Squeaking from dashboard C70

[scot850]

Be careful jamming stuff between the dash top and the windshield in the middle. Where the sensor sits on top is not that strong and will crack. Nearly all the ones I have repaired have been cracked in that area. Try away from the center area where it is stronger.

What Chuck is suggesting is to gently 'nip-up' the bolts. So light hand pressure to take any slack out. If they are broken then they are broken.
There is no easy way out of this. And yes, the bolts can loosen a little over 25 years.

Neil.

[CoupeC70]

I'll give it a try. But from what I've read, it seems that it hardly worked for anyone...

Neil
It is already broken
A few weeks ago when I changed the heater core, the crack got bigger. Completely through from front to back. No idea if the crack can also move deeper down

[scot850]

The crack can get bigger, but the front section (maybe 6-8cm) is the weakest. It is just a thin plastic lip.

Tightening the bolts is a last hope before you realize you are screwed and the dash has to come out for repair. Just be happy it is a V/S/C 70 and not an 850! Center console is easy on those, 850 is a pain.

Neil.

[CoupeC70]

@scot850

Then it would be better if I stuff foam under the lip.
I have attached a photo and marked it. Can it break there too?

I'm screwed if this has to be done, I don't have the space or the skills for such a big job
And I don't have a mechanic who would do it either...

[scot850]

I would not expect it to break that far down. While anything is possible, I have not seen one as bad as the one in your picture. Even the one on my buddies 850 which was really bad (2 mounts cracked and 2 completely broken off and broken A pillar mounts) was not that bad. That damage was more likely caused by poor removal breaking a cracked piece off.

You could try something thing thin like butyl tape. I'd would not put them within 10cm of your red marked area.

Neil.

[Sveedy]

You really don't need a lot of skill or space to fix your dash. It's one of those things that seems more daunting than it actually is. Lots of
write-ups and videos. Take out a few screws and the glove box is out. Take out a few more, and the dash pad is out. At that point you could better assess what the problem is. If at that point you had to go further and remove the rest, you'd feel pretty confidant about doing it. Saturday, Sunday job at the worst.
All that said, I have had more than a few cars that went years and years with match book covers, folded business cards etc, stuck in strategic positions in order to stop squeaks.

[CoupeC70]

Oh, so much time has passed again. I had more or less “success” with a long, thick piece of rubber between the windshield and the dashboard. I’ve taken it out again because I really didn’t like how it looked. Now in winter the dashboard only starts to squeak once the heater gets warm.

The dashboard still seems quite stable; on the left and right sides there’s maybe a little bit of play when you move it by hand.
I went to my Volvo mechanic to talk about this problem, and he said he has never had such an issue before.
He’s also never repaired anything like that. He just said: removing the dashboard and see if something can be padded/taped/repaired. I did make the appointment for next year but I don’t have high hopes when someone has no experience with this kind of thing. And he is also always very busy with his car repair shop.

That’s why I started experimenting again with a simpler solution. I had already tried spraying Osixo Anti-Squeak Aerosol behind the windshield to hopefully reach any cracked areas, but unfortunately without success. Then I looked again at pictures of the brackets and saw that they’re connected to the air duct. Unfortunately, I didn’t have any Osixo left, and I foolishly (more on that in a moment) sprayed a nearly empty can of ceramic powder spray through the side of the round air vent and also through the vents at the top center of the dashboard. And what can I say — the noise stopped immediately. I drove several laps with the car and there was absolutely zero squeaking.

Unfortunately, it didn’t last long and the next day it started again. I made the mistake of using the wrong spray. It’s also suitable for eliminating noises but not really ideal for plastic-on-plastic friction. I’ve now ordered another 100 ml of Osixo — it’s damn expensive, and the product was specially developed to permanently eliminate noises. So I’m going to try it again and spray it thoroughly using a spray probe. Then I’ll monitor it until the appointment at the workshop.

If it doesn’t help, I’ll keep the appointment. If it does help, I’ll cancel/postpone the appointment for now to see how long it lasts and whether it continues to work in spring/summer (on hot days).

[Chuck W]

It's squeaking because one or more of the mounts at the front are broken. Spraying all of that stuff is only going irritate the mechanic when he tries to pull things apart.
The fact your "Volvo" mechanic says he hasn't heard about the P80 dash mount problem is suspect to me, personally. Sounds like someone I'd not want to tear the inside of my car apart.

Before you spray anything else behind the dash, pull the wipers and cowl cover in the engine bay and put a wrench on the 4 bolts that hold the dash to the firewall. Seriously. Pick up a wrench and do it.
You will know for sure then if any of the 4 mounts are broken (If they will not tighten at all) or you'll snug things up enough to quiet things down.

[CoupeC70]

He is still quite young, maybe at most 40–45 years old. Maybe that’s why he hasn’t heard anything about it yet? You have to consider many factors: he is young (when did he start working at Volvo?), and when do cracked dashboards start to appear? After 10 years, 15 years, 20 years? My car is now 25 years old…
But yes, of course I would also prefer someone who has already repaired 20, 30. 40 dashboards

You misunderstood me. I sprayed into the ventilation duct now — unfortunately with the wrong spray — but it worked for one day. In other words, I hit the cracked brackets that are attached to the ventilation duct. The cracked areas of the brackets are apparently directly at the ventilation duct in my case, and not on the brackets themselves
After I did that, it immediately stopped squeaking

My assumption is therefore that the (micro?) cracks are directly at the ventilation duct, right where the brackets are.
Also not really good news… but I wish I had come up with the idea to spray into the ventilation duct almost a year ago, instead of spraying between the windshield and the dashboard.
That way I would at least already have a little ‘long-term study,’ haha

[erikv11]

You must check those four mounting nute/bolts under the cowl. If no one has tightened them ever, good chance they are loose.

Although likely *every* P80 has cracked dash mounts by now, you can sometimes buy a little time (peace and quiet) by re-tightening the mounts.