1.5 diesel,revs then slow to/wont return to idle

[hill billy]

Hi,

got the GLD running, changed r/h engine mount, timing belt, tensioner, head gasket and put on a different injector pump off the spares car ( it looked newer than the pump that was on the car).

Problem I have is that if reved to about 2500rpm it wont return to idle or takes a long time, maybe a few mins, any ideas?



Steve

[imported_brackie]

Govenor

Sounds like the govenor in the pump is sticking. Make sure that you got all of the air out (did you prime it?) and also check the return springs on the throttle linkage on the govenor housing top. If the pump has been lying around for a while they could be sticky. Doesn't sound like a timing issue, but when you replace a pump with another it's best to set it with a dial guage.....If you can get one!

[hill billy]

thanks Brackie,

this is my first ever diesel so I've got a bit of learning to do.

timed the pump, to .86, it has a yellow dot, with a dial gauge, made an adapter out of a 8x1 bolt drilled out on the lathe. Also made a lock plate for the cam and a lock pin for the pump so the timing should be pretty good, it certainly sounds better than it did, it had a woodruf key in the cam wheel + timing was a fair way off.

took off the banjo's on top of the pump and poured some atf in, does that qualify as priming?

checked return spring on top----it's ok.

haven't driven it yet, will any air in it bleed out with driving? same with the govenor?

so many questions!

Steve.

BTW, I got the diesel manual of ebay, cheers, will have it soon.

[peter_j_g]

Hi,

Sounds similar to what I have experienced...

How far have you driven the car? I've found that it takes a good 10 - 20km for things to settle down, so that all the atf is used up and any air bubles in the pump and lines have cleared.

Are you getting any black smoke when the engine is under load - accelerating or going uphill? You can try backing off the mixture screw a little, mine was slow to return to idle and this was the trick that fixed it. Only 1/8 turn makes a big difference.


Hope this helps!

[hill billy]

hi Peter,

I haven't had a chance to drive it yet, tommorow (Sat.) I will. Its blowing blue/white smoke, so I may have to do pump timing again. I'll see if that settles after a drive though.

Steve

[imported_brackie]

White smoke

White smoke suggests retarded timing. That would at least partially explain idling problems too.

[peter_j_g]

Hi,

Just a thought - when you set the timing did you push the injection advance knob in? If you don't then you end up with retarded timing...

[hill billy]

Hi,

re-timed the pump ( to 1.0, with the advance knod pushed in) on Saturday and took it for a run, the smoke went away after a few k's, seems to be running pretty well and starts easily, although was still blowing smoke on start up on Sunday morning.

One thing I didn't check was the hieght of the pistons, just ordered the head gasket that was fitted previously, 4 notch, i've read that low compression can also cause white smoke

thanks for the input

Steve

[peter_j_g]

Hi,

Good to hear that it is going! How is the fuel in the car? I had some problems a couple of months ago that in the end proved to be a load of dud fuel. Suggest you fill up with fuel of a known good quality and let that run through the system and then make a judgement on the amount/colour of any smoke. A compression test is also good info.

[gldgti]

lots of white smoke says retarded timing (unlikely after all your efforts) or lack of air to me... got a nice clean air filter in it?
the "max fuel under load" screw on top of the pump (has a locknut and crimped collar ususally) is a bit of a "tuning" point on the pump for those that wish to get more oomph out of their diesel - yours may have been tampered with. If its set too far out your pump will not give enough fuel for any serious power but you'll always get great economy. if its screwed in too far, you'll have plenty of power but you may experience runaway at idle or above... try backing it out a little as mentioned above - tho not too far as you may be dissapointed with the power. in any case its easy to ge to and adjust so on the run adjustments can be made fairly easily (NOT while engine running..)

also if i were you, err on the side of advanced timing - you'll have better starting, economy and power at the cost of some extra diesely rattling.

there is a good way of dynamically adjusting the timing with engine running that ensures a good setting too. i can write it up if you like...

aydan

[imported_brackie]

Please write it up!

