Muffler Exploded '92 240 Wagon Fire Damage Rear Axle

[UsmcScott]

OK, this is the story. I'm on the highway, the engine is running rough, backfires several times, then a loud bang....engine barely running, I get off the nearest exit, pull into parking lot and there's a fire under my car. I got a fire extinguisher, but it took a few minutes and I got the fire out before the whole car was engulfed. Heat was enough that it lightly melted a foot square spot on the underneath of the rear seat. Apparently, the muffler filled with gas and it exploded....split at the seam.

Took to a shop, they say all the seals and bearings in the rear are damaged, and it's going to cost more than the car is worth to fix it. And that's without determining what caused the fire in the first place. So now the car sits in my backyard. The fuel line burnt in half, but the fuel pump still works. So my first step is to see if I can repair the fuel line and start the car.

I was told it will probably be easier to replace the rear than repair. I'm not sure if a novice backyard mechanic like myself can do this. Your thoughts are appreciated.

Can someone direct me to a good link on repairing or replacing the Volvo rear axle ? Will I need any special tools?

Would I be better off repairing (136k miles on old one) or going to the junkyard and getting a whole axle?

TIA, Scott

Pic of exploded muffler....

[Three Fat Tigers]

Amazing, never hoid of such a thing happening on a Volvo before.

Would be better and much cheaper to replace the axle assembly than to try to repair the present one, somehow I wonder if the diagnosis was correct. You should have no problem replacing the rear axle assembly yourself, easier with some help though. Make sure you source one from a 240 with ABS so your speedo will read correctly.

As for the cause, pull the vacuum hose off the fuel pressure regulator (at the front end of the fuel rail) sniff it and see if you smell any raw fuel which would indicate a failure. Otherwise I'd replace it anyway. Next check the injector connectors, one terminal should show 12V+ whenever the ignition is switched on, the other should not show a ground with the ignition on/off, car not running, if it does, there is a short in the harness or a bad fuel ECU.

Otherwise it might have been some sort of ignition system failure.

If the battery hasn't been disconnected, try checking for any stored ODB1 codes: http://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm

[UsmcScott]

Yeah, just my luck TFT

I got a feeling this project's going to take me a little while. First goal is to see how much damage is done to the fuel line, and try and repair it so I can at least turn the key without pumping fuel allover the ground.

[UsmcScott]

I think the guy said all he had to do was turn the rear wheels from side to side and he could tell the differential was messed up, and he said something about the brakes. The car acutally looks undamaged even tho right before I put the fire out the flames were coming out from underneath and flicking up the sides of the car and reaching a foot or two above the roof ! And all you see is just a tiny bit of smoke residue on one side, and that's if you look twice.

[UsmcScott]

Ok, this is what I'm looking at...4 lines running next to the fuel pump. The one closest to the drivers connects into the rear axle about 10 inches from the differential, it's missing a couple feet.

Another fat seperate line that runs to the same place on the rear axle is damaged and needs replacing, it's a short one?

Fuel line has about 2 feet damaged near the pump.

[Three Fat Tigers]

Yeah there is going to be a bunch of stuff messed up under there. Sounds like the flexible rubber brake line is toast, IIRC there is only one flexible brake line to the rear axle with ABS. There is also probably some sort of vent tube on the top of the axle somewhere. It's been a long time since I was last under one of these where I was paying much attention to stuff back there. Note that some of those component may be exclusive to the '92-'93 year models.

I'd go look at my '92 but it's in deep storage, been there for 12.5 months now, plan to pull it out of moth balls and put it back in service sometime in early August.

[UsmcScott]

OK, I was wondering what that fat line was called.

And when I pulled what was left of the skinny line off the axle, I did hear the sound of a puff of air like a vacuum letting loose.

I really liked this car, I hope I can fix it.

[UsmcScott]

So, how do I get that ABS line to the rear axle off?

Can I repair the fuel line and the vacuum/air line to the axle simply by removing the damaged sectionsand splicing in new sections of hose?

[Three Fat Tigers]

Rear flexible brake line: never had to replace one before but from looking at a new one, I'd say you will need some flare nut type wrenches.

Fuel and vent lines: no idea, I'd have to look at it to make that call, will depend on the materials that the fuel line is made of.

You may need to drop the gas tank to make sure the rubber couplers and seals for the filler tube are not compromised.

