galvanising +rust

[srtames]

hi all , I am considering upgrading to a 940 and wonder how effective is the galvanising at combating rust. All the cars (non galvanised) I have had developed rust under the underseal and wonder if that zinc coating can stop salt attack? I have heard that if there is spot damage ,you get all the corrosion current rushing to that spot.
Thanks, Steve

[dave r]

Hi Steve,
Iv'e got a '92 940 and there isn't a spot of rust anywhere. I keep it polished and wash it with clear water regularly and I havn't seen any corrosion at all, even where old untreated stonechips are.
Dave

[RollingThunder]

All 940s were fully galvanised which is why you don't find any rusty ones around. I had a copy of an advertising picture a while ago which showed the whole body shell coming out of the dip tank. I believe that only Audi and Volvo were producing fully galvanised bodyshells at that time (1990).

The only problem arises when the panel is damaged - as you'll be aware galvanising results in a coating on the panel - which can become cracked or penetrated. Any break in the galvanising layer will allow oxidation of the panel at the breach, which is why you should be very wary of any rust found on a potential purchase - its more than likely due to accident damage.

The problem with older non galvanised vehicles is that the rust proof barrier applied will hold moisture between the barrier and the metal - which arguably is worse than leaving the panel to dry in the air.

Correction! - there is one place that most 900s have (limited) rust - its along the weld on the top of the front chassis rails - you'll see it towards the bulkhead if you look under the bonnet.

[ivor940]

I did a complete cut up dismantle of the body shell of a '92 945T ( so I can keep my '94 945T rust free). The only corrosion was as follows:

Front suspension turret to chassis rail - small amount of corrosion between the thick vertical flange of the chassis rail and the thin metal of inner wing There are 5 spot welds from the turret to the firewall area. This corrosion is due to lack of sealant at the joint to keep corrosive salts out of the joint. If there is corrosion, drill out the 5 welds, clean and treat corrosion. Reprotect and re attach the inner wing to the rail ( either use 3/16" steel blind fasteners or re spot weld. If there is no corrosion, seal joints ( LH and RH ) to prevent corrosion in the area.

The cross member which supports the radiator - corrosion between the ends of the support (where they are attached with 3 spot welds) and the flat panels below battery / washer bottle. There is also a verticle bracket attached to the crossmember on the inboard sides of the chassis rails. The whole support channel can have surface corrosion and it is not expensive from Volvo ( about £20 ). If there is no corrosion, seal all edges of the support where it attaches to the body.

Some surface corrosion hidden between the exhaust heat shields ( aluminium ) and the lower surface of the body shell. ( all heat shields)

Rear passenger door weather seal channel - channel corroded and missing 2" at aft end just aft of RHS window.

ivor940

[neil stevenson]

Well you learn something every day.
I did not know that the complete body shell had been dipped. That explains why they last so well.
Are the latest vehicles volvo produce dipped these days?

What rust? My old '92 945T (bought done 100,000 miles and sold done 150,000) had been used by its previous owner for boat shifting, backing boat trailers into the salty estuary regularly, and it lived on top of a cliff by the sea in Suffolk. The towbar suffered, but not the shell - one or two bolt heads showed corrosion and I did have to replace one of the fuel tank straps. That's all.

When did you ever see a rusty 940?
cheers Simon