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Mazdax605 UltraDork
10/8/16 3:39 p.m.

Hey guys,

My Delica just started knocking really badly today. Mostly at low rpm with a big load (Accelerating from a stop), but even some knocking when revving in neutral. Sounds like ball bearings in a coffee can. Smoking pretty heavy too when the knocking is happening. Bad turbo,bad engine,engine failure of some sort?

Please help I'm afraid to drive it like this.

ebonyandivory UltraDork
10/8/16 4:34 p.m.

Bad Injectors? What's the smoke look like? What's your coolant level at?

dean1484 GRM+ Memberand MegaDork
10/8/16 4:38 p.m.

Can you tell if it is mechanical or fuel/compression related?

Mazdax605 UltraDork
10/8/16 4:54 p.m.

Smoke looked black, sounds compression related more than mechanical.

jstand HalfDork
10/8/16 5:36 p.m.

Sound like a bad injector.

The black smoke and knocking are the symptoms that lead me to think that.

How does it sound at idle?

Is it mechanical injection or electrically controlled?

Mazdax605 UltraDork
10/8/16 5:42 p.m.

Mechanical injection. Sounds fine at idle.

jstand HalfDork
10/8/16 6:50 p.m.

If it was present at idle it would be easier to determine which cylinder.

Depending on the exhaust manifold design you make be able to use an IR thermometer to identify the cylinder that isn't running the same as the others.

You can also loosen injector lines ( just enough to cause the rpm to drop) one at a time and then bring the rpm up to see if the noise is gone/different. If you loosen a line enough that you see fuel leaking around the line but but no change in idle that would also id the problem injector/ cylinder.

Once you ID the bad cylinder you can swap injectors between the bad and a good cylinder and then repeat the process to see if it follows the injector.

Mazdax605 UltraDork
10/9/16 8:53 a.m.

Should I stop driving the van?

jstand HalfDork
10/9/16 9:29 a.m.

If it was mine, and I had an alternate vehicle, I would stop driving it until I know what is causing the noise. Once you determine the cause, then you can make a more educated decision on whether there is risk of serious damage.

Keep in mind the injector plays a role I the timing, and not just the pump. If an injector is bad and is opening at too low a pressure that cylinder will fire early, and may not atomize the fuel completely leaving unburnt fuel in the exhaust (causing knock and black smoke). Or if the opening pressure is higher than spec it will fire late, which could also cause noise but probably not the black smoke

Worst case would be the injector is stuck open (or almost no spring pressure on the poppet needle), which would allow fuel to go into the cylinder without any pressure building, so cylinder temperature would be all that controlled the firing of that cylinder and leave unburned fuel in the cylinder that could leak past the rings.

As part of the investigation you should check the oil level for any changes. If the injector is leaking you may start to see the oil level rise due to excess fuel getting past the rings.

A decent diesel shop should be able to test injectors for spray pattern and pop off pressure. I've used Dario in Shrewsbury/Worcester (rt 20) before to have injector tested, cleaned and rebuilt with good results.

Mazdax605 UltraDork
10/14/16 8:18 a.m.

So I brought the Delica by a local diesel shop yesterday. He listened to the engine idling, and then revved the ever living shot out of it for about a minute or so. When I mean revved the ever living E36 M3 out of it, I mean pedal to the floor revving way higher than I felt comfortable with. It sounded fine, and only had a small puff of smoke every now and then which he wasn't very concerned about. He repeated this a few times, and everything seemed healthy in his opinion aside from the small puffs of smoke that he thought could just be from its age.

I then drove the van home, and had a few instances of the knocking with some black smoke. Also it seemed every time it happened it was either from a stop or a low speed and accelerating. When this happened it felt like the engine sort of fell on its face for a few seconds, made the bad noises, smoked, and then caught itself and ran fine. I drove it around a bit more during the day, and only had a few more issues with it. I'm almost wondering if it's turbo or egr related? Sticky waste gate? Maybe the egr valve is hanging open at times, and then it falls flat on its face with the not so great air going into the engine, aside from nice boosted air? Any of this make sense? Or am I just an idiot, and my van is about to explode? I was hoping to take it to a car show on Sunday, and with the way it revved up at the diesel shop I don't think it really is in any danger at this point, but I don't know for sure. Maybe a video of the symptoms would be wise so I can show you guys.

rslifkin Dork
10/14/16 8:24 a.m.

