Reconditioning an Engine 101

We received a call awhile back from Barri Stallworth, a great customer that was in somewhat of a tight spot. He said his 88 325i convertible was in the shop, and it needed a new engine. The German mechanic, wanting to make sure the car was absolutely tip-top, insisted on ordering a refurbished motor from BMW to the tune of $4500+… Yikes! We all know the M20 engines are fine for 200+ thousand miles, and our e30’s don’t exactly hold enough value for most of us to justify an engine in this price range, so we fixed Barri up with a very nice used/partially reconditioned engine for his cabrio.

Luckily we had just pulled the same engine from an ’87 325is! The engine was running very well when we pulled it, but we like to do things right the first time, so we started to inspect it. After pulling the valve cover, we found that one of the old style head bolts had broken off. This could likely lead to a head gasket failure in the future, even with the head bolts replaced. At this point we decided to remove the head and have it checked out and reconditioned. On top of that, we offered our services in making the whole engine a little easier on the eyes with some detailing and powdercoating!

We pulled the dirty thing a part and sent the head and some of the top end bits off to the machinist for inspection, rebuild, and a good ultrasonic cleaning. Think of it as a baptism for your car’s soul!

We pulled a head kit gasket set and head bolts (we sell this as a complete kit HERE). Important to get new head bolts since the OEM bolts stretch when you install them (the technical term is “torque to yield”). If your M20 engine has head bolts with hex heads heads, you may want to look into swapping them for the newer torx style bolts. Not all of the hex head bolts fail, but it is fairly common. We’ve had two engines in the shop in the last 6 months wioth broken head bolts. Both of these engines happended to have “Ribe” brand bolts (the brand is embossed on the head). We’ve not seen any other brands have this issue, but some will say any hex head bolt should be updated.

While the top half was at the machinist, we focused on the bottom half. The mileage on the motor is considerably low, at about 130k. The cylinder bores looked pretty fresh. So we just gave it a good cleaning and then a refinish on the outside using Dupli-Color Ceramic Engine Enamel.

Now the block is all tidy, and we got our head back from Kevin at Head Solutions. As usual we are quite happy with his work!

Now for assembly. As stated before we used all new gaskets for the top end. Of course, following the torque specs and sequence covered in the Bentley repair manual. We put both the bottom end and the head at TDC (top dead center). If you do not have the lower timing cover on to find the make on the shortblock, just put piston #1 at the very top of its stroke.

We installed a new water pump and a new timing belt. The water pump was a must, for two reasons. A. we had no idea how old the other one was, and B. The cooling systems on the 6-cylinder e30’s changed in 1988 (the year of the car where this engine will be installed), using a slightly different water pump.

Next we put our freshly powdercoated valve cover, intake manifold, and timing covers on there!

So, if you’re ever in a pickle and have a tech telling you to order a new engine from BMW… give us a call. We’ll get you setup with a nicely redone M20 that will make all the local E30 guys jealous!