The Diesel Stop banner

1 - 20 of 26 Posts

·
Registered
Joined
·
48 Posts
Discussion Starter #1 (Edited)
Oh boy.

Pulling my camper home over the weekend (about 9.5K pounds), about 230 miles from home I notice a slight exhaust haze in my passenger side mirror. It seemed to come and go a bit, but eventually settled on a definite puffing of black smoke out of the exhaust any time you were in the throttle. It seemed like one cylinder was putting out more smoke than the other. Clearly not a solid stream but a puff puff puff. Truck ran great otherwise. All temps were normal, power was good, EGT's were right were I expected them. Suspecting a bad load of fuel, I decided to monitor it closely and press on. The smoke level appears to remain the same for 225 of those miles.

Then about 5 miles from the house, all hell broke loose. Sounded like it was throwing a rod . Huge knocking. Massive amounts of white-ish, tan-ish smoke. Power was down noticeably, but otherwise the gauges were all normal. I was in the second to far left lane in traffic, and nobody seems to want to let a blowing up truck over. I had to run about a mile or so to get over and get off a bridge with no shoulder. It was still running, the knock seemed like it kinda came and went. Sacrificing my truck for our safety, I limped it up an on ramp and almost made it into a shopping center parking lot where I had to stop for an idiot running a stale yellow light. Truck died and would not restart.

Luckily, some nice guys in a Ram pulled my whole rig into the parking lot where I had to leave it for the night. Upon retrieval, I experimentally tried to start it. It cranks at a good speed, and sounds like it almost wants to fire, but then there is a "dead spot" in the cranking that sounds like it skips a beat. If it was a gas engine, I would say it jumped time.

I can't tear into till the weekend, so I am trying to come up with a plan of attack. My immediate guess is an injector issue, due to the black puffing for a couple of hours before the come-apart. Clearly had to be fuel and not oil and not antifreeze. At the last stop (pee break for the wife) it did idle with pretty good grey haze coming out of the tailpipe, but it was not steam, or oil smoke to my eyes. Injectors are fairly new (under 10K miles) 180/30s. I have heard (and read up) where some guys state a bad injector can sound like a bad rod knock. But this was awful. My wife asked what the noise was and my initial reaction was that the motor just blew up on us.

So... "hope springs eternal" and all that, I am praying that its just an injector issue. If so, would that be something I could see if I pulled the injectors? I would think that even with a single bad injector, it would start and somewhat run. I am well equipped with most mechanics tools, but I lack the advanced diagnostics stuff. I see an oil slick under the truck, but I did try draining the fuel bowl.

Can anyone offer up a road-map of where to get started and what to look for? Any help in developing a plan would be appreciated. I planned on yanking the valve covers and possible the injectors this coming weekend, but if there other things I should do first, I might be able to tackle them.

Tim
 

·
Registered
Joined
·
5,307 Posts
Did you check oil level and if so, what was it? If it lost injector tip you could be dumping fuel and it would not run. The fast pulse during cranking is the dmage to cylinder from fuel dump. Take oil filler cap off and have someone turn it over while you feel for a significant pressure pulse out of filler hole if it broke a piston.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #3
Did you check oil level and if so, what was it? If it lost injector tip you could be dumping fuel and it would not run. The fast pulse during cranking is the dmage to cylinder from fuel dump. Take oil filler cap off and have someone turn it over while you feel for a significant pressure pulse out of filler hole if it broke a piston.

I checked oil level at the first fuel stop after I noticed the puffing. Oil level was a little low, but still well above being off the stick. I added oil to bring it up to withing operating range. I have not checked it since. I'll check it and do the oil fill pressure thing tonight when I get home from work.

And actually, its not a fast pulse when cranking, but maybe a slow pulse. It sounds like every cyl is hitting, expect when it gets to one, it kind of skips over it. Hard to describe. Maybe I can get a video tonight too..

Tim
 

·
Premium Member
Joined
·
14,671 Posts
It sounds pretty typical for a cracked injector tip. Don’t try cranking it again. The broken tip and leak fuel into the cylinder causing a hydrolock. Crank on it and you break a rod or piston. Pull the injectors and inspect the tips. It should be pretty obvious.


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
5,307 Posts
Cranking engine over has a rhythm from it slowing on compression build on a cylinder and it passes top dead center and engine speed picks up until it gets to the next compression stroke. When a cylinder doesn't build compression from piston or valve damage then it gains extra speed for that cylinder's compression stroke before it comes to another compression stroke and breaks that rhythm..
 

·
Premium Member
Joined
·
14,671 Posts
The change in cranking could ALSO be from the increased compression in a cylinder that is filling with fuel. Really, the only way to tell would be to pull the glow plugs first (then rotate the engine over by hand a few times) and do a compression test. THEN, pull the injectors and look for the cracked tip. If Jimmy is right and you've destroyed a cylinder, you'll get one compression reading really low or zero. At that point, take it around behind the barn and shoot it. If you caught it in time, then you might have one cylinder slightly above normal (or all the same) at which point, pull the injectors and find the one with the cracked tip.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #7
It sounds pretty typical for a cracked injector tip. Don’t try cranking it again. The broken tip and leak fuel into the cylinder causing a hydrolock. Crank on it and you break a rod or piston. Pull the injectors and inspect the tips. It should be pretty obvious.


Sent from my iPhone using Tapatalk

Well of course I didn't see this post till after I tried Jimmy's suggestion. I noticed the oil level was higher than I remember it after adding oil. It might have a touch of a fuel smell it. I really cant be sure. It's not an overwhelming smell, if its there. I had it cranked over while I held my hand on the oil filler. No significant pulsing or pressure. I would say the pistons are intact at this point (no holes). No abnormal clunks or mechanical sounds during cranking, just a brief change in the rhythm at a regular interval..





