Tech Tip: Oil Leak by Crankshaft Seal on Porsche Boxter Engines

Tech Tip: Oil Leak by Crankshaft Seal on Porsche Boxter Engines

Engine oil leaks in area of crankshaft sealing ring on flywheel side may be coming from the crankcase and intermediate-shaft flange bolts.

Models Affected: 97-’04 Boxter/Boxter S M96.23, M96.24 Engines

Examination of engines that were the subject of complaints revealed other oil leaks in addition to those found in the crankshaft sealing ring on the flywheel side. These engine oil leak areas included:

• Crankcase bolt threads
• Intermediateshaft flange area.

Since March 10, 2004, bolts with a sealant coating on the thread and head have been used during assembly to fasten the crankcase halves in the area of the flywheel.

On vehicles manufactured prior to the above-mentioned date, the four crankcase bolts and the three intermediate shaft flange bolts must be replaced in addition to the crankshaft sealing ring in the event of an oil leak in the area.

Parts Information
999 85 004 09    New/Coated crankcase bolt, M6 x 35 (4 ea. required per vehicle)
900 385 275 09  New/Coated bolt for intermediate shaft, M6 x 20 (3 ea. required per vehicle)
999 113 490 40  Shaft seal

Repair Procedure
1. Replace crankshaft sealing ring (Figure 1, Item C). (see Technical Manual, Group 1, Repair, 13 59 19 – Removing and installing crankshaft sealing ring – flywheel side.)

2. Replace four bolts on the crankcase (Figure 2, Item A).

2.1 Unscrew and remove the four bolts (Figure 2, Item A) and clean oil residues out of the threaded holes using a suitable cleaning agent (e.g., brake cleaner).

2.2 Screw the new bolts, Part No. 999 385 004 09, completely into the threaded holes. Tightening torque: 9.5 ft.lbs. (13 Nm)

3. Replace fastening bolts on the intermediate shaft flange (Figure 3, Item B). Since the intermediate shaft flange is loaded by the chain tensioners, the fastening bolts must be replaced only one at a time.

3.1 Unscrew and remove one fastening bolt and clean oil residues out of the threaded hole using a suitable cleaning agent (e.g., brake cleaner).

3.2 Fully screw the new bolt, Part No. 900 385 275 09, into the threaded holes. Tightening torque: 7.5 ft.lbs. (10 Nm)

3.3 Repeat steps 3.1 to 3.2 for the second and third fastening bolts.

Some or all of this information was provided by the Automotive Parts Remanufacturers Association (APRA). For more information on technical bulletins available through APRA call (703) 968-2772 or visit

You May Also Like

AP Emissions Unveils August New Product Announcement

10 new 46-state Federal EPA part numbers have been released.

AP Emissions is pleased to announce the release of 10 new 46-state Federal EPA part numbers covering more than 3 million vehicles in operation.

The newly released part numbers and their application coverage are:

-Part #s AP 644240 / CATCO 5447 / Eastern 30662, 2015-2019 Lincoln MKC 2.3L Front, VIO: 29,450

-Part #s AP 645141 / CATCO 9640 / Eastern 30669, 2018-2023 Ford Expedition 3.5L Right; 2018-2023 Lincoln Navigator 3.5L Right, VIO: 409,150

Hunter Engineering Expands Supply Capabilities in Missouri

Company continues to efficiently serve customers despite supply chain challenges.

Autel Adds EV Diagnostics, Maintenance to Class Roster

Classes are intended for current and potential owners of Autel EV diagnostic tablets.

SMP Expands Emission Control Program

SMP’s Emission Control program offers more than 1,500 EVAP components and 4,000 products for crankcase and EGR emissions.

Schaeffler Recognized as PACE Award Finalist

The company was named an award finalist for its eRocker System.

Other Posts

Stellantis Expands, Enhances Parts Business

Stellantis’s bproauto aftermarket parts brand is expanding to North America with 30 parts categories.

FCS Adds 57 New Numbers

All of these units are in stock and ready to ship on the FCS website.

Autel Releases 2023 ADAS Calibration Coverage

The new DTC analysis feature provides detailed fault cause possibilities, and suggested fault solutions.

SEMA Awards 80+ Scholarships, Employee Loan Forgiveness

The scholarship winners include 87 students, while 17 employees of SEMA-member companies received loan forgiveness.