If you don't already have one, I highly recommend the Robert Bentley 240 service manual, under 32$ delivered from amazon.com

http://www.amazon.com/gp/product/0837602858/

[UsmcScott]

I did read something about flare nut wrenches in the Haynes manual I have for the 240. I'll have to look into the Bentley book.

Both lines/hoses appear to be a very thin walled plastic or pvc material. The vacuum/air line, I'm missing about 5 feet. The fuel line....there's about 2 feet damged right next to the fuel pump. The damaged is fairly localized. I don't think it even got the sensor wiring on the differential because it looked good at first glance. Nor did it go very far forward.

There is a fat line that runs to my right rear hub that is damaged and became disconnected at the hub. It looks a lot like my emergency brake line to the other hub.

I'll examine the gas tank and filler tube.

[Three Fat Tigers]

One tank to main pump fuel supply line and the system return line, you might get away with some normal fuel line to patch it with, I'm not endorsing this method but have heard of others doing so, it' not like either one is going to be under a lot of pressure. Personally I would only do such a repair until I could correct it back to factory spec.

If the sensor wire to the differential is not damaged, I must seriously question the diagnosis of the damage to the rear axle. It would be much easier to replace the pinion shaft seal and the right rear axle seal if needed. Odds of there being damage inside the differential while there is no damage to the sensor wiring is extremely remote.

It does sound like you will likely need to replace at least the one emergency brake cable.

[UsmcScott]

You wouldn't happen to have an exploded diagram of the rear axle so I can see what we're talking about. I'm unfamiliar with those parts.

I'm willing to go thru a re-diagnostic process with your guidance, ....as long as your patience lasts.

Yeah, I'd like to just do a temporary patch of the fuel line first just so I can move it around in the backyard when I need to. Would clear fish aquarium tubing work? I wonder if I'm going to have any brakes.

[Three Fat Tigers]

You wouldn't happen to have an exploded diagram of the rear axle so I can see what we're talking about. I'm unfamiliar with those parts.

I may have access to one, but it may be a few days before I can produce it on line.

I'm willing to go thru a re-diagnostic process with your guidance, ....as long as your patience lasts.

I'm here for the long haul

Yeah, I'd like to just do a temporary patch of the fuel line first just so I can move it around in the backyard when I need to. Would clear fish aquarium tubing work? I wonder if I'm going to have any brakes.

I hope the aquarium tubing was a joke, you must use hose specifically formulated for use with fuel, aka fuel line. Thanks to the ABS circuit design, your front brakes should still be fully functional.

Also if the fire was really strong enough at one wheel to damage the axle seal, odds are the dust boots for the brake caliper pistons and possibly the piston seals will be likely need replacing.

[UsmcScott]

Good to hear my front brakes will probably work. That flexible brake line, tho not burnt all the way thru in any place, when I squeezed it to check it, a little wet bubble appeared appeared in one spot.

Thanks, I'll definitely check those rubber brake parts.

This project is going to take a while. Fortunately I'm not under any time pressure other than getting it done before the weather turns cold here in Maryland. I don't have a garage to work on my cars, so I won't be working on any during the winter.

I figure I'm going to have to replace that whole pressure relief air/vacuum hose, and probably the whole fuel line too. Any suggestions on the best place to buy those parts.

by the way, I did go to the local Pep Boys auto shop the other day, and they didn't have any hoses that resembled what I needed, plus I don't think any of their prepackaged stuff was over 18 inches.

[Three Fat Tigers]

Well I don't think anyone is going to have the hard plastic fuel line except Volvo, you might give fcpgroton a call, they often have or can get parts they don't list on their web site. As for patching the existing stuff, I'm really not sure what to say without a first person inspection, to start with I'd want to measure the diameter of the plastic line to get an idea what fuel line might be usable.

From researching this I've come up with:

"the supply line to the pump from the sender is 1/2". The return line from the engine to the sender is 3/8"

That should be close enough to work.

The axle vent tube is nothing special, it's just there to keep pressure from building up inside and dirt and water out.

If you are going to buy new, I'd try fcp first, otherwise used can be found, I'm pretty sure there are some decent wrecking yards in your area, there are number of active members at Turbobricks.com forum that would be able to tell you a lot more about whats around there. I'd post a question about local MD junk yards in the off topic forum.