Exhaust leak, loosing boost

[v8volvo]

Sounds a little to me like a sticky governor or worn pump plunger, though as mentioned above air ingress could be a factor too, since air will play havoc with everything about how the pump operates including dynamic advance, internal pressure, governor behavior, etc.

I did see something one time that was unusual on an old 1.6L diesel VW injection pump, with a great many miles on it, where over time a low spot had been worn in the main plunger. The result of this was that the control collar wanted to hang in one position, right on that low spot, and the engine revs would stick there (I think this was around 1500 rpm, depending on engine temp) until you disturbed it by dragging the engine back down to idle with the clutch or by making a large control input with the accelerator. So internal IP wear is a theoretical possible cause for a hanging issue or other non-linear response issue like this.

But before considering that, ruling out all the common and easy variables is definitely the first step: air leakage in, fuel pressure leakage out, fuel supply restriction, fuel return restriction, fuel quality. You could also run some diesel purge if you want, which usually doesn't make a difference but sometimes does.

And one other thing to not forget about is the internal pressure relief valve, screwed into the pump at the drive end from the top. If this is out of adjustment or has fallen apart, it makes the engine run weird since it throws the internal pressure curve off which controls dynamic advance, etc. It is a rare issue but the one thing that can help cause it is operating with a plugged fuel filter -- which I think you did experience one time not too long ago if memory serves? Running with the fuel restriction sucks the pieces of that valve apart and then the retainer can fall out and the valve spills its guts into the bore. No big deal to fix it, you just carefully rescue all the pieces from the hole and reassemble the valve (being careful to let no dirt inside!) and reinstall. If the basic checks don't give you any progress I would check this next.

[RedArrow]

Hi,

I don`t see any bubbles in the clear line between the fuel filter and IP. Not in the morning, not at idle and not at slow or high rpms.
Although it could maybe be possible for the system to introduce air somewhere under the clamp where the hose reaches the IP. IDK. I`ll check that just in case.
Also I could use a similarly clear line for the return side and inspect. That may be a good idea, I think.. not sure.
I personally don`t think it is air-related. How annoying that it seems like a clogged filter limiting but it isnt. Last time it helped but did not solve my issue fully.
But I also had an air bleeder bolt there with stripped threads. Since then I swapped on another housing from another d24.

I used to drive a 240 diesel car for years where you`d see air in fuel hose every morning. It got air in at multiple spots and took time to find them all. Car was used for fishing&hunting most of which on really bad, sometimes rocky unpaved forest roads or literally through fields... used as a sleigh That car always found the way to get air in the fuel system so I know how it sounds and feels when a sudden oversize bubble makes it in. same for the brakes

I had a chance to experiment on my engine stand d24t too when the clear hose bet filter and ip was not attached correctly, also it was split at some point but not seen (underneath area). It hardened and the clamp cut into it but it only got air in at certain RPMS, weird.




IDK what other names the `fuel adjuster` has but isnt it called smoke screw too? idk. Basically it is the first thing dieselers touch when they bought the car. )))
circled in green, pict #5



Just so you all know, the ip has recently been flushed using atf from a jar and left sitting... and should be relatively clear inside.



Here`s a fresh video, taken with a fully warmed up engine, to illustrate the RPMs and the range I`m talking about. Notice how it stops in both directions at about 3000rpm. Doesnt stop but sticks, kind of.
I suggest watching the video SLOWED DOWN. Youtube has that option. Set it to 0.25 or 0.5 speed to see it best.

Look at this video and lmk, can this be caused by injectors? Nozzle failure or whatever? I doubt, but what do you guys think? Worst case scenario i`ll just get the pump off and install the other one but I don`t feel like messing with it.

It might be the case that I have to for many reasons :0)

A few days ago one of the fuel hard lines, cyl#4, started leaking drops of fuel and it stinks. Not much but at least I know why. The end at the IP side got too tight or it simply aged. I think the end deformed just a tiny bit, maybe. Is there a way to touch those up and fix it?

Sorry one more thing, two of the threaded parts where these hard lines screw `up` on the ip, were loose yest. I removed the entire fuel line assembly and took a look. I took care and was aware of the rubber vibration dampeners etc.
Havent seen damage... The 2000 grit sandpaper helped the end of the leaky line but it didnt fully cure it. Can I fix it better? maybe modify it back to more of a cone shape at the tip? then it flattens anyway when you tighten it. I know it is a very sensitively small torque.

I grabbed a nonturbo assembly and used the cyl #4 part of it and will swap that one piece into my turbodiesel assembly.

I think that even if those two were loose it would not affect my ip bc it is not the side where air would go inbound. Anyways. Looks like I`m around the Ip this time.
Today it gets the pipe from the nonturbo in then I`ll see if it leaks or not. The IP side nipple looked intact (the part that is part of the pump).

also this:
The front head of the IP always seemed to look `wet` by fuel so Im sure there was always something going on there. It is high time to reseal this entire IP btw.

I think it leaks near the wax arm too, on the side, and although i have a full reseal kit idk yet if I should touch such a million-piece item (=INJ PUMP)

It prob leaks at the rear seal too or idk... although in that case the air-rpm limit would be explained at least, right?

