Bubbles around glowplug

[Flynn]

I've got a problem with my diesel which I thought I had figured out. The car is idling rough and the fumes smell more strongly (because the fuel is not combusting properly) and bubbles are appearing around two of the glowplugs (although mainly one). I thought it was down to a sticking injector because you can hear that it's only on one injector and every other crank rotation. But I typed "bubbles around glowplug" into Google which seems to suggest that it could be a problem with the threads in the cylinder head for the glowplug. The injector also has a stuck sealing washer (made of copper) which was stuck to the base of the cylinder and due to multiple attempts to pull it out is quite heavily scratched/dented in the metal. I am thinking to try to remove this copper seal in the injector hole by heating it up until red with a blowtorch, but is that okay on the cylinder head? I have heard of heads warping because they have been too hot in one place, I dunno if this would have the same effect. Originally I thought the injector was sticking and a bad spray pattern was causing the bubbling, I'm not so sure now so don't want to replace a perfectly good injector for nothing. Or should I replace the glow plug? I could do with some advice here guys.

[CarlosA]

So the copper washer was used to try to seal a glowplug seat? I have an eroded seat and similar issues as you right now.

If you aren`t using heat shields at the base of the injectors that will cause all sorts of problems starting with lower compression, overheated injectors, etc.

What year is this one?

[Flynn]

It's a 96 bud. About the copper seal, that is for the injector. The glowplugs on mine don't have washers.

[82vdub]

I'm not a machinist, and don't use a gas wrench set very often, and the times that I have, it hasn't been much.

My first thought is that if you're going to try to heat up just the bottom of the injector hole, you're going to heat up way too much, damage something, and likely even damage/blow a hole through the cup/insert that's at the bottom of the injector hole. Can you even get the flame to the bottom of the hole with no real outlet for the fuel/flame/pressure?? Just screwing up the cup is going to require you to pull the head to fix it, if it's even repairable. So, the default opinion would be to either take it to a repair shop that deals with stuck things in automotive applications, or pull the head and then have a machine shop or someone get it out. In either case, I think if your last resort is to use the gas wrench set, it's probably time to solicit the help of professionals because I can't see the outcome being very positive. I am continually dumbfounded at what my mechanic can extract from something in no-time that I can spend days to do the same thing. The difference is that he does this for a living, and I do it a couple times a decade.

[Quantum-man]

IDI or TDI, you don't specify.
Photo of heat shield in injector hole will determine it's condition. Don't use heat to remove, plenty of heat from the running engine has failed so far. Coppper @red heat is way above head melting temp.
Use a small screw-driver, or reverse end of a small metal file to clear the carbon from around the circumference of the heatshield, then use a large wood screw and vice grips to remove.

Remove offending glowplug. Check seating condition of head if viewable. Check that glowplug has not crimped onto glow 'tube' if so has been previously overtightened. Don't repeat this with next glowplug. PTFE tape on glow plug thread will seal...

[Fatmobile]

I wonder if cranking the engine with that injector out would pop the heat shield out.

[Flynn]

I can't see that helping TBH, fatmobile. It seems to have melded with the head. When I changed the injectors some time ago I broke the end off a small flat blade screwdriver, god only knows how it didn't fall into the cylinder. Quantum-man, it is an old style mechanical IDI lump. Now I'm not sure what it is causing the misfire because if the injector is bad that is the most obvious thing but if it's not that means I'll have to try and get that damn washer out which is gonna be a pain in the ass! And that's assuming that the glowplug is not the problem!

[Quantum-man]

I can't see that helping TBH, fatmobile. It seems to have melded with the head. When I changed the injectors some time ago I broke the end off a small flat blade screwdriver, god only knows how it didn't fall into the cylinder. Quantum-man, it is an old style mechanical IDI lump. Now I'm not sure what it is causing the misfire because if the injector is bad that is the most obvious thing but if it's not that means I'll have to try and get that damn washer out which is gonna be a pain in the ass! And that's assuming that the glowplug is not the problem!

Flynn,
Don't link the shield issue and the bubbling glowplug threads with the rough idling. Even finger tight plugs and injectors will function correctly [not recommended though ;o)... ]
If you do not have a spare injector, then you probably don't have an injector tester either, so there are 2 things to try:
1) Swap the injector to a different place, or
2) Remove injectors, remove fuel lines, and reattach upside down so that the injectors are fireing skywards or similar. Have someone crank engine over for a couple of seconds, enough to visually compare all four sprays. Cover engine with a few sheets of newspaper. They should be similar, but not neccessarily identical, but none should drip down the threads.

