Yeah, it sounds like a bad injector, but cracking the injector lines doesn't make the sound go away. It is most noticeable at idle and comes and goes, but it is present more then absent. It seems like it is coming from the drivers side more then passenger, but it is hard to tell. There is a lot of blow by smoke coming out the CDR hole in the valve cover and oil in the intake hat. Oil pressure is still rock solid, checked via aftermarket mechanical gauge. It hasn't changed since the noise presented itself. The knocking doesn't get louder when engine RPM's are increased. In fact it goes away when the engine is revved. Boost is good, and it runs good, but the EGT's still keep me from keeping my foot in it.... that is about the only current symptom besides the noise.

I'm currently double checking the timing to be sure that hasn't changed. I'm looking for ideas on what else to check that doesn't require major disassembly since I'm 3000 miles from home.

 

we've cracked all the injector lines, and it doesn't affect the knocking

We checked the timing. Oddly, it was around 3 deg, so we adjusted to 7, and it still knocks.

It feels like a misfire occasionally at idle, but at higher RPM's, it runs fine.

We are going to try the fuel-filter-ATF soak and see what happens.

Any advice would be VERY appreciated, because I'm currently in the Yukon, and it would be nice to make this engine more stable for the remaining 3000 miles down the remote areas of the Alaska Hwy.

 

Here's a video

 

If you're keeping your foot out of it to keep the exhaust temp down try backing off the fuel screw a flat or two. I wouldn't think that would be your problem since it isn't spitting black smoke, but it's an easy procedure since you're on the road.

ATF in the fuel filter is a good idea too. I've actually used Sea Foam in the fuel filter before and it helps eliminate chatter from old injectors and IP. Good luck since you're on the road. We've got our fingers crossed.

 

a bad injection pump gave me these symptoms. I was able to run with it that way for four years, but it sucked. when the pump finally quit & I replaced it, cleared it up.

 

The ATF seemed to help, but it's still slightly knocking and misfiring. We changed out one injector that we thought might have been the culprit, but it didn't resolve the issue completely.

We are going to try and drive the Alaska Hwy as is. It's a 3000 mile drive to Los Angeles, and we hope it will make the journey. Any other ideas?

I did bring a spare old injector pump, but I DON'T want to go thru that hassle unless I absolutely have to. The really odd thing is, the knocking isn't consistent. It's hard to figure it out. Sometimes it sounds like a perfectly fine engine... then it misfires and ticks a bunch. Hard to diagnose. No smoke from the exhaust. We pulled the return line and it flowed fine and it didn't change the knocking sound.

 

I'd do an oil change then take your filter to a decent shop and cut it open. If it's a bearing knock you should find some metal. If your filter is clean you can likely blame the IP.

 

Sorry if I scare you and I definitely hope it isn't something serious especially being far from home but I would definitely do this, it almost sounds like a spun crank or rod bearing. Unless they completely wipe out at once they can come and go until they finally do.

If it starts knocking and shaking really hard and puffs black smoke then it's almost a sure sign.

Did you run that additive for engine bearing breakin? It's like a clear looking fluid (forget the name)

 

I just drove from Fairbanks last week in my '89 7.3L and arrived in Sioux City. So far only had to do minor electrical work, replace alternator, and vacuum pump. Hopefully I left some good energy along the black top for you. I know how unpleasant it can be fearing a breakdown in the Yukon.

 

Don't know how many you've run into, but a spun rod or crank bearing doesn't come and go, it's constant. Plus an actual spun bearing is the result of overwinding, severe overheating, or running with no oil pressure, none of which the OP has had happen.

 

If you say "oddly" the timing was around 3 degrees BTDC before bringing it up to 7.This implies you didn't set it there so far retarded,so it's likely the IP is failing.
This also is me assuming you have recently timed the engine (at least sometime within the last 50k miles but it's likely a safe assumption,since you own timing equipment.)


I'm not hearing anything unusual in the video.So much normal diesel clatter I suppose that's drowning out what you hear in person.If your seeing your timing in unusual places from where you last set it though,you kinda found something way out of whack.
Yeah,I wouldn't suspect the bottom end coming undone or anything.A spun bearing isn't going to clear up and run fine then come back.

 

Thanks for all the responses.

update: we made it back to the states. We are in a hotel in Montana. Basically, after the ATF soak, the sound and misfire was still there. So I just assumed the ATF didn't work.

However, after a hundred miles of driving, it must have cleaned up the IP or injector that was causing trouble. It runs fine now.

however again, a new thing busted on us. Gearvendor went to hell. Tailshaft seal broke and spilled all the oil on the road. Didn't realize it until it rwas too late. We did a roadside reseal and filled it with new oil. Wanted to clean the filters but I didn't pack a spare pan gasket. Now the overdrive won't shut off once it is engaged, so we drive from Fort Nelson to Montana without the overdrive. It's slow going. We're going to wisconsin without the OD tomorrow too. This is going to suck.

 

I've seen this happen from old tractors to a 2012 6.7 powerstroke. They normally pull down almost like turning the ac on and have a tap similar to a loose wristpin.

The key is to notice it before it eats the crank and journals. They start to turn but become off and then back in line again. This can happen for a while before it completely comes loose if it's a tight motor.

Glad it was something simple.

I've heard mixed reviews on gear vendors but there were several brands that offered something similar. Us gear or something comes to mind. Maybe one of these units could be more reliable?

 

A US Gear unit by design is a stronger unit. It's strictly relatively heavy gears and is somewhat designed like an Eaton 2 speed differential. In fact if I remember right, it uses the same electric shift motor as an Eaton 2 speed rear end. The Gearvenders uses a planetary unit, more prone to failure and less tolerant of any kind of abuse.

 

That's a bummer that your GV unit broke a seal. I rarely hear anything bad about them.