Dang Fire!

kpfoten · 08-14-2003, 07:04 PM

I've had a problem with my right heat-exchanger... I think once the car heats up, a fire starts inside the heat exchanger! I must have oil/grease inside there or something. Anyway, I live in NM (don't need the heat), and I pulled the hoses off the heat exchanger when I pulled the engine and never put them back on upon reinstallation.

I've got the right side of the car on a jackstand with the tire off. I'm going to run the car and investigate further... This is the second time it's happened and I don't know what to do...

(I have a couple 5lb extinguishers handy though...)

makaio · 08-15-2003, 09:28 AM

Ifyou don't need heat, just cut the heat box portion off. This will eliminate the oil burning smell, and get rid of extra weight.

As for having a fire inside of it, I seriously doubt it. It gets hot in there, but not that hot.

kpfoten · 08-15-2003, 09:58 AM

I swear flames were puffing out of the front oriface of the heat exchanger!

I think there is some oil/grease in there. I'll run it tonight to be sure, and maybe take a picture before grabbing the fire extinguisher...

wrx paul · 08-15-2003, 10:24 AM

If you really think a fire is happening, maybe take it off the car. Put it somewhere safe and light it. Once it burns itself out then you can be sure there is nothing left to catch on fire again.

CHILI · CHILI's Garage

Quote:

Originally posted by kpfoten
I swear flames were puffing out of the front oriface of the heat exchanger!

I think there is some oil/grease in there. I'll run it tonight to be sure, and maybe take a picture before grabbing the fire extinguisher...

Don't forget the marshmellows! Common' it's Friday, so I couldn't resist!

kpfoten · 08-15-2003, 01:00 PM

When it's dark out, the front part of the exchanger where the flames come from looks rather Polynesian.. Luau anyone?

kpfoten · 08-15-2003, 06:38 PM

Okay, so I was crazy and ran the thing until the heat exchangers caught fire again! Found out that there were grease-cakes on the metal plate that overlays the entry of the manifold into the right heat exchanger. These were catching fire! Took them off, and no fire!

I'm a bit concerned that there might be grease inside the heat exchanger as well, as I saw flames shooting out the entry sites (hoses off) at one time a few days ago.

Also, is the exhaust manifold supposed to get red hot? Mine glows a bit...

makaio · 08-16-2003, 03:37 PM

Quote:

Originally posted by kpfoten

Also, is the exhaust manifold supposed to get red hot? Mine glows a bit...

I believe the old thermal reactors got pretty darn hot, like red hot.

RoninLB · 08-16-2003, 03:55 PM

generally..
lets say the EGT is 1,000 deg 2in from the head.. then it's about 100deg less for every added inch into the tube.. and fuel injection will run hotter than carbs.. and don't quote this..

and the good news is that I have a new Sigla windshield waiting for the install ..........Ron

Roger 911 · Roger 911's Garage

I guess I was somewhat relieved when I saw this post about the "flaming heat exchanger". I managed to set mine on fire in the exact same manner yesterday.

I had just finished some engine mods (cams and carbs), reinstalled the motor, and fired it up to break in the new cams & rockers. After about 15 min @ 2000 rpm, I noticed flames inside my right heat exchanger. There was a breif period of panic, followed by a thorough dusting with a fire extinguisher. I then realized that I had forgotton to tighten the oil lines inside the fender that attach to the remote filter housing ('72). This proceded to spray oil onto the exchanger, which ran down the pipes and into the enclosed box. I had also disconnected the heater hoses from the exchanger, which made the pipes extremely hot. Oil + Extremely hot pipes = Fire! (I guess I better not apply to Mensa anytime soon.)

I would prefer to simply remove the SSIs and put on headers. Unfortunately, I am afraid of (more) broken exhaust studs and the TREMENDOUS pain of dealing with this, especially with the motor back in the car. Therefore, I think I will try to clean the oil out of the exchanger, and hook the blower hoses back up to the exchangers. I may put some sort of cap on the output end of the exchanger to reduce the airflow a bit. This should still keep the header cooler while not robbing too much cooling air from the motor.

Any other suggestions?

kpfoten · 09-22-2003, 01:24 PM

Why would the heat exchangers get hot without the heater hoses disconnected? Am I reading that right?

Roger 911 · Roger 911's Garage

For clarification, I disconetced the hoses from the fan housing to the heat exchangers. These constantly blow air over the header pipes. With these disconnected, the pipes are encased in the exchanger housing with no airflow whatsoever, not even ambiant airflow. This will make them real hot. I'm not sure it would be a problem by itself, but if anything does leak onto them, there would be an increased chance for ignition.

lateapex911 · 09-22-2003, 02:44 PM

A couple quick thoughts. Cooling the exchangers might provide some cooling to the engine as well. They are under the engine, (heat rises) and they are attached to the heads, (heat transfers fastest mechanically). I see your point about sending more air to the cooling fins, but I think it may be debateable. Remember, the 911 engine is oil/air cooled. make sure the oil half is up to snuff.

Secondly, and this might be a sneaky trick that has a downside I haven't thought of, but what about rinsing the grease/oil in the exchanger with brake cleaner?? I assume