Chapter 8 — Inspection and Maintenance
8-16 Part No. 750-184
R. FUEL OIL METERING VALVE
In the event that a leak occurs in the packing of the metering valve, the
packing nut should be snugged gradually to stop the leak.
Do not over tighten the metering valve packing nut. Exces-
sive tightening of the packing nut prevents free movement
of the metering stem. Failure to follow these instructions
can cause damage to the equipment.
If replacement of the metering valve packing is necessary, procure kit P/N
880-370 and install in accordance with the following procedure.
1. Shut off the oil flow. Be sure no pressure shows on the gauge.
2. Match-mark the cam hub and drive shaft. Match marking will enable
replacement of the cam in its original position and result in a minimum
of cam adjustment when the burner is refired.
3. Clamp or hold the metering stem in the down position.
4. Loosen the setscrews in the cam hub and rotate, or move the cam to a
position where it does not interfere with stem removal.
5. Withdraw the metering valve stem and spring. Do not drop or mishandle.
Check for nicks or scratches. Check that the pin holding the metering
portion is not protruding. Back off the packing gland.
6. Remove the capscrews holding the jack shaft support bracket so that the
bracket can be moved. It may also be necessary to loosen the supporting
bracket on the far end of the shaft.
7. Remove the existing packing and guides. Do not reuse the packing and
guides.
8. Lightly coat the stem with the lubricant provided with the packing kit.
Place the new packing, O-rings and guides onto the stem. The beveled
face of the guides and the teflon rings must face upward, with the
exception of the upper brass guide which is faced down. Be sure that the
O-rings are properly located.
9. Using the stem as a guide, insert the assembled packing into the cavity,
then withdraw the stem.
10.In the event the packing is too high, remove one teflon packing from each
side of the middle brass guide as needed.
Under no circumstances eliminate the two teflon packings on only one side
of the brass guide.
11.Replace the gasket, put the support in place, and secure all fastenings.
12.Replace the metering stem and spring. Lightly lubricate the stem to
facilitate insertion and easy movement. Use care when inserting so that
the orifice and the stem are not damaged.
13.Snug the packing gland, but only sufficiently to place slight tension on
the packing. The stem must move freely from the force of the spring.
14.Work the stem up and down several times to ensure that it moves freely.
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