pre chamber questions SD
 

Hi ,

I just bought a new cylinder head for my 80 300SD, It was totally bare except for the guides, I installed the studs, and lapped the valves, but the original pre chambers are to big to fit into the new cylinder head, (bottom part) all the part numbers are the same on each cylinder head??
Was there two differnt sizes of prechabers made for the turbo
and the non turbo? Or is the head manufactured wrong?:eek:

I checked Fastlane and didn't find any pre chambers for sale, does anyone know how much pre chambers are?, or should I get the cylinder head machined to the size of my original ones,
Which would be cheaper?

thanks

Dave

86 190 2.3-16v
80 300SD
69 911 Iroc

Look on FastLane under "diesel prechamber" in their search function. ~$119.00 each.


Use search on this board and you'll find a thread where one of the boys used a lathe to increase the radius of the external part of the prechamber to make it fit. A very thorough discussion, with a defining comment from a tech on the lack of precision of the castings on a new MB head. Someone really covered the procedure in detail. I'll try to find it later, but give it a "search" (had pictures and the whole nine yards).

thanks 007 .. I found the thread, My problem is the bottom of the
p/c is about 1mm to big for the new cylinder head hole in the combustion area , Maybe I should take the bosch drill to the new head???. NOT, 120 each for p/c is to much, I only paid 200 for the new head, and 200 for the SD with a steamy exhaust,
I guess i will take it down to the machine shop to have the combustion hole enlarged to fit the old pc,

thanks
Dave

You need to be carefull here.... I don't have a 617 turbo engine manual but there are MANY running changes made to the non turbo prechambers over the years. The 616/617 engine book has several pages that talk about the changes and details which prechambers can be used with with heads ect ect. I'm not 100% sure but I also think that certain prechambers should only be used with certain types of pistons.

One other measurement that is critical is the dimension that the prechamber tip protrudes out from the head. There are dimensions in the book that MUST be followed. Pistons hitting prechambers is not a good thing.

If you start drilling/millling on your used head to accomdate a prechamber that it was never designed to accomdate you are sailing into uncharted waters.... Be careful.

Tim

The prechambers for a 61x.91 normally aspirated engine are NOT the same as those for a 617.95 turbo engine (illustrated in job 01-417) and they must NOT be interchanged (OM60x turbo and non-turbo prechambers are likewise different and can't be interchanged). Last time I checked, Balo made prechambers that were considerably less expensive than the factory parts and I've had NO trouble with the Balo replacements. I haven't bought any for 4-5 years but prechambers for a 601.921 engine were ~$60 each then vs $90+ from Mercedes.

Marshall

When any adjustments are made to the precombustion chambers the reamer is supposed to be used before the glowplugs are put back in.... OR, can you spell " c r u n c h " ?

Well,

When people talk about machining the prechambers to fit-in all cases I've seen refer to 603 engines.

You need to make sure you have the correct head. On non-turbos, there were early and late styles. Different piston designs and prechambers... I believe my 81 non-turbo has the same chambers as a 82+ turbo. Someone with the cd handy could check.



Michael

The 116, 123 and 126 tubodiesels all show the same part number for prechambers for their respective 617 950, 952 and 951 engines. part # 617 010 03 52. The non-turbo (including the '81) show two different 615 and 616 part #'s.

I am assuming it is a factory head?

Oh once you figure out how to get them in.. there is a protrusion tolerance and different gasket thickness to adjust. Just don't want you to have problems=)

951 precamber should be a 617 010 03 52

Is the engine orginal to the car?

Michael

Thanks Mike

I bought the head down to the machine shop to get the holes reamed to fit my old p/c, You wouldn't have the specs for the p/c so I could measure it? My hanes doesn't have it in there
thanks
Dave

Ok I got the head back from the machine shop, the 50 dollar reaming turned into the 150 dollar ream after the BOSS found out it was a MB head, :mad: but he also rerounded my prechambers for a tight fit

The P/c fit very nicely now, I bolted on the head and fuel systems , adjusted the cam and valves ,I will fit on the turbo and exhaust today, I will have to wait until Monday for a NEw chain rail pin to hear her run, The one and only piece missing.
It turns freely with nothing hitting, but there is still a compression stroke one time during a revolution, Is this the diesel pump making pressure? all of the injectors out and pc whisling like a ol steam engine:D I also used loctite 574 around the prechamber seals, Best stuff for metal to metal seals!!!
holds porsche racecar halfves together,

So when all said and done the 617 engine is a million mile engine if valves and oil,filters changed evey 2500 miles or so?

Plan on a valve job every 250,000 miles or so, MB doesn't use stellited valve on the 617 and the exhaust valves will get worn badly enough by then to leak.

Bottom end should go 500,000 without repairs, at which point the rings are usually leaking enough to cause trouble.

Ditto for the gas engines, by the way, except that the rings should last longer in the aluminum blocks.

Peter

Dave,

"I also used loctite 574 around the prechamber seals, Best stuff for metal to metal seals!!! "

617's have a gasket. You did use a gasket right? I forget if it was Aluminum or copper washer- but there is one unlike the later 60X engines.


Michael

Where is this thread they refer too???

Hello?????