Jackshaft bearing

[Dieter H. Marschall]

Good morning all,
Below you find the description of an engine problem, which a Danish Stag driver described:

Triumph Stag and Tr7:
Both engines have shown a tendency to wear the underside of the front intermediate shaft bearing surface (jackshaft) in the block.
This results in reduced oil pressure and ultimately a jammed intermediate shaft.
An initial symptom of excessive wear on the front bearing is failure of the water pump drive gear due to
insufficient lubrication spraying from the front intermediate shaft bearing.
Some people simply replace the intermediate shaft and water pump without realising that the cause of the problem is the
is the worn front intermediate shaft bearing.
The only solution is to completely disassemble the engine and have the front shaft bearing repaired,
by drilling into the block and installing a new bearing bush.
This wear is only visible when the engine is disassembled, and even then some experienced engine repairers have overlooked it.

What can be done to prevent this?
Best wishes,
Dieter -from Germany.

[jbuckl]

Prevent what? …. Overlooking?

[Dieter H. Marschall]

No, the seizing of the front shaft bearing! ...

[jbuckl]

Don’t over tension the cam chains.
Don’t have too much oil pressure.

[Wheelz]

As Julian says ^ and when rebuilding an engine, always check for any excessive wear at the front bearing and rectify if necessary. If the block is worn or badly scored, it will have to be bushed.