M30 Dual Chambered Oil Sprayer Bar (DCOSB) How-To...

Date: November 23, 2003
From: IceHaus Dave

Yesterday I was working with a good friend to get his Dad's 5er in shape. One of the required maintenance items was a valve adjustment. So, I remove the valve cover and surprise! The oil sprayer bar was broken into three pieces. The rebuilder of the head had not used Loctite on the banjo bolts and the rear bolt had worked itself loose allowing it to come in between the sprayer bar & one of the rocker arms. Thus, putting enough strain on the oil sprayer bar (OSB) to break the thing. And thatís not all. The idiot had cross-threaded the rear banjo bolt so that it took some real finesse to get the thing back together. Hereís pic of the broken OSB alongside the new, and IMPROVED, OSB.

The new bar has been pinched to create a "Dual Chambered OSB (DCOSB)". This post is a short "How-To" on creating & installing one of your own. This is a very simple and effective way to cure a common ailment of M30 motors. Specifically, the front most cam lobe does not receive enough oil because of the lack of oil pressure in city driving. The long hollow OSB does not develop enough pressure at the front of the bar to oil the front cam lobe. Thus, the front cam lobe wears too quickly causing the M30 motor to run badly. The DCOSB solves that problem by creating two pressure chambers to feed oil to the cam at higher pressure. The time to perform this upgrade is logically at your next valve adjustment. So hereís a quick overview of how to remove the OSB and create your DCOSB.

This assumes you have the Valve Cover off and are looking at the open valve train. Looks like this:

Remove the two 12mm hollow bolts (AKA, Banjo Bolts) as noted by the red arrows in the above pic. Be careful to not let the aluminum washers fall into the head. I usually cram a rag underneath to catch these if I should drop them. There are four washers associated with these two bolts. One washer is nearest the bolt head and one beneath the oil sprayer bar, which acts as a spacer and sealing ring. So two washers each side, for a total of four washers. Do Not reuse the old washers as they are crush rings and cannot be reused. Call the dealer (or whoever you buy parts from) and order, two hollow bolts 11 42 1 738 621 & four ring washers 11 42 1 252 343 . As an option, you can reuse the old hollow bolts. Just be sure to use medium strength Loctite when you reinstall the bolts. However, these are so cheap, I usually go for the new ones. When you reinstall the hollow bolts, use a tightening torque of 11-13Nm (8.1-9.6 Ft/lb).

Now to remove the OSB. First rule is to remember that you should not try to flex or deflect the OSB from its plane. The bar has two weak points in its length that could cause the bar to weaken and crinkle if you try to bend or deflect it. So treat it with respect. Take some WD40 and spray on the bar to lubricate its length. Then take a small wooden buffer and place on the end of the bar closest to the front of the motor. Take a small hammer and gently tap the bar rearward. It will slowly move so that the end will pass through the retaining clamp. When the end just clears the backside of the clamp, gently lift the OSB so that it clears the clamp and put some soft article under the bar to act as a spacer to keep the OSB clear of the clamp. Then take one of the hollow bolts and partially insert it in the front OSB bolt hole & while holding the bolt gently tap the head of the bolt toward the front of the motor so that the OSB moves out of the rear clamp. Once free, take the OSB out and clean it. Clean the bar, inside and out. Use compressed air to blow out any remaining moisture and/or debris.

OK, now on to making the DCOSB. Locate the center of the bar and make a pencil mark all the way around the bar. It doesnít have to be precise, just approximately in the center. Then find two 17 or 19 mm deep sockets and take the bar and sockets to a vice. I wouldnít recommend using pliers or vice grips. Use a vice, because it gives you the ability to exert force in a controlled fashion. Situate the bar between the two sockets as shown below. Make sure the center mark is in the center of the sockets. Also make sure that the bar is situated so that the ends of the bar are perpendicular to the floor. This keeps the bolt holes and the pinch you are about to create in the same plane. The bar is situated as in the pic below.

Now GENTLY & SLOWLY begin to close the vice jaws, making sure the sockets are not dragging/binding on anything and that they are parallel as they close on the bar. You will see the hollow bar compress until it gets difficult to achieve further compression. You see about 1/8Ē between the sockets as below.

You have now made your own DCOSB and saved yourself not only $75 for the price of the bar, but perhaps the cost of a new camshaft and all the grief around that little job. Hereís the finished product in different views.

Reinstalling is the reverse of installing. However, just remember the caution about flexing the new DCOSB. It now has another weak point (the pinch youíve created) in the hollow tube and it will bend easily if you are not careful. Lubricate well with WD40 and when you install the DCOSB in the rear clamp, insert the hollow bolt in the rear bolt hole and gently tap the head of the bolt toward the rear of the car to move the bar into place.

This is a simple upgrade to perform that has long lasting benefits. It certainly isnít cosmetic, but it does give me piece of mind. Whenever I buy a new M30-motored car, this is one of the first things I do.

BTW, Jim Rowe of Metric Mechanic (MM) fame created this little jewel originally and still sells them. I bought one and saw how easy it was to make one of my own and did so. If you donít feel confident in creating one, you can still buy them through MM.