Help II - 2.4d DW engine - Noise when revving
 

Hello.

This engine is really testing my resolve.
It's in a 1983 VW LT camper. I've had it about 2 months.
Trailered it onto my drive after buying it and there it's sat ever since : (

Anyway. It had fuel problems (air in the lines and a leaking injector pump seal) which I fixed. Then the timing was out so I fixed that
All good.
I decided to change the glow plugs as part of general servicing. Took a while as the IP and vacuum pump were in the way and I didn't want to remove them if i could help it but I managed.

I then found some new injector cores (needles and nozzles) which I've just fitted. However, I now have a worrying sound going on.
I've just read this thread and it might be the same issue (hopefully nothing more sinister) but I'll post my vid anyway.
If it just just something with the injectors, this will be a relief.

https://drive.google.com/open?id=1vu...zm3lBF5aPUOwtg

It starts and idles OK but doesn't sound smooth or 100% on all cylinders. It smokes a bit too.
I've cracked open the pipe on the top of each injector in turn and the engine is affected by all 6 (the revs noticeably drop for all)
As you can hear from the vid, it revs OK most of the time but will then make an awful knocking noise. I'm worried about valves, cam, crank.
However, during my previous fixes on this engine, as mentioned above, it didn't seem to do this at any point before rebuilding the injectors but the sound seems pretty drastic.

Any help / ideas / advice gratefully received.
Based on the other thread I linked to, I think I'll take out all of the injectors again and just recheck everything.

My car sounded absolutely bad&horrible each time an injector gave up.

I thought it won`t make it another mile.

Forgive my question, but it all sounds unclear to me, did you actually replace the old nozzles with new(-er) nozzles and then also bench-tested them (the injectors)?

Good and well-set injectors (properly set to factory specifications) make a ton of a difference in how the engine runs. You didnt share details on how and what you did on around the injectors but I assume you did change the injector heat shields also (to new ones). They absolutely must be replaced every single time you take out an injector.
I`ll try to find my video to share.

The timing might be off a little. The more you write on your repair, the more someone will be able to help you figure it out. The secret is in the details.

Also, a few VW Camper with d24 engine pictures would motivate the heck out of us. :)

Yeah your video def sounds like you have the `bad injector thing` that I had.

I never took apart the bad injector that caused me the sounds that seem identical to the sounds in your video, but once I took out the bad one and installed another good injector, bad sounds disappeared and all the knocking was gone...

Then another injector did the same in a few 100 miles, I also did the same, again, and the sounds disappeared.

I probably had a bad luck on 2of6 injectors, that`s all. They were the GTD versions BTW. They were set to 170 not 155 and they ran so great and all sounded great for about 2000 miles only, then 2 of 6 injectors quit being healthy.
Your knocking sounds like you have one of the 6 injectors bad.

My car sounded exactly the same, even worse, much worse, when one injector started acting up.
If you have the patience to take the injector apart, you may find it that the internals are simply misaligned. But once you take them apart you must follow torque specs for the two halves and retest the injector for factory settings, spray pattern and pressures, etc before installing it in the car again.

At this point im not sure you even did that earlier so that could be the case but correct me if im wrong.
I also really wish to find some place where i could send a set or two, of injectors, to get them rebuilt in a surgically clean environment and by a pro, as it always should be done BTW. On the internet, currently available nozzles seem to be all from the wrong places and the wrong quality and not stock.

Ideas welcome.

PS. When my injector gave up and I heard the bad knocking sounds, I drove the car very gently to arrive home to diagnosed it.

One by one,

I loosened the fragile hard lines on top of the injector. One at a time. The car was running. I wanted to figure out which injector was giving me trouble. Dont let fuel touch on the coolant hoses.

My knocking sounds were only present when I increased the rpm, not at idle! At idle the car was normal and no knocking.

So I loosened the 1st hardline and revved the engine gently to see if I can hear the knocking. Yes there was knocking so it was not injector #1.

Then i gently tightened it back to torque specs and went to the other hard line and raised rpm to see if there was knocking.

By the time I reached the 5th injector, I knew it was that injector bc I raised the rpm and heard no knocking (because the hardline was loose and rpm raised and NO KNOCKING)

Fortunately I was able to take out injector #5 relatively quickly ... thanks to the tilted injector pump position.

Report back on the project. Nice truck!

I think you guys are right on, that sure sounds like an injector knock to me too.

Hi guys. Thanks for the replies.

I've changed the internals of each injector for new - this is just the lower part; needle and nozzle. They are all Bosch - made in France and came wax coated. I'm pretty sure they are good quality replacements.
Yes, I have replaced all the heat shields.
Buy no, I've not 'set' them up, other than putting them back together and in the engine.

So, I've decided to put the old cores back in, made sure they are centered and refitted these into the engine. Two of the new ones I fitted were slightly off center - you live and learn - the same as these needing properly set up to the correct pressure : )

I regret messing with these as it was running OK with the old injectors to begin with. I just thought it was prudent to replace the injector nozzle / needle as part of good servicing since the original setup could be almost 40 years old.

