Did you check each piston for protrusion fore and aft?

Does this engine have EGR?

Sixto
83 300SD

Make a profit?? Only if you could hand carry it.

__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

No time or tools for that. I am studying abroad, so any time not spent studying is spent traveling.

I am having issues find a OM603 cam period, of any suffix. I think finding a 603.971 is going to be near impossible based on import numbers of the S350.

I am fairly certain that is the head gasket I installed. I was wondering about the 606 head gasket as it is MLS and therefore stronger, but I found out that it is thinner. The last thing this engine needs is a higher CR.

Thanks for the performance tips. Now I need to bring this car back to 100% stock and sorted out before I get started on of them. I am not looking to turn heads as I have a few other cars that are good at that, I just don't want to be a hazard when merging onto the freeway like a car with 37lbs/hp would be in Michigan.

The car is not/was not in Germany, I am just here for school. I have also heard about there not being an issue with the S350 in Europe based on the higher quality of diesel here.

I plan to get new lifters with the new cam, as I know it is generally never a good idea to mix and match items that are broken in. The cam is beyond repair, and the only option is to get a different one. I have found new cams for $400-$500, but that is very hard to swallow when a dropout 606 is $1200
and I only paid $500 for the car.

I checked protrusion aft of the rod on each cylinder, and yes there is an EGR.

If you return to MI without a cam let me know, I might have a used one that you can have for far less than new (need to look in my stash).

__________________

Gone to the dark side

- Jeff

Thank you for the offer, I should know early december whether or not I will be able to find a cam.

IIRC when checking for bent rods the goal is to compare piston protrusion fore and aft. Lower in front means the rod is bent. I suppose lower in the back too but that's not how they tend to bend. Focus on #1 and #6 as bending starts at the ends of the crank.

Sixto
83 300SD

I'm betting he has at least one bent rod.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

The method I had available to me would not allow to compare for and aft protrusion. There was no marring on the cylinder liners, so it is back together and waiting a cam.

Based on what evidence?

Interesting topic/rebuild here.

Interesting topic for an interesting engine. Seems there is a lot of negativity towards it though.

Yes there is. Deserved depends.

Part of the problem was the 3 liter version had close to a bulletproof block and head design issues. The 3.5 cured the head problems and substituted the block problems.

For the money these cars cost new people should have gotten better. Still after all these years the manufacturer has not released the reason the lower block fails. We all can take guesses though and do it seems.

Since we do not know the causes for certain. We cannot take any form of absolute countermeasures. Nor could the engines manufacturer on already existing engines I suspect. Although the beefed up rods help.

I suspect as soon as the problem materialized. Adding nickel to the engine castings in production as well might have helped a little as well.

Personally like my international 9 liter truck engine. It did fine unless you let it idle a lot. The 9 liter engine was as good as the day we brought the truck when we sold it. . I might treat the 3.5 the same way if I owned one.

Mercedes for whatever reason chose not to improve the block material strength when the engines started this and where still in production.

I can think of many reasons and they all favor the company over their customers. The replacement stronger rods where a nice gesture and did help but not the best answer. I suspect the company was all too aware of this. How do you tell the American customers back then that the engine needs premium diesel fuel when it was not available in north America?


I think the only true break we as buyers of these used cars get. If the engine does fail. The lower block of the 3 liter can be substituted.

Then with the vastly upgraded head of the 3.5 it should be almost bulletproof. I would buy one if the general condition was good enough and the price cheap enough. Then buy a 3 liter engine and put it into storage if ever needed. If never needed it should resell in the future. The existence of the 3.5 liter engines almost guarantee this.

Some people would have issues with finding long term cheap storage of an engine and others not. You could probably pick up a three liter block with head problems for a Hundred dollars or so. You got the 3.5 car because everyone told the owner probably that the engine had serious damage and it could have been that way. Or he had heard of the problem and decided against dealing with it.

I also gave some thought about the weak heads on the 3 liter. Those that own them should let them idle for a minute before shutting them down. This reduces potential hot spot fatigue in the head castings. Also a few members have picked up that the grade of material used in the head castings might not have been a good choice. It apparently has tested softer than it should be when older. If they were as soft when new is the unknown question. Also some of the owners of this number 14 head may have just had a luck of the draw situation. Their heads just being cast of a better consistency or grade of the same metal.

Both suggestions are not proven and just remain suspicions. In any case it would do no harm to observe them. I would but own neither engine.

There then also is a good chance that running celane boosters are a good ideal if the tales about no failures of the 3.5 are true in Europe. I could as easily be wrong as right.

Interesting method that lets you measure one point but not two but I suppose that's possible.

Fair enough and in retrospect I wish I'd done the same. I'm sure a new head gasket would have cleared most of the oil consumption. Bent rods or not, a .97 out torques a .96 in a meaningful way. This is the cross hatching on a 603.971 #1 cylinder with a measurably and visibly bent rod -



Here's how I measured bending -





What's negativity to you is experience to me The major flaw of the US 140 Diesel is that it wasn't offered in LWB. Soft rods I can live with

Sixto
83 300SD

Blowby and oil usage.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

This is pretty much my plans at the moment. It is not my primary vehicle yet, and I can afford the time to get it sorted out.

I did not know they made cetane boosters, I will certainly look into them.

My method was a magnetic-mounted dial indicator set on the block deck. I could orient it so that I can compare cylinders with very good accuracy, but using this method for fore/aft measurements would most likely leave too much room for error.

From the story of the previous owner, his wife daily drove it and one day it just started puking a ton of smoke and leaking oil on the driveway, so they stopped driving it. The blown headgasket pretty much proves this, and it was only leaking on the driveway thanks to a blown flex pipe. I have pondered the possibility that the oil in cylinder 1 couple have bent the rod, but even if it did, it will take a little while to show the symptoms. So I will cross that bridge when I get to it.

Love your surface plate Sixto! Next time I'm in SF I need to buy you a nice slab of granite.

As far as the above "problems" with the early heads and the late blocks:

I love the 124, long story that begins with being an Engineer and working with Mercedes-Benz on the original design, running the hell out of one with accelerometers all around us to measure vibration, etc. Strong car and a "game-changer" in chassis stiffness, IIRC the body is over 30% high-tensile steel. Watch one at the crusher sometime.

Because of this and having too much extra shop space, I bought several used diesel 124s, and a couple of 126s. The 300Ds that I owned all had #14 heads, all made it to the quarter-million mark, and NONE of them had any issues with the heads (sold some nice ones as drivers, others I sold the heads on ebay). Why if this is such a significant flaw did this get by Mercedes-Benz Engineers and how did all of mine make it so far into life without issues? I suspect that the head was adequate for normal conditions, but once the car got older and more neglected (every car overheats if it gets neglected when old). The water pumps get older, flow gets restricted, owners don't change the coolant every 2 years and don't use HOAT coolant, radiators leak or get clogged, ... this was just the weakest point and in typical German fashion they continued to improve the thin-wall area that fatigues in the combustion-chamber area as well as the front oil-journal and head gasket (as evidenced by the HG change and the head changes/evolution through #22).

Same thing with the OM603.97x (3.5L "Rod-Bender"). I had a very nice '91 350SDL, had 250k miles on it, block appeared to be original (but I can't verify, not a reman though), used no significant oil and bores looked good when I tore it down to use its crank and other parts for different projects. I still have one OM603.971, running strong in its original hole, with 298,000 miles and the only oil-burning problem it had was recently solved with new valve seals and a turbo rebuild. Starts, idles, runs strong, original owner is one of my neighbors from whom I bought it for my teenage Son (he still has a beautiful '91 350SDL, also for sale but not cheap, and his "baby", a gorgeous '85 300TD).

So again why is the 3.5L such a bad engine? Lots of speculation, and even the brain trust here (which BTW I've found to be a pretty knowledgeable bunch) agrees that there is no "smoking gun" answer. One theory is that it is from oil leakage into the #1 cylinder where hydrolocking will bend the rod. That's one I consider a strong possibility. If you have ever had the engine apart, you will notice that the bottom of the head is flat (except for the protruding valves and pre-chamber, for which there is a recess in the piston), and the pistons actually stand proud of the deck at TDC! No room for error and even a teaspoon of oil could do damage (well, maybe a tablespoon) as the only place for fluids to go would be into the tiny pre-chamber holes and cold oil doesn't flow quickly.

My OM603.971 has had the headgasket serviced once, was using oil and likely leaking into #1, which I believe is common. Had it not been caught early it is possible that this engine would have been replaced long ago.

So in summary: Early heads bad? Possibly, but also possibly just not robust enough for neglect and abuse.

3.5L bad? Again possibly only as collateral damage from a (known issue) gasket failure and lack of proper service to correct before catastrophic damage occurs.

As cars/engines age, these "problem areas" show themselves more often, and eventually 100% of all engines will wear out, ... faster if not properly maintained.

__________________

Gone to the dark side

- Jeff