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Gone runaway, now what.

KrisML

Active Member
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Location
Space coast, FL
So an I posted in the carnage thread I had a slight issue with my 6.5 over the weekend. Little back story first.

The truck had been having transmission issues for a while and between lack of either money or time it took me about a year and half to finally fix it. So I finally get the trans fix and go for a test drove around the block. Truck starts acting like it's out of fuel. So after confirming I have fuel to the injection pump. I do a compression test just to make sure. Engine had a 390 psi average. Cylinders 7 and 8 had an ever so slight film of oil on the glowplugs. I figured that was do to sitting for several months. So figured was well enough to try running again.

Intially she was running very rough with a miss on at least 2 cylinders and blowing a large amount of grey smoke. Though the filters weren't old I changed them anyway. Started her back up with fresh filters and the smoke was all gone and so was the miss. But she suddenly developed a vibration around 1500rpms. So with her at idle I start looking under the hood to see if something accessory wise is possibly coming apart. Since I need the engine speed higher then idle and I'm alone so I'm reving the engine by pushing on the throttle lever on the injection pump. I'm holding the throttle at about 1200rpms (judging by the sound) when she suddenly all at the same time. Starts blowing an insane amount of grey/black smoke, knocking like crazy and revs to the heavens. When it happened i was leaning over the engine, I simply ran. Ranaway for probably 30 seconds or so when she finally slowed to a stop. Was a graceful slow down not a sudden stop.

Once my heart rate slowed to a normal pace I noticed a moderately large puddle of oil under truck right below the air filter. First thing I checked was if the engine was locked up, nope still turns by hand. Decided to do a leak down test. Started with the drivers side since they're easy to get to. Cylinders 1 and 3 when tested showed a 40% leak rate and push that air into the oil pan. Made a nice gargling noise unless I took the oil fill cap off. Cylinders 5 and 7 didn't produce the noise but were around the same leak rate. This was done after turning the engine to make sure the valves were closed. I haven't even bothered with the other side yet. I'm thinking it ate the rings. I'm still not sure what caused it yet or how great the damage is.

Sorry for the long story, more of a rant then anything.
 

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Intercooler. Sweet.
Never had a runaway yet. Except for a PMD revup. I get the feeling its mostly bad news from here...
 
Sux. If it cranks normal, redo the compression test, since you just did it you should know something there right away. Kill power to fuel solenoid. Before the test, cycle it a bit with all the plugs out to watch for oil misting. Fingers crossed for ya.

Sounds like a classic oil fed run away to me. I keep thinking of putting a block off safety valve on mine- with your inner cooler plumbing there, it could go inline easy just to make sure it never gets you again.
 
Didn't even think about the turbo itself. Good place to start since the whole intake is covered with oil internally. I'll check that and then I'll redo the compression test. Cranking it with no glow plugs will clear the cylinders of any excessive oil that didn't burn off.
I'm really hoping nothing major got damaged cause I really don't want to do another engine is this truck.

Only second time I've had an engine go runaway on me. First time I was leaning over it. Scared the shit out me.
 
Yeah, don't kid yourself- you got scared because that goes deadly in a hurry. Your instinct to run is not a bad one. I was near a ford 7.3 that turned into a grenade from run away. Part of a rod went through the driver side fender and stuck 3" deep into a concrete filled block wall. Be glad yours wound down instead of exploding.
 
No one was hurt - then I'd say exit stage left was the correct choice. The engine can be replaced... Again No One Hurt is all that matters.

Also stay clear after a runaway stops for a bit in case the cooling system explodes from heat soak.

If you break a piston or burn a hole through a crack you can gets lots of oil through the CDR system. High runaway RPM is likely to bend valves and can put a lot of oil in the CDR system. (Poor drainback from extreme RPM can run the oil pan dry with all the oil in the heads. (Olds 455's were famous for this at just high RPM.) IMO rings are fine, but, you may have holes in the pistons from hitting valves.

Quick and dirty: how much oil is in the CDR and CDR oil soakable intake pipe in front of the turbo? That's awful clean oil for a 6.x - you sure it's engine oil?

I would suspect the IP and keep a air shut off board or plan the next time you light anything with that pump.

Some turbo shops will check your turbo for free and tell you if it was leaking oil. I suggest this is done as part of the failure analysis. It may be clear as day with a busted shaft or broken wheels.
 
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Oh I'm very glad I ran. My dad taught me at a very young age that when playing with cars to alway give yourself an out.

I'm 80% certain it's oil, could have fuel mixed in it. I'll check once I'm home from work. I don't recall it having a fuel smell to it. The oil level was still on the dipstick but I'll confirm tonight. The oil is very clean because I changed it about 20 miles before my Trans started giving me issues. So it's damn near new.

I think the compression test will be a good indicator of whether or not it burned a hole in a piston.
 
Pull all the glows and whirl it over to pump out that oil to keep it from hydrolocking and busting stuff. Or busting more stuff..
 
OK found some time after work to do some digging. Checked the oil and it does have some fuel mixed as it has a slight fuel smell. Checked the turbo for excessive shaft play and it is well within the normal range of movement.

Pulled all the glowplugs and pink wire from the ip and cranked her over to purge the cylinders. All gps were dry expect #8 had a decent coating of oil on it. Engine spins very freely so went ahead with redoing the compression test.
Results are as follows.
8- 350. 7-365.
6- . 5-360.
4- . 3-320.
2-370. 1-325.
I didn't get to 4 and 6 since they're the hardest to get to with the turbo manifold and I was being attacked by bugs. So I'll get those two in the next day or so. Engine had a 390 average so how 1 and 3 lost 65 psi each is a little troubling. I did them twice just to be sure I didn't mess something up.

CDR valve had some oil residue but that's it. The tube from it to the intake preturbo had enough oil in it to actually move around. So something cause the oil to blow out the cdr.
 
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