starting a 5 ton

[MAdams]

bdstick, I know a mobile mechanic that works in the high desert that can help if you feel you need the help. He's $85 but worth every penny. Let me know if you want him phone number.

 

[red]

Cam....

that's exactly what I'm thinking. It's why I asked where are all the valves that are no longer moving.

 

[WillWagner]

Or broken flywheel bolts. OP, does the damper turn when you crank it? Gas in a can ain't gooood for ANY diesel, try and avoid it, use something a bit less destructive, like a gas soaked rag or brake/carb cleaner.

 

[doghead]

Don't spray ether directly into it.
Doghead you shouldn't say that statement this guy could be new to the hobby and take you seriously because of your years here and post count.

It did not start so he thought ether would fix the problem.

He probably broke it using either.

With the same logic originally applied, spray more ether and the problems go away.

 

[bdstick]

I am sorry I did not start with all the necessary info. it is a M923A2 , 8.3 cummins, with auto trans. I have started over a hundred of these military trucks that have sat around. this is the first time I encountered this problem. I usually only use spray for a few seconds. the engine has approx. 3/4 inch of rocker clearance. pushrods not bent but going up and down. it has to be in the lifters. any info is appreciated.

 

[bdstick]

the only three valves lash that seems normal are intake 1, 3, 5. I removed lift pump to make sure entire cam was turning, before I removed the valve cover noting that all push rods are moving.

 

[WillWagner]

The tappets are flat slider type.

 

[74M35A2]

Sounds like the valves are bent and not returning to their fully seated positions? Carefully check their heigth compared to all others in relaxed state. Or those cam lobes are worn down to a greatly reduced base circle.

 

[bdstick]

where can I find lift info on the cam , the valves and springs all appear to be approx. same height, am I looking at removing engine to replace tappets ? or pulling cylinder head ?

 

[porkysplace]

where can I find lift info on the cam , the valves and springs all appear to be approx. same height, am I looking at removing engine to replace tappets ? or pulling cylinder head ?

[h=1]TM's for the 939 series trucks[/h]

 

[WillWagner]

When a C over speeds, it will do a couple of things, IF it over sped. heads of the tappets break off, the rocker bolts are pushed out of the head, the threads just pull right out. Before you start rippin' and snortin' into it, you should probablt troubleshoot it.

Are you sure the engine hasn't been torn into by soldier A that didn't know what he/she was doing and it is just assembled loosly/incorrectly?

To put tappets in it, radiator out, front off, pump gear off, upper rockers off, oil pan off, cam out, tappets come out the bottom.

 

[red]

I am sorry I did not start with all the necessary info. it is a M923A2 , 8.3 cummins, with auto trans. I have started over a hundred of these military trucks that have sat around. this is the first time I encountered this problem. I usually only use spray for a few seconds. the engine has approx. 3/4 inch of rocker clearance. pushrods not bent but going up and down. it has to be in the lifters. any info is appreciated.

FYI, any more than a split second shot of starting fluid can cause major damage. When sprayed at the air filter it can become soaked and cause a quick runaway.

I'd start by loosening off all the rockers and check them. Then measure the valves to make sure they are the same length.

 

[bdstick]

I want to thank everyone for there help. I did find pieces of the tappets in the oil pan. will proceed with repairs . thanks again.

 

[98G]

Thank you for following up to let us know what you found.

 

[WillWagner]

The cam will be out, I wouldn't screw around, just put a new cam in it while it's out. Put new push rods in it too, the adjustment seems to go away quickly if all the tappets and push rods aren't replaced as sets.

A 10 t press will take the gear off. To put the gear on, it must be heated. DO NOT use a torch, you will take the temper out of the gear, use your wifes oven or a bbq. 350 degrees, let it go 2 hrs, it will drop right on. Don't forget to buy a cam key or pin, which ever it uses, the key might come out of the old cam but the pins never do.

Oh yeah, removing and replacing the tappets will require tools. Go to your fav hardware store and pick up 6, 36 inch long x 1/2 round wooden dowels and some rubber bands. Cut them in half, the dowels, on one end, use a hack saw and split the end apx 1/2 inch down from the end.

With the overhead removed, put the split end down into the tappet through the push rod holes, give them a tap to seat them in the tappet. Gently lift the two dowels for the same cylinder and use the rubber band to pinch the dowels together. This will hold the tappets up so the cam can be removed. After the cam is out, remove the rubber bands and pull the dowel out, the tappets will fall out, some might hit the ground, some will hang up in the engine.

It helps to have 2 people so the guy on the bottom can see what crank counter weights are clear of the tappets and the guy on top can pull the dowels and rotate the engine.

Going back in, push the dowels into the tappets and put them up from the bottom, again 2 people is kinda a necessity, one on the bottom to push the parts up and the other on top to secure the dowels with the rubber bands and rotate the engine.

I think Cummins SRT for a cam replacement is something like 7 hrs, Piece of cake!

PM me if you need help