Philes’ Forum – Spring 2016
by NJ BMW CCA
By Vic Lucariello, Sr.
Hello, bimmerphiles! This time out I have some tips for both E90 owners and E30 owners. How’s that for spanning the decades?
Out of respect, let’s begin with the venerable E30 [’84 – ’91 3-Series], which in my opinion may be the best car BMW has ever built. The E30s were available with several engine types, but the vast majority of them came with the M20 six-cylinder, which was also available in the 5 -Series of the era.
The M20 six, available in the U.S. in 2.5 and 2.7 liter displacements, is about as bulletproof an engine as you are likely to find, especially the low-revving 2.7s. This, provided you replace the timing belt at the interval prescribed by BMW. [For you non-gearhead types who read Philes’ simply for its stunning literary content, the timing belt is a cogged, flat “rubber” belt that drives the engine’s camshaft. If the belt breaks or slips, expensive noises escape from the engine, followed by profound silence punctuated only by the expletives emanating from you when you learn the cost of repair.] Insofar as I know, despite the improvements in timing-belt materials in the last quarter century, BMW still recommends 5 years or 50,000 miles [whichever occurs first] as the replacement interval. More modern timing-belt engines from other manufacturers have longer intervals, typically 100,000 miles.
M20 timing-belt replacement has been written about extensively over the years, both in Philes’ and elsewhere, so I won’t bore you with the whole procedure. However, every time I replace one I think of one or more things I would like to share with you, and the latest job was no exception:
- You don’t have to remove the radiator, but the radiator fins will gladly lacerate your knuckles if you don’t wear latex or nitrile gloves.
- Replace the water pump whether it needs it or not. Buy a quality pump either from your BMW dealer or a supplier of OE-grade replacement parts. Aftermarket pumps usually come with the gasket, but at your dealer you will need to order it separately. The astoundingly poor quality of some aftermarket parts is a constant topic of conversation and ranting on professionaltechnician forums such as iATN.
- Conti makes a nice timing-belt kit that includes a new timing-belt tensioner. Always replace the tensioner.
- Being you are draining the cooling system anyway, this is a good time to flush it out. Be sure to obtain a new seal ring for the block-drain plug. Part # 07-11-9-963-200.
- Before you install the new water pump, check its block-mating surface for any imperfections and run a very fine file over the surface as shown in Photo #1. This will identify and remove any high spots or machining burrs, and yes, there will be some.
- Before you install the new water pump, thread the engine-cooling fan onto the pump hub to ensure that the pump threads are good. Remember it is a left-hand thread. See Photo #2. Uh, remove the fan before you install the pump. I like to put a bit of anti-seize compound on the pump-hub threads.
- After thoroughly cleaning the block-gasket surface, use gasket cement to attach the new pump gasket to the block surface. Ensure the gasket is installed in the correct “clock” position.
- Before you put the pump in place on the block, make yourself a guide pin by cutting the head off an M8-1.25 bolt that is about 40- mm long. Install this stud temporarily in one of the water-pumpmounting- bolt holes in the block. This will greatly facilitate getting the pump in the correct position on the first try without moving the gasket out of place. You can use the same M8 stud for reinstalling the drive-belt pulley on the crankshaft damper.
- Ensure that you use the correct-length water-pump-mounting bolts. One time, Bimmerphile Mark Derienzo and I went nuts trying to figure out why several new water pumps we installed on a 5-Series M20 leaked as soon as we put coolant in. One of the water-pump bolts was a tad too long and was bottoming out in the block. The correct bolt is 20-mm [about 25/32] from under the head to the end of the threads. Part # 07-11-9-903-039 [3 required]. Install new M8 wave washers on the bolts [07-11-9-932- 095].
- The standard procedure for tensioning the timing belt is to release the tensioner-pinch bolt and pivot bolt after installing the new belt, then tighten them. What I like to do after doing this is to rotate the engine through two complete crankshaft revolutions, recheck that the timing marks still align, then release the tensioner-pinch and -pivot bolts again, then tighten them to specs.
- Before you rotate the engine as described above, #1 Cylinder is already at TDC, so adjust its valves. As you proceed through the two crankshaft revolutions, watch the other valves, and when they are closed [watch the camshaft and rocker-arm positions], adjust them as well. Your M20 will love you for it.
The E90 tip is a simple one, but it can save you some time and angst, especially if you are doing the job in the evening or on the weekend, when parts sources may be closed. This applies to E9X 3-Series [’05 – ‘12] with manual transmissions. If you change your clutch-slave cylinder, be advised that the replacement cylinder [especially if it is an aftermarket part] may not mate up with the old metal hydraulic line, as some part-number supersessions are in play here. The result will be a leak. Your safest bet here may be to source both the line and the slave cylinder from a reputable source of BMW parts. [That is good advice regardless of what part you are buying.] The clutch-slave cylinder and hydraulic line are listed as fitting a plethora of BMW models, so this tip I think applies to other models as well.
That’s all for now, bimmerphiles. See you next time.
Anyone wishing to contribute to Philes’ Forum can contact me at firstname.lastname@example.org. I’m interested in tech tips, repair/maintenance questions, repair horror stories, emissions-inspection sagas, product evaluations, etc.
© 2016; V.M. Lucariello, P.E.