On at least the '92 4.0, there's a TSB out regarding serp belt squealing. It has something to do with the P/S pump pulley being slightly out of alignment and needing a shim behind it. Let me see if I can find it on my trusty TSB thingie...
...hmm, doesn't seem to apply to the '93 Grand. Here's what it says for a '92:
NO.:
07-03-92 GROUP:
Engine DATE:
Oct. 19, 1992 SUBJECT:
Drive Belt Noise MODELS:
1992-93
(XJ) Cherokee
(MJ) Comanche
(YJ) Wrangler
SYMPTOM/CONDITION:
The vehicle may exhibit a serpentine belt chirp coming from the upper idler pulley or crankshaft damper. This may be caused by the power steering pump pulley not being correctly positioned on the pump shaft.
REPAIR PROCEDURE:
If the vehicle exhibits the chirp, inspect the pump pulley. The vehicle may be equipped with either a steel or a plastic pulley.
Inspect the area in the center of the pulley as shown in Figure 1. The pump shaft depth should be 7.25 mm +/- .25 mm (.275" +/- 0.01 ") with respect to the pulley hub face. If the depth is not within the specified range, remove the pulley and reposition it using the procedure in section 19, pages 10 and 11 of the 1992 Jeep(R) Service Manual.
Inspect the pulley hub position on the pump shaft. The end of the pump shaft should be flush with the end of the pulley hub (+/-.25mm or 0.01") as shown in Figure 2. If the hub is not flush, reposition it using the procedure in section 19, pages 10 and 11 making sure that the shaft is flush with the end of the hub.
POLICY:
Reimbursable within the provisions of the warranty. TIME ALLOWANCE:Labor Operation No. 19-70-45-90 ......... 0.9 Hrs.
FAILURE CODE:
51 - Improperly Installed
