Freshening up The Beast

When I bought my 1991 M5 last month, I knew it had gotten good love for most of its life since Graham at Bimmers Only had been servicing it. It has great bones, but at 141K , the paint has seen better days and some motor maintenance is required.

Unfortunately this car went to the drive thru car wash one too many times. Lots of abrasion marks on the paint, and the 4 doors have uneven surfaces of oxidation. The upside is, there’s no rust…so I guess its not too bad a deal.

Since this is my 2nd e34 M5 I learned a lot from the first one. One of the most important functions of the motor is maintaining proper vacuum as the DME picks up its signal from that as do the brakes.

As robust as the S38 is, a vacuum system that’s not working will make it run very lean and can cause an early death to the motor.

So we decided to park the M and get it sorted before the season gets fully underway.

All taped up for wetsanding and compounding.

I know it looks like madness, but once you follow the schematic, its actually quite easy to R&R hoses. Most of the wetness is from wd40 and brake cleaner and a leaking VC gasket from the front edge.

The ” before ”  of the the M5’s intake plenum

Time to clean !

Man, thats 21 years of intake on the ITB’s

Here are some of the vacuum lines and a main rubber hose that sends vacuum to a switch. It broke as I wiggled it gently. The rest of the hoses were dried out and shot.

With the valve cover off. Both cams looked good. Lobes aren’t pitted and they actually look new. Evidence of prior valve adjustment from just looking at some shims. All in all the S38 looks as it should.

M5 Valve cover ” before “… thats 21 years worth of grime and dried up cosmoline.

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