Bruno ist Kaput! - PeachParts Mercedes-Benz Forum

LUVMBDiesels · #1 01-11-2008, 06:54 PM

My faithful 300SD just bit the big one today.
For the past six months or so the oil pressure needle would vibrate when I lifted off the accelerator. As the pressure NEVER went below 1.5 and always went right up to 3+ under load I did not think much of it.

Driving to the train today he started sounding like something was grinding almost like the alternator fan was hitting something or something was vibrating loose like an exhaust shield. I got to the station and the noise got really loud. I pulled into a parking lot and shut it off to check the fans and belts. Remember that the oil was always over 3 when running over 1200RPM and never dropped below 1.8 at idle. I checked the fan and the alternator and the belts and everything was OK. I started the engine and the noise was real bad and the oil pressure gauge was now bouncing in time with the noise. I was just turning the key off when "CLUNK" something broke and the engine just stopped.

I am not thinking it could be the timing chain as it was checked not three months ago by my indy. I would not trust myself for 'mission critical' things like chain tension.

Anyway I had him towed back to the house I am renting and I am now out of ideas. I don't want to go through another engine swap (the original one was in bad shape when I got Bruno and I replaced it with one with 1/2 the mileage) but he is still in good shape otherwise

Everything works Tach, Cruise control, Climate Control, Sunroof, windows, even the clock keeps accurate time. His body has seen better days with the usual rust over the rear wheel arch and the interior is not so hot either. I was gathering wood to replace is tortured veneer (PO tried to remove it by prying it from the front and ruined most of it) but he always rode well and has been a great trooper.

So I need your help...
Do I try to figure our what happened to this engine?
Do I get another junkyard special and swap it?
Do I put him up for sale as a donor car?
Do I get the chance to move up to a nice SDL?

Hmmm Maybe I should make this a poll...

Thanks for reading this as I needed to vent.

NickCox · #2 01-11-2008, 07:03 PM

Did your oil pump chain possibly break?

LUVMBDiesels · #3 01-11-2008, 07:25 PM

It could have snapped. I don't know. Do you know how hard it would be to drop the pan to look at it? When the original engine started rod knocking my indy said that it would be cheaper to just pull and replace it than to try and fix any bottom-end issues. Could the chain be replaced assuming it is the problem easily?

Diesel911 · #4 01-11-2008, 07:58 PM

If your pan is like my 84 300D you should be able to take off the small steel pan and you should be able to see the oil pump/chain. However I do not see the point of doing that. The bearing surfaces of the whole crankshaft need to be looked at as well as the connecting rod bearing bores to see if they are scored and have metal deposits on them. To do this you would need to have the both oil pans (mine has 2 the small steel one and a larger aluminum one) off and it dose not look as if this can be done with the engine in the car. If you remove both of the pans you should also be able to view the lower half of the cylinders and get an idea as to their condition.
In the past I have seen crankshafts polished up with 600 grit or finer emery cloth (as long as the out of roundness and score marks were not deep) and new bearings rolled into place. This will not work if a bearing spun and enlarged the connecting rod bearing bore or if the cylinders are scored up. If you are not doing the work youself it would be cheaper to find a used engine. Besides being too expensive a hired mechanic would not like to do this type of patch up job as they cannot warrent it.

LUVMBDiesels · #5 01-11-2008, 08:10 PM

Diesel911,
That is kinda of what I thought too. If the chain is broken it had to go somewhere and chew up the internals. I mean the engine just went bang-stop no sputtering or trying to run, it just seized. It is too bad since it was finally running well, had fixed the vacuum leaks, had the valves adjusted, did a Diesel Purge, etc...

Trouble is all my tools are in NY and the car is in WV.

Even if I wanted to drop the small pan I can't do it in the driveway of my rented house.

kernelpanic · #6 01-12-2008, 08:08 AM

Quote:

Originally Posted by NickCox

Did your oil pump chain possibly break?

Sure what it sounds like to me too.
It still had oil pressure at the time chain broke.. with luck bearings are ok.
Chain most likely bound up in there and caused it to stop.
IF this is the case , replace the chain via the small oil pan and you're back on the road.
For the small cost of the chain and the minimal labor involved I sure would try.

LUVMBDiesels · #7 01-12-2008, 09:11 AM

Quote:

Originally Posted by kernelpanic

Sure what it sounds like to me too.
It still had oil pressure at the time chain broke.. with luck bearings are ok.
Chain most likely bound up in there and caused it to stop.
IF this is the case , replace the chain via the small oil pan and you're back on the road.
For the small cost of the chain and the minimal labor involved I sure would try.

I will try this. Thanks! If not then I will either have somebody drop in a new(er) 617 or try to sell it as a parts donor and buy an SDL

jbach36 · #8 01-12-2008, 09:48 AM

Maybe try a very low cost shade tree mechanic, or take it to a vocational school where they can fix it?

Just a thought.

jeff

Hatterasguy · #9 01-12-2008, 11:21 AM

Sounds like the oil pump chain broke, or it threw a rod.

TheDon · #10 01-12-2008, 11:30 AM

see if you can rotate the engine by hand..

pawoSD · #11 01-12-2008, 12:18 PM

Thats surprising at only 223k....does the car have a good service history?

LUVMBDiesels · #12 01-12-2008, 12:21 PM

Quote:

Originally Posted by TheDon

see if you can rotate the engine by hand..

I will check that, but I don't think I can. I think it is seized in place.

LUVMBDiesels · #13 01-12-2008, 12:26 PM

Quote:

Originally Posted by pawoSD

Thats surprising at only 223k....does the car have a good service history?

The engine was from a junkyard 300D that had only 137K on it. It has run very well for me for about 2.5 years.

I change the oil every 4000 mi with synthetic, change the filter every 2000 mi, just had the valves adjusted and the timing chain checked for stretch in October. Engine ran with hardly any blow by, did not leak oil (new valve cover gasket fixed the last leak) etc. Of course it could have been abused for the entire 137K of it's previous life.

The engine that was originally in the car had been abused and about a year after buying the car it developed a bad knock. I just pulled it and replaced it.

The block is intact with no holes and the oil is still up at the full level.

I am hoping it is just the oil pump/chain that went.

pawoSD · #14 01-12-2008, 12:30 PM

I hope you can save it, that would be a shame.

Mustang_man298 · #15 01-12-2008, 12:41 PM

It could be your pump chain and it bound as mentioned, the fluttering pressure is curious though, I'm wondering if the pump was getting tired and the gears got sloppy, enough so that they finally landed just right to hit tooth to tooth, which locked it and caused the engine to halt, or possibly popped the timing chain, since the pump chain is driven from the timing chain. You should be able to hand spin it backward, it doesn't sound like you would have any major damage though right now unless the timing chain went. If it's ok, I'd fix the pump or it's chain.
Give it a looking over, that'll tell you where to go from there.