Philes' Forum by Vic Lucariello

Hello, Bimmerphiles! This month we have a special treat for you motorheads. Lime Rock hotshoe Warren Brown has submitted an account of how he successfully changed the infamous 'Profile Gasket' on his 318is. I have reproduced Warren's material verbatim, and my comments are shown parenthetically [Uh, Big Al, that's like THIS!]. Also, I have had to do some editing of Warren's detailed submission to fit it into the newsletter format. If anyone desires a copy of the entire file, contact me and we will get Warren's permission to send it to you. Also, we will attempt to include two photos of the disassembled engine in next month's conclusion of this topic.

The profile gaskets on M42 engines tend to go at the 50 to 100k mark, mine went at 71K, 6 years. I have always used BMW antifreeze changed at 2 year intervals. Mine started to leak suddenly and significantly, the last trip I lost 2 quarts of coolant in 8 miles. On my car it was very hard to pinpoint the exact location of the leak. Water seemed to be leaking from somewhere above the AC compressor and dripped down so the it looked as if the leak was behind the AC compressor bracket. [The M42 engines are the 1.8 l, DOHC motors that came in the E30 318 is and Z3s. The Profile Gasket is installed between the timing cover/water pump housing and the cylinder head. Its main purpose is to seal the coolant passage between them.]

Replacing the profile gasket is a lengthy job, it took me the better part of a weekend. I am not a mechanic by trade, I do not claim to be a speedy mechanic. This is the first engine repair I have done on this engine so it was all new to me. In my previous life I have done a fair bit of mechanical work on my '73tii so I do know my way around the tool box. This is an excellent opportunity to also replace the water carrying hoses on the intake side, many of these are only accessible after removing the intake manifold. [While you're at it, change the water pump as well. The M42 uses a timing chain instead of a timing belt, so you don't need to worry about belt replacement.]

1. Drain the antifreeze from the radiator and block.
2. Separate the header from the catalytic converter. Heat the bolts with a propane or acetylene torch if necessary.
3. Remove the upper and lower radiator hoses both from the radiator and the thermostat housing.
4. Unplug the 2 connectors from the engine electronics box under the [intake] manifold. These wires come from the trigger contacts mounted on the front of the upper timing chain cover and down near the AC compressor.
5. Remove the bracket holding the wires on the front of the engine.
6. Remove the 5mm socket head bolt that holds the upper trigger contact to the upper timing chain cover. The lower trigger contact doesn't have to be removed.
7. Remove the thermostat housing and thermostat, note the orientation of the thermostat.
8. Remove the fan clutch, this is a left handed thread. You will need a 32mm or 1.25" open wrench. [Be sure to do this prior to loosening the alternator drive belt. Whacking the wrench with a rubber mallet usually does the trick.]
9. Remove the water pump pulley.
10. Remove the boot between the air fuel meter and the throttle body.
11. Remove the wire from the throttle position switch.
12. Remove the accelerator cable and cruise control cable if equipped, note the relative position of the cables for re-assembly.
13. Remove or at least loosen the "happy faced" shaped bracket located at the base of the throttle body. This bracket holds the oil breather hose to the throttle body.
14. At the throttle body, remove the hose from the fuel vapor canister.
15. Remove the throttle body housing. Disconnect the small vacuum hose from the fuel pressure regulator.
16. Remove the throttle body heater if equipped.
17. At the rear of the upper intake manifold, remove the hose that leads to the throttle stabilizer.
18. Remove the upper intake manifold. You may want to remove the bracket supporting the upper manifold at the rear of the engine.
19. Unplug the fuel injection cable from the engine electronics box.
20. Mark for re-assembly, then remove the fuel hoses, be sure to plug them and be prepared to catch fuel that will leak from metal tubes. [Now's the time to change your underhood fuel hoses! See Philes' Forum - May '98] Be extremely careful with any fuel which may spill at this point, make sure the trouble light is well out of the way. Hot trouble lights and cold fuel don't mix!
21. Remove the brake booster vacuum hose from the brake booster,
22. Remove the front lower intake manifold support.
23. Remove the bracket that supports the engine electronics and fuel line.
24. Remove the lower intake manifold. [An alternative is to separate the lowermanifold from the head and pull it to the left side of the engine compartment with bungee cords. This will reduce the number of things which must be disconnected.]
25. Remove the wires from the temperature sensors. Be sure to mark each wire for re-assembly.
26. Remove the heater hose from the [rear of the] head.
27. Remove the spark plug cover.
28. Remove the ignition wires and the plastic tray under the plug boots.
29. Remove the spark plugs.
30. Remove the plug wire heat shield.
31. Remove the valve cover.
32. Remove the upper timing chain cover. There is 1 bolt just below the boss for the trigger contact that is hard to see.
33. Rotate the engine in the direction of travel till the intake and exhaust valves of cylinder #1 point toward each other. There will be arrows on the frontof each cam gear pointing up.
34. Lock the flywheel with the special tool, lock the cams with another special tool. The special tool for locking the flywheel is a stepped pin that fits into a hole in the block and indexes on a hole in the flywheel. The hole in the block is accessed from the top, it is located below the starter between 2 triangular webs cast into the block. The hole should be covered with a white plastic plug. Due to the triangular webs it is difficult to see the white plastic cover or the hole. The cam lock is designed to hold the square lugs cast into the rear of the cams at right angles to the top of the head. When the tool is properly installed, the bottom surface should be in contact with the top of the head.
35. Remove the timing chain tensioner located just above the AC compressor.
36. Remove the upper timing chain guide between the 2 cam sprockets.
37. Remove the 5mm bolt that retains the left hand timing chain guide.
38. Remove the timing chain sprockets.
39. Remove the head bolts, be sure to remove with a magnetic tool the washers from underneath the head of the bolts. Removal of the head bolts requires an E12 Torx socket with a maximum outside diameter of 0.680" = 17.3mm. I purchased mine at PEP Boys as part of a set, I did have to turn it down a fair bit on a lathe. Facom and Snap-On both offer 3/8' drive sockets that look as if they will work. [Since the head bolts are of the 'Torque-To-Yield' type, they must be replaced with new ones.] 40. Remove the head with the exhaust header.

Whew! That's enough for one month! Warren will be back next month with the conclusion of his profile gasket saga.

Anyone wishing to contribute to Philes' Forum should contact me via the info on the masthead. I'm interested in tech tips, repair /maintenance questions and/or tips, dealer horror stories, product evaluations, etc. Please call before 8 PM, and if you leave a message, PLEASE INCLUDE YOUR WORK PHONE NUMBER. Also, please be patient, I try to return every phone call, but it sometimes takes awhile. The best way to contact me is via e-mail.