I also appreciate that revving in my video is not something that would naturally happen under load / normal driving.

However, having said all this, I'm a little more reassured that my engine hasn't developed some terminal fault and, once I've sorted this, should be good and strong.

I added a few photos of the camper / engine to my other help thread HERE if you're interested : )

Thanks again for the replies.

That "'set' them up" is an important step(s) that cannot be overlooked. :o

Apparently you did not know that injector rebuilding (nozzle replacement) entails more than simply R/R the nozzles and a visual that they are centered. That is just the first step.

The injectors need to be calibrated. Requires a POP tester and shim kit.
1. Set to correct POP pressure
2. Good spray pattern
3. No leaking, dripping, peeing, as pressure is slowly raised to POP
4. Balanced POP between all injectors to a small percentage of variance

Requires extreme cleanliness workspace.

This is an iterative process. GUARANTEED you will not achieve at least #1 and 4, probably 3, with a simple nozzle R/R. GUARANTEED the POP will vary wildly as the new nozzle dimensions are different enough than the old ones to easily affect the POP. Even simply disassembling and reassembling an injector without changing anything can result in a different POP.

Even if you marked which original nozzles were in which housings and put them back together that way, you won't get the correct POP.

My advice:
Get a POP tester and shim kit, learn how to use it, and spend the day calibrating and balancing the injectors.
Or have a reliable shop calibrate them.

A set of correctly balanced and calibrated injectors can really bring these engines to life.

Ha ha. My naivety strikes again :rolleyes:
Thanks very much for your frank reply.

Your description exactly describes what I expected initially; actually I never even gave it a thought. You live and learn.

I actually did do some reading on the subject after posting yesterday and realised the depth of the 'rabbit hole' after my oversimplification. As you say, pressure calibration and unification of all injectors etc etc.

I've put the old nozzles / needles back in and it runs better but, I'd obviously like to get this aspect perfect. I'm just glad the initial noise wasn't anything worse than this.

I think my choices are:
Buy a set of recon injectors, although I'm not sure if these will all be calibrated the same so they are all deliver exactly the same fuel at the same pressure? I'm looking at genuine Bosch recon items @ £45gbp each.

Do you think they would be?

Or

Get someone more competent than me (not too hard) to set the ones i have up properly.

I could do as you suggest; get a pop tester and shims but am unlikely to ever do this again and might waste more money on gauges and still not get it right.

I'll have to do some more digging I think.

Thanks again for the reply. It's good to be able to run my woes by you.

That's a good honest evaluation that brings us to this option:

Have them reinstall the new nozzles and test/calibrate them.

These injectors are not rare or oddball; they are in fact used in a wide variety of IDI diesel vehicles and marine and industrial equipment. Older Mercedes, VW, GM, and many other brands use them. The key is finding a reputable service shop. In my area, for example, there is a local injector service shop that is also a Bosch accredited service center (an indicator of quality) that primarily caters to the local diesel trucking industry but they instantly recognized what I had when I brought mine in.

Hopefully you can find a suitable shop near you.

You will want to "interview" them to find out if they can do the following for you:
1. Install the "new" nozzles
2. Check spray pattern
3. Check injection sound (squealing buzz)
4. Check POP (15.2 - 16.3 MPa) (1780 - 1920 psi)
5. Leak/drip test (no leaks or drips as pressure is slowly brought up to POP
6. Shoot for 10% max variance in POP between the 6 injectors.

Don't forget you will need new heat shields.

Thanks very much again for such a comprehensive reply.
I'm always tempted to get the tools to do this myself. I'm always in the market to learn new things but, I have to stay focused : )

I just need the van sorted as quickly as poss. for the least money.

I've asked a few injector repairers about this but still wonder if units reconditioned by Bosch would all be set up as per this by default?

If so, I think I might just buy a new, recon set (£270gbp) - quite a lot of money but would hopefully last me a while so I can forget about them.

Initial reply from recon firms is £20 gbp per injector to set up but I'd need to be 100% sure they were done to the specs you mentioned.

Thanks again

MAYBE, if you got them from Volvo as per Volvo PN, but as these injectors are used in a wide variety of applications with varying POP specs how would you know what they were set to? Maybe you could ask the reconditioner?

Ex: The same injector is used on the D24 and D24T, yet the POP specs are different.

Hi. Thanks again for the reply.

So, I did decide to buy new injectors but they are set up for DV engine (D2.4t so I understand)

I have fitted them as I needed to get the engine going again (and van moved) and it's much better now. Thanks for all your observations and advice : )

So (more questions : )
What is the difference with internal setup of DV injectors and what will the effect be when using them in my DW engine with DV settings as opposed to the correct settings? Short term / long term - performance, fuel economy etc. Mainly though; will it damage anything?

I guess all of the different settings are defined by the shims above the spring and hence the spring pressure / tension?

