#5 and 6 Glowplug replacement - 740

[clandyuk]

1989 740 D24T was suffering cold start problems. My local volvo mechanic has changed plugs 1-4, but says that 5/6 require a lot of dismantling to get to and replace.

Starting is better but idle is rough for a few minutes, so I guess they need doing pdq.

A previous posting implied that this can be done with nimble fingers, so can anyone give me some pointers as to how I should go about it.

I'm still smarting from the cost of a Cambelt replace and the 4xGlowplugs and losing the car for a week, so I'd rather do it myself if at all possible. Trouble is, Diesels are a total mystery to me and I need some guidance.

Any good sources for 'Haynes equivalent' for Diesel engine maintenance?

Andy T

[Peter Milnes]

Your best bet is the Green Book which will cost you £30 from your dealer. Perusing the archives should turn up several messages on how to obtain the Green Book with the correct part number. Careful investigation should give you a pointer as to how to do this. Basically undoing the busbar nut (loosening but not removing) should enable the correct spanner to be fitted to the body nut. With spanner in place slip a noose of string over the plug insulator. This should stop it falling when fully loosened from the head. It should then be easy to remove the glow plug. It should then be possible to (using spanner and pressure from a finger to fit the new glow plug. No 5 is removed/replaced in a similar way but using the busbar (with loosened top nut) to hold the plug as it is removed. Transferring the busbar to the new plug will facilitate replacing it.

It would, of course be better to test the plug's resistance before attempting to remove it. It should read about 1.3 Ohms if good and will nearly always read quite high when knackered. Obviously a good Ohmmeter is essential.

My 5 & 6 are due for replacement which will be done when the Cam and Pump belt are changed which gives a little more room to reach them.

All the best, Peter

[clandyuk]

Peter,

Many thanks for that.

I'll check with my local dealer tomorrow (oops - today) re the Green Book. Saw your post giving the Part# - V97000164.

Not knowing what a Glowplug even looks like is kinda holding me back at the moment, so the GB seems just what I'm after.

Testing the resistance - can you tell me how to go about that (or will it be covered in the book)?

Thanks again,

Andy T

I always first remove the buss bar from #4, 5,6, and pull the wire that goes to the temperature sensor onthe back of the head and move it out of the way, then # 6 is easily reached with a 12mm angled box end wrench(spanner) turned over ( the end of the wrench that would normally be angled up and out, turn it down toward the head)slip it in from the back of the pump bracket and you'll be able to work # 6 out from the back without too much trouble at all.
the flipped over wrench helps on #5 too
The best way to reach this is to lay some padding across the passenger ( oops, that would be drivers side for you) fender and lay on your stomach and access the #5, 6 glow plugs with your left hand.It's really quite easy this way. Trying to reach them from the other side is a nightmare.

A good idea to use a touch of anti sieze compound on the threads of the new glow plugs so the'll come out easier next time.

Have fun.

[clandyuk]

Robert, Thanks for that - I'll try it at the week-end (weather permitting).

I'm a lefty, so I guess I'm ideally suited to this job. I can lie down as well, excellent.

Now off to purchase some glowplugs.......

[Peter Milnes]

It should be in the book. You will need a goood digital meter with an Ohms scale/range. Measure between the top bolt that holds the busbar on (with busbar disconnected) and the block (or body of glow plug). Good should be about 1.3 Ohms, anything more should be suspect.

All the best, Peter

[clandyuk]

An Update.

Have now obtained the 'Green Book' and the 2 Glowplugs and off I went to fit 'em.

S'funny - great big oil mark down side of Engine and marks on our driveway. (One big plus of the 740 is that its never dropped any oil, unlike friend's Alfa :-) )

Had a look under the Vacuum Pump with mirror to find that it has been refitted (post #4 Glowplug change by local V Mechanic) by the top fixing ONLY. The bottom fixing is to the left of, not over, the stud which does have its nut affixed. Retired, fuming, to calm down.

At the moment am a bit bemused as to how the Pump can actually fit in this postion and not have any apparent effect on the car's performance. If anything it seems a bit quicker on acceleration :-O So what does the vacuum pump actually pump?

I will be taking photos tomorrow as I remove, inspect and (hopefully) replace in correct position on BOTH studs. Then I guess it'll have to be a steam clean to stop the dripping and check oil level.

Here beginneth my re-entry into the world of Driver maintained vehicle........

[Peter Milnes]

How did the pump come to be fitted in this way? Was it your mechanic? I would go back to him and tell him that he left your car in a dangerous condition which could have resulted in a) no braking b) broken camshaft c) A very large bill to put everything back together properly after the camshaft break had destroyed the engine. How on earth can they do that knowing what is involved? Tyhe sealing ring would not be able to do it's job and he probably hasn't replaced the pushrod for the pump either!! The pump is used to create a vacuum via the one way valves in the pump body to provide vacuum for the braking system. It is not the most satisfactory method of obtaining vacuum although I am working on a system to avoid the pitfalls.

All the best, Peter

[clandyuk]

Peter, Yup a 'time served' Volvo mechanic. Whilst it was off I took the time to check #5 Glowplug. Luckily it is showing a good reading on the digital meter (= to one of the new ones), so it stays. #6 is dead as the provervbial Dodo though :-( Am trying some penetrating oil in the hope that it'll move later in the week.

As to the mis-fit of the Vacuum Pump - boy have I been lucky. The oil level on the dipstick was down to minimum (it always stays just below max between oil changes), but pump and pushrod don't appear to have suffered. I guess that the pump was actually still working, but leaking oil like a seive - 1 ltr over the side of the engine makes quite a mess.

Also found that the top hose to the radiator wasn't fitted tightly and spurted Anitfreeze when I happened to lean on the hose. A lot of the other unions appear to be weeping as well, but I will have to reserve judgement until the steam clean is done.

On a brighter note, I found a set of flexible head ratchet spanners in Halfords over the week-end and they certainly made life easier. Never thought they could improve on a spanner.

Will probably mention above to mechanic when next I see him, but I expect I'll get a shrug and, maybe, a reluctant apology.
I know working on cars is a pretty thankless task and even simple tasks can turn into nightmares cost wise, but now I have the missing piece to go with my Haynes BoL I think I'll be a DiY'er from now on.

Thanks to you all for the advice.