The idling issue may be merely timing. Does the engine start easily? If so retarding by a couple of thou may help.

[Flynn]

Quantum-man, the engine does take a few cranks to start even though the fuel pump is fully advanced. Once running at over idle it smooths out. This is the same with vegetable oil and diesel, although on diesel it does seem to run better.

[Quantum-man]

Veg oil will add a few degrees of advance. If that makes life worse, then the pump may well be over advanced for your engine. This can be the case if your injectors have aged and the break pressures have lowered. This is not neccessarily a bad thing, indeed I deliberately run my TD on around 125bar. However this means timing for me has been as low as 0.5mm, and currently a little over 0.7mm. Make yourself an injector tester out of a car jack.

Having said all that the engine should start with advance pushed in, during summer months. Experimenting with + or - timing adjustments is the way to go.

[Flynn]

If the pump is too advanced for the engine, would that cause starting troubles? I know having too much retard does. I'm tryna figure out if the starting and the rough idling are connected. I know on my previous injectors the engine used to run lumpy for a couple of seconds but that was cured when I replaced them. The problem that I have now is that it goes through several "clean cranks" without any attempt to fire before it fires, compared to how it used to fire after about two cranks. Hence why I thought maybe an injector was sticking. But the rough idle is the main problem because of the smoke that it makes. Time to experiment I think!

[82vdub]

How do the glow plugs test? Is this start problem a cold start, hot start, or either start issue?

[Flynn]

It constantly smokes, but it never used to. I have made a video of the tail pipe which you can see:

The car is running at a fast idle, but it is the same all the time. A puff of smoke every rotation.

Regarding the glowplug bubbling, I have removed said glowplug, cleaned the threads and then torqued it back up, didn't see any bubbles although I didn't run it for that long either. Still got the missfire.

I have also set the pump to the middle of the timing bracket.

Below is a picture of the mangled washer that I tried again to get out (but failed):



I dunno if this is causing the missfire or not. I've tried some old injectors in there replacing one and then testing it after each one, still the same problem. One thing I did notice about both sets of injectors is that the pintle ends did seem to be flat on them. I scrubbed the nozzles with a wire brush some time ago to get the carbon off, perhaps this has interfered with some of the finely controlled spray patterns of the injectors? I can't remember if I did that with both sets or not though.

The only other thing I can think of is the head gasket, but it is smoke that comes out of the tail pipe, not steam. You can tell because it is quite acrid.

[Quantum-man]

Hi Flynn, first lets sort out your fuelling issue. You state that whether at idle or fast idle, that regular puff occurs.

Assuming that the engine doesn't otherwise shake like a belly dancer, I think your problem is a regular build-up of unburnt fuel. I suspect that in the absence of extremely low compression,the most likely cause is a leak from an injector during low compression period.
A dribbling injector can also be otherwise giving a good spray pattern. The only way the rogue heatshield could be involved, is if the centre of the shield is away from the face of the injector and 'sheltering' some of the diesel cloud, and then releasing it by delaying it's vapourization, and combustion. An injector tester would really help.

One thing you could try, is to slacken the timing bolts on the pump and alter timing of pump whilst idling, and see if the pulsing disappears.

Nasty shield problem; I would try using an artists brush to paint onto the heatshield's circumference foam oven cleaner. This will remove the surrounding carbon that is helping to hold the shield firm. Wipe off with toilet paper. Pull out shield using a 4" woodscrew, cut down to 2". It should snatch out.

[Flynn]

Is it possible that the copper heatshield could be allowing the injector to be tightened down further than it is supposed to be in it's damaged state? Even if the torque setting is the same? With the fine tolerances involved, surely that could lead to the spray pattern to being incorrect? I find it hard to believe that both sets of injectors had the same problem. Unless it is a blockage in the injector pipes. Has that ever been heard of? I rebuilt my pump using grease (which doesn't dissolve) to hold the various internal mechanisms together before putting the head back on, perhaps some of that has got into the injector pipes and is blocking them? Normally you are supposed to use petroleum jelly but I didn't have any at the time so had to use the grease. Even though I now have a replacement unopened pump on it, so that rules out the pump causing it. Also I don't think changing the pump timing whilst the engine is running will help any because I have tried the pump in several different positions which hasn't made a difference at all. The smoke seems consistant. I would like to build an injector tester but the money spent on parts would afford me a new set of injectors.