CM870 no start
02-26-2022, (Subject: CM870 no start ) 
Post: #1
CM870 no start
Hi,

just looking for some advice on my CM870. It's a 2006 Kenworth, demandated and programmed by Mommaburt. it has been brutally cold last week, in the -35C range

My driver had been using it for our regular freight run while the other truck was in the shop. It had been running fine when he finished his load on Friday afternoon. He shut off the truck, plugged it in and it sat till Sunday afternoon. When he started it on Sunday, it was making a popping noise in the intake, and seemed to have a miss on one cylinder. he shut it off, and called me. We tried to restart it, but it would only crank over one or two times, and then it seems like we have a hydra-locked cylinder, as it won't turn over. I don't want to try it again in case I bend a rod or something.

Could we have a failed injector leaking fuel into a cylinder? And how do I figure out which one? I have Insite and an Inline 6 adapter but haven't had a chance to check any codes. I finally got in in the shop yesterday to start working on it. Is it safe to bar the engine over to do an injector bubble test? I have the adapter plate and hose tool like rawze shows in the video

thanks for the help
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02-26-2022, (Subject: CM870 no start ) 
Post: #2
RE: CM870 no start
Popping sound from the intake is likely a problem with an intake Valve. Pull all the rockers and pressure test the head to find it. Sounds like inframe time though.


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 Thanks given by: Rawze
04-18-2022, (Subject: CM870 no start ) 
Post: #3
RE: CM870 no start
So I finally got around to working on my truck. It still won’t crank over, it’s does one or two flips then locks up. I took the valve cover off and discovered the cross head on the exhaust valve for #1 cylinder laying in the bottom. It’s broken on the end where the jake actuator passes through. Insite code show low fuel pressure with stop engine light flashing, but I’m assuming that’s from it not cranking enough to build fuel pressure. Any thoughts on what I do next?


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04-18-2022, (Subject: CM870 no start ) 
Post: #4
RE: CM870 no start
you need to find out why that valve did not close all the way. That is what broke that cross-head.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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04-18-2022, (Subject: CM870 no start ) 
Post: #5
RE: CM870 no start
(04-18-2022 )tsolson Wrote:  So I finally got around to working on my truck. It still won’t crank over, it’s does one or two flips then locks up. I took the valve cover off and discovered the cross head on the exhaust valve for #1 cylinder laying in the bottom. It’s broken on the end where the jake actuator passes through. Insite code show low fuel pressure with stop engine light flashing, but I’m assuming that’s from it not cranking enough to build fuel pressure. Any thoughts on what I do next?

Make sure you egr block of plates didn’t come apart and cause the valve to hang open pull the charge pipe of intake side and post a picture of it and as far as not cranking over or feeling like hydrolocked will be when it comes on that cylinder it’s companion probably also has both valves closed and now that cylinder has both valves shut along with companion the poping sound is from it letting the exhaust gas escape from the intake side since the cross head is broken the valve will stay shut.
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04-19-2022, (Subject: CM870 no start ) 
Post: #6
RE: CM870 no start
I pulled the intake off this morning. Looks like a fair bit of carbon, but the blankoff plates are all there and intact and not deteriorated at all. Looks like stainless steel material.


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04-19-2022, (Subject: CM870 no start ) 
Post: #7
RE: CM870 no start
(04-19-2022 )tsolson Wrote:  I pulled the intake off this morning. Looks like a fair bit of carbon, but the blankoff plates are all there and intact and not deteriorated at all. Looks like stainless steel material.

Larger peice of hardened carbon could have caused the valve to hang open slightly when the engine started to pull in air to try to fire and the exhaust cross head got slammed once the valve shut doesn’t mean valve is damaged you can look through the valve spring and look for damage or measure valve height compared to rest or pull exhaust manifold and see valve stem the first thing I would do I borescope the cylinder to take a look at what’s going on with the valves or piston just to be sure also pull the intake cross head of and so both are shut and see when barring it over if you have large amount of air escaping on the exhaust manifold on that cylinder.
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04-19-2022, (Subject: CM870 no start ) 
Post: #8
RE: CM870 no start
A cross-head failure like that is nothing to take lightly.

How many miles/hours are on this head?. engine?.

Something caused that valve not to close all the way, binding the cross-head and breaking it.

- Pulling the injector and boroscoping the cylinder, piston, valve seats, valves, etc. properly would be the next step. Also, it should be assumed that the valve stem has gotten stressed and now has a chance of being bent in some way.

Putting the cylinder at TDC with the injector out and removing the valve springs for that valve, checking it for any "bent" condition would be prudent too.

After that, if all checks out well, injector re-installed, all the rocker shafts should be loosened up so that all the intake/exhaust valves will shut. Then the intake manifold and the exhaust manifold plated and pressurized to one at a time to 30 psi shop air, checking the valve train for seepage/pressure losses.

Then,. lastly, ensuring there is no issues with the engine brake rockers or their brake-rocker-pistons, etc. that could have hung up and caused it to keep the valve pressed open when it should not have.

That is what I would do if I owned it any ways.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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04-19-2022, (Subject: CM870 no start ) 
Post: #9
RE: CM870 no start
ok thanks Rawze.

I'll have to get a borescope to take a look. The valve spring looks normal, and the spring retainer doesn't look damaged at all.

I'm unsure of the actual hours on the head. I know it is not the original, as it's unpainted, so it's been changed before. the previous owner said it had been rebuilt and he had put around 2000 hours on, but i don't have any documentation for that. I've put about 3000 hours on the truck since I've owned it.
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