Delivery valve internal leak as a cause of nailing? Yes? No? Maybe??? - Page 13 - PeachParts Mercedes-Benz Forum

Diseasel300 · #**181** 12-01-2017, 09:28 AM

He changed his mind and decided to do it again. The website linked in Post 179 is his new website

oilslick · #**182** 12-01-2017, 09:58 AM

Quote:

Originally Posted by Diseasel300

He changed his mind and decided to do it again. The website linked in Post 179 is his new website

This is great news!

OM617YOTA · #**183** 12-01-2017, 10:33 AM

Quote:

Originally Posted by oilslick

I was there to order new DV springs. He informed me that 9/10 times the only thing that needs to be addressed on these M pumps is the delivery valve itself. He said that the “piston” will become pitted and grooved causing a loss of pressure and that the pump will try to compensate for this and it results in knock, rough idle, loping idle, and even smoke at idle. He said they only change springs if they’re broken. He priced me a complete set of DV’s for around $225 with tax. That’s $35 per DV. He said he’d order the springs for me if I really wanted them, but wouldn’t recommend them. The springs are $8/each 😳. This guy is always very helpful and free with sharing info. I’m taking my “vintage” Bosch pop tester to him later this week and he said he would test it for me and see what it needs for me to be able to rebuild my own injectors. He appears to be very helpful. We’ll see. 😁

That's fantastic info. Did he by chance have photos of what a bad DV looks like?

My nailing has come back, and even when it was "fixed" I still had to warm up the truck for ~10 minutes. It was still nailing at idle when cold, and would knock badly if I just started it and drove off. Even just pulling it out of the shop so it didn't fill the building with exhaust. Wondering if I should do DV's after all.

Diseasel300 · #**184** 12-01-2017, 11:13 AM

Quote:

Originally Posted by OM617YOTA

That's fantastic info. Did he by chance have photos of what a bad DV looks like?

My nailing has come back, and even when it was "fixed" I still had to warm up the truck for ~10 minutes. It was still nailing at idle when cold, and would knock badly if I just started it and drove off. Even just pulling it out of the shop so it didn't fill the building with exhaust. Wondering if I should do DV's after all.

I'd be looking for something else wrong. Injectors, compression, timing... A worn DV will cause nailing, but it won't cause you to have to warm up the car that long or cause excessive smoking. It's just noisy, usually worse when the engine is hot.

OM617YOTA · #**185** 12-01-2017, 11:30 AM

Injectors were done by Greazzer not many miles ago. Compression specs out, timing(both injection and cam) is perfect. Will be completing my pop tester shortly to verify I haven't boogered the injectors since Greazzer did them.

Finding that faulty DV holder and replacing it, and replacing all the DV seals, has been the only thing that's made a difference for any length of time. I was able to isolate the worst cylinder to #5, retorqued that DV holder and it got significantly better, so on the right track. I am back to "get an expert diagnoses" at this point.

Been chasing this issue for years and if I could have paid an expert $500 to fix this years ago, I happily would have.

Edit: Other interesting tidbit, if I turn the glow plugs back on after a cold start while it's clattering and nailing, the engine quiets down and smooths out nicely.

Diseasel300 · #**186** 12-01-2017, 11:52 AM

It's important to understand the difference between nailing caused by the DV and nailing caused by spray pattern or pop pressure:

The DV has 2 jobs:
1: Prevent reverse-flow back into the pumping element after an injection event. Essentially a check-valve.
2: Provide a very slight negative pressure in the injector hard line to help give an abrupt end to an injection event. Helps prevent a drip or "piddle" as the injector pintle seats.

Nailing caused by a DV leaking or not seating fully can be caused by a delayed injection if it is leaking back, or a prolonged injection caused by the drip or "piddle" from the lack of an abrupt cutoff in the injector. The DV will have no effect on the spray pattern or pop pressure of the injector.

Nailing caused by the injector comes down to poor fuel spray. It can be "peeing", it can be spraying off to the side, it can be fanning out too far, the pintle can be dragging and causing leakdown of the injector, the pop pressure can be off, the list goes on. If turning the glow plugs on stops the nailing, you likely have injector issues. The DV's will nail even with the glow plugs on since they are a different source of injection problems.

