Oil pressure springs

James Avis · 01-12-2003, 01:02 AM

Iam rebiulding my 911 engine On the bottom and the side off the engine there are two spring loaded pistons i think they are to do with the oil presure .One has more tenntion than the other which goes where Thanks for your help James

Wayne 962 · Wayne 962's Garage

What year is your car, and have you had the oil pump by-pass modification done to it?

-Wayne

James Avis · 01-12-2003, 01:09 AM

The engine is a 2.2 S 1971 it has the bypass

James Avis · 01-12-2003, 01:14 AM

Should both pistons be without the holes when the bypass convertion is done

Wayne 962 · Wayne 962's Garage

Oil Pressure Relief Pistons - Towards the oil pump area of the case, there are holes bored for the oil pressure relief pistons and springs. Install these two assemblies into the case, using new springs, new pistons and new aluminum sealing rings. If you have performed the oil bypass modification, you must use the late-style oil pressure pistons. The older style ones are not compatible with the bypass modification and will rob your engine of oil pressure when you start it up. The main pressure relief valve is located on the bottom of the engine, and contains a small piston and uses the longer spring. A handy upgrade is to replace your early-style flat-head oil pressure relief cap with the later-style 17mm one (part number 999.064.026.02). If you purchase the updated spring and piston kit to use with the oil bypass modification, these newer 17mm caps are usually included with updated kit. The springs don’t seem to wear out often, but it’s a good idea to replace them with new ones when you’re rebuilding your engine. The new and old kits are shown side-by-side in Figure 3-36.

Wayne 962 · Wayne 962's Garage

The new ones do not have holes...

-Wayne

jcbear · 11:40 PM

OK, I'm confused and new at this but ... I just ordered new pistons and springs for the oil bypass modification. I checked my Factory '71 Spare Parts Catalogue and also checked the 'Parts & Technical Reference Catalogue - 911 Models 1974-1989' which both indicate that the main and secondary spring has the same key # and part number (901 107 531 00). I ordered 2 springs, using same part #, but now I see after reading above and looking at Fig. 3-36 in Chapter 5 that the new springs are different lengths. I apparently am going to receive one spring that is wrong for the new pistons. I also did not know there was a piston update KIT.

Question: What reference source do you use for part number references? Is the data in the 74-89 Parts & Tech. Ref. Catalogue unreliable or unusable because incomplete? What is the best way to find out about update kits, such as the one mentioned above (I looked but could not find any oil pressure relief parts at all on the Pelican WEB parts catalogue)?
P.S. What is the part number for the other spring -, if not the (901 107 531 00) part ; what is the number for the update kit?

An extra $2 spring is not a problem but to avoid bigger ones in the future, I would sure appreciate any help or direction on how to identify the correct parts (for an older 71 using significantly later edition parts catalogues) that I will need to complete various update modifications and get my engine back together.

Thanks - appreciate everything.

Wayne 962 · Wayne 962's Garage

I don't have this info handy right now, but it is in the Appendix of the final edition of the book (part number reference). I think that the 1974-89 book supercedes to the later-style springs, but I can't recall off the top of my head.

This page has them listed, but you're right, it's not clear here either:

http://www.pelicanparts.com/cgi-bin/autocat/load_page.cgi?page_number=7&bookmark=7&model=911M&currsection=enginA

Just give Tom a call in sales (1-888-280-7799x221), and he can get you the proper kit.

-Wayne