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Yet another S14B25 rebuild thread

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  • here the normal 2.3 pump, now you can see the differences between the 3 pumps
    And yes, changing that bolt would be the easiest solution


    http://www.bmwm3shop.de

    Comment


    • Thank you for the replies!

      The pump I use is an S14B25 pump - at least that’s what I ordered when I bought it a few years ago. However, it clearly doesn’t have the machined surface where this bolt goes in, which can be seen on Markus’ first photo. I will check the original pump tomorrow - as this is a stock S14B25 I am rebuilding, there should be a difference between the two pumps, which I didn’t spot when comparing the two...

      On your photos I also noted that the 2.3 pump does not have washers under the bolt heads. Removing this washer would certainly already help a lot, but I will try to find a button head bolt, as this will cetainly be the solution which will give me the most clearance.

      Is there any other way how I can confirm that the pump I have installed is actually a 2.5 pump?

      Thanks again.

      Marc

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      • Hi Marc, I really appreciate the detail you have documented in your rebuild. When I refreshed my 2.3 I thought I took a lot of pictures but every time you have a question or comment I check my pictures and I don't have a similar one to provide an answer. I guess lady luck was on my side as the engine not only started on first crank has run for a few thousand kms..

        Please keep the pictures coming. This is up there with X-Works documentation.

        Happy New Year from Canada.

        Comment


        • Originally posted by evo_3 View Post
          Removing this washer would certainly already help a lot, but I will try to find a button head bolt, as this will cetainly be the solution which will give me the most clearance.

          Is there any other way how I can confirm that the pump I have installed is actually a 2.5 pump?

          Thanks again.

          Marc
          Any hardware store should have grade 12.9 metric button head Allen bolts. Don't worry if it doesn't say "BMW" on it.



          Comment


          • the problem with the oilpumps is that the 2.5l one is NLA for over 5 years now, and if you are going to your dealer and order a EVO3 one you will get the "493" 2,3l one because they have replaced the 2.5l one with the 2.3l one :(

            http://www.bmwm3shop.de

            Comment



            • jwbavalon, thanks a lot for your feedback. I'm glad that my thread is interesting and helpful for others as well. Your time, as well as the time of everybody else helping me here, spent looking for information and answers to my questions is highly appreciated.

              Markus and Ironhead, I checked my old oil pump and Markus was spot on. The original S14B25 oil pump which was originally installed in my engine actually had that machined surface where this one bolt goes in (see attached photos). At the time when I started my rebuild, I decided to replace the complete pump by a new unit, as I stripped the thread of the pump gear when removing the gear nut, which was installed with very strong Loctite. Later when I dismantled the pump, it turned out that the gear and rotor were scratched, so a replacement would have been required in any case.

              Now, given that fact that I have the old pump available, I have several options:

              1) Rebuild the old oil pump, using new inner and outer rotor and intermediate plate (roughly 140 Euro€ for the three parts) and keep the new one as a spare unit.
              2) Leave the new pump installed and just use a button head allen screw without a washer (I use Loctite on all oil pump bolts anyway, so the wave washer should not really be required)
              3) Dismantle the new oil pump casing part and have it machined by a few millimeters, just like the original S14B25 pump

              I have attached a few photos of the old pump after dismantling. Can there be any critical wear on the pump, other than the two rotor parts and the intermediate plate, which could be a reason why option 1) would not be viable? Is the slight wear inside of the housing part in which the rotors are sitting critical?

              Thanks for your feedback.

              Cheers,
              Marc

              Comment


              • When I did my rebuild a few years ago, no Sport Evo pumps (nor at that time, any pumps) were available, so I did just as you suggest and rebuilt mine. While BMW was not selling complete pumps, they were selling all the parts I needed.

                You just have to inspect your parts for wear. Mine at some time had ingested a piece of oil seal spring, so both rotor parts were visibly damaged (although it was still working fine when I pulled it)so I replaced them. Like you, I also stripped the threads on the sprocket shaft. I replaced it with the "upgraded" shaft from VAC: https://store.vacmotorsports.com/vac...e30-p1247.aspx. While I am often leary of "upgraded" critical parts that are claimed to be better than OEM....in this case I think it is an improvement.

                My engine has oil squirters, and since the Sport Evo pump was designed to be used with the squirters, I liked the idea of rebuilding my pump rather than waiting for/tracking down a 2.3 pump.

                So to answer your question, there is no reason why you cannot simply rebuild the pump you have. To me it actually makes more sense than buying a new one. Most of the parts are "minimal-wear" items....and all the parts that are subject to wear are available from BMW (at least they were 3 years ago).

                Looking at your parts specifically...you can see some damage on the rotor parts...were it me I would replace those. The shaft is a separate part that has to be pressed in/out of the rotor. I doubt your housing is damaged at all....mine looked brand new.
                Last edited by Ironhead; 12-30-2017, 10:18 AM.

                Comment


                • I just looked up the head thickness of a button head allen bolt, versus the standard hex bolt in M6, see attached screenshots of the DIN standard dimensions. The standard hex bolt has a head thickness of 4mm, while the button head bolt has a head thickness of 3.3mm. A standard wave washer in M6 has a thickness of 0.5mm, so in total I would win 1.2mm when installing the allen bolt without a washer. Factoring in the rounded button shape of the allen bolt, I would probably achieve a minimum clearance of more than 2mm between the bolt and the conrod, versus the 0.75mm I have now.

                  I have no idea how much the oil pump moves at high rpm, but I would consider this as a good clearance - what do you think? Is there any other reason why I should go with the old pump and rebuild it? According to the information I found, the EVOIII pump has a different setting of the overpressure valve. Is that correct, and which influence would that have on my engine?