The other thing I've noticed with DV problems on my own car is that the nailing usually doesn't start until the engine starts warming up, when cold and the diesel is more viscous, it doesn't seem to cause much of an issue. Running straight diesel-purge of course stops the nailing since it is much higher in cetane rating than pump diesel.

When you get your pop tester going, pull a suspect injector and check 3 things:
1: Pop pressure + spray pattern (should be tightly grouped and even)
2: Internal leakdown rate (after it's popped, the residual pressure should not fall quickly)
3: Chatter. Pull the lever slowly and watch the spray pattern and watch for the injector to "chatter". If it just sprays with no chatter, it will hang up and nail.

I'm currently playing with the 2 injectors I had issues with a few weeks ago. Both of them popped good and had good patterns, but failed the "chatter" test. Once they'd pop, they just kept spraying until the pressure dropped far enough. After an ultrasonic bath and a re-lap of the sealing faces, they test textbook-perfect. Once I get some heat shields they'll go back in the engine for testing.

oilslick · #**187** 12-01-2017, 11:55 AM

Part 7k will develop a groove around it where it seats itself into part 7g. It will also develop pits on its seating surface. I do not have any pics to show.

Diseasel300 · #**188** 12-01-2017, 12:01 PM

Quote:

Originally Posted by oilslick

Part 7k will develop a groove around it where it seats itself into part 7g. It will also develop pits on its seating surface. I do not have any pics to show.

Check out Posts 108 and 109 way back in this thread: Delivery valve internal leak as a cause of nailing? Yes? No? Maybe???

The DVs in those photos are from the derelict IP that was in my car when I got it. Broken Odo showed 173K, but probably more like 250K on the car. The DVs in that pump were not worn out, but were dirty. I don't have photos of the ones from the current IP, but they were about the same. The IP in the car is from a vehicle with 250K on the clock. I'd say unless the fuel system has been seriously neglected, the DVs should last several hundred thousand miles easily, though they may need some TLC as they age.

phlfly · #**189** 12-01-2017, 01:08 PM

I think they are getting dirty due the fuel quality. When I was doing purge, I got very dirty fuel (purge) in just few minutes of running. I got more purge today another two cans, I will run one can first than drain dirt and run another again. It helped me a lot. Today morning started was best I ever had for last few months. The exhaust smelled more healthy diesel, than unburn diesel fuel.

Diseasel300 · #**190** 12-01-2017, 01:13 PM

It isn't so much fuel quality, but lack of maintenance. People dump fuel in and run the car until the filters clog so badly that the engine stalls or loses power. By then, there's a ton of crap all spread throughout the fuel system. Diesel Purge should be run every so often to clean out the fuel system just like injector cleaner in gas engines. If it's been a long time since the fuel system was cleaned, you can expect some seriously nasty stuff to come out in the first purge cycle. Mine came out pitch black the first time I did it. Looked like engine oil. Car had 175K on the clock at the time and I'll guarantee it had never been done before.

phlfly · #**191** 12-01-2017, 01:20 PM

Same thing pitch black even fuel pure clean is coming out fuel tank. Some components in fuel system might be has leak intake air. May be ALDA?
This is reason I will be installing oil separator later.

Quote:

Originally Posted by Diseasel300

It isn't so much fuel quality, but lack of maintenance. People dump fuel in and run the car until the filters clog so badly that the engine stalls or loses power. By then, there's a ton of crap all spread throughout the fuel system. Diesel Purge should be run every so often to clean out the fuel system just like injector cleaner in gas engines. If it's been a long time since the fuel system was cleaned, you can expect some seriously nasty stuff to come out in the first purge cycle. Mine came out pitch black the first time I did it. Looked like engine oil. Car had 175K on the clock at the time and I'll guarantee it had never been done before.

Diseasel300 · #**192** 12-01-2017, 01:45 PM

Quote:

Originally Posted by phlfly

Same thing pitch black even fuel pure clean is coming out fuel tank. Some components in fuel system might be has leak intake air. May be ALDA?
This is reason I will be installing oil separator later.

