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Old 04-13-2020, 08:32 AM
blix99 blix99 is offline
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Default 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.
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  #2  
Old 04-13-2020, 04:25 PM
RedArrow RedArrow is offline
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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.

Last edited by RedArrow; 04-13-2020 at 04:33 PM.
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  #3  
Old 04-13-2020, 04:43 PM
RedArrow RedArrow is offline
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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!

Last edited by RedArrow; 04-14-2020 at 09:13 AM.
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  #4  
Old 04-13-2020, 08:14 PM
v8volvo v8volvo is offline
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I think you guys are right on, that sure sounds like an injector knock to me too.
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  #5  
Old 04-14-2020, 01:41 AM
blix99 blix99 is offline
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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.
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Old 04-14-2020, 03:59 PM
ngoma ngoma is offline
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That "'set' them up" is an important step(s) that cannot be overlooked.

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.
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  #7  
Old 04-15-2020, 02:31 AM
blix99 blix99 is offline
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Ha ha. My naivety strikes again
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.
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  #8  
Old 04-15-2020, 11:17 AM
ngoma ngoma is offline
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Quote:
Originally Posted by blix99 View Post
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.
That's a good honest evaluation that brings us to this option:

Quote:
Originally Posted by blix99 View Post
Get someone more competent than me (not too hard) to set the ones i have up properly.
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.
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  #9  
Old 04-16-2020, 02:03 AM
blix99 blix99 is offline
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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?

Quote:
  1. Check POP (15.2 - 16.3 MPa) (1780 - 1920 psi)
  2. Leak/drip test (no leaks or drips as pressure is slowly brought up to POP
  3. Shoot for 10% max variance in POP between the 6 injectors.
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
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Old 04-16-2020, 09:55 AM
ngoma ngoma is offline
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Quote:
Originally Posted by blix99 View Post
...wonder if units reconditioned by Bosch would all be set up as per this by default?
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.
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