300TD Hot Idle Shaking - apparently solved - Page 2 - PeachParts Mercedes-Benz Forum

#16 05-26-2003, 10:39 AM

Interesting write up, I wonder if really bad motor mounts with good shocks would manifest the same symptoms?

Heck, I'm mine own worst enemy at times! Being a mechanic, (just not on cars) I have pretty good troubleshooting skills. BUT...., My employer does not actively discourage shot-gunning, and readily supplies any and all parts needed, as they want things fixed, and they are very adverse to taking risks.

When I don't forcefully change my mindset prior to working on my own vehicles, my wallet quickly feels the pain!

On the issue of outside opinions, it would seems so much of working on and troubleshooting vehicles is tactile, it's hard to fault someone for bad advice on something that they have not seen/touched, plus they need to make a living as much as the next guy.

Gotta Go, I have a big box of assorted parts to install, err, I mean return for a refund. Mack

dieseldiehard · #17 05-26-2003, 01:12 PM

Mack, interesting topic, a bit off the original re: motor shocks.
I agree that the shotgun approach covers some improvement in the general worth of a car, so that is not bad if overall reliability is improved as a result. Assuming the owner will pay for it, some won't.
I had a fight with the Saab people, I even called the US rep to look into the issue over a transmission cluster that came apart just out of the 1 year warranty, that was the last new car I ever bought! They agreed to split the labor ($800 in 1972!). The factory had an improved locking washer, the type that has several ears that fold over the hex on the big nut that secures the end of the cluster. Of course they never advise of this in a recall or anything. I found the truth from talking to the mechanic, who I had buddied up to over the year that it was in and out of the shop. The manager found out he had told me of the improved locking device and I think he caught hell. I sold the car and chalked it up as a SAAB Story, LOL!

But I have to add, that if a "shop" mechanic tried one thing, that didn't fix the problem, then tried another and so on until they "hit the source of the problem" I can assure you they would not normally then spend any time uninstalling the previous work that was uneffective. It is a way of life in the fast lane here in the US. I suppose in other countries that may be different as labor is much less, and the scarcity of parts might be an issue.
If you read the fine print on some service agreements it probably adresses this issue.
OTOH, a weekend mechanic on his own ticket can do whatever he wants - especially if its their hobby car or one they don't drive every day.
Oh, here I am wasting time on the keyboard (my second job) I Need to change the MSD ignition out in the 220, and the Weber (BBQ) becons.
BTW I wish I were out at Lake Travis watching the skinny dippers, do kids still go up those chalk lined river beds and drink beer on a hot day? (how do I know? - I spent one summer in Austin on the UT campus when I was 18. That was before they called it UTA.) cheers!
Dieseldiehard
1971 220 (gas) 4-spd manual 102600 current project.
1979 300TD w/ ’85 turbo engine 287690
1983 300D 234200
1985 300TD 202,820

revray · #18 08-06-2003, 04:24 AM

Aloha,

Would like to change both motor shocks on my 116 (1980 300SD). Have not done this before. Is there anybody who can, and would like to give me a run down on how to proceed? I'd love to have your input and instructions.

Appreciate it,

surfblau · #19 08-06-2003, 12:20 PM

I think on your engine, all you do is unscrew the retaining bolt on top and bottom of the shock. You will need an adjustable wrench or a 7 or 8 mm open end wrench (better) to keep the shaft of the shock from spinning as you loosen the nylock nuts on top and bottom. Access is bad for the passenger side shock- you will probably have to do it all from below. Start with the driver side. You probably don't need to jack anything unless you want more access.

Last week, I was planning on replacing my engine shocks (on my S class), but when I got them off, they had plenty of resistance, but the mounts were either broken or cracked. That is, the mount that holds the engine shock top to the engine arm. That may not be a part that is used on your car.

IN OTHER WORDS, IT IS EASY TO CHECK THEM TO SEE IF THEY ARE STILL GOOD BEFORE YOU BUY NEW ONES AT AROUND $50 EACH!

I removed the shocks and the shock mounts in about 30 minutes total. Not too tough.

