New owner, a few questions - PeachParts Mercedes-Benz Forum

Gvr4-330 · #1 06-04-2006, 10:52 PM

Hi,

I've lurked around here for a bit after purchasing an 84 300D, but now I have a couple questions I was having trouble finding the answer to.

First, fluid changes. Is it ok to change to synthetic after 243,000 miles? I know my Mitsubishi started leaking afterwards cause the sythetic cleaned out a lot of the crud that was holding the seals together. Also, the trans fluid. I've heard if the fluid isn't regularly changed, it might be better to keep it.

Second, I'm trying to figure out why my car runs so rough when it's cold started. I thought it would be a bad glow plug, but all the plugs tested fine for resistance and the relay was feeding power to them. If I have some free time, I'll pull them and test them to see if they glow. The car runs real rough and has no power until it's warm. Also, I feel like the car should have more "from a start" pickup. Once it starts building boost though, the car has enough power.

Thanks!

Rob

A pic for clicks:

t walgamuth · #2 06-04-2006, 10:58 PM

the sluggish take off is normal within reason. they will be pretty slow til you have travled twenty or thirty feet, then the boost comes on and off to the races.

personally i would not change to synthetic in a car with those miles, but many will disagree.

the tranny i would change fluid and filter right away and do the torque converter too.

you are on the right track with the glows i think.

tom w

sailor15015 · #3 06-04-2006, 11:05 PM

The startup trouble could also be valves that need to be adjusted or possible a stretched timing chain. On my '85, roughly checked, the chain was about seven degrees stretched and even with good valves and cleaned, balanced injectors I'd still get a stumble on startup. However, on the '84, the chain, also roughly checked, registered two degrees of stretch maybe and it purrs even in winter time.

Nice looking car by the way.

mybenz123 · #4 06-04-2006, 11:13 PM

Hi Rob.

Many times the ruff idle will be cause buy worn injectors.
I have the same problem and I'm having my injectors rebuild
and new nozzles installed by Tom, also member here.
I don't have them yet since they are on their way.
So I can't say if it makes any difference
Should be a nice difference in idle and overall drivebility.

How are your fuel filters?
Have you replaced them or do you know for sure
they are good?
Bad filters will cause loss of power although it would be
over the whole rpm range.

For the moment one of my GP's is not working and I know this
because I need to pre-glow atleast twice in the morning even
on days when the temps are in the higher 50s.
Then it will start without problem.
Other wise I need to crank the engine for 20-30sec in order
for the engine to start.

Louis.

Gvr4-330 · #5 06-05-2006, 12:05 AM

Thanks for the quick responses.

I need to do the valve adjustment, just in case, but I don't have the wrenches. Also, I couldn't really find out how to check on timing chain stretch. I am considering rebuilding the injectors too, but this is a second project car!

If my glowplugs are showing the proper resistance, is there still a chance they are bad?

I am definately going through a bunch of fuel filters, cause the car had algae in the tank and I'm trying to kill it off and it all ends up in my prefilter.

You can't tell, but the car some rust, the worst being rust-through around the front passenger side jacking point. But I hope to get that fixed. I got a good deal anyway.

One more question... can the ignition lock be rekeyed? It's been replaced, and it uses a different key than the other locks in the car, which is kinda annoying.

sixto · #6 06-05-2006, 12:35 AM

I've never had a 300D but I had a 92 GVR4 a few years ago and a couple of GGSXs before that. Do you know Nate Pharr, Todd Day or Tom Stangl? How about the TRE guys?

Sixto

sailor15015 · #7 06-05-2006, 12:56 AM

Valve adjustments aren't hard, even if you don't have the wrenches. Others will argue this, but you really don't need them. After the first time, I could do them all in less than half an hour with my plain ol' 14mm wrenches. As for the timing chain stretch, do a search with those or similar words with the username "dannym". He did a write up on how to check it the proper way but I believe he also outlines the easier way, which is fine to get a good idea. I think gp's can measure good resistance but still not be lighting off like they should. Have you made sure they're all getting about 12v right after you turn on the key? I think the actual voltage is around 11-11.5v. Another good way to test them is to take them out and use a pair of jumper cables to see if they glow properly. Attach the negative end to the thread on the gp and the postive end to the tip. It should glow red-hot in a matter of seconds. When I first got the '85, all gp's measured resistance just fine in the car but when I got them out, two wouldn't light up using the cables.

1983/300CD · #8 06-05-2006, 02:03 PM

To improve the acceleration from a dead stop, you could look into adjusting the ALDA.

Maroon 300D · #9 06-05-2006, 02:05 PM

Beautiful car.

It's not unusual for GP's to test fine in terms of resistance but not to work right anyway. If you don't know when they were last replaced I would just replace them.

Your lack of power at startup COULD be the result of a bad/misadjusted rack dampener pin. This is extremely easy to check and adjust so it's worth trying before most other things. I was shocked after adjusting mine; the car idled much more smoothly and had a lot more pre-boost power. It sounds to me like the GP's could very well be the issue with the lack of power and the rough start in your car, though.

I doubt the ignition lock can be re-keyed, but I bought a new one from the dealer recently for $66.50. It came with a new key and it's the same key that can be used for the rest of the car. The ignition lock cylinder is easy to get in and out provided you can still turn the key in it, which doesn't seem to be an issue for you.

My car has always had dino oil and I haven't tried synthetic because I've read too many accounts of stories like the Mitsubishi one you wrote about. Same deal on these cars, evidently.

Good luck!

Gvr4-330 · #10 06-05-2006, 10:54 PM

Ok, a few more questions:

Do the switches in the upper dash (antenna, sunroof, rear light, defroster) light up? Mine don't (except for the defroster in "on"). So how do you change the bulbs?

Rob

#11 06-05-2006, 11:12 PM

Quote:

Originally Posted by Gvr4-330

Do the switches in the upper dash (antenna, sunroof, rear light, defroster) light up? Mine don't (except for the defroster in "on"). So how do you change the bulbs?

Yes, they do light up. There is a single bulb in a socket behind the switch panel that supplies some little fiber cables to each of these switches. It's kind of a PITA to reach this bulb. Try removing the switch panel and look for the bulb. Hope you have skinny fingers.