I developed this miss over the winter and blowby pulsating out of the oil cap. There's also blowby floating by the firewall but that could be coming from the breather.

I don't think i have a vacumm leak because my defrost works. Can bad injectors cause blowby?

Here's a video, sorry for the wind noise.

Sorry I dont know why my sigs not showing up.

154000 mile 6 speed, with edge comp and 5 inch exhaust. Mostly stock truck.

I would highly suggest to have the injectors either pop tested or replace depending on how many miles. This would deal with the miss. Blow by could be produced by bad valve guides and valve seals too as I learned on mine. Start with fixing the miss by dealing with the injectors. 

@Rotket for sure go after the miss.. you can also do a leak down test since you are going to have the injectors out. Pull each piston up on its stroke with all the valves closed on the cylinder. And apply shop air pressure with a leak down tester and then see if it holds. If you have a bad valve, seals, or rings that should tell you. The pressure will leak down very quickly and you will hear where it is coming from. ( make sure you have the crank held in whatever position you apply pressure or it will move.) I did this not long ago and found out number 5cyl had a broken ring even though it would pass a compression test. 

Bad valve seal ONLY shows up with the engine running and under load. Being with the piston at TDC both valves are closed and no pressure applied to either valve seals. Typically valve seals show up as oil smoke on startup either hot or cold. 

What would be oil smoke on start up? White smoke?

And honestly I don't even know if it has a miss. It just seems loader than usual and it never had blowby besides when the vacuum line was busted.

Its just so hard to believe that such a low mileage truck with regular maintenance and few power mods has compression issues.

15 minutes ago, Rotket said:

What would be oil smoke on start up? White smoke?

 

Watch closely. Now you might have to chase the cloud and take a sniff of it. Oil smoke is going to be mostly white with bluish tint. It will for sure smell like burnt oil. Now bad injectors or low pop pressure can do the same thing but when you chase the cloud and sniff the cloud will smell of fuel and might burn your eyes. Both types of smoke look about the same but there is a for sure smell difference.

 

Remember we are oil burners by design... 

Edited February 22, 20196 yr by Mopar1973Man

4 hours ago, Rotket said:

What would be oil smoke on start up? White smoke?

And honestly I don't even know if it has a miss. It just seems loader than usual and it never had blowby besides when the vacuum line was busted.

Its just so hard to believe that such a low mileage truck with regular maintenance and few power mods has compression issues.

What's low mileage, half of my valve guides were shot at 157k

Just now, Dieselfuture said:

What's low mileage, half of my valve guides were shot at 157k

Same here at 355k miles and the head gasket leak.

I think head gaskets have more to do with age unlike my valve guides something had to be wrong

My truck has 153,000 miles, and had an easy 19 year life. Are valve guides and seals something I could tackle myself? I've replaced injectors on a 5.9 before and I'm assuming it's a little more involved than that.

The truck puffs black smoke on start up and then smokes a little if it's cold for a couple of minutes. It doesn't smell like oil, just cold diesel. I guess I should have someone else start it up and take a whiff of that puff, ha.

On 2/22/2019 at 5:19 PM, Dieselfuture said:

What's low mileage, half of my valve guides were shot at 157k

Would bad valve guides and seals show up in a leak down test? How would I know I need to replace those over something more serious like actual engine damage?

28 minutes ago, Rotket said:

Would bad valve guides and seals show up in a leak down test?

 

No. Because both valves are closed. So there is only pressure in the cylinder. No pressure in the intake manifold or the exhaust manifold.

 

29 minutes ago, Rotket said:

How would I know I need to replace those over something more serious like actual engine damage?

 

Pull the head. Then inspect the cylinders. While the head is removed have the head serviced. Like my total bill between the head work, ARP studs and a gasket kit was close to $2,000. Mine was already leaking oil about 1 quart every 3k miles past the valve guides. Very easy to tell start it up and it could fill my garage with oil smoke and you could smell it. 

Valve seals can be done without removing the head. Problem is if the valve seal has failed most likely the valve guides did too because like in my case I had chunks of valve seals all in the top of the head. This is caused by the valve rocking in the guides and it tears the valve seals. 

 

 

Yeah that ^^^

I sent my oil in today to have it tested to see if theres anything out of the ordinary. I'm going to have it compression tested this week.

I didnt think there were any vacuum issues but someone mentioned to put the havac on blast with the setting on the floor and if you have defrost coming out you have a vacuum leak.

All if the main vacuum lines were went over again and no obvious issues. I guess ill rebuild the vac pump if everything else turns out okay.

9 hours ago, Rotket said:

I sent my oil in today to have it tested to see if theres anything out of the ordinary. I'm going to have it compression tested this week.

I didnt think there were any vacuum issues but someone mentioned to put the havac on blast with the setting on the floor and if you have defrost coming out you have a vacuum leak.

All if the main vacuum lines were went over again and no obvious issues. I guess ill rebuild the vac pump if everything else turns out okay.

In the FWIW column mine has always vented some thru the defrost in the floor only setting. It vents more in the floor defrost setting. It has done this since the truck was new. Always thought this was normal,

On 2/23/2019 at 9:48 PM, Mopar1973Man said:

 

No. Because both valves are closed. So there is only pressure in the cylinder. No pressure in the intake manifold or the exhaust manifold.

 

 

Pull the head. Then inspect the cylinders. While the head is removed have the head serviced. Like my total bill between the head work, ARP studs and a gasket kit was close to $2,000. Mine was already leaking oil about 1 quart every 3k miles past the valve guides. Very easy to tell start it up and it could fill my garage with oil smoke and you could smell it. 

Valve seals can be done without removing the head. Problem is if the valve seal has failed most likely the valve guides did too because like in my case I had chunks of valve seals all in the top of the head. This is caused by the valve rocking in the guides and it tears the valve seals. 

 

 

 

Can you see if the valve seals need to be replaced by just pulling the valve cover off? 

2 hours ago, Rotket said:

 

Can you see if the valve seals need to be replaced by just pulling the valve cover off? 

 

No. I didn't even know the seal where laying in the bottom till the head was dump on its side for the entire night to drain. You would have to remove all the springs to check. You can pull all the springs without pulling the head. At that point, you most likely end up pulling the head because of valve guide wear. 

2 hours ago, Rotket said:

Can you see if the valve seals need to be replaced by just pulling the valve cover off? 

You can kinda see seals behind springs with flashlight, may have to rotate motor to see some. If they are ripped like in picture above then you should be able to see that. I know after I redid my head some seals ended up working their way up and got hammered by retainers, I could definitely see that through the springs. But like Mike mentioned it's hardly ever you can change seals and have them last more than likely guides need replacing, so if you're thinking about doing seals might as well do the whole head. To each their own though, some get away with just changing seals.

The machine shop I took my head to I asked about that. Justin told me that typically if the valve seal goes it typically the valve guides that cause the seals to fail. Very rare does just the seals fail by themselves. 

I was just wondering so I can have an idea of whats going on with the truck. Since if I can confirm the seals are gone by removing the valve cover I can atleast have an idea of valve health.

Though having to pull the head off a mostly stock low mileage cummins would definitely not feel too good.

Blowby... This is a fail.