Volvo 760 Long Life Design Faults

[volvo B230ET]

Im currently doing a vast amount of development into restoring my 760T
saloon,I'm aiming to rebuild the vehicle to last another 60 years and with a
budget of £18'000 and 17 months worth of research and redesigning i hope to
succeed.

Anyway the current list of Design Faults that have occurred over 30 years or so
Are as follows:

Headlining glue - melts
Heater vent foam - Disintegrates
Heated seat matt contacts - Not durable enough
Lumbar support plastic worm gear - brittle plastic
Odometer reset sprocket - brittle plastic
Fuel Gauge - intermittent
Electric window switches - arcing/no relay
copper heater matrix - galvanic corrosion
Dashboard - cracking
Piston slap - Oversquare engine Design
ZF Auto gearbox - pump isnt engaged when idle
Rear nivomats - leak and fail in heavy use


They are the only design faults i can think of so far, if anyone can come up
with anymore ideas to help in the development i would be greatfull.

[Laird Scooby]

Originally Posted by volvo B230ET

Im currently doing a vast amount of development into restoring my 760T
saloon,I'm aiming to rebuild the vehicle to last another 60 years and with a
budget of £18'000 and 17 months worth of research and redesigning i hope to
succeed.

Anyway the current list of Design Faults that have occurred over 30 years or so
Are as follows:

Headlining glue - melts
Heater vent foam - Disintegrates
Heated seat matt contacts - Not durable enough
Lumbar support plastic worm gear - brittle plastic
Odometer reset sprocket - brittle plastic
Fuel Gauge - intermittent
Electric window switches - arcing/no relay
copper heater matrix - galvanic corrosion
Dashboard - cracking
Piston slap - Oversquare engine Design
ZF Auto gearbox - pump isnt engaged when idle
Rear nivomats - leak and fail in heavy use


They are the only design faults i can think of so far, if anyone can come up
with anymore ideas to help in the development i would be greatfull.

A few of my observations over the years to add to what you've already listed.

Headlining glue is fine - it's a brushed nylon backed foam (PVC foam i think) and the foam, just like the heater vent foam, disintegrates with time. Closed cell polyurethane (PU) foam might be a better option for the heater vents, for the headlining try one of the newer, similar designs as the later foam is more durable and lasts longer.

Lumber support gear and trip meter rest gears, 3-D printed Delrin items or Nylatron will last much longer.

Fuel gauge - fails due to cr@ppy lead-free solder as enforced by the EU. Either build your own LED bargraph fuel gauge or chance your hand at resoldering the SMD components in the OE gauge.

Electric window switches, regular cleaning (once a yearsay) with contact cleaner to prevent build up of residue causing high resistance which causes arcing/heat and burning of contacts

Dashboard can be repaired with cold cure rubber or foam. https://www.mbfg.co.uk/foam-medium.html

They have colour tints/pigments so you can even match the colour. They also do cold cure plastic resins for the hard plastics of the dashboard/trim etc.

Piston slap is more prevalent on the B200 with a bore of 88.9mm than the B230 with a bore of 96mm - both have a stroke of 80mm, go figure as our USA cousins say! It's the long stroke that does it or maybe a long piston but in all cases, it's the rear cylinder that suffers most due to restricted cooling and oil supply.

ZF box - swap it for an AW71 or if you prefer, an A341E mated to a 1UZ-FE V8, the AW71 and A341E are virtually indentical so just sort some engine mounts and the ECU for the Lexus lump, you've got rid of piston slap and gained 1700cc and 120bhp, not to mention an awesome exhaust note!

Nivomats - i'm one of the sites despisers of Nivomats as they weren't fir for purpose even when new - they only restored the rear ride height to 30mm below what it was before loading so to me, that isn't self-leveling. Better off fitting standard springs and shocks, no more "Herald of Free Enterprise" experience as you drive along!
Alternatively go for a full air suspension package :

https://airride.co.uk/air/product-ca...kits-for-cars/

While you're at it, add some extra soundproofing just to make life more pleasant and if you really plan on keeping it 60 years, consider an LPG conversion, especially if you go for the 1UZ conversion. For a start, it's considered an "Alternative Fuel" so no ULEZ charge in London, or wherever else they levy it, secondly it's a lot cheaper and thirdly, i doubt petrol will be available in 60 years from now but hopefully LPG still will be.
Also some serious rustproofing measures, on the whole they're pretty good but i'm sure you've already identified the main areas they rust so should be simple to rustproof it now, rather than having it repaired and then rustproofing later.

Keep us posted with your project, however it unfolds!

[mjk164]

Fuel gauge; my experience on my 1993 960 380k miles, the fault lies with the in tank level switch. If the 760 gauge is the same, then after a long time period, the float operated slider contacts gets badly worn and gives intermittent readouts. The fix is to take it out and make up a new sliding contact; the other contact is a flat rod (about 7" long) that the float travels along and that's generally OK. When you have the unit in your hand, its easy to see the problem. I repaired mine about 5 years ago and its been fine ever since.
On Nivomats, I don't necessarily agree with Dave; I renewed mine about 150000 miles ago and they are still good and the rear end sits at the right height. Secret is don't buy cheap replacements or copies. The real Nivomats are not cheap.
Good luck.

[aardvarkash10]

60 years you say?

Pull the dinosaur-sauce powered lump and replace it with an electron-driven device. In 10 years hydrocarbon fueled private transport is going to be history, so you won't be able to get petrol easily anyway.

