Oven Repair II

OK, so the top oven gasket has been fixed (twice), next job was to repair/replace the button that had broken off the control panel on our Zanussi ZCG551GXC cooker.

Broken middle button on control panel

This meant getting under the hood, so to speak. For repairs to anything this is not always a straightforward process as you need to find and remove all the connectors holding the item together and often it takes a specific twist or order of disassembly to successfully to separate the pieces without damaging anything.

For white goods there are a few places to ask for help that often turn up trumps. Whenever I get stuck the ukwhitegoods forums are often helpful, but not in this case unfortunately. Other places to try are DIYnot or the Screwfix forums, but being more general they are often less helpful for this type of question. So it seemed that I was basically on my own with this one.

First task was to pull the oven out from its alcove, dislodging one of the feet in the process (this would have been part III if it hadn't just screwed back into place). Then another bucket of soapy water was made and I cleaned as I went along.

If you are reading this with a view to take apart your own machine, please for the love of Mike make sure you have disconnected it from the power before you start poking around in it. What follows is what I did, the description may include stupid and/or unsafe practice. I'm not liable if you repeat this and stuff something or yourself up. Nuff said.

At the back of the machine there were two T15 Torx self-tapping screws on either side of the hinge assembly for the glass lid that came out.

Location of cooker top retaining screw at back of oven

Followed by another three T15 Torx screws and washers underneath the stainless steel fascia.

Front cooker top retaining screws

On top of the hob each of the gas burners was held on with two T10 machine screws

Hob burner retaining screws

and each of the controls had a knob that could be pulled off with a bezel attached by a further two T15 Torx screws. The grill/top oven control had a small spring between the knob and the gas control.

Location of bezel mounting screws underneath control knobs

Twenty-three screws later and the top was loose. What I should have done next was lever off the stainless fascia and remove its earth tag giving access to the command panel,

Fascia retaining clip and earth tag locator above first control knob recess

this might have allowed me to remove the command panel without disconnecting the whole cooker top, But instead I removed all the spade connectors from the command panel at the front (4) and the hinge housing (16) at the rear of the hob, making sure that before I disconnected them that I had a note of what went where.

Command panel connections viewed from rear of machine

Hinge housing connections view from front of machine

Connection diagram Zanussi ZGC551GXC

This allowed the cooker top and attached lid to be lifted forward and off the oven and the command panel to be removed from the two silver retaining clips.

Command panel released from cooker top housing

The command panel could then be released from its translucent brown plastic enclosure and the remnants of the broken button were released.

Disassembled command panel

To repair the button I drilled out a 1.5mm hole along the shaft of both broken ends of the button, inserted a suitably sized piece of stiff 1.5mm wire and glued it back together with superglue.

REME

All that remained was to repeat the disassembly process in reverse

Reassembly of oven

Including the door gasket fix I reckon to have saved £30 in parts and £120 in labour for an engineer. JOB DONE.

Time spent : 1 day including cleaning/drying time
Cost : £0.00

Oven Repair Ib

Fixed, but not for long; the door gasket was found hanging down into the main oven about two weeks after it was put back into position. On the plus side it wasn't the repair that had failed, on the minus side it was broken again. Back to the bench for more aluminium foil and staples and straight back on. Let's see how long it works for this time.

Time spent : Another 30 mins
Cost : £0.00

Oven Repair I

Moving along, the next item suffering is the oven. There are two faults, a broken button on the control panel and a failed seal on the top oven/grill. The oven is a Zanussi ZGC551GXC gas oven.

I started with the seal, just because this should be the easiest one to sort, in access terms at the very least.

Broken top oven door gasket

Removing the damaged seal was not a problem, it was held on with 4 hooks at each corner. So the whole thing just pulled out easily. The next part of the job was to get a bucket of hot soapy water and start cleaning both the stuff as it came off the oven and the exposed areas left behind.

Rear view of removed gasket 

You can see from the picture that the top portion of the seal has had more heat damage than the bottom which why it has parted there.

A quick trip to the Zanussi support pages yielded no information. Not even a link to their on-line parts shop where all the part diagrams, part numbers and prices are! So a replacement seal would have been £21 plus £2 p&p and another £8 for a replacement timer button, or £31 for the pair. The seal is only mildly expensive compared to button which costs its weight in 9 carat gold. Time to make do and mend I think...

Cross-section of door gasket

On inspection I found that gasket was originally sealed by inserting a joining piece into a void running the length of the gasket. It seemed that I could just replicate this. As I wasn't sure how hot the gasket would get in operation I plumped for a piece of thick aluminium foil folder over.

Foil from top of coffee can

Folded across a wire to make require profile

Using this and a piece of wire to form the spike in the profile I made a 4 inch piece to join the ends.

Home-made joining segment

As you can see from the photo, this was only partially successful as the perished rubber had a tendency to part. When I refitted the gasket to the door the aluminium kept slipping out of the rubber so to prevent this and deal with the perishing I reinforced it with four staples underneath the flap of the gasket.