Go on... We'd love you to. The bottom bolt on the the injection pump is a bitch to get at. What's the trick?

[peter_j_g]

I'd like to hear how you do it with the engine running too! Mine would be a challenge exercise as it has airconditioning, so there are brackets for the compressor and the alternator covering the injector pump mounting bolts...

[gldgti]

i'm not sure about the air conditioning, since i've never had a good look at that setup - only once and briefly.

NOTE: OBVIOUSLY, I ACCEPT NO RESPONSIBILITY FOR ANY DAMAGES INCURRED SHOULD ANY OF THE FOLLOWING ADVICE BE FOLLOWED. IN READING THE FOLLOWING YOU ACCEPT YOUR OWN RESPONSIBILITY IN ANY MODIFICATIONS YOU MAKE TO YOUR VEHICLE OR OTHERWISE.

now that that is out of the way...

basically, you loosen all the pump bolts (dont forget the one at the back of the pump under the outlets). the bottom one is a big problem, yes, but can be accessed with some unorthodox methods. this involves buying a cheap 13mm spanner and putting two 45deg bends in it so that the open end ends up being at 90deg to the ring end, and each bend is approximately 15mm from the either end of the shaft of the spanner. this should allow you access to the lower bolt. remember you only need to loosen it to allow the pump to turn.

note: your new spanner can now be named "VW tool #XXXX-XXXXXXX" and placed on the shelf with all the others, like the tube for holding the pump srocket in place, the bar for holding the camshaft in place etc etc

mark the position of your pump before you move it, so you can go back to where you were before should anything not work properly.

with the engine warm and the cold start out, start the car, then loosen the top bolt so you can rotate the pump. take note of where the pump is, then rotate the pump in the ADVANCE direction (top towards camshaft cover) until you hear the idle revs begin to drop off. you will notice as you advance the pump, the dieselling noise will get louder. this is expected. NOTE: you are listening for a very small decrease in revs. at this point, note the position of the pump (getting somone else to mark this is handy). Now, retard the pump by between 0.5 and 1mm, and snug down the top pump bolt. take note of the new position of your pump.

listen carefully to the engine. ideally, it should be rattling away happily, and if you have advanced it from previous position, it will be louder. you may notice less smoke from the exhaust. take it for a drive and see if you have any more power etc. you are likely to notice the increase at all rpm's.

it may turn out that in this process, you retard the timing, if your timing is already well advanced. in this case if you experience an increase in power, then you have probably saved your engine a bit of stress and prolonged its life. hence, be mindful of advancing the timing too far. at the same time, my 1.5 has had its timing advanced significantly from previous setting for a year now, and is running better than ever.

note that if the engine revs begin to drop immediately as you turn the pump to advance it, then you are already advanced too far, and do not advance it any more.

you are aiming for a point 'just' retarded from where revs begin to drop off when the pump is advanced. note, the engine should rev most at this point, because everything is optimal. listen carfully to your engine during this process and you cant go wrong.

remember to tighten all the bolts back up, and please remember to do all adjustments with the cold start cable out.

if everyhitng goes well, you should experience and increase in mpg, power and better cold starting. I have successfully performed his operation on my own car, and so has my dad on his, and have even ported a similar method accross to my friends '91 diesel cressida import, all with great results.

good luck

aydan

[peter_j_g]

Thanks for the detailed description!

Have you checked what the setting you end up with is with a dial indicator? Is is more/less/same as the recommended lift of .88 to .92mm?

Regards, Peter

[imported_brackie]

Excellent account!

Yeah, Aydan... Good description. A lot depends upon your "ear" but anybody who knows diesels should be able to do it. Is it possible for a pic of the spanner you made up and the angles you used? I reckon we should all have one of those! Also, we diesel owners should get together and buy a timing set that we can share as needed. What do you reckon, Dieselers?

Peter, I had a diesel with aircon back in WA and it was hard to get at anything on the front of the motor. Somebody had fitted a device that cut out the compressor when the car was under acceleration. I never got to have a good look at how it worked before the old girl died but it was excellent as the compressor only cut in when cruising or decelerating.