Yes the various shims thicknesses are used to create the necessary spring preload force on the nozzle pintle for the desired POP pressure. That and the nozzle (pintle and orifice) shape and design determine the spray pattern. Also affect ultimate timing.

What nozzles (Bosch P/N) are in your new injectors?
Stock nozzle for D24T is Bosch DN 0 SD 1930 (USA/Canada), DN 0 SD 293 (other markets)

What is DW/DV?

Hi again.

Thanks again for the reply.

I'm not sure of the nozzles in the new injectors as they are fitted now and would also require taking them apart to see.

It might have been on the box but I had to exchange with my old ones and that required sending them back in the boxes. I took a few photos. I'll see if it says (they are on my phone)

DW and DV are the engine types. From Wikipedia regarding the VW LT van:

So, DW is what I have - straight six non turbo. The injectors I bought were for the DV engine - more or less the same but with the turbo

Based on what you have said, it sounds like the difference between the DW and DV is the same as what we would think of as the D24 and D24T, but expressed in VW engine codes rather than Volvo codes. In that case the only difference is likely the "pop" pressure calibration of the injectors -- 130 bar for the naturally aspirated D24/DW and 155 bar for the D24T/DV.

The higher pressure turbo spec injectors will run just fine in the non-turbo motors. The extra injection pressure is mainly needed in order to overcome the higher initial combustion chamber pressure in the cylinders of the turbo engines when the turbo is delivering full boost pressure. The higher injection pressure is not necessary in the non-turbo motors, but it certainly will not damage anything at all, and most likely will make no noticeable difference of any kind.

Buying the Bosch reconditioned injectors sounds like it was a good move. I have installed a few sets of those with good results. Bosch seems to do a reasonable job with quality control on them, at least that was the case as of my last encounter. I used to sometimes test batches of their recon injectors before installation using a cheap DIY-grade pop tester and most of the injectors out of Bosch boxes were right on, a few a little high or low, but they were probably at least as good as many fuel injection shops might produce. In theory a set redone by a really good independent fuel injection specialist might be best of all, if done very carefully by someone with a lot of experience and attention to detail and plenty of time available to spend on them, but as you point out, it could just as easily be hit or miss with that, if working with a shop you don't already know well and have confidence in.

The only small but noteworthy implication of running the higher pop pressure turbo spec injectors is that the actual in-cylinder "start of injection" (SOI) timing will be retarded slightly, versus where it would be with the same set of injectors at a lower pop pressure. This is because it will take maybe another degree (or perhaps a fraction of a degree, who knows) of rotation of the fuel injection pump, and the engine, in order for the pump plunger to build enough pressure to pop the injector open and begin injection. So, in theory, you might find with the new injectors that cold weather starting and power and fuel economy see a small negative effect. If you do find that, you could advance the injection pump timing very slightly. You have been through that process now so you know it's not too difficult once you have the hang of it! :)

However, you may also find there is no noticeable difference. This effect of injector opening pressure on in-cylinder timing is real, but it would take a lot of complex engineering calculations to know exactly how significant it is, and it may be that it's miniscule at the pressure difference you have here, or if measurable it may still be well within the acceptable range. If you are happy with the way the engine starts and runs, and with the mileage, then there's no reason to worry about it. Just raising it since you were wondering what *possible* effects might be seen from the turbo injectors in the non-turbo engine. :)

Nice photos of your van, and nice work getting it up to shape for use. Hope you will get some good use of it this summer now that you have it running well! Those are neat vehicles, too bad we didn't have them here. You might have already mentioned this somewhere, but do you know the history of the last timing belt and water pump change? If not that is something you may want to consider doing before putting on too many miles.

Hello.

I know I keep saying, 'Thanks for the reply' but I really do appreciate it as I'm learning all the time with this engine.
I'm either used to basic, old, VW air-cooled engines and some experience of newer VAG engines (I've had many newer VWs, Skodas, Seats and Audi's)

But this kind of 'middle section' of engines have passed me by : )

Anyway, thanks for all this info. I did consider the timing for greater pressure might be slightly delayed but, other than trial and error of advance / retard, over a period of time, I think, as you say, it would be almost impossible to ascertain pros and cons of running; unless it was awful and noticeable, which it isn't.

I could go nuts over this stuff. Your reassurance of no harm running these is great and I think I'll just see how it goes. It starts and idles better than it did. I've never even driven it yet, after just over two months of ownership!!

I have some welding to do for it's MOT (yearly government test for vehicle safety here in the UK) Hopefully once that's done I can drive it around and really see how it goes.

I think the timing belt / water pump will be done after this but before any serious travel - I just need to get it roadworthy first. Then I'll be pretty happy I've done what I can to make it as good as possible. It is almost 40 years old but has a mileage of around 120k, which isn't too bad and will hopefully be good enough for the time I'll have it.

Also, after all this I still have to rebuild the camper part; inside and out - re-framing, re-wiring, re-plumbing and on and on ... :)

I'll get there.

Cheers :D