It's amazing to me that a simple injector failure can sound so much like a destroyed rod, but I am keeping my fingers crossed. Tear-down begins on Saturday. I will keep you informed on what I find.

Tim
 

·
Registered
Joined
·
48 Posts
Discussion Starter #8
Update to this issue:

Between work and life, it took til this weekend before I got to look at the truck. I'm gonna call RT the man, because he was exactly right. Pulled all 8 injectors. Only took me about 2.5 hours (although I am still dreading getting the bolts back in the passenger side valve cover). Before I started, if I were made to guess, I woulda guessed that #7 was the one. Dunno why, but I just felt in my bones it was passenger side. I was totally wrong. By one whole cylinder. It was #5. LOL. The whole side of the tip is missing (bottom injector in pic)



As it's hard for me to get my head in over the injector holes to visually inspect the cups, I used my phone and snapped pictures of each one. They all look exactly like this:



Except for #5, which looks like this:



It's hard to tell, but could that be the broken piece of the injector tip is sitting at the bottom of the cup (blocking the hole into the cylinder)? As I know it, the injector tip sits in the hole at the bottom of the cup. It would seem to me that if it were to break off, it would surely wind in the cylinder doing God knows what. Could it even be remotely possible that the tip was cracked but didn't actually break a chuck off till I pulled it out? It seems like that would be a miracle right up there with the Loaves and Fishes... But there is clearly something down there. I'm going to see if I can borrow a borescope for a better look at it. I don't want to even breathe on it till I find out what it is.


Stay tuned!

Tim
 

·
Premium Member
Joined
·
14,671 Posts
What's the plan to get it out? I can think of a couple of things to try, but I've never done any of them. One would be to pull the glow plug and hit it with compressed air. You'd have to be on top dead center on that hole OR pull the rockers in order to keep air from escaping out of an open valve. Another would be to put a shop vac in that hole. Not sure if that would have enough force. Guess you could squirt some ether down the glow plug hole and set it off. Probably would blow the tip into your forehead though. Might want to stand to one side if you try that. :rocket::grim:
 

·
Registered
Joined
·
507 Posts
Update to this issue:

Between work and life, it took til this weekend before I got to look at the truck. I'm gonna call RT the man, because he was exactly right. Pulled all 8 injectors. Only took me about 2.5 hours (although I am still dreading getting the bolts back in the passenger side valve cover). Before I started, if I were made to guess, I woulda guessed that #7 was the one. Dunno why, but I just felt in my bones it was passenger side. I was totally wrong. By one whole cylinder. It was #5. LOL. The whole side of the tip is missing (bottom injector in pic)
Here's a tip for those passenger side valve cover bolts - remove the wheel well liner and you have easy access to all of the bottom row of bolts as well as the one at the rear. In the end it's probably a wash on the amount of time it takes since you'll have to remove and then reinstall the wheel well liner. If the bolts are not rusted, you can get the liner out in 10-15 minutes.
 

·
Premium Member
Joined
·
14,671 Posts
Low fuel pressure is a major cause. Could just be a stress fracture.


Sent from my iPhone using Tapatalk
 

·
Super Moderator
Joined
·
25,410 Posts
You might try a super magnet pickkup tool to get the tip out of the hole, if that's what it is.
Although RT's ether idea sounds exciting. :worried:

@RT: good call on the cause of the issue. :thumbsup:
 

·
Premium Member
Joined
·
599 Posts
I see on the Riffraff site that injector cups are stainless steel, with this being in the heat zone would the injector tip be stainless also? If it is stainless it’s probably a high heat alloy like 330 and not magnetic? I’ve never had to deal with injectors yet so I don’t know what material they’re made of- I know you don’t want it falling in the hole if disturbed.
 

·
Premium Member
Joined
·
599 Posts

·
Registered
Joined
·
74 Posts
Low fuel pressure is a major cause. Could just be a stress fracture.

So, if your truck had ever gelled to the point, while driving, that you had to slow down and pull off the road. This likely could happen. Even years after the gel event? Or this is something that happens during a low fuel pressure situation and forcing the motor to keep going. Even though the motor is telling you, knocking, not to?
 

·
Premium Member
Joined
·
14,671 Posts
That's a good question. I don't know if anyone has done a study on exactly when a catastrophic failure occurs relative to the event. I suppose it is possible that a low-pressure situation could cause micro-fractures that develop over time. I just know that the injector rebuild people see this a lot in trucks that had a fuel related issue - like a bad pump or clogged filters. I hadn't even thought about gelled fuel. Might be worth calling Ryan at Full Force Diesel.
 

·
Registered
Joined
·
507 Posts
I see on the Riffraff site that injector cups are stainless steel, with this being in the heat zone would the injector tip be stainless also? If it is stainless it’s probably a high heat alloy like 330 and not magnetic? I’ve never had to deal with injectors yet so I don’t know what material they’re made of- I know you don’t want it falling in the hole if disturbed.
The vast majority of 7.3 engines have brass injector cups.
 

·
Registered
Joined
·
48 Posts
Discussion Starter #19
Never even thought about the magnet thing. D'Oh!

I got a pencil sized neodymium magnet that'll degauss a homing pigeon from 50 yards. If it has the slightest bit of ferrous content, it'll grab hold of it. Lacking that, I was thinking a glob of axle grease on the end of a wooden dowl.

Tim
 

·
Premium Member
Joined
·
14,671 Posts
My luck, the magnet would get stuck to the bottom of the cup. I know it's brass, but there is cast iron just on the other side of it. Axle grease? Boring. Remember that old adage, "there is no problem in this world that can't be solved with the correct amount of properly placed explosives."
 
1 - 20 of 26 Posts
Top