Can Seafoam in the tank possibly hurt your car?
 

Is it possible for Seafoam, run though the gas tank only, to injure an engine?

We are talking about a 300DT with nearly 700,000 miles on it.

This is a 1,000$ car with alot of mystery surrounding it. I found grass and bees in the engine compartment, telling me it sat for a while. Another oddity is that when I went to order a breather hose for it ( old one crumbed in my hands after changing air filter), and when I looked on the peach parts website, the only one that fit was one for an 81, although it is an 83, so I don't know if the whole thing was replaced or not. As you can tell by reading this, I'm largely ignorant of cars in general, certainly not a mechanic.

I used to run a can through my old Honda once or twice a year, thought it did some good, and figured I might try in on the Mercedes- "clean it out" a bit- but I'm nervous about it.

What do you think?

Seafoam is a solvent, doesn't belong in your tank. Still, many people believe in it, if you're one, have at it.

Personally I've been happier with Red Line's Diesel Fuel Catalyst or 85+ (both are the same, different label), which is a detergent-based fuel system cleaner.

Biobor's biocide will also be a good idea in your tank, there are micro-organisms that live happily in the water/diesel fuel layer in neglected diesel tanks, you'll be finding out soon if this is a problem.

If it's been sitting a long time, might be best to sample the fuel, have spare filters on-hand.

wow, 700K! go get all your badges from your nearest MB dealer!!!
at that mileage you will be posting plenty of questions here, and we will be happy to answer every one!
first off, you have to post pics of the car, pics of the interior, pics of the speedo showing that awesome mileage, and pics of the engine.
it's likely that at one point or another a donor engine was swapped in, and you may not have the correct items for your car in place.
a few pics and we'll be happily pointing out all the problems and recommending remedies!

Yeah
 

In a casual search for Seafom and diesel engines, I came across a few people mentioning Red Line's Diesel Fuel Catalyst. Almost asked about that instead.

I'm not married to Seafoam- if this would work better as a detergent additive then I will give it a shot. Do you have a cheap online/ physical retailer you prefer? I would change the fuel filter before I attempted this.

This has been a daily driver for me, runs great so far. Bought it out of desperation, but I've really grown attached to this thing.

Thanks for the response :)

@vstech

Hell yeah!

I hope to start a thread soon( soon as I get a decent camera) chronicling the quirks of the beast and asking for advice.

I'm really glad to have found this place, you guys are great :)

oh, I'd leave the filters in place and run the can through a low tank say below 1/4 and run it until the R (*don't run out of fuel!!!) does your reserve light work on your car? that way maximum cleaning will get done. and drive it to a filling station, change the filters, and prime them very well before you try to start up. fill the filter with the redline. and prime with the top bolt loose, until all bubbles are gone. and you should be good to go.
many here recommend Diesel Purge from Lubri/lubro Molly (in stock at most NAPA's)
what issues are you having with the car that makes you want to try a fuel cleaner?
rough idle? trouble starting? low power? Smoke?
give us the skinny, and we'll point you along the path of remedies!

That needs expanding, i'm pretty clueless. Really, Its more me being afaid of f'ing the thing up- I use this thing everyday to go to school and I'm horrified of breaking it. The breather hose thing kinda traumatized me.... if I had another car it would be a different story- I generally love experimenting and getting dirty. I need to get over this/get a backup car.

I guess I was just looking for something that could (possibly) improve the car without actually doing anything to it.

The car starts great for the most part, it failed to start when cold once or twice, but this was, I believe, user error( didn't crank it long enough).

What distresses me is a significant amount of rattling( I would say spark knock if it wasn't a diesel) during acceleration when the car is cold. This goes away when shes warmed up. Also, if you 'gun it' when the engine is relativley cold, there is a decent amount of black exhaust.

Who knows, it could be normal. Is the Deisel Purge an additive that goes directly into the fuel tank, or is it administered some other way?

