my truck won't run right

[Brent Phend]

Why Is Number 5 And 6 Died In My truck. Its A 1988 998 E9 Mack.

[rsb502]

well thats all under one head so Id bet for a head gasket or some type valve or rocker shaft shaft issue if your having trouble from one pair of cylinders in an E9, got 1-2 frt right, 2-3 back right, 5-6 front left and 7-8 back left, pull the valve cover on that head and see if the shaft is broken or there is a smoking gun staring back at you, if not pull the head and see what the gasket looks like. Its actually really hard to diagnose a problem from, why have two cylinders on my truck died, need more info.

[theakerstwo]

Before you pull the head do what I always do. Find out if its a injector or pump. I have a old 673 injector line and injector that I connect at the pump of the ones you think is dead and run with injector pointed away from you and watch the spray from it and then connect to a good firing cylinder.On a V8 its harder to determine which is dead and which is good than a 6 cyl.What I do if I can decide if its dead or not is break an few more line loose at the same time that your checking the one which you think is missing. With say 4 more lines loose the one that your going to break loose is more pronounced when you do cut it out.Once you know your fuel system is not at fault then you have head or whats under it to check including the cam shaft.