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U1250L DOKA
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Discussion Starter #1
My diesel guy is pretty well convinced my injectors are not at full health. Considering the motor has 209k + KM /9K + hours on it, I can't really argue the point with him.
As I am going to spend the $$ for the IP to be checked and new injectors I would like to boost the output of the motor while I am at it. Being a cheapskate, in the wrong hobby, I do not want to put an IC on it at this time.
So my questions; what was the max HP spec of the OM352A non intercooled motor in an SBU and what year/models were these motors in?
The place that I will be getting the IP work done at and the injectors from is a MB engine warranty shop, they can throw enough fuel at my poor little motor to melt it right down if we just go crazy/get it too wrong. Which is why we are trying to get the MB spec so that I won't have to drive via EGT, as I have had to do on some of my previous diesel rides.

Thanks,
Nate
 

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Vehicle: 1397 Portative Organ Normally Aspirated....U411, U2450,463 300GD
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I am not a diesel expert, but I have spent untold hours studying the TDB (Technical Data Books) I own a fairly late variant of the 352A... the 353.959 which is rated stock @ 170 hp. I am pretty darn sure it was the highest hp offered before they went to the 366LA intercooled motor. The TDB gives all the Bosch numbers for IP, injectors, etc which are mated to this motor so it is invaluable if you are trying to build one. I would recommend a search on this forum as this has been discussed many times. There are varying opinions on piston cooling (whether it is required). I am also fairly sure most of the motors originally rated at 170 hp shipped with piston cooling. Some of these companies in Germany such as Hellgeth that hot-rod them may also give you some answers. hth...
Also... guys like VON or Merz-Ben who post here have torn these things apart and built them up, they will probably illuminate you further.
 

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1991 1250L Doka Unimog, 2002 ML320
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Rostige is right on with his number of 170hp factory w/out inter cooling. Mine is set up that way. Either way I'd make sure you have a good EGT gauge before uping the power. If nothing else, it's peace of mind to know how your engine is feeling. I recently rebuilt my injectors and it's much happier. Good luck,
Chas
 

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4Sale: 230G, U1200 Ag, 1017A, lots of MB cars, Volvo c303, 416 raildoka, LR D110 TDi
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1,217 Posts
Hey Nate,

170 hp is the highest hp that any of the OM 352A's without intercoolers were set at at the factory AFIK. The 170 hp version had a different IP that and most of them had a unit that adjusts the fuel in relationship to the turbo boost, and have different injectors... and they have the piston coolers. The lower hp pump on your motor can be set to give at least 150 hp if you do not have the piston coolers, and up to 180 hp with the piston coolers if you go ahead and go for the bigger injectors while you are replacing them, and you install an EGT gauge to monitor temps. You really need an EGT gauge if you are going to change the pump settings, wether you drive by it or just use it as a tuning or saftey device depends on how far you want to go. THe major factor on how much hp you can get out of the engine is going to be wether you have the piston cooling or not... and there really isn't a good method for checking for it without pulling the oil pan and visually inspecting for the cooling jets, it is kind of hit and miss up intil about '86 or '87. In order to avoid having to drive by the EGT, I would just have the pump set at 150 hp and go with a step or two bigger injectors, since there were a few versions of the OM352A with 150 hp and no piston cooling, this should be safe no matter the internal configuration.


Cheers,
Ben
 

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U1250L DOKA
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Discussion Starter #5
Will have an EGT. It might be my first time around the block with a 'mog, but not with building power with a diesel. Want to set the tuning so it is a safety device, not something I watch more than my tach or speedo. BTDT it gets old.

Pan doesn't look anyworse to drop than one off of a DT in a 3800 chassis, so I might do that anyway, just to make certain.
 

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1991 1250L Doka Unimog, 2002 ML320
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Lyrch I wanted mine set up so my wife could drive it and not blow it up. My fuel is set so that maxed underload it doesn't go above about 1100-1150f. I noticed that with the rebuilt injectors it stays about 50f cooler then before and doesn't stink so much at idle. I still can't pull the front wheels off the ground though,
Chas
 

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U1250L DOKA
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Discussion Starter #7
Lyrch I wanted mine set up so my wife could drive it and not blow it up. My fuel is set so that maxed underload it doesn't go above about 1100-1150f. I noticed that with the rebuilt injectors it stays about 50f cooler then before and doesn't stink so much at idle. I still can't pull the front wheels off the ground though,
Chas
LOL, I would just like to pull hills without making 'friends' behind me. As it is now, I will drop to 35-37 mph on a midsized hill.

Chas, was your tuning trial and error, or did they dial it in right away?

Nate
 

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mogless, except for my friends MB4-94. And a bunch of other diesel junk.
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Hey Nate,
and there really isn't a good method for checking for it without pulling the oil pan and visually inspecting for the cooling jets, it is kind of hit and miss up intil about '86 or '87.

Cheers,
Ben
Ben and all, in regards to pulling the pan, I recently bought one of these for a similar inspection
Fiber Optic Scope with Lighting
If you do a lot of work in tight quarters where you don't want to have to tear things down if you don't have to, it kicks ass. Well worth not having to buy and install a new pan gasket, plus you get to use it for all sorts of other things, like "what's my daughter dropped into the garbage disposal today?" or "is there a squirrel living in the bathroom ceiling?" Good investment for certain. Anyhow, back to topic. Whatever you decide to do to the IP and injectors, please post and egt results. I recently had my injectors rebuilt to stock spec and the results were admirable. Best of luck.
 

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1983 U1200 (parted out), 1979 U1700L
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Have you tried the fiber scope, I tried one on my 1200 and found that the pick up screen is right over the oil pan drain hole, so it was a no go.
 

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1991 1250L Doka Unimog, 2002 ML320
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Nate I had the work done by a Bosch company once I pulled it. They told me it was set for 10% over the base for my horsepower. They could do a few uprated things to it but I was going to wait. As I found out later, my injectors were Poo. Once I had them rebuilt to specs it feels like I figured it should for the HP rating. I would say get your injectors and IP pump checked for a base and then go up....until the temp or smoke bothers you. It's nice to know that it's all working properly as a base. Von on this list really likes the HotRod side of things and could really help. Others have done high HP versions on the list also. Good Luck,
Chas
 

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U1250L DOKA
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Discussion Starter #11 (Edited)
Nate I had the work done by a Bosch company once I pulled it. They told me it was set for 10% over the base for my horsepower. They could do a few uprated things to it but I was going to wait. As I found out later, my injectors were Poo. Once I had them rebuilt to specs it feels like I figured it should for the HP rating. I would say get your injectors and IP pump checked for a base and then go up....until the temp or smoke bothers you. It's nice to know that it's all working properly as a base. Von on this list really likes the HotRod side of things and could really help. Others have done high HP versions on the list also. Good Luck,
Chas
Not looking for real Hot Rodding, just want to know that I can pull a hill and not have to be concerned that I might have to down shift through the airsplitter. Wouldn't really want to go for real speed on my chassis. U1200 a bit short in wheelbase and tall in elevation for me to really want to do much more than the 54 mph or so I have now. Just want to have that on uphills as well :D
 
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