdoe · #4 11-01-2009, 03:20 PM

I wonder if I have a bad switchover valve?
Would that lead to white smoke and the shudder at certain speed?
Are these two issues even related?
Someone mentioned on another thread, that it could be a cruise control malfunction. I tried to hold the c/c in the off position at these speeds and it does not help.

macdoe · #5 11-01-2009, 11:47 PM

I bought some exhaust valve seals, but I do not want to pull the head off since it runs so well aside from these two things. Some one told me that it may be the turbo seals??
Any ideas?

leathermang · #6 11-03-2009, 08:19 AM

Quote:

Originally Posted by macdoe

I bought some exhaust valve seals, but I do not want to pull the head off since it runs so well aside from these two things. Some one told me that it may be the turbo seals??
Any ideas?

Ok... lets back up a second...

IF you are using the correct nomenclature for what you are talking about the head does not have to come off to install them.

Also, ( unless you are on bad drugs ) you would not take the valve train system down to where you could install JUST the exhaust valve seals and not do " as a matter of principle" the intake valve seals also...
But if you are referring to some other seals all bets are off..

ALSO, valve stem seals of any kind I do not believe can cause any kind of shudder ( except the shudder of thinking about having to take all those things apart and being sure the piston for the valves you are working on is at TOP DEAD CENTER to keep the valves from dropping into the bore ) ... the need to replace them will typically be shown by smoke upon startup but which clears in a few miles after the oil which has dripped into the area where it can be burned is burned up... but at some point they will get bad enough that oil is allowed to enter that area when driving also... so oil usage will become measurable.

GregoryV022 · #7 11-01-2009, 11:56 PM

the orange marks on the speedo are the shift points

pawoSD · #8 11-02-2009, 12:31 AM

Quote:

Originally Posted by GregoryV022

the orange marks on the speedo are the shift points

They are the maximum shift point for each gear....one dot, max of first....two dots, max of second...etc...

Ideally you are shifting long before those dots, or else you're running to near red line in each gear every time....

babyjames · #9 11-02-2009, 01:07 AM

Impeller shaft center-support bearing/mount? Homey didn't match the halves of the shaft properly upon reassembly and it is now out-of-balance?

Shudder or hesitation?? When you say "shudder" I think vibration....

Jay.

TchTchr · #10 11-02-2009, 07:23 AM

Years ago a friend had a gasser truck that did the same thing. If I recall correctly, egr valve was acting up.

macdoe · #11 11-02-2009, 11:43 PM

Yes, it is more of a vibration I guess. I say shudder because it is very brief and seems to come about when between 50-60 kms/hr mark and then it's over. I would think if it is something like the drive shaft put together wrong then the vibration would be there all the time,but maybe not?? I took it out today and it seems to be alot less severe than it used to be, but it is still there. You may be on to something though as I did feel it close to the trans. tunnel this time....How can I tell visually if p.o put it together wrong? I do have the little dots at various speed intervals. The orange marks that I speak of are more like orange lines..five or six ticks between the 50-60km range. They are different than the shift interval marks I think.

zeke · #12 11-04-2009, 10:51 AM

Had a similar shudder in our TD - valve adjustment took care of it.

leathermang · #13 11-04-2009, 10:56 AM

You should check all the rubber mounts, supports, flex deals drive system, the engine and third member supports that are rubber. Some of them ought to be replaced on principle at this mileage unless you have good info they have been replaced at normal intervals..
Then you can start to work down a checklist knowing the obvious but hard to check ' in action' items are in good shape. A perfectly good item next to one that is bad will soon be bad itself ...having more or different vibration input and stress than it was designed to deal with.

t walgamuth · #14 01-21-2011, 04:36 AM

Quote:

Originally Posted by leathermang

You should check all the rubber mounts, supports, flex deals drive system, the engine and third member supports that are rubber. Some of them ought to be replaced on principle at this mileage unless you have good info they have been replaced at normal intervals..
Then you can start to work down a checklist knowing the obvious but hard to check ' in action' items are in good shape. A perfectly good item next to one that is bad will soon be bad itself ...having more or different vibration input and stress than it was designed to deal with.

Yes, and I would say that motor and tranny mounts are suspect in my mind first second I would put the center bearing support (rubber).

The motor has a normal harmonic vibration that occurs briefly at a certain rpm but in a car with an automatic you normally don't feel it. I feel it in my stick equipped 300 because it has less isolation.

hobberslobbers · #15 11-07-2009, 02:33 AM

Quote:

and when I hit the accelerator pedal there is a big puff of whitish smoke that clouds over the cars behind me. It seems as if I can tailor the size of cloud the car leaves behind by how much I mash the throttle when taking off

i about fell out of my chair laughing so hard when i read this!