My truck is a 98 12 Valver w/219k miles, that was running great (until an hour ago). I drove it (30) miles from work-home and parked it. Got in it about an hour later drove (2) blocks and the engine started missing.

I knew something bad was happening so I turned around an came back home. As I was getting closer to home, the missing got worse and it sounded like and exhaust leak under the hood. It then began to smoke pretty heavily under the hood. I got the truck under the car port and shut it off immediately.

I popped the hood and looked around for signs of fluid leaks or any damage. Everything appeared normal. I waited a few minutes and then fired it back up. It took longer than usual to fire up, and resumed missing. I let it run about 10-15 seconds and shut it down again. This time there was NOT any smoke.

The only thing I can think of is the head gasket must have blown. ???? The coolant level is still the same.

The only thing out of the ordinary I've done is add PS Kleen/Cetane Booster for the last couple of weeks. It made a HUGE performance improvement!

I'm wondering if I may have accidentally added to much Cetane Booster and caused too much cylinder pressure as a result.

What could've happened ???

 

My bet is an injector failed.

 

I hope that's all it is. This would be a good excuse to get those bigger injectors I've been wanting!

How do I verify if it's just a bad injector and rule out bigger issues ????

I should mention that the Oil Pressure is fine and I haven't noticed the Coolant overheating at all.

I have noticed though that the exhaust has been a bit "smokier" during cold start, during idling and taking off from a stop. The smoke appeared to be white to me but did smell of burnt oil. ??? This has happened the last couple of weeks since I added the PS Kleen/Cetane Booster ?

Injector going bad ??? Too much Cetane Booster ?? Smoke issue related ??

 

I just checked a few the Oil and it appears normal. The appears fine as well.

I'm thinking the under hood smoke was coming out of my BHAF (during the misfiring).

Do Diesels backfire through the intake system like that ??

 

Too much fuel conditioner is not a problem, that will not hurt a thing. But, it can suspend sludge from the tank and plug your fuel filter and create a miss.

I would take a stethoscope and check each injector with the engine at idle. Listen for one that is particularly noisy, maybe knocking or hissing.

What may have happened is that you suspended and flushed water when you added the fuel conditioner. Water, even suspended, if in too great of amounts will blow deposits off the ends of the injectors and can cause the pattern on one or more to be such that it will create a miss. This usually happens on a truck that has not been regularly worked hard enough to burn off the carbon and coke deposits that normally build up on the injector tips.

Sudden excessive smoking that stops after setting a while, yet a continued miss, is almost always dirty injector tips or coke working out the the pop off seat area of the injector. A heavy load pull will almost always clear the dirty tips, but coke working out of the sacless valve on the tip of each injector nearly always requires removal and disassembly of the injectors.

Also check the overflow valve on the injection pump. When that fails you will start missing and can get very hard to start. Though smoking is not normally a symptom.

I would look for a crack in the hose from the intercooler to the intake horn, especially right around that bellows with the metal ring. Also check air hose connectors from the turbo to the air intake horn.

If an intake valve sticks open you can get smoke out of the air filter. Running your stethoscope down each valve cover may well locate a loud clicking from a stuck valve.

The valve seats will eventually crack on a 12 valve head if the engine is routinely pulled hard. Your mileage is about where the valve seats begin to fail.

 

It's a simple check, this happened to me as I was merging onto a highway...it sounded like the engine blew up, a little smoke and no power. Truck would idle fine, and no signs of fluid loss. It took me some time to locate but it was just a hose clamp! I'll keep my fingers crossed that's all it is!

 

Have you pulled the air intake and looked at the filter to see if it's come apart, and inspected the turbo?

How about intercooler boots? I don't think it's either one of those, cause you say that it misses at idle. Maybe something got in your turbo and is blocking the exhaust path...

Check your connections to your injectors. Any programmers?

Does sound like an injector, tho. Maybe hanging open. That sucks, hope you get it figured out...

 

If you can't hear an injector problem with the stethoscope and assuming you have the miss at idle loosen the fuel line at each injector one at a time, engine running.
The one that doesn't make a change in engine sound with the line cracked is the bad one.

 

RCW, I've always heard that mechanics would pull the injectors and soak them overnight in Techron. Come morning, everything is clean and with injectors put back, runs fine. Let me clarify; always heard from someone who knows someone who . . . (you get the picture).

Techron is a pretty good fuel additive to clean injectors on running engines, but soaking? Do you know of anybody that actually tried this and what the results were?
Back to morning beverage of choice . . .

 

Thanks for the tips folks.

I'll go find my stethescope and check things out.

I'm going to "try" and take a video of it running as well.

 

1st things 1st, pull the valve cvr and take a looksy...fire her up for a few sec, and see that everyone is doing what they are supposed to be doing.
If all ok like you say just replace the injectors since you were going to anyway.
As far as a stethoscope deal, never had much luck, there is way too much noise for me and the diesel dieseling.................... LOL

 

Alright. Here's the latest.

- Checked all intercooler boots. All appear ok.
- Checked Oil. No milkiness. Smells burnt. Oil changed 1k ago.
- Started fine. Idle ok for a minute, then began missing. Let it idle for 2-3 minutes (missing). Began to increase engine revs (easily), held around 1500RPMs for 5-10 seconds and then the engine start RAPPING LOUDY!

Here's a very short video clip I was able to capture of the RAPPING.

http://katmanduonline.net/videos/EngineMiss.MOV

It sounded to me like a gasser with a collapsed lifter or a rocker arm smacking a valve cover. It then began smoking heavily from under the valve covers. I shut it down immediately.

I let it cool down a few moments and fired it up again. Fired up easily, idled fine with the engine missing but NO loud rapping. Let it idle for 20-30secs and again increased the idle easily to about 1500RPMs and the LOUD RAPPING and smoking returned. I shut it down immediately.

I'm thinking broken valve spring. ?????

What do you experts think ??

 

Wish I'd seen this 1/2 hr ago.

I think this is the next step.

 

Anyone know what the rapping noise may be ??

 

Failed injector is dumping more fuel than can be burned in the power stroke causing it to try to fire during exhaust stroke.