350 head pulled. - PeachParts Mercedes-Benz Forum

DslBnz · #1 03-29-2006, 03:43 PM

Well, I got a short look at it, as I was in a rush. I took some pictures. I will take MANY more once I get my block back.

Appears the number one cylinder is worn excessively, and the piston has a hole. Several, actually. Lovely. Anyway, the head is pitted up as well. I am dropping a 3.0 liter block in my 350 as it needs a complete longblock assembly.

OK, I expected this. I also noticed how closely the cylinders are spaced. There's no metal between them, almost, at all.

Here's my first day's photo scrounge

barry123400 · #2 03-29-2006, 04:13 PM

You are perfectly right. The lack of any meaningful mass between cylinder bores might just be the unknown factor of why these engines bend rods. Until your photos I would never have believed a company would engineer that thin. Since the bores are pretty large it almost appears there is a large real lightly supported bore area considering the stresses developed. The rods may not be bending and causing the problem. Almost more likely the bore is being forced out of shape and the rods bending to conform as time goes on. I will never own one of those engines after seeing that. Almost looks like they need a set of sleeves installed over whats there just to get perhaps adaquate strength to help stop the distortion of the bores. Amazing the block does not crack. Are the stronger improved rods just to try to support the piston in the bore? If I were the mercedes company I do not think I would talk about this problem either. Thought they had good engineers. This makes me wonder. Plus to continue that block in production for as long as they did almost amounts to low corporate ethics. Also its amazing to me they can keep a head gasket functional in that settup. Thats perhaps where the real engineering is because it does not appear to be in the block. I remember when their designs were sophisticated and rugged. This is neither in just my opinion.

DslBnz · #3 03-29-2006, 04:35 PM

My father believes exactly as you, Barry.

This is the second engine. It was installed in July of '95 making the engine a '96 model year engine.

It already has the stronger rods and pistons.

I'm smelling a serious class-action lawsuit.

Brian Carlton · #4 03-29-2006, 09:34 PM

Quote:

Originally Posted by barry123400

You are perfectly right. The lack of any meaningful mass between cylinder bores might just be the unknown factor of why these engines bend rods. Until your photos I would never have believed a company would engineer that thin. Since the bores are pretty large it almost appears there is a large real lightly supported bore area considering the stresses developed. The rods may not be bending and causing the problem. Almost more likely the bore is being forced out of shape and the rods bending to conform as time goes on. I will never own one of those engines after seeing that.

My thoughts........exactly...........

Walgamuth might be on the money with this one.

Hatterasguy · #5 03-29-2006, 11:12 PM

I don't know, the bore of the 3.5L block and the 3L block need to be measured.

I havn't seen a 3L with its head off for a couple of years, but they look the same.

I bet the spacing between the cylinders is the same if not real close on the 3L block.

Brian Carlton · #6 03-29-2006, 11:13 PM

Quote:

Originally Posted by Hatterasguy

I bet the spacing between the cylinders is the same if not real close on the 3L block.

2mm difference in the bores. This means 2mm additional material between the bores. The difference might be significant.

Hatterasguy · #7 03-29-2006, 11:20 PM

2MM could make a big difference.

This is a very interesting engine, I wish their were some hard numbers of how many fail. It seems outside of this forum this problem isn't very well known. I have gotten some looks when I talked to "MB diesel experts" about this.

Most shops don't seem to know about this.

BenzDiesel · #8 03-29-2006, 11:26 PM

Is Mercedes now using Elring gaskets as an OEM part? In the first picture, #2 injector at the prechamber looks great; no oil or soot. Do you know what is causing the wet oil look at #1 and #3 prechamber? It looks like unburned fuel or the cylinders weren't firing properly to get that wet, shiny, and oily look. For the guys saying they will never own that engine. Once they drive one, their opinion will change, I'd bet; and they would be trying to get that thing fixed, bent rods, smoking, using oil and ALL; if that car will keep running like it does when it is running good. These cars will "SLOW", coast at 80 mph. And you can drive 1200 miles in one day and won't even be tired. Get up the next day and drive another 700 miles.

BenzDiesel

DslBnz · #9 03-29-2006, 11:28 PM

Here's a 3.0 liter shortblock.

Brian Carlton · #10 03-29-2006, 11:32 PM

The difference is obvious. The 3.0 looks barely adequate for the task. The 3.5 looks ridiculous.

I'd never own one.......after seeing the aforementioned photo........it's amazing that any of them go 100K.

Hatterasguy · #11 03-30-2006, 12:27 AM

The 3.5L doesn't put out THAT much more power. The car should still move right along like any 300SDL which isn't exactly a dog.

What are those lines coming out of the fire wall? They look like heater hoses of some sort that connect to hard lines? I know these cars pretty well and I don't recall seeing those before?

Hit Man X · #12 03-30-2006, 12:43 AM

I have pics of a 3.0L somewhere on the comp with the head gone, they're a bit closer. I'll try to find them and post.

Hit Man X · #13 03-30-2006, 12:44 AM

Quote:

Originally Posted by Hatterasguy

The 3.5L doesn't put out THAT much more power. The car should still move right along like any 300SDL which isn't exactly a dog.

What are those lines coming out of the fire wall? They look like heater hoses of some sort that connect to hard lines? I know these cars pretty well and I don't recall seeing those before?

Looks like a W124.

Hatterasguy · #14 03-30-2006, 09:47 AM

Its a W124 your right.

BenzDiesel · #15 03-30-2006, 10:34 AM

of the head gasket is going to benefit this engine significantly independently of any other engine work that will be done. In the picture that shows oil on top on the left side of the head gasket between cylinder #5 and #6, (looks like according to the big picture showing all six cylinders, but can't tell which cylinders they are in the small, upclose shot) definitely shows a breach of the seal between those two cylinders. Why was the head taken down? And how indepth are you going to refurbish this engine?

BenzDiesel