Thanks again :)

ahh.
ok I understand. first the hard start you had was mostlikely due to your failure to wait long enough before attempting to start.
this car has glow plugs, and assuming they are all working (the yellow light with the curly cue in it does come on right?) you should not try starting the instant the light goes out. especially when it's cold. you want to try this. with the drivers door open, and the dome light on above your head, turn the key to the glow position. your dome light should dim, notice that when the glow light goes out, the dome light is still dim, count to around 40, and then the dome light brightens up. when it's really cold, do this twice. turn the key back off, and back on to the glow position, and watch the dome light dim. when it brightens up, then hit the starter, and it'll fire up instantly.
try it.
next, the issue of f'ing it up. don't worry. you won't.
if you follow our instructions well. and you're not scared of it you'll be fine.
when you say rattling, you mean it noticeably makes knocking noise when you accelerate? that could be the injectors out of tune. they have pressures "pop" pressures that need to be set. if yours are worn or bad, they could be "nailing" you'll not be able to fix that on your own. you should find a diesel shop and get a quote for pop testing and pattern. and see if it's in your budget.
the black smoke could be a simple dirty air filter. it could also be that someone has tweaked your alda and overfueled it just a tad. not a bad thing if it only emits black smoke on occasion.
the rattling could also be as simple as your air filter bracket mounts are broken.
open your hood, and grab the large round air filter can, it should be tight and not move.
it's bolted to the bracket on the engine in three places looking at it from the front of the car, there is a mount at 1oclock, 9oclock and 6oclock. grab it at these points and see if it moves. that'll be your rattle if it does.
also the large turbo tube that exits the air filter can has large 10mm bolts with screwdriver slots on them, these must be fairly tight to keep the filter can from rattling.
do this. find a long flat straight road, and from a stop floor it and see how long it takes to get to 60. 12 seconds is average good performance. what's yours do?

The guy who sold me 'the beast' was sure to educate me about the glow plugs when I first jumped into the seat. The "double charging" is a great tip for when its cold though, thanks.

Yes, it is a "rattling" knocking sound only when cold, when you first start it up, It does this for a few blocks, then goes away. It's hard to describe it in any other way then "rattling."

Because it goes away after it warms up, it makes me think its not something under the hood that is physically loose, but I will check it tomorrow with your described procedure. I'll also try flooring it and recording the performance, and report back:) .

If it's working well, I suggest driving it for a while and getting comfortable with the sounds and feel of it before changing anything other than fluids/filters. That will give you a baseline.

As far as fuel injector cleaners etc., putting one in the tank risks loosening up crud that is currently doing you no harm, and causing it to start fouling filters. BTDT. Keep an eye on the clear pre-filter in the engine bay, if it has sediment in it, tell us what it looks like and change it for a clean one.

Seafoam can effect bearing wear, it is a pretty strong solvent, and I'd not want to be using it continuously, especially if that includes cold starts, where solvents and fuel can seep from the prechambere and wash down the cylinder walls.

Id use a purpose-specific tool.

Seafoam would likely be great for cleaning injectors and going other stuff, but I'd want to either run it like diesel purge (which is the preferred 'straight run' solvent), or else dose something at the right treat rate.

the car should perform like this.
at a light/stop, floored it should pull weakly, then as the RPM's climb toward 2000RPM, it'll pull much harder to the point where cornering is difficult. on a straight pull, the car will hit the 2K mark about 12mph. it should pull to 4Kish when floored, and jump into 2nd gear at about 20mhp, then pull solid to 4K again at around 45mph, then shift into 3rd where it will pull until you get startled with the speed, or 75mph whichever comes first. if you carry on, 4th will engage there, and the acceleration will gradually continue until you lift your foot off the pedal. I think the car tops out around 108mph, but it'll be a LOOONG time before you get that fast.
if this does not sound like your car's performance, let us know.
I'd really like to see a pic of the motor. your comment about the broken tube, makes me think you have an amalgamation of N/A and Turbo parts in your car...