I dont think it is my fuel shutoff valve that wets the front head but I could look at that too. I just hate messing with Ip in-car. backbreaking exercise to reach in


here`s that rpm video. slow the playback down to 0.25 speed or 0.5
https://youtu.be/TwqBGBq7tlM

Thank you for the earlier responses too! I`ll follow v8`s advice on the order of diagnosys/fix.

I attached a picture and circled in purple the nipple where the hard line developed a leak. Can these be touched up? Shall I swap in another nipple from another pump? Or is it always the hard line itself that creates the `leak`? I guess so.

Also , what is the hole for? two, circled in yellow. THX

[ngoma]

Forgive me, I'm easily confused. To my perception, you're asking a lot of questions here, and jumping all over the place. Can you please:

1. PRIORITIZE your issues, in order of importance.
2. NUMBER your questions, keeping them aligned with each issue.
3. REFRAIN FROM adding superfluous information that does not pertain to your prioritized issue.

Right now, all these things are swimming around in my thoughts and don't know what to do with them:
fishing
sandpaper
backroads
cracked line
hardlines
wax arm
reseal kit
wet head
vibration dampers
cyl #4
rear seal
million-piece item
nozzle failure
fuel adjuster
yellow holes
bleeder bolt
brakes
fuel shutoff

Don't worry about me, I'll get better

[ngoma]

Moved side discussion to its own topic to avoid hijacking this thread.

Discussion: Injection Pump Pressure Control Valve and Varying Amounts of Electronic Control

[v8volvo]

Thanks for moving those posts.

Back to the original question of a slight hang at ~3000 rpm:

I think the most important question is: is this a NEW issue that recently started, or has it done this all along? And can you feel it when you are driving, like it's a driveability problem? Or is it just something you can notice if you are carefully watching for it with the engine revving with no load, but makes no difference in the way the car drives?

Also, are you sure this is happening in the engine itself, not just in the tachometer? The old tachs in these cars often move with a bit of a jerky motion. What happens if you raise the revs more gradually than you did in that video? Does it still hit a sticky spot at 3k?

IMHO: as long as it doesn't present a problem in how the car drives, or represent a sudden new issue that is rapidly getting worse, then this might be one of those problems that's not worth putting too much worry into. The internal governor in the IP is a complex mechanism and there are lots of different ways it needs to respond to RPM, load, temperature/pressure, etc. What you are seeing might just be a fairly normal part of its operation, or close enough at least.

If there's no visible air in the fuel either entering or leaving the pump, and it has a good fuel filter on it, and the car's performance is still good and not detrimentally affected by this phenomenon, then I would probably just keep running it and see if the problem changes.

Could it run a little better/smoother/more evenly with a freshly rebuilt IP? Maybe yes. But it sounds to me like this issue is subtle enough to not be worth all that work and expense, at least not right now, as long as the IP is working fine otherwise (starts good, quiet, clean running etc) and not leaking.

The leaks from delivery valves (what you described as the nipple) at the pump head are common, since those valves often want to unscrew themselves when you take the fuel pipe off. Tightening them to their required torque in the IP head (can't recall but you can look it up), then the fuel delivery pipe to the valve with its required torque, should fix. The fuel pipes do crack every now and then. If you discover that's the reason for the leak, let me know, I have a box full of spare fuel delivery pipes and will send you one.

[v8volvo]

I read your earlier post again a little closer. A couple more things:

1. Injector nozzles probably are not the issue here, they don't really have any control over engine speed. I would not worry about them at all, at least not for this issue (I know you have had some other issues with them though). Failed nozzle will cause smoke, knocking, misfire, etc, but not changes in RPM control.

2. Static timing setting probably isn't related either. If the timing is close enough for it to start cleanly, then it should be close enough to rev through the full range.

3. I think I am understanding that you turned down the "smoke screw" / quantity screw / fuel adjuster, as we are referring to it here. Just as an experiment, what happens if you turn it back in a little bit, like a quarter turn? Does that improve response and get rid of the dead spot you are noticing? It might create a little smoke too but let's just try it for the sake of knowledge. That screw has a large effect on the motion of the governor parts and it could be that it's the reason the engine is not as snappy as you would like.

[RedArrow]

I will report back how it went,
thank you for the parts offer and your valuable response.

[RedArrow]

Thanks for the responses, and i`m sorry for not returning to this thread with some results. I`ll write an update once I have some extra time.


In the meantime, I`d like to know where to find the dome-shaped metal gasket that is in the turbo wastegate area under that cover that is held up by four nuts. I think I will also need a new cover and probably all studs will break at removal. UGH...
I think, old Mercedes cars used that very same gasket btw, I would need more than one, at least two, if anyone could locate it pls let us know.

I can see signs of an exhaust blow-out (grey stains) below the unit, between the two lower nuts. The cover also rusted away pretty badly, i`m not sure I can reuse it. As far as I remember, that cover is just a flat plate, right? THX.

Probably there is a complete kit with every part necessary for a full turbo rebuild project (gaskets, studs, dome gasket, other gaskets and nuts etc, bolts for the turbo and its housing etc)? I`ll search ``Garrett T3 rebuild kit``.

gasket is this: 409262-0000 Actuator Gasket
Post #8 here: http://www.peachparts.com/shopforum/...te-gasket.html