Engine Idle Surge, DTC 30 (Idle Speed Control) Set

9226cadillac01

Bulletin No. 86-79
File in Group 6A
Number 79
Corp. Ref. No. 616105
Date Aug '86


SUBJECT:
HT4100 SERVICE OPERATIONS FOR DISTRIBUTOR GEAR WEAR

MODELS AFFECTED:
ALL WITH HT4100 ENGINES

The following information will summarize the appropriate service operations for vehicles which experience abnormal distributor drive gear wear. This information supersedes Bulletin T-86-246E Dated:12/1/85 which should be destroyed.

Some Cadillacs equipped with the HT4100 power system may experience abnormal or premature distributor gear wear. The symptoms of this condition are idle surge and/or code 30 or loss of power. If these conditions are exhibited, the following service procedures should be followed:

1. Remove ignition distributor as described in Section 6D of the appropriate Service Information Manual.

2. Inspect both the drive gear on the camshaft and the driven gear on the distributor shaft for evidence of advanced wear.

3. If either gear is worn, the following three actions must be completed:

A. Replace the distributor driven gear. A redesigned gear, P/N 10499163 has recently been released to supercede 1979546. This new gear is identical to previous designs except that a tin plating operation has been added to improve break-in characteristics and minimize premature tooth wear. It can be easity identified by its "silvery" appearance. GMWDD service stock of distributor assemblies has also been updated with this improved part.

B. Replace the camshaft. P/N 1628822 is used for all engines. Refer to Bulletin T-84-90. Be sure to prelube all contact surfaces including the distributor drive and driven gears with the lubricant provided in the cam kit (lubricant available separately as P/N 1052365).

C. Remove the engine oil pan and oil pump and inspect the oil pump gears and housing for wear. Replace oil pump and clean oil pan as required.

For warranty purposes, use labor Operation T6135 with the following appropriate time.

Vehicle Time

1985-1986 FWD Fleetwood and De Ville 9.6 Hours
1982-1985 RWD De Ville and Brougham 8.6 Hours
1982-1985 Eldorado and Seville 10.4 Hours
1986 Eldorado and Seville 10.7 Hours