Hey guys. I got a pretty loud knock happening with the old Cummins and could use some help identifying it. My alternator went out on a business trip this week. In an attempt to limp the truck to the next town I ran it dead. I had a new alternator put in it and got it all charged back up. 

When I fired it back up it was smoking a lot I had a miss and knocked real bad. I put about 20 miles on it and the miss/smoke went away but the knock is still there. 

It changes up and down with engine speed. I have checked under the hood or tools left over belt issues and anything obvious. Boost fuel pressure and exhaust temp are all normal. 

No check engine light but I will pull codes next time I get a moment. 

Any help would be greatly appreciated!! 

SHOTS FIRED!!!   

1 hour ago, Ilikeoldfords said:

Ok I have it narrowed down to a cylinder. I went through and loosened up the injector lines one by one and the knock completely went away when I loosened #6. Apart from the dead miss all the extra noise was gone until I tightened the line back up.

On a side note, I just noticed there is a lot more blow by then normal too It is almost enough to lift the oil fill cap all the way out of the hole when just sitting in the valve cover. That is not a good sign.

Paying attention whats said here. I would pull number 6 out and inspect the injector. Personally I go back to what I said pull all 6 injectors have them pop tested and inspected. Now while there out you can do the compression test to see if #6 is indeed damaged a piston. Don't bother with a blow by test we already know there is enhanced blow by when you mention the oil cap. Did you check your valve lash yet?

I have not had a chance to check the valves out yet. I will do that next time I have a spare moment. I will also start working on getting a pop test and compression test done as well.

Just finding that spare time is pretty hard!! You guys know all about that though.

 this was my #6 from cold start from oil cooling starvation from metal being made by lugging the engine towing a load.  at 9-10 sec you can hear the first hollow pong sound as the cylinder warms up enough to combust then knock.

 

full engine rebuild

 

 

this is an injector knock (after rebuild and before break-in). the time my injector pump sat in the engine bay during rebuild something got stuck in it and caused the injector knock. i drove it around later that day couple times around the block and it cleared.

 

 

 

this is what it sounded like as soon as it cleared a few minutes later

 

 

 

Edited January 18, 20169 yr by CUMMINSDIESELPWR

Thanks for sharing those videos. Unfortunately for me I think mine sounds more like the first. The knock doesn't get any "smoother" with more RPM's. 

Not really an update, but I have a trusted diesel tech taking a look at the truck later this week. He works for a very reputable diesel and machine shop in Missoula and is going to look farther into it. I just really don't have the necessary time to look it over myself. I am actually on another business trip at the moment. 

He is going to check valve lash, pull and test the injector and do a compression test for me. We will get this thing figured out. 

Ill post any results he passes on. 

Thanks again everyone!! 

Well I got some updates today. My guy checked valve lash, pulled the injector, and bore scoped the cylinder. Valve lash was good. Cylinder not so good. 

Piston is pretty beat up and he said he could see shadows cast by the grooves in the cylinder wall.  It will require a tear down and cylinder re bore on #6 at the very least. I have checked with 2 very reputable shops in my area of Montana (including his) and seems the going rate for a full 24v build is about $10k. 

I don't have the space, equipment, and most importantly, time to do any of the work myself right now. The way I see it I have 3 options. 

Have the engine done and not worry about it. 

Look around for a good used engine and hope for the best. 

Sell the truck for what I can get out of it and go buy something else. 

 

What do you guys say? 

Ouch!

All the choices suck, but I think I would try and find an engine somewhere if the rest of the truck is worth it. Mine would be worth the look anyway.

10 minutes ago, dripley said:

All the choices suck, but I think I would try and find an engine somewhere if the rest of the truck is worth it. Mine would be worth the look anyway.

That is where I am having a hard time deciding. I like the fact that my truck now is set up almost exactly how I want it. But I could maybe find something that doesn't have 250k miles on it. I just don't know what to do right now I guess. 

Rebuild what you got... I'm going to beat most of what you got is still in good shape other than #6 piston is damaged. So only one bore to be sleeved. The rest I bet could be honed out and put to service again with fresh rings and bearings.

My buddy just had this happen to his early 07 commonrail. He bought a used motor and will swap it out come spring time. #6 toasted, under 200k miles.

Do you have another car to make it through the winter? Used vp motors are going for $1800 around here, a lot of them under 100k miles, body rotted around them.

If it were me, given what I have in the rest of the truck... at minimum I'd find a used engine and then sell the truck.  More likely though, I would pull the motor and if I couldn't rebuild it, find a used core to overhaul.  

Given the miles, it will need a full head job too, and those can be expensive (ask me how I know)

Used motor and roll on.....

I think I will check around for a good used engine to start with. It will be the most cost effective solution for the time being. The only problems I have with that is you dont know how the engine was cared for by the previous owner. I might try to find a wrecked truck with a good engine in it. At least then I could here it run and do all the preliminary checks on it myself.

As for rebuilding mine, I know the head needs done too because it has went through a couple set of valve stem seals over the last 100k miles. The transmission really needs to be done too. Gets very noisy pulling hills and towing even with new fluid every year.

I just need to really think about how much I want to keep this truck. This might be the opportunity to upgrade to a 3rd Gen with a crew cab. Any way you look at it, I will be out at least $5k-$10k.

$10,000 to rebuild a 24v??????

 

I rebuilt mine with new pistons,rings,bearings,gaskets also with a polish on the crank and a .20 overbore for under $3500, runs strong and reliable.  Just giving you a real estimate if you did it yourself.

you will pay more for a used engine probably. I have a article on a poor mans garage rebuild in the database, lists the steps of putting it back together. hardest part was getting all the accessories off and putting them back on. I took my time and had the engine put together in a total of about 12 hours by myself.  If you can find a garage for a couple weeks, order all the stuff you need, get the engine apart and order the rest of the stuff you need then slap it back together.

Hard to beat the 3rd gen trucks with how comfortable they are and how much more cab room there is. 

This is just me.... If you're on a tight budget, pick up a used engine (like you said)

If you've got the money, upgrade to a 3rd gen with less miles, but be prepared to drop some coin on making it as reliable as your 24v.

5 minutes ago, CUMMINSDIESELPWR said:

$10,000 to rebuild a 24v??????

 

I rebuilt mine with new pistons,rings,bearings,gaskets also with a polish on the crank and a .20 overbore for under $3500, runs strong and reliable.  Just giving you a real estimate if you did it yourself.

you will pay more for a used engine probably. I have a article on a poor mans garage rebuild in the database, lists the steps of putting it back together. hardest part was getting all the accessories off and putting them back on. I took my time and had the engine put together in a total of about 12 hours by myself.  If you can find a garage for a couple weeks, order all the stuff you need, get the engine apart and order the rest of the stuff you need then slap it back together.

Labor isn't cheap, and he said he doesn't have the time. 

I would love to be able to do everything myself. I could even find the space to do it too. The real problem I am having is finding the time. I am really only home one, maybe two days a week. It would take me months to get anything done. I dont think I could wait to have my truck back that long. I do not doubt at all the amount of money I would save is huge, but my time is worth a lot too.

you could get an old ford.

1 minute ago, CSM said:

you could get an old ford.

Very funny     I wouldnt mind having another one but I would rather have a cummins again

Sooooooo, any ideas what the heck happened? Pulling any grades hard lately?