number 6 glowplug

[Battleship Potemkin]

Have replaced 5 and car is now starting after 20-30 seconds on key.
Are there any tricks to do number 6 as I cannot get a spanner or socket on.
940 td auto

[v8volvo]

Even with only 5 working plugs it ought to start better than that. Cam and injection pump timing correct? Cold start advance device working properly? Valves adjusted, or does your car have a hydraulic head? I guess a 940 probably is hydraulic. Are you using good-quality glow plugs? Proper Bosch plugs are the only ones to use in these engines; other plugs will affect starting and fail sooner.

The #6 is not impossible, just tricky. There are a few good approaches. One is to remove the rear timing belt cover and go in from the back of the motor. No room for sockets with the #6; an 8mm angled box wrench can be snaked through from the back to undo the buss nut, which only has to be spun off a few turns because the buss is forked at that end so it can be slipped off the plug without removing the nut entirely. Then you can slip your 12mm open-end wrench (or a forked spanner, I think you would call it over there? ;-) over the glow plug and spin it out, then remove and carefully install new plug using long needle-nose pliers.

The alternative method that you may find easier overall is to remove the vacuum pump and the fuel lines. This has a few extra steps: to remove the vacuum pump, first turn the engine to #1 TDC to make the pump easier to remove and install and ensure one of its mounting ears doesn't break under the strain. Do this by turning the engine with a 27mm socket on the crank harmonic balancer bolt until you see the notch in the back of the injection pump drive gear come around and line up with the notched marks on the outboard edge of the injection pump bracket, right near the heater hoses. Once the marks are lined up, you are at #1 TDC which takes the spring load off the vac pump drive plunger. Remove the vacuum pump (two 13mm nuts with flat washers) and tie it up off to the side, remove drive pluger/rod from head before it falls out on the ground, and put it aside in a way that you will remember to reinstall it in the same orientation it came out (i.e. same end facing in as before). Putting it back in the wrong way can wreck the cam lobe that drives the vac pump. Then remove the six hard lines to the injectors as a unit, with their clamps still installed. Immediately wipe/wash off any oil or fuel that spills on your coolant hoses while removing the vac pump and fuel lines, and wrap tin foil around the fuel unions at the injectors and on the IP to keep dirt from entering. At this point, you should have easy access to the #5 and #6 plugs. Remove the nuts from #4 and #5 to free the bus from them, then just slightly loosen the nut on #6 so that the buss stays attached. It needs to be loose enough that the plug can turn freely under the buss, but not so loose that the buss is flopping around. Then you can unscrew the glow plug with the bus still attached, and remove the plug by fishing it out of its hole on the end of the rear buss. Install by the same method. Remember to use a bit of anti-seize on the threads of the glow plugs, especially the rear two... if one of them gets stuck back there later on, you will really be in a bind!

Replacing the #6 is fiddly and tedious no matter how you do it but not that bad. However, it is enough work that if I were you I would try to test the plug before undertaking replacement. You have to remove the buss bar from the plug to disconnect it from the other 5, and then you can use an ohmmeter to check the plug's resistance. It should have between .4 and .9 ohms resistance to ground at the terminal. If it has infinite resistance then the plug has failed open and needs replaced. If it has less resistance than .4 ohms it needs replaced. If the resistance is in spec, then the plug is OK and your starting problems are being caused by something else as described above.

If you do use method #2, removing the fuel lines, then you may want to take advantage of having them off to check other possible causes and get a read on the engine's overall health. For instance, with the fuel lines off you are most of the way to doing a compression test, which is valuable info to have, and having the vac pump off may make it easier to check and set injection timing. If you are able to get your hands on the tools for those procedures, I would highly recommend them while you are in there. If you need tips on either of those jobs, just ask.

Welcome to the forum!

[Battleship Potemkin]

Thanks for the detailed information.
I used Iskra glowplugs from Slovakia,with a 5 minute warranty!
First job is to replace with Bosch as you suggested.
Forget about crack,these cars are more addictive.
Cheers
Mike

[v8volvo]

Yep, the Bosch plugs are the only ones I have found to have a reasonable lifespan and perform reliably. In the US we see a lot of Autolite and Champion plugs, which are all junk... if you are lucky they just burn out quickly, if you are unlucky they swell up or distort so that they are difficult or impossible to remove, or worse yet, they break off inside the prechamber and cause havoc inside the motor! Genuine Bosch is the only option for good starting and least chance of having a glow-related problem.


Forget about crack,these cars are more addictive.

I'm afraid I can vouch for that....

[ian2000t]

The Beru plugs from GSF seem to be holding up well - tested them the other day and all fine after 6+ months on WVO.