Repair reinforced with staples

This worked and the whole thing went back into place with no problems.

Repaired and refitted top oven gasket

The less damaged part of the seal is now at the top of the oven aperture and hopefully we'll get a further 4 years of service out of it before it needs properly replaced. On to the snapped button!

Time spent : Day split over an afternoon and morning
Cost : £0.00

Dishwasher cleaning products

Yes, I have got the bit between my teeth regarding maintenance of the dishwasher. As I noted the water matrix looked a bit gunky but impossible to clean manually. What to do? Use a dishwasher cleaner I guess.

Based on a Google search for dishwasher cleaning products, the three most commonly mentioned are Finish, Bosch and Dr Beckmann. But what's in them, what do they do, and are they really required anyway?

Let's start with Finish which has been available in two formats.

New Finish

Old Finish

The older one appears to mostly be citric acid (15-30%) and a non-foaming detergent (5-10%). Why non-foaming? Because this is what happens if it isn't. While the newer one is exactly the same thing but with a splash of EDTA and bit of glycol ether (presumably to help form the upper blue phase and assist the detergent's effect). So in both cases it appears to be a bit of acid/chelator to descale and break down any fatty deposits and a non-foaming detergent to help shift any stubborn stuff.

As it's a powder, Dr Beckmann's has a different set of active ingredients being mostly sodium percarbonate (20-25%) and some coyly named oxygen-based bleaching agents (15-30%) which are probably also peroxide derivatives or activators for the percarbonate (I wouldn't be surprised to see EDTA in the mix again as well).

Dr Beckmann

Finally the Bosch dishwasher maintenance powder has a more comprehensive set of ingredients but the main constituents are citrate and percarbonate. There is also sodium silicate (an astringent), sodium carbonate (washing soda), longer chain detergents, EDTA, and a couple of industrial enzymes, amylase (a starch buster) and subtilisin (a protein buster).

Bosch maintenance powder

In summary the cleaners appear to be either citrate and/or percarbonate based plus/minus a non-foaming detergent. They are targeted at descaling, dissolving fatty deposits, and shifting stubborn residues that your regular dishwasher detergent isn't moving.

On the question of "Are they worth it?" there seems to be a lot of debate. The commercial cleaners generally recommend a monthly application. So, at anywhere between £2 to £6 per dose (or £25 to £75 a year) and given that a reasonable dishwasher will cost about £300 and should last ten years, if you are not using one of the commercial products and if (and it's a big if at that) this halves the lifespan of your machine you would have paid almost as much on even the cheapest cleaner as it would cost to replace your dishwasher every five years rather than ten. In that light they appear to not be very cost effective. More so as the bulk cost of the component chemicals is only a few pence.

The following comment from the Money Saving Expert forums gives an expert perspective,

"So do use the salt chamber and keep it full, buy rinse aid and add it and you will get nice clean stuff out every time, don't waste money on Calgon, dishwasher cleaner or tablets with added rinse aid or salt either because it's just a marketing con, I used to build and repair £20,000 commercial dishwashers so I know a thing or two about them."

Reading the thread a range of cheaper substitute options are suggested, vinegar, bleach, baking soda, washing soda, and bicarb. Of these vinegar seems the most commonly recommended, both as a cleaner and as a rinse aid (see here and here).

However there is some controversy about whether using vinegar (aka 5% acetic acid) will damage the seals and internal tubing of your dishwasher. A bit more digging shows that more seals are compatible with citric acid than with acetic acid, which may be one of the reasons why some of the cleaners are citric acid based. Whether this matters if vinegar is only being run in the machine a few times a year as a cleaner rather than routinely as a rinse aid I can't be sure.

Certainly some manufacturers specify that vinegar is safe to use in their machines, but the manual for ours didn't. The best way to establish if it is safe or not would be to contact the manufacturer, but with Neff that's another story...

In the meantime, the Finish bottles contain about 30-60g of citric acid which is easy to get hold of in food grade form. Five pounds will get you enough for twenty 50 g (=2 tbsp.) doses that can do the job of £80 worth of Finish cleaner. The loose crystals just be bunged into the powder compartment and run through a hot program. Percarbonate is also readily available but replacing the non-foaming detergent is a more awkward, but not impossible, proposition.

But if I'm just trying to replace a vinegar clean then a citric acid only swap seems most straightforward. I think I feel a trial coming on.

Dishwasher MRO

Ok, so now the dishwasher is back in action how do I keep it that way? Well the manual for the machine had some advice

􀊋 Check spray arm for grease and limescale deposits.
If you find such deposits:
􀊋 Fill detergent dispenser with detergent. Start the appliance without utensils in the programme with the highest rinsing temperature.
Clean the appliance with detergents/appliance cleaners which are particularly suitable for use with dishwashers.
􀊋 To extend the life of your appliance, clean the appliance regularly with a special dishwasher detergent.
􀊋 To ensure that the door seal always remains clean and hygienic, regularly clean it with a damp cloth and a little washing-up liquid.
Regularly wipe the front of the appliance and fascia with a damp cloth; water and a little washing up liquid are adequate. Do not use sponges with a rough surface or abrasive detergents, as these could scratch the surfaces.
Special salt and rinse aid
􀊋 Check the refill indicators and, if required, refill salt and/or rinse aid.