[Laird Scooby]

Originally Posted by mjk164

Fuel gauge; my experience on my 1993 960 380k miles, the fault lies with the in tank level switch. If the 760 gauge is the same, then after a long time period, the float operated slider contacts gets badly worn and gives intermittent readouts. The fix is to take it out and make up a new sliding contact; the other contact is a flat rod (about 7" long) that the float travels along and that's generally OK. When you have the unit in your hand, its easy to see the problem. I repaired mine about 5 years ago and its been fine ever since.
On Nivomats, I don't necessarily agree with Dave; I renewed mine about 150000 miles ago and they are still good and the rear end sits at the right height. Secret is don't buy cheap replacements or copies. The real Nivomats are not cheap.
Good luck.

The 760 gauge and tank unit is exactly the same (except on saloon models with the long range tank and a sender unit in each tank) but i can definitely confirm it is the gauge at fault in most cases. This sorted it in my last 740 :




Bench testing the build ^^^^^


Real world testing ^^^^^



I'm not saying the sender unit isn't a potential problem but i can be driving along now with my fuel gauge playing possum and turn the heater to the vents at full speed/hottest setting. Within 5-10 minutes, the gauge wakes up and shows how much fuel i have (or haven't) in the tank. For the record, i have tested the sender unit for the problmes you suggest and no fault found.

As for Nivos, if you read Boges own description of them, you will find that once loaded, they will pump the height up to within 30mm of normal ride height within the first mile or so of a journey. That means that the back end is still low. Therefore they are not self-leveling and will raise the headlamp aim enough to dazzle oncoming traffic.
With no load, the ride height is normal obviously.

Thankfully Nivos are NLA, i've had several vehicles with them on (not just Volvos) and one in particular had the pair renewed shortly before i bought it (felt guilty as i gave less for the car than the Nivos cost the previous owner!) and although that rode the best out of all the Nivo-equipped cars i've had, it still wasn't as good as "normal" suspension.

Ash- anti-gravity engines and warp drives are the way forward! Potentially up as well!

[aardvarkash10]

Originally Posted by Laird Scooby

Ash- anti-gravity engines and warp drives are the way forward! Potentially up as well!

Flux capacitors will be a valuable commodity, and we will all be speaking in cod-scottish accents "I d'nae think the engines will handle it Jim!!"

[360beast]

Shameless plug here...

I will have an AW71 with hydraulic lockup and propshaft available when I do my manual conversion if you wanted to do away with the ZF gearbox.

[Rversteeg]

I hesitate to call these "design faults". Any car is typically designed to last say 15 years and maybe 200K miles. Anything outlasting these parameters is basically overdone and if more expensive, a waste of cost and profit from the manufacturers point of view.
Having said this, I own one of the last 940's and appereantly Volvo improved some of the design flaws you mention, as in 21 years I have only experienced of this list a broken the lumbar support (easily fixed with a few tiewraps), a leaking heater matrix (replaced after 16 years of service) and worn rear Nivomats (normal wear part after 120 K miles). Quite normal after 400K miles I would say, but it might seem different if there are only a few miles on the odometer...

The fuel gauge does not seem to be an issue on later models, just as the piston slap was dealt with on later engine versions. The Nivomats suffer when the main suspension is getting less stiff over time, as they will have a harder job trying to keep the ride up to the nominal level.

There are a only handful of components that are prone to premature failure (within the normal design life), such as the fuel pump relay and in tank fuel pump. I am running mine on LPG (Vialle LPi) and the majority of the problems I have had over the last 18 years were LPG-system related. Vialle obviously did a better job of building their systems within the usual vehicle design life...

About the ZF-gearbox: I have heard people before claiming that the oil pump is located on the outgoing shaft and therefore not running when stationary, but is this really the case? If oil is not pumped around, how can the converter transfer any power and how will the hydraulically actuated clutches engage first gear when you want to set off?
There seems to be design flaw in the gearbox. When coming from D, and P or N is selected, the oil pressure to the first clutch pack is not bled off easily enough. As long as there is residual oil pressure, this clutch pack will remain partially engaged, resulting in heating / burning of the friction material while idling in P or N. When revving in P or N the gearbox will heat up even quicker. I guess when the gearbox was new, this bleeding would have been quick enough, but that it will get slower over time due to contamination.
This is also the reason behind a service bulletin to wait for at least 90 seconds before doing an emission test with the engine running at 3000 rpm.
Could this be the background of the dubious ZF reputation and the "oil pump is not engaged when idle" story?

[Laird Scooby]

Originally Posted by aardvarkash10

Flux capacitors will be a valuable commodity, and we will all be speaking in cod-scottish accents "I d'nae think the engines will handle it Jim!!"

Nah there's no future in flux capacitors IMHO Ash.

Perhaps ionic propulsion instead of warp-drives combined with anti-gravity would work well.

However, it is likely to be decades before that technology filters down to us mere mortals so in the meantime, i'd suggest LPG or possibly find a wrecked Tesla and transfer the electric drive system. A bit like this :

https://youtu.be/cJo79s-f_Fo

Just for fun as i like the wheelspin in the first bit of the vid, here's a 1st gen Honda Accord with Tesla propulsion :

https://youtu.be/0KSt_Y4gZgM

Alternatively, if you live near a beef/dairy farm, collect all the cowshed confetti and store it, capturing the methane released as it decomposes. Compress that and fill the LPG tank with it. Just be careful not to let it run rich or it will torch the head and/or pistons.

[bob12]

Recently I bought some black 'Sugru Mouldable Glue' to see if that will fill the small cracks in the top of the dash. I'll leave a comment when I have tried it.

I believe that the 760's had Yazaki clusters rather than the norm of VDO fitted to many 740's. Each had their unique age related problems.

As far as I was aware you can still buy Sach Nivos direct from Volvo. There are four versions which come as a pair to suit 700/900 Series. They also come with new bump stops and springs.

Bob