The ALDA works off of the intake manifold pressure. It has no connection to the fuel system other than operating a lever inside the injection pump.

Air in the fuel system will come from leaks, old hoses, or loose clamps. The hard lines under the car are also known to develop pinholes from rust. Be looking mainly on the suction side of the lift pump for air ingress.

Why do you need an oil separator? There's a baffle built into the valve cover that does a pretty good job of separating oil, even if the PCV valve has given up the ghost like mine has. If you're blowing oil out the valve cover, you need to address why, the 603 is a relatively low blow-by engine. Excessive oil in the intake manifold is likely from the turbocharger.

OM617YOTA · #**193** 12-02-2017, 12:09 PM

Quote:

Originally Posted by Diseasel300

It's important to understand the difference between nailing caused by the DV and nailing caused by spray pattern or pop pressure:

The DV has 2 jobs:
1: Prevent reverse-flow back into the pumping element after an injection event. Essentially a check-valve.
2: Provide a very slight negative pressure in the injector hard line to help give an abrupt end to an injection event. Helps prevent a drip or "piddle" as the injector pintle seats.

Nailing caused by a DV leaking or not seating fully can be caused by a delayed injection if it is leaking back, or a prolonged injection caused by the drip or "piddle" from the lack of an abrupt cutoff in the injector. The DV will have no effect on the spray pattern or pop pressure of the injector.

Nailing caused by the injector comes down to poor fuel spray. It can be "peeing", it can be spraying off to the side, it can be fanning out too far, the pintle can be dragging and causing leakdown of the injector, the pop pressure can be off, the list goes on. If turning the glow plugs on stops the nailing, you likely have injector issues. The DV's will nail even with the glow plugs on since they are a different source of injection problems.

The other thing I've noticed with DV problems on my own car is that the nailing usually doesn't start until the engine starts warming up, when cold and the diesel is more viscous, it doesn't seem to cause much of an issue. Running straight diesel-purge of course stops the nailing since it is much higher in cetane rating than pump diesel.

When you get your pop tester going, pull a suspect injector and check 3 things:
1: Pop pressure + spray pattern (should be tightly grouped and even)
2: Internal leakdown rate (after it's popped, the residual pressure should not fall quickly)
3: Chatter. Pull the lever slowly and watch the spray pattern and watch for the injector to "chatter". If it just sprays with no chatter, it will hang up and nail.

I'm currently playing with the 2 injectors I had issues with a few weeks ago. Both of them popped good and had good patterns, but failed the "chatter" test. Once they'd pop, they just kept spraying until the pressure dropped far enough. After an ultrasonic bath and a re-lap of the sealing faces, they test textbook-perfect. Once I get some heat shields they'll go back in the engine for testing.

Thanks for explaining all of that and helping me (ahem) nail down this issue. Seems incredibly obvious now but your post really underlined it, of course nailing can be caused by multiple things. I think I've been chasing two separate nailing issues, possibly back and forth, for awhile now.

I did have severe fuel quality issues for awhile. Now I've both solved the issues and have ridiculous overkill filtration that would catch said issue if it ever happens again, but at the time I was just running stock filtration and I think that might have undone Greazzer's work on my injectors.

Completing my pop tester is now high on the list.

Thanks again.

Diseasel300 · #**194** 12-02-2017, 12:18 PM

Nailing is indeed very hard to "nail down" *tah-dum-tiss* the source of the problem, but the injectors are definitely the very first place to start. Make sure they are *PERFECT* before moving on to something else. Injectors can be considered more of "routine maintenance" compared to the DV which isn't something that should have to be messed with.

If you had fuel quality issues, you may find your injectors piddling or hanging up. In the past, I cleaned my injectors by soaking in solvent. This time around I'm using an ultrasonic bath and there is simply NO comparison in how they spray or operate. It's a night/day difference and I'm getting impatient waiting for the new heat shields to show up so I can test them out.

funola · #**195** 12-02-2017, 12:22 PM

Can a burned exhaust valve cause nailing sounds? Somehow I think it can.