.... blah, blah, blah, yawn.

More succinct instructions were to be found on the Which website, where a nice man in a suit shows us how to clean an immaculate dishwasher. I kid you not, look

Britain's Best-dressed Dishwasher Repairman

The list of to-dos is straightforward and the provision of repeat periods means the information is easy to put into a recurrent job.

1. Clean the dishwasher filter - Weekly
2. Wipe the dishwasher door seals clean - Weekly
3. Top up with dishwasher salt and rinse aid - Monthly/when indicated
4. Remove and clean the dishwasher spray arms - Six-monthly
5. Run the dishwasher empty and hot - Six-monthly

JOB DONE.

Break-time over

Ah well, back to it.

Currently we're having a white/brown goods situation, so let's start with the dishwasher, which presented itself like this,

mmm, lovely.

After emptying the machine by hand and checking that the pump wasn't blocked and was running freely, running a rinse cycle replicated the problem so it wasn't a flyer. Taking the machine out of its' alcove showed that the waste path out of the washing chamber didn't seem too bad.

Water handling matrix of a Neff S51E50 dishwasher

The waste flow is the corrugated pipe coming in from the pump on the right-hand side and going up into the matrix, the flow then loops over and exits out via the white pipe to the back of the machine. Visually it looked OK. There does appear to be some residue in part of the matrix but A) I'm not sure this is causing the problem and B) there is no way in to clear it out as the matrix appears to be a sealed unit. Running a rinse cycle into a bucket worked fine.

The next port of call was the path from the waste pipe into the sink waste water plumbing. No need to see that part of the process, it was pretty foul (it'd gie yer the boke).

40mm waste water pipework

40mm trap seal (L - old/R - new)

After cleaning out many years of grot and replacing a dodgy 40mm trap seal that had been stretched and was leaking slightly it went back together no problem.

So all good, replaced the dishwasher waste pipe and ran another rinse cycle and hey presto! No change.

Disconnected and repeated the rinse cycle running it into a bucket: no problem. Is the pump not efficient enough? Ran another rinse cycle with the waste pipe elevated above the height it would usually connect at; no problem. Hmm..., reconnected it back to the waste piping and now it's back to working normally.

What was the problem? Basically I'm not sure. Current and final thoughts are

• Waste water was not draining, but pump was working. Therefore, probably, not due to a blockage in the waste path.
• So either the programmer or an associated detector wasn't working properly.
• No reason why it should just start working again if it was the programmer.
• A flaky sensor is a possibility but that is likely to reappear as a fault.
• Or the check valve on the waste outflow (if there is one) was allowing waste to siphon back into the machine.
• But on the first occasion the water was very gunky, indicating that it hadn't been through the rinse cycle at the end of the programme, so siphoning seems unlikely.
• Or the pump wasn't working properly.
• But if this was it, it must have been a blockage rather than a mechanical issue with the pump.
• Or repeated rinses may have removed an obstruction or crud and this might have brought it back to life.

Or in short, I have no idea but don't care as long as it keeps working.

Time spent : Day and a half, off and on.
Cost : £0.59 for replacement washer.

Throne MRO

That's Maintenance, Repair, & Operations for those of you who, like me, hadn't come across this TLA before. Well the repair to the Family Seat lasted only for a while, first the fake screw head came away, then the bracket holding the large toilet seat started pivoting and coming off the hinge bar at one end, leading to a seated experience akin to riding on a tea tray. The Codger had a go at it and put in a new screw but, despite his confidence that it would work and my speculation that the stump of the old screw meant it wouldn't, it was in the end a very temporary fix (2 weeks max). So I should be junking it….

But, it hasn't come away completely and is only pivoting on the good screw, so if this could be prevented the whole thing might well last a while yet. Bargain!

The first job was to decontaminate the whole thing (ten minutes of surface cleaner to clean it up and some vinegar to shift the verdigris that had formed on some of the metal parts). The business end of the job was one hole to drill and one screw to fix; forgetting to refit the brackets for attaching the seat to the toilet before capping the hinge bar made that two screws to drive. An M4 12mm zinc-plated self-tapping screw makes a stud to stop the main seat hinge from rotating off the bar. Not a pretty repair by any standards but who takes that much notice of the underside of a toilet seat. All worked as planned but the single screw holding the hinge onto the seat is somewhat shaky.

If it breaks it's the bin, or perhaps a stainless steel bracket could be made that would hold it for a bit longer…

Either way, JOB DONE.