240 chassis rail repairs
 

As they get to be a few decades old, 240s often suffer with rust in the rear chassis rails.

I have recently repaired a car for Georgina, a customer of mine. I thought it might be useful to others to see the process. It's a significant piece of work, but well worth doing on an otherwise good car. An investment here will give many more years of service.

Estates tend to suffer worse here than saloons. My theory is that the estate shell flexes more, due to the absence of a rear bulkhead, which over time can crack the underseal and allow water to creep into the seams.

Often, the biggest tell-tale signs are inside the car, under and behind the rear seat. Even if there are no holes, any bulging or rust stains here are a sign of something structural underneath that needs to be addressed.

Lower down, the damage may be hidden under the sound deadening pad, so check it carefully for any bulges.

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The first stage is to cut out the rust. This shows the work in progress, and illustrates that the strength of the shell here is vital due to the shock absorber and spring mountings. Just patching inside the boot would definitely not fix this properly.
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Inside the wheelarch, it took very little pressure to make the rusty chassis rail crumble away.
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At the base of the inner wheelarch, the strengthener needs to be temporarily removed to give access for repairs. I left the rear seat mounting in place to ensure it stays accurately positioned.
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This is how the area looked with all rust cut out
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The repair process starts with making accurate templates of the repair sections in cardboard. I overlap the sections, particularly at high-load points, to give the necessary strength.
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Making the repair pieces
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The L-section piece, bottom right, is to replace the vertical seam inside the wheelarch. This original spot-welded seam is to facilitate easy manufacture of the bodyshell, but it's a rust-trap in several ways, so I delete and replace it during repair (unless the customer values an original-looking inner wheelarch over strength and rust prevention).
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All parts are protected with high zinc weld-thru primer before fitting
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Repair sections being welded in place
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After welding, I prime the area and apply a thick layer of flexible seam sealer around all the joints to stop water getting in
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The wheelarch is painted, then protected with Dinitrol underbody wax
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Inside the car, after welding in the new floor section, I sealed the interior seams and repainted the areas. The final stage (not pictured) was to inject rust-proofing wax inside all the box sections
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Job done. Stronger than when it was new, with 10mm thickness of metal seam welded around the shock absorber mount. Should last a few more decades now before more attention is needed here!

John

How many hours' labour went into the repair? It's just that I might need something similar done in the near-ish future.

It really depends how extensive the rust is, but as a ball-park figure, 15 hours per side. I charge £25 per hour

John

Another excellent post - this is turning into a mini-series! :)

My 1989 240 probably needs the same treatment on the rear. My outrigger was like as shown but a bodge/ pass MOT repair done for £100 but more rotten, like last 4 inches of the outrigger.
It was 3 years ago when I last removed the seats and fixed boot section and no rust showing. Certainly now though when I did the rear brakes last year the chassis was rusty like the pic and at the bottom of the wheel liner.

It's definitely rust that will kill them off, eventually.

If I win the lottery I would give it a full overhaul inc rust repairs and full respray, add aircon and ABS.

James:thumbs_up:

You're probably right, but it's a shame. Rust doesn't have to kill them off unless it's widespread or has been allowed to progress too far.

Values of 240s are rising steadily and if (like me) you see your 240 as a life-time keeper, an investment in properly dealing with the rust feels like good value if it gives the bodyshell a couple of decades life before attention is next needed.

Back when they weren't worth much, a lot of people scrapped 50s/60s/70s VW campers on the basis of a few hundred pounds-worth of fixable rust. Now, I bet those people wish they had fixed and kept them!

John

I agree with you but I haven't got any spare money as saving like mad.
I certainly think my workhorse with 231,000 on the clock I would be lucky to sell for 1k. I plan to keep it until something terminal happens and plan in the spring to get the grinding disk out and clean un the chassis legs and see how bad they are.
If I can only get another 2 years it's been cheap motoring for 7 years at a purchase cost of £350.00. It would seem only truly immaculate one owner low mileage 240's are sought after?

I currently have a 1996 940 turbo SE estate on SORN and plan to give the 240 a semi retirement and an easier life. I'm self employed carrying out property maintenance and a plumber by trade and the 240 has been a good workhorse.
I fancy the 940 automatic as very smooth compared to the 240, ABS brakes and would like to get the AC working.
You never know the 240 has less to go wrong than my 940 eg 940 has cat, air mass meter, turbo, oxygen sensor, so more complex than the 240.

I have got attached to my 240 automatic and would be sad when he goes. He has so far been extremely reliable but I need to sort out a possible leaking heater matrix, (Looking at this weekend) and a new heater fan as died 3 years ago.

James:thumbs_up:

By sheer coincidence, a mate of mine was just telling me about a mate of his who has an elderly Merc (a W123 by the sound of it, though not sure) that's in good mechanical nick but rusting in sundry places. I think my mate is envisioning this vehicle ending up as a project for me - which is a bit forward since there's nothing to suggest that his mate has any plans to get rid. But it has got me thinking about welding projects... although my 740 is currently front of the queue!

Sadly, no hope for the next year or so due to lack of facilities plus injury. One day, though, one day... :)

Gosh that's an awful warning of what could be lurking. It looks so superficial from the outside.

It's certainly a key point to keep well doused in waxoyl etc inside the rail.

Another point to watch is at the front, hidden by the brake pipe octopus and the engine shield, also by the rear jacking points.

Exactly how I feel about my first Cortina, a yellow MkIII. Rare as hens teeth now. Ah, the folly of youth.