Kangarooing and lumpy idle (occasionally)

[wil892]

Hi there

I have 3000 miles on a rebuilt pump and injectors on 1.6td 80hp (Bosch certified shop, and well known in UK)

Symptoms are:

- intermittent shaky idle, worse when alternator loaded. It’s not missing, engine just has a slight unevenness/jumpyness to it which seems like resonance. Other times idle is completely smooth.
- engine likes to kangaroo if say 1250rpm at 30% throttle when cold

I have a feeling these two are linked and may be something going on in the injection pump at low loads or injectors.
Engine has healthy even compression, and hasn’t burned any oil. Minimal smoke at wot, otherwise smoke free.
Have checked driveshafts and engine mounts, all seem fine.

Any ideas?

[ORCoaster]

Check those bolts that hold the IP to the engine itself, are they loose causing the IP to shift under a load?  Is the lower bolt that secures the IP tight? 

I forget about the one through the pulley on the lower hole on the front sometimes.  Check em all.

[scrounger]

You said that the motor does this when cold. Once it warms up then it is okay? How about if the cold start lever is out? Mine kind of bucks if that lever is closed  too early. 

Contributing factors that might be included are glow plugs that are not fully heated up and or fuel injectors that have poor spray patterns.

[wil892]

I will check IP bolts, though all of them were torqued when IP was installed.

Bucking stops when motor is warmed, but you can tell it is still slightly present (hard to describe, but you can tell the motors moves back and forth in a similar fashion, just not as extreme)

Bucking is actually better when cold start is pushed in straight away, which leads me to believe it’s something in IP.

Bucking stays present for a good 5 minutes after starting so glow plugs will be long off by then.

I did think of injectors, but no smoke present. Could this happen if one of the injectors has a different pop pressure to the others?

I was reading about similar issues on VE pumps which could be some of the idle/overrun cutoff mechanisms not working properly.

IP was rebuilt due to sticking idle mech after sitting too long on bench. Shop disassembled found some corrosion, removed and rebuilt, then tested on Bosch machine. However I do seem to remember this issue before, just a lot less pronounced.

[fatmobile]

I'd play with the timing.
If it runs better with the cold start pushed in,
 it might be too advanced.

Do you have clear fuel lines?

[srgtlord]

Sounds like it could be an air leak somewhere

[wil892]

Yes my initial thoughts were air leak, and there was one when first installed, but this was fixed. I have clear lines running into and out of the pump and no air bubbles so fairly confident its not that.

I will check the timing again. I originally set it to 0.95mm which is top limit for this engine.

Its a weird issue, but I think they are both linked. I guess the bit that I find most strange is the smooth idle when unloaded (no alternator load), and jumpiness of idle when the lights are on.

[ORCoaster]

I had a hard time trying to time my Caddy until I decided to put a new set of injectors on it.  I pulled all four out and with a pop tester I set them up to find out what they were prior to me changing them out. 

I didn't notice the bodies being much different but the first one never got to 155 bar.  It popped off at closer to 130 bar.  I thought that was strange but set it aside and did the next one.  I let go at just about 153 bars.  Not bad I thought, but then #3 again let go near 130.  #4 again close to 150. 

I started to clean up the bodies with a stiff wire brush and to my amazement, I indeed had two of each in the head.  I figured out that was my main problem.  Trying to time for the longer amount of time it would take to get the 155 bar ones to let go would have had the others already delivering their stroke.  I had no problem getting it to idle smoothly after all-new 155 bar nozzles were put into the head.  I had a loping idle prior to that.

So you might look to see if you have a mixed set on the head.  I would never have thought it possible but clearly the PO didn't know what he was doing when he put the parts on it.  Yeah, injectors are different even if they look the same. 

[wil892]

Just to update this:

Kangarooing was caused by poorly adjusted speed mech and the fast idle mech.

Lumpy idle was mostly caused by alternator overcharging and knackered pulley damper putting some weird vibrations into the belt. The alternator is changed now and its mostly gone but I think my Crankshaft pulley vibration damper is knackered as the V belt has a lot of flap to it and makes a noise.

The crank pulley itself is all well secured, fully cleaned up brake cleaner and torqued with new genuine bolt, so i'm not too worried about it damaging the key at the moment.

However I do need to sort this V belt arrangement out due to the vibration it creates when alternator is charging. I can't seem to find a new pulley anywhere.

Really tempted to go with a multi ribbed belt like TDI, but have heard issues with swapping the brackets as the 1.6 block lacks one of the mounting points.

I am investigating a bolt in replacement alternator which could have a clutched pulley fitted, then I can buy a new crank pulley damper and associated water pump pulley. If anyone has tried this before please let me know.

[fatmobile]

So this is in a MK2 like the one in your signature?
 Without AC?

[wil892]

Yes, mk2 without AC.

Main V-Belt runs Water pump and alternator, then another v belt runs the PAS pump

I'd like to have a ribbed belt so a clutched pulley on the alternator can be used, as well as being able to source a new crank pulley damper. The 1.6td crank pulley damper I need cannot be found new.

Ideally would just swap an AAZ or AHU serp setup but the 1.6 block is missing a mounting point and have seen a few people have breakages occur after some use. Therefore I'd like to stick with the current 1.6 alt bracket and fit an alternator capable of having the ribbed belt pulley on it. If thats a possibility

[fatmobile]

There is a place that rebuilds crank pully dampers but I don't have a link.