I played around with fire this week getting the blue wagon back together.

Patient is a 1990 245, 134k miles, spent the first 15 years of it's life in uber salty Boston, MA. Original Volvo brake fittings and hoses... all hopelessly seized except at the junction box and brandy new calipers. I had to replace all of this stuff while replacing the strut tubes. No flare wrench was pulling this stuff apart. I tried everything (penetrating oil, and selectively cutting lines and using 6-pt sockets/wrenches) before bringing the MAPP torch to bear on the problem.

First was unexpected: one end of brake hose unconnected, heat seized fitting on other end red hot (at the treaded portion, NOT the crimp), turned my back and the hose exploded at the crimp. Sounded like a rifle shot.

Second hose (now armed with safety glasses): Snipped the rubber hose flush with the crimp, hard line removed from junction box, heat fitting red hot (torch was only on the fitting for a little over ten seconds), within seconds, BAM! remaining rubber explodes at the crimp. Plus side is that the fitting is now easy to unscrew.

Other trials were similar, when heated red hot, hose explodes, but fitting is easily unscrewed. When not heated red hot, not explosion... but fitting wasn't any easier to unscrew.

I'm only passing this along as a quick safety note. I don't have a vendetta or axe to grind with anyone. These were original Volvo hoses, and in better shape than others that I have seen (except for the seized fittings!). Use of a torch was enough to cause the crimps to literally explode in an open system without any brake fluid to pressurize.

Message is clear: Fittings do need to get red hot for heat to be worth it, but heat damages the crimps in the hose, and explosively for me. Be careful when using heat around brake hoses. Eye protection, etc. If the fittings don't explode during heat application, it's probably foolhardy to reuse the hoses as it's *impossible* to keep the heat at the end of the fitting from conducting to all areas of the crimp itself.

-Ryan

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Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars, GT Braces
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars
Buckeye Volvo Club

Ryan,

Yes to everything you said. The next time, try wrapping a sopping wet rag TIGHTLY around the metal fitting at the top of the flex hose while GENTLY heating the frozen flare fitting. This keeps some of the heat away from the hose-to-metal crimped coupling.

I experienced just what you did, but when I started using a wet rag, the flex hoses stopped exploding (and the brakes kept working). Saved my ears, my eyes, and my wallet.


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Don Foster (near Cape Cod, MA)

If a hose exploded on me, I'd stop doing it and look for alternatives. Definitely wouldn't put on the safety glasses (and ear protection?) and try again. Nor would I wrap the hose in wet cloth and try again.

I'd just resign myself to mangling the fittings and getting/making replacements.

"If a hose exploded on me, I'd stop doing it and look for alternatives."

That's exactly what I did, though I'm a slow learner... so it took two hoses before the message sunk in.

Anyway, I've found that the wet rag trick is used by others......
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Don Foster (near Cape Cod, MA)

Yeah red hot they do explode. I've done that. But you don't need to heat them red hot. Heat them less than red hot and then give them a shot of cold water. I don't know why but they usually crack loose easily after this.

Mmmm... true. I didn't have the fittings blazingly red hot... just til I saw an inkling of red. Then BAM!

A nice cold wrench on the male fitting worked well. :-)

-Ryan
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Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars, GT Braces
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars
Buckeye Volvo Club

Snipped the rubber hose flush with the crimp, hard line removed from junction box, heat fitting red hot (torch was only on the fitting for a little over ten seconds), within seconds, BAM!

Assuming this was the feed end of the flex hose, where do you suppose the seal against pressure relief was forming? I would have used my flame wrench in exactly the same manner. Although I can envision the nylon innards of the hose melting closed, I can't picture how this is happening. I'll certainly heed your warning in the mean time.
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Art Benstein near Baltimore

The early bird gets the worm, but the second mouse gets the cheese.

Hi Art,

Before resorting to heat, I first used flare wrenches and penetrating oil (working against gravity) at the hose to hard line unions. I was careful, working the flare wrenches to and fro, but it was clear I was getting nowhere and things were starting to look rounded.

Plan B was disconnecting the hard lines at the caliper and junction box (these seem to be consistently easy to remove) and snaking an 11mm 6-pt wrench around to the seized fitting. No go. One flare "nut" on a hard line actually broke, with the threaded end stuck in the hose. That hose was a write-off then! :-)

At this point, I was using 6-pt 14mm/11mm box wrenches (or even deep sockets!) and getting nowhere. Enter the MAPP torch. First time I had intact hose and hard line (sans fluid since both ends had been opened above). That was the first explosion. It was the crimp that blew.

The second time, I had both the metal line and hose snipped close to the union. Zero fluid involved, neither end was sealed whatsoever from cutting... just whatever bit of rubber hose that is held by the crimp was left. Heat just until I saw any sign of "red", and the crimp exploded a few seconds later.

All I can think of is that something *intrinsic* to the crimp is smoldering/expanding till it hits that critical point. I didn't get a great look at the remains (I was many hours in at that point, and the sun had long since set!). Maybe I'll fish them out of the trash and give them a better look to see what happened.

-Ryan
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Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars, GT Braces
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars
Buckeye Volvo Club

Thanks for making the scene absolutely clear. It is still puzzling, but brings to mind the rapid bubbling and foaming (before catching fire) from the rubber remains of a control arm bushing I heated to get it knocked loose from the arm. Your detailed post makes it certain it doesn't take much.

This and jjnutall's reminder about how quickly our eyes can be ruined made for a sobering Saturday on the Brickboard. Based on your experience, I suppose I will use the Dremel to slit the crimp before resorting to the torch on those flex line joints. Thanks!
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Art Benstein near Baltimore

With her marriage she got a new name and a dress.

Thanks. Good reminder.

Heat can be your friend...but you have to be careful.