1987/12/01 Caterpillar

Improvements To Prevent Oil Leakage At Cylinder Heads

Usage:

3500 Family Of Engines

Description of Change: Four improvements have been made to prevent oil leaks at the cylinder head gaskets and at the spacer plate gaskets on the 3500 Family Of Engines:

... A new, coated steel head gasket is used. The former composite metal/asbestos head gasket would relax (compress further) over a period of time with engine operation. This caused a loss of head bolt torque. The new gasket will not relax. Also, the new gasket has a rubber bead on both top and bottom sides around the pushrod compartment area to provide extra thickness in this area where clamping forces are lower.

... A new spacer plate gasket has a coat of sealant on the cylinder block side around the pushrod compartment area to provide improved sealing between the spacer plate gasket and cylinder block.

... There are eight 3/4" cylinder head bolts in each head. The two shortest of these bolts have been replaced with longer bolts and hardened spacers. The extra length is needed to give more bolt stretch and therefore better retention of bolt torque.

... The two 3/8" cylinder head bolts (L2070) are tightened to a torque of 55 N·m (40 lb ft) instead of 42 N·m (32 lb ft). This increases the clamping forces around the pushrod area.

Adaptable To: The new parts are direct replacements for the former parts. If there is a leakage problem, it is best to install all the new parts at the same time.