Bypassing the heater core........ need some help

[Boarderx192]

Car: 92 325is
Relevant Mods: FDM

I got stuck in rush hour traffic of friday on my way home from work. I was on the phone with my boss when I heard a loud pop behind the dash which was instantly followed by scorching hot steam coming out of every vent in the cabin resulting in 2nd degree burns to the top of my right foot and left ankle.

I shut the car off, coasted to the shoulder and got out to look. Coolant was pouring underneith, right above the trans. Popped the hood but everything was dry up front and on the firewall. Crawled under the car to take a look and it looks like its coming out of the cabin

Symptoms:
Steam out the vents
Soaked carpet
Coolant leaking above trans
Dry firewall

Conclusion:
Something exploded in the heater core

Ive been doing a lot of searching on here today to figure out how to bypass the heater core, but I need a little more clarificaition.

My understanding is this:

1. Block off coolant passage on rear of the head using DIY block off plate or one purchased from BW
2. Splice the forward section of the spider hose into the return hose of the expansion tank thus eliminationg the spider hose completely and routing the coolant back into the system to go through the radiator. I also saw someone suggest using a single hose from the front motor coolant passage directly to the expansion tank but I didnt see anything else about others who have done this.

Are these the correct steps? What elses needs to be blocked off or re-routed? Anyone have good pictures showing the hose routing before and after?

[Boarderx192]

I ended up getting 2 plugs at Lowes from the plumbing section. Bought 2 brass and 2 PVC but the brass ended up being a little to small; no resistance when put it in the end of the hose, so PVC it it is. I only removed the elbow off the throttle body along with the MAF. That gave me enough room to snake my hand under the manifold and reach the hoses. I used a long flat head screw driver and was able to loosen the clamps on the firewall and the control valves from the topside and grabbed the hoses with my other hand to pull them off under the manifold. Both lines were plugged in ~30 mins.

[Avec]

Did you confirm it was the heater core or was it the plastic manifold between the three hoses (two from heater valve and one return)?

[Boarderx192]

Fix was short lived. Drove to work at 6pm last night and got home around 4am. Went back out to the car around 6am and then went to bed. Was woken up at 8:30 by 2 officers and a fire marshal asking if I drove a black BMW. This is what I walked out the door and found:

http://img.tapatalk.com/d/12/10/04/teqa8uzy.jpg
http://img.tapatalk.com/d/12/10/04/ehare7ut.jpg
http://img.tapatalk.com/d/12/10/04/muby2ava.jpg
http://img.tapatalk.com/d/12/10/04/a2edumym.jpg

[Avec]

WTF dude! Any idea what the cause was? Did something get on the exhaust and ignite? That dies not look like a problem caused by your heater bypass. That blows. Sorry to see that

[BJS]

I'd hazard the guess that he still had moisture in some or a few of the plethora of electrical junctions under the hood that shorted out and started a fire under the dash. There's quite a few always hot circuits in there and up under the carpet with plenty of junctions.

[TWong1200]

Yikes!!! I'm curious, too, as to what caused this? Sounds like a separate issue to me. But who knows.

[1Sik150]

Thats a sad sad day! Sorry to see that. Any more photos? Interior? Atleast it was parked in a garage like mine is.

[Boarderx192]

The thought is the steam from when the core blew melted insulation on some wires and caused it to short. When it started to short, it kicked the starter over a few times lurching the car backwards and knocking it into a brick pillar (visable behind the car in one pick). Pillar fell over and lifted the rear of the car off the ground. The fire marshal said he had never seen anything like that (starting by itself) and once I told him about the heater core blowing up last week, he said that the steam prob burnt some insulation off the wires and caused the short to start. Once it started smoldering, it just went from there.

Car went to the scrap yard today..……got $200 for her :( should have parted it out but don't have the time or facilities to do so.

[Avec]

You got $200 as in two- one hundred dollar bills? That is an absolute rip off

[mike318]

Really bad luck, hope you can find a decient replacement.
Are there hoses on the cabin side of the heating system that
the we need to be concerned with? Mine is as old as yours.

[1Sik150]

I would have gave you 250 for it!