What's wrong with this engine

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By Frank Surber - 10 Months Ago
Bob's 2001 Mack CH613 with the E7 427  with Jacobs brand engine brake,the engine has about 950,000 miles. I have been on him to either let me or have someone run the overhead on it for 3 years. or over 350,000 miles So Finally yesterday I ran the overhead. actually I was not satisfied with what I found that I bared it through and ran it 3 full times Once with jack eliminators by removing the jakes and torquing down the rocker assemblies the first time I only found a total of 3 valves that needed adjustment the intake and exhaust on #6 were both .002" off and the exhaust on #5 was .003" # 6 intake was at .014" I adjusted it to .016" #6 exhaust was .026" adjusted to .024" #5 was .027" adjusted to .024" after returning the jakes I checked them only 1 was off @ .023 adjusted to .021"
Almost every other engine I've ever ran the overhead on I've had to adjust most of the valves.
 I feel like I wasted my time.
 And before anyone asks yes the engine was cold not having been started since the day before..  
By tundra - 10 Months Ago
whats wrong you ask
that's simple
ittsa mack        lol
By Geoff Weeks - 10 Months Ago
Got to be careful when adjusting Mack valves to follow the procedure in the manual. The Cam profile for engines with brakes is weird and will throw you off if you just crank until both valves are closed than set the lash. Ask me how I know!
By Frank Surber - 10 Months Ago
Yeah they have a spot that is ground way down and will allow the exhaust valves to have over .100" clearance and the little pin that sticks up about .250" that the jakes push on can get broke off Or you push down on the exhaust valve rocker and see a lot of movement on if you are unfamiliar with the design of those engines you might think the valve is supper loose due to the way the cam is ground. 
 even the E6's and E7's that don't have brakes have the cam goofy cam profile 
By Needle-Nose - 10 Months Ago
Don't forget the annual rabies shot as well as a good de-worming. 😂
By glenn akers - 10 Months Ago
Frank what Geoff is talking about is for a dnytard brake and the valves have to be set 20 degrees after TDC but the timing pointer on those engine will have a pointer with two pointer one for VS and other for pump timing.That was on a Vmac but I may be wrong but have never seen a dnytard brake on a 01 engine which is a Etec.Even on these engine of mine wich is VMAC they don't wear the valves and seats very much.The truck I drive will get about 65000 miles a year and there is no reason to check the valves for 3 years.on the ETEC like what your working on I would say if you find any valves that are loose on the setting then a lifter and cam is going down.They had cam problems.
By Frank Surber - 10 Months Ago
Glen the flywheel on this one is marked the degrees before TDC then at 20° after TDC is the mark with valves #1&6 labeled then 120° the valves 2&5 then 120° Valves 3&4. If you press on the exhaust rockers on the cylinders not on compression you will have about .120 of movement which would mean that it has the same cam for an engine with the dynatard brake. Or at least this is how I see it .
 I really expected to find it a lot further off than I did.
 We have regularly sent off oil samples for the past 150,000 miles since installing the OPS and I keep a journal of the results on my computer the samples steadily improved for the first few samplings then have leveled off. but not started going south.  
By glenn akers - 10 Months Ago
Sounds like you have done check it out and yes that is a dnytard cam.I am forgetting some of this .
By glenn akers - 10 Months Ago
After I think about it Frank some of the E7 engins built after 1999 did have the dnytard brake so the cam would or could gave the ram before TDC like the early VMAC