oilpumprepairkit

[450sl]

I was lucky to find a very cheap   " Nos- Oilpump repairkit 280SE-late '' 

Turns out the gears are 4mm wider than mine , so i suppose this is a bigger capacity pumpkit.

I now face the dilemma; should i grind down the gears or look for an bigger housing?

any thoughts appreciated

Mark

[Benz Dr.]

I would buy a new pump.

[perry113]

I was lucky to find a very cheap   " Nos- Oilpump repairkit 280SE-late '' 

Turns out the gears are 4mm wider than mine , so i suppose this is a bigger capacity pumpkit.

I now face the dilemma; should i grind down the gears or look for an bigger housing?

any thoughts appreciated

Mark

When you said grind down the gears my hair stood straight up 

I agree with Dr. Benz. The oil pump is far too critical to cut or grind corners on.

[Rolf-Dieter ✝︎]

Mark,

Your photo shows two gear sets, I assume the original and the spare you obtained. Did you measure the housing internal to establish internal clearances? I ask this perhaps you don't have to adjust anything.

If I was in your shoes I would do the following;

A) establish internal clearances of original and the new set.
B) find out what the clearance should be (from the Blue Book or people that rebuild them)

If absolutely required go to C) below. I would not hesitate to go to that step reverse engineering is done every day all over the world. Also consider machining / grinding tolerances and acummulation of those allowable tolerances. Keep in mind that there are no machined parts that are excactely the same for the aforementioned points. The internals of your pump housing as well as the two gear sets you have a +/- machining / grinding tolerance. Based on the minimum and maximum the design engineer establishes a running clearance.

C) find a good tool and dye shop (there are good father and son establichments out there) and have them grind the new set to duplicate your original set.

One more point that concerns me is ... Why did your original pump fail? Could it be that the clearance was too much and the original gear set was the cause of failure? Once you measure your housing and establish actual clearances and you find out what the clearance should be the question might be answered.

As said ... This is what I would do.

Dieter 

[Benz Dr.]

Oil pumps are not that costly relative to the price of your car or for that matter, your engine. If you bought a rebuild set '' cheap '' on the internet, that's what you have. Cheap stuff you bought that doesn't even fit. Those gear sets are made of very hard metal and they won't be easy to work with.
 
Your oil pump doesn't create oil pressure, it creates volume. As long as your volume is adequate and your main and rod bearings are tight, you will have oil pressure. Even if you could fit those gears into the pump the pump body may still be worn and that can't be fixed. Get any one of those very fine tolerances wrong and you could damage you engine.

 A high capacity pump, which is what I use, will allow for a bit more wear before oil pressure starts to go down. A good 113 engine will remain pegged on the gauge even at hot idle. However, as long as it shows full pressure at or before 1,500 RPM you should be OK.  If your gauge falls below full peg at road speed you are not OK. Either you are low on oil or you have very worn main and rod bearings.

I won't back up a rebuild without a new oil pump and neither will any place that's worth your money.. Lots of fine broken pieces or grit can and do run through the oil pump if your engine is failing because that oil is not filtered before the pump. When, where, and how that happens is anyone's guess, but I won't take the chance of using a worn out pump. Neither should you.

[Dave H]

Not just the gears but also the driveshaft is longer...

[450sl]

Thanks Guys, for your comments.

Just to clarify ;I want to rebuild a 280 engine as a spare for future use.
Could bring it to a specialized shop , but want to do this by myself , mostly as a challenge , to do the best job without spending a fortune.
As an engineer running my own shop with cnc machinery for over 37 years , this grinding job should be well within my confortzone.


I think the donor engine has seen a few miles : the cilinders are well worn but  (just) can be honed to first oversize , have no clue how many miles this represents.
The oilpump in my view also looks well used.
The BBB - section 18-7/1  only mentions the use of a bigger capacity oil pump , no further specs about running internal tolerances.


Just was curious in howmuch the bigger oilcapacity would benefit the engine
If anyone has oilpump-tolerances ; i would be very happy.

Thanks
Mark

 



 

[Pinder]

if you are thinking of going to first oversize  you may want to check the prices of the pistons for first oversize and second oversize. the second oversize is a more commonly available size from my research and a lot cheaper than first oversize. for example I paid around $1100 for first oversize but I could have bought second oversize for only $700. In hindsight i should have gone to second oversize for my engine rebuild.

[wwheeler]

I totally agree with Pinder. I just priced pistons for my 220SE and what a difference the repair size made. $200/ea for the 1st and 3rd repair. $400 for the second repair. So you are talking a difference of $1200!!!

So yes, get that quoted first and then decide what repair size you need to be at. Each engine will be different with supply and demand in full force.

[450sl]

Thanks Guys, i have noticed the remarkable pricedifference in 1st en 2nd oversize as well .

I was fortunate to hunt down, some good condition used 2nd oversize pistons , they are the flat head type , i think  with a fresh set of rings they will do the job fine.

[ja17]

Original oil pumps may be NLA or extremely expensive. I believe that some rebuilders are using the oil pumps from the M110 twin cam engine. Which is a higher capacity. Only some minor change is needed, possibly a mounting bracket or pick-up.  Seems they are keeping this a secret for now since these pumps are a readily available and much less expensive. Its time to solve the mystery so we can all benefit!

Mark, original MB piston rings (ATE) are extremely expensive. Many have used the Deves rings (Sweden) with good results. 

[450sl]

Joe thanks for the info.

I might be getting a used bigger capacity housing , to overhaul and accommodate my replacementgears.

If not i will be looking for a 110 pump , more oil always sounds better .
In the set is a new pressurevalve included ; i suppose this one is already setup to specs and can deal with more oilflow ?

Mark

[Benz Dr.]

I think the pressure relief valve is set to about  6 -7 bar but I would check with a data manual to be sure.  I know a 190 SL oil pressure gauge goes up to 90 PSI which is quite normal with a cold engine so 100 PSI breaking pressure sounds right.
It's tight main and rod bearings that create oil pressure and at some point  you want to limit that pressure from going too high and causing damage to all sorts of things. 

[450sl]

thank you Dr.

Heard rumours about  there being 3 different MB engineconficurations :

1 engines with oilpumpreliefvalves
2 engines with  enginehousing reliefvalve
3 engines with  enginehousing  AND oilpumpreliefvalve..

Seems no reliefvalve can cause serious problems like exploding filters etc.

Dont know if the above applies to our engines /cannot check at this moment : but i think my 280 uses 2 valves

[gordon]

Can anyone confirm ja17,s post that an oil pump from a M110 twin cam engine  will fit a 230 SL. New SL pumps seem not to be available.

[Benz Dr.]

I can't confirm that but I recall that the ones I'm using have a relief valve on the oil pump and the original ones didn't have that. Good bet it's from a M110. Given all of the moving parts in that engine, I can see where additional volume would be needed. Maybe not needed in our engines but not harmful either.

I could imagine the relief valve opening when your oil is cold and/or higher RPM's when your oil is cold. Not a good idea to rev a cold engine anyway......... 

[Shvegel]

Joe or Dan can confirm this but my understanding is that the M130 has a Siamesed Cylinder block which means there is no water flowing between cylinders. It is a solid casting between the bores.  That said it is also my understanding that the M130 is much more prone to overheating when you reach second oversize.  If your engine is original to the car also keep in mind you probably will not be able to sleeve what has now become a valuable "Numbers Matching" block.  Might want to hunt down some first oversize pistons if possible.

[ja17]

Not really sue what the Siamesed  block has to do with the oil pump Pat? But you are correct, they are Siamesed. The machined water slots between the cylinders was to aid cooling in the 280 engines.

[Shvegel]

Joe,
A few posts back the OP mentioned buying 2nd over pistons and his intent to bypass first over and go up to 2nd over.

[450sl]

Final outcome for my repairkit:

Found a used M110 pump, removed its 34mm wide gears and machined the housing to fit my 32mm gears.

So there are at least 3 types of pumpgears ; 28mm(M130) ,32mm (for the repairkit) and 34mm wide (M110).

2 possibly things to go wrong :

Lenght of the complete (edited) M110 assembly is longer, this can be compensated by using a different oilpickup cup or
(as i did) buy a new (improved +0,5liter and 7mm deeper) oilpan.

The bigger capacity of the pump should match the internal bores of the oilpumphousing.  M130 pump bores are a lot smaller then the M110 bores.

Mark

[ja17]

Latest version M130 engines had a deeper oil pan. The little rubber pick-up snorkel on the oil pump was added to accommodate the deeper pan. Look for the "ribbed" metal oil sub-pan.