EGR sticking open could definitely cause some funkiness. I know that forcing the EGR open on a MK4 TDI at idle leads to it chugging like a tractor and smoking like hell.

Brokeback Reader
10/14/16 9:34 a.m.

As mentioned earlier, make sure to check the oil frequently to make sure you're not getting diesel straight into the crankcase. This was the demise of my friends 02 Duramax motor - outward signs were small puffs of smoke at times, but the crankcase filled up and damaged the engine.

Your call on continuing to drive it - what's your risk tolerance?

gearheadE30 HalfDork
10/14/16 9:54 a.m.

Sounds like a sticky injector or two to me. Overfueling and some timing issues (both injector-caused) would cause all the symptoms you describe.

jstand HalfDork
10/14/16 11:10 a.m.

Replace he fuel filter and run a good quality additive/cleaner/lube for a few tanks and see how it does.

Also check the external linkages in the fuel pump for anything sticking.

The advance in the fuel pump could be sticking occasionally causing the issue you occasionally see during acceleration.

gearheadE30 HalfDork
10/14/16 12:25 p.m.

Rod knock would be consistent, all the time, once it starts. That this is intermittent tells me that it is probably timing/quantity of fueling causing a combustion knock.

iceracer PowerDork
10/14/16 5:46 p.m.

"Ball bearings in a coffee can" is usually detonation. Lugging can cause this. Quality of the fuel is suspect.

BrokenYugo UltimaDork
10/14/16 7:18 p.m.

Maybe try running a can of that injector cleaner the Mercedes diesel guys all like through it? The stuff you run it on straight for a few minutes through a rigged up fuel tank. EDIT: Liqui Moly Diesel Purge.

kb58 Dork
10/14/16 10:53 p.m.

I didn't know there was even such a thing as "combustion knock" in a diesel. I mean, every combustion event is a detonation in a diesel by its very nature. There's volume of fuel and when it lights off, but it probably always lights off at about the same point in the engine cycle because it has to rise to the same temperature, no?

jfryjfry Reader
10/15/16 12:05 a.m.

Really interested to find out what the problem is - you've got several different options from some pretty smart guys. My diesel knowledge is limited to what I can glean off of these guys.

Esoteric Nixon
Esoteric Nixon UltraDork
10/15/16 8:00 a.m.
BrokenYugo wrote: Maybe try running a can of that injector cleaner the Mercedes diesel guys all like through it? The stuff you run it on straight for a few minutes through a rigged up fuel tank. EDIT: Liqui Moly Diesel Purge.


bearmtnmartin GRM+ Memberand Dork
10/15/16 2:45 p.m.

Any chance someone put gas in with the diesel? I happen to know that will give you a bitch of a knock.....

Mazdax605 UltraDork
10/15/16 2:53 p.m.

No chance I put gasoline in. If it was mixed in the tank at the station maybe, but I never would put gas in a diesel.

BrokenYugo UltimaDork
10/15/16 3:45 p.m.

Speaking of fuel, where do you get your diesel from? I've read it's generally a good idea to get it all at a truck stop, rather than a random gas station. I'm not sure how diesel goes stale or whatever (water contamination aside) or if that would cause problem though.

44Dwarf UltraDork
10/15/16 9:49 p.m.

Stop driving it and send out the injectors for pro cleaning don't mess with e-bay kits or side show shops that offer cleaning send them to a real injection shop like Marren injection.

2nd change the filters and add a quart of 911HEAT or other water and lube additive.

You may have mold / algae growing in the tank as well many home heating / plumbing supply houses have small 1/2 pint bottles of a water and algae growth killer called WP3.

Mazdax605 UltraDork
10/16/16 6:24 p.m.

Today I decided to take my chances and bring the van to Japanese car day at the auto museum about an hour away. It ran flawlessly all the way up to the show. Had a spectacular time with friends and even won a couple of trophies somehow! Jumped in the van for the ride home and it started acting up as I was leaving. No noises, but lots of smoke and low on power for about a mile or so but only when accelerating from a stop or slow speed. The rest of the trip home (1 hour plu) was fine and I even stopped for a quick bite to eat and it was fine after that as well. I thought the smoke looked white when it was acting up, but my friend who was behind me said it was black. I'm really confused.


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