                  Cheers,
                  Marc

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                  • ..

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                    • Ironhead, thanks for your feedback. Given the fact that I also have the oil squirters installed, I like the idea to rebuild the old pump more and more. I would definitely replace the rotors because they are scratched. The housing does show some light wear but no scratches, so I doubt that this is critical.

                      Comment


                      • I think 2mm is adequate clearance. The oil pump is not going to move at all, and if your rod is moving around that much the engine is dead anyway.

                        You likely will actually wind up with more like 4mm or so clearance from the button head bolt. It is only 3.3mm dead in the center...around the edges much less.

                        Even .75mm was probably adequate clearance....but like you it would not have given me a warm feeling to run it that close.

                        But again...I think just rebuilding the 2.5 pump might be a better plan.

                        Comment


                        • I vote for rebuilding. I rebuilt my 2.3 pump when you could still buy pumps as a decent price. There are only a few wearable pieces in a pump so the less cost solution is a rebuild. Marc, in your case, you will end up with the factory clearance,which I know you will document for others on their rebuild.

                          Happy New Year.

                          Comment


                          • First of all, happy new year to all the M3 enthusiasts. Looking forward to finally be amongst the M3 drivers again this year.

                            Yesterday I took the time to dismantle also the new pump in order to compare both pumps. Having done some previous research on the forum, I knew that the only differences between the 2.5 and the 2.3 pump are the housing part machined by a few millimeters where one of the bolts goes in on the 2.5 pump, as well as the pressure relief valve, which is equipped with a double spring on the 2.5 pump, while the 2.3 pump only has one spring.

                            During dismantling, I found out that actually both pumps have a double spring arrangement. I then looked back in my old invoices from BMW and found that I bought this new pump already in 2009 (for 160 Euro...) and that it is actually a 2.5 pump with the part number 11411316853. So it turns out that this newer version of the 2.5 pump was assembled with an incorrect housing to be operated safely in an S14B25!

                            Other than the spring lengths which were slightly shorter in the old pump, I did not find any further differences between the pump components.

                            On the old pump, I have some wear in the form of a slight recess in the housing part in which the pump gears rotate. I therefore decided to continue using the new pump but that I will have the housing part machined just as the old pump to obtain the design clearance between the pump and the #1 conrod.

                            Also, when dismantling the pump gear nut, I damaged the thread on the axle again because of the Loctite I used - so it seems that this axle is made out of very brittle material. This is however not really a big deal as I planned to use the VAC upgrade kit for the axle as recommended by Ironhead. I ordered this kit today, so that will take some time to get to Europe, which gives me some time to get the engine ready for installation.

                            Today, I installed some more small auxiliary parts to the engine and decided to also replace the O-ring on the rear cooling water connection to the cylinder head. I didn't replace it when the cylinder head was dismantled, as that would have required me to somehow fix the head to the workbench, but now as the engine is on the stand, I thought that it would be only a few minutes of work. Unfortunately this seems to have been a mistake. I was able to loosen this fitting quite easily and then I was able to turn it easily with the wrench for maybe about half a turn when suddenly the thread jammed. As I didn't want to force the thread, I tried to turn the fitting clockwise again to help loosening it, but after a few degrees of free rotation it was jammed again. Now I am not able to turn the fitting anymore in any direction without using excessive force. I am anxious about potential thread damage in the head, given the fact that this is an aluminum thread, so I just stopped there and decided to ask for advice. Did any of you guys loosen this fitting on your heads and had similar problems? It is an M36 thread, so hopefully not that sensitive, except if it has been damaged by corrosion. The fitting is still available for a few Euros, so if the dismantling method should involve destroying the fitting, then that would not be an issue.

                            Thanks for your help.

                            Cheers,
                            Marc

                            Comment


                            • Hi,
                              What is worth checking with the new pump is carefully measure the depth of the rotor housing then the thickness of the inner and outer rotors, mine worked out at 0.004” ( it will be larger than this when hot).
                              I reduced mine to 0.002” to reduce pumping loss by carefully sanding the main housing on a flat block with 600 wet and dry paper. Cleaned up everything and rechecked with a straight edge across the pump housing and and gears with a feeler blade for clearance.



                              E30 M3 1987
                              Mini Clubman GT
                              BMW E36 323 Msport
                              Toyota Corona
                              KTM 200EXC
                              Honda CB50 (1979)

                              Comment


                              • Well, it turns out that wanting to replace that stupid O-ring was a terrible idea... After having applied WD40 over night I tried again to remove the fitting today. I was able to turn it by a few degrees back and forth each time, and to slightly loosen it a little bit more each time without having to apply excessive forces, until it finally came out. The frustrating result is that the thread in the cylinder head is severely damaged, while the thread of the fitting is completely gone, see attached photos. The only idea I can think of how I could repair this is getting an M36 tap to repair the thread as best as possible with the material that is still there and then reinstall a new fitting with strong Loctite and never take it out again. Ideally I would then additionally like to secure it to the head, but how...? Any comments or recommendations on how to get out of this disaster would be highly appreciated...

                                Dave, thanks a lot for your comment regarding the possibility to reduce the pumping loss of the new oil pump. As soon as I will have the problem above sorted out somehow, I will check this with my pump.

                                Regarding the machining of the pump housing, I decided to use a countersunk M6 allen bolt like in the DTM pump posted by Markus above. Those bolts are available everywhere and I can easily machine the housing on my drilling machine, compared to the method of the 2.5 pump where I would have had to bring it to the shop to have it machined.

                                I need a beer now...

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