There is a more complete outline in the factory CD if you need it.

alec

WANT '71 280SEL · #20 08-06-2003, 06:34 PM

Where exactly are the shocks? I haven't seen them on my 300SD.
Thanks
David

surfblau · #21 08-06-2003, 07:10 PM

The engine shocks (if you have them) are near (probably in front of) the motor mounts.

alec

gasman · #22 09-04-2003, 04:03 PM

I have same symptom of rough idle when hot. Is changing the engine shock difficult? Do I need to jack up or support the engine? Thanks for any tips.

surfblau · #23 09-04-2003, 04:57 PM

I think that it is just loosen at the bottom and top and remove.

I just changed the shock mounts on my s-class and it went really easy. Use a small (7 mm?) open end wrench to hold the shaft or the shock to keep it from turning.

Remove shocks and test to see if they offer smooth and steady resistance before buying new ones. There is a chance that your shock mounts are broken also.

Before you do anything else, check the motor mounts and the rack damper screw and the valves....

86560SEL · #24 11-20-2003, 08:58 PM

The 84 300SD I am considering also has this severe shake ONLY at idle. However, from the sound of the tailpipe- it has a "miss" sound to it. Someone else said it was that "rack damper screw". I just want to know if it is something that is not going to cost big $$ to repair, before I but it.

dieseldiehard · #25 11-20-2003, 10:59 PM

Odd, that sound might be a symptom of an injector problem or IP problem or valve timing or . . . .?
I'd have the valves lashed if its time.
The rack dampner will not cure any engine problems, it only smooths out the idle to prevent "loping"

Dieseldiehard
1971 220 4-spd manual 104646
1979 300TD w/ ’85 turbo engine 290820
1983 300D 238890
1985 300TD 207980
1976 300D (still waiting to see what it needs to get running

86560SEL · #26 11-20-2003, 11:06 PM

What is "IP"? I am dumb when it comes to Mercedes.

Quote:

Originally posted by dieseldiehard
Odd, that sound might be a symptom of an injector problem or IP problem or valve timing or . . . .?
I'd have the valves lashed if its time.
The rack dampner will not cure any engine problems, it only smooths out the idle to prevent "loping"

Dieseldiehard
1971 220 4-spd manual 104646
1979 300TD w/ ’85 turbo engine 290820
1983 300D 238890
1985 300TD 207980
1976 300D (still waiting to see what it needs to get running

dieseldiehard · #27 11-20-2003, 11:25 PM

The IP is the main thing that makes the engine tick in a diesel, its the Injection Pump. There are rubber seals in it that after a long time start leaking instead of putting the identical pressures into each cylinder they give some cylinders more fuel than others. This is not something that can be rebuilt outside a fully equipped Bosch repair shop (go ahead someone will say it can be done at home...?!)
DD

surfblau · #28 11-21-2003, 11:52 AM

(all of this is from memory, so don't quote me too much).

I don't think an 84 SD has too much rubber in the IP, on the top are delivery valves that are seeled with copper washers.

However, the 86 and up SDs and SDLs have rubber and copper washers on the delivery valves of the IP.

All are changeable by an average DIYer and may help this problem, especially if there is leaking fuel from the top of the IP.

The real guts of the injection pump are another matter. But, it has been said several times that injection pumps themselves really don't often or ever fail.

alec

dieseldiehard · #29 11-21-2003, 10:48 PM

Yes, but they slowly get out of spec, and cause an engine to "lope" - why else woud Gus have so many to rebuild over at Pacific Fuel Injection in South San Francisco?
Dieseldiehard

surfblau · #30 11-22-2003, 09:21 PM

when I last talked to gus, he said it was basically a waste of time to rebuild the IP in a 60x or 61x mercedes diesel. He said that you could get the IP to spec on the bench, but the likelihood was that once you put the IP back in the car, the problem would not be cured. He said there were just too many other variables on these old cars. If anyone out there thinks a new - used IP is the cure to their problems, I have a functioning one from an 84 300D all boxed up and ready to go.

alec