3.0 or 3.5? - PeachParts Mercedes-Benz Forum

loneranger · #1 12-20-2005, 08:39 PM

The 1990 350 SDL I bought recently was advertised as a 3.0 liter, the car came with a 3.5 liter. Where is the stampnig on the motor so I know which it is? I see there have been problems with 3.5 engines. This engine runs well and car is in excellent condition with 179K, just would like to know what engine it has in it.

greasybenz · #2 12-20-2005, 09:01 PM

its a 3.5 and you just bought yourself the worst diesel in mercedes history, good luck keeping it in top shape! Should have looked for a 300SDL or a 300SD but the 350's cant be trusted they just love bending their connection rods and all kinds of other things that lead to catastrophic engine failure.

DslBnz · #3 12-20-2005, 09:14 PM

Well, a quick, and user-friendly way to find if you have a 350 is to drive the car at WOT from a stop, where you can. If the kickdown switch works, it should shift at about 4400 rpm if a 350, and 4800 rpm if a 300. Or, you could have a look underhood at the injection pump stamping numbers (PES 6M 55C 320 RS 178 = 350 engine pump). Or you could look on the side of the block for the casting. Usually the EGR is different too, an integrated into a computer that cuts boost when disabled. Try that.

If its a 350, its not the end of the world, but ANY type of oil consumption in these things should be cautiously monitored; as you will find upon reading through the archives.

WANT '71 280SEL · #4 12-21-2005, 09:26 AM

Also keep in mind, if this engine is one of the rod-benders, there is a good chance it would have already done so. So, if it did ever bend a rod, one of the PO's would have fixed it because it would be bellowing smoke if it currently has bent rods.

Thanks
David

andmoon · #5 12-21-2005, 09:44 AM

Quote:

Originally Posted by greasybenz

its a 3.5 and you just bought yourself the worst diesel in mercedes history, good luck keeping it in top shape! Should have looked for a 300SDL or a 300SD but the 350's cant be trusted they just love bending their connection rods and all kinds of other things that lead to catastrophic engine failure.

I have heard of the rods but what "all kinds of other things"?

TheDon · #6 12-21-2005, 10:04 AM

over heating these engines i belive have an aluminum head unlike the 617's that have cast iron or something not aluminum

Hit Man X · #7 12-21-2005, 10:32 AM

Quote:

Originally Posted by DslBnz

Well, a quick, and user-friendly way to find if you have a 350 is to drive the car at WOT from a stop, where you can. If the kickdown switch works, it should shift at about 4400 rpm if a 350, and 4800 rpm if a 300.

Well I'll be damned. That explains why mine short shifts 1-2.

I know my kickdown switch is bad but wasn't aware it caused that problem too.

#8 12-21-2005, 10:32 AM

Your only issues you need to worry about are the bending of rods and the overheating of the car and likely cranking of the head.

If you use no oil or water...you are set

If the PO has already adressed the rod issue...more power to you. The 350 is a powerful engine when you get that rod issue taken care of.

What sort of oil use/water use are you looking at thus far?

Anthony Cerami · #9 12-21-2005, 11:16 AM

My 350SD is the quietest diesel I ever heard .......i have never had a problem.
Just keep the oil changed.....

dieselbeagel · #10 12-21-2005, 11:40 AM

The 350's r a fine car. They r actually well made.

The root problem of the rod bending, over heating, oil consumption ... etc is the EGR valve. The carbon particles that deposit along the walls and eventually fall as rocks into the engine cause the above problems. This is my story and I am sticking to it !

Some on the forum have a different theory as to why the above problems occur.

If I ever own a 350, the first order of the day would be to disable the EGR. The disabling is not straight forward as it is computer controlled.

There may be many ways of doing this. This forum have shown 2 ways on how it can be done.

U can use a chip board or go to a dawes boost pressure sensor. There may be more ways but I am not aware of them.

Some on this forum have had good luck with their 350's and have said nothing but good things about the car.

If u r unable to get the EGR disabled, I would suggest, periodically, taking off the crossover and intake manifold and cleaning them out.

rg2098 · #11 12-21-2005, 12:40 PM

I always figured if they were gonna bend, they would do it within the first 100k. I personally would love a 350SDL with the updated interior. I'l take it off you hands for no charge at all. I'll even come pick it up for free.

DslBnz · #12 12-21-2005, 12:46 PM

The 350 is a much more refined vehicle compared to the 300. The idle, when it is in perfect tune, has no indication of it being any different than the gas version. Even when cold there's no clatter whatsoever.

The 3.0 liter 603 can be relatively OBNOXIOUS!

ConnClark · #13 12-21-2005, 12:48 PM

Wow! People don't like the 1990 350SDL almost as much as the EGR valve.

Hit Man X · #14 12-21-2005, 12:50 PM

I'd take a 350SDL if the price was right.

Interesting about the EGR, even if it is computer controller... it's not going to hurt power or throw a CEL in the dash anywhere. I'd just yank it off there.

Anthony Cerami · #15 12-21-2005, 01:51 PM

I have been driving my 350SD about 200MI a day as a daily driver...since the E300TD is apart at the moment.....with no problems to date. I have disconnected the EGR valve, cleaned out the intake, calibrated the injectors, resealed the IP and set the timing.

As for the E300TD ...The EGR is disconnected as well. I cut off the steel line coming from the exhaust and plugged the opening. I machined an adapter fitting and installed a small "Tuner" style air cleaner to the intake side....Someone else on this board had done a similar thing....The computer thinks the EGR valve is still sucking soot.......NOT!!! Now the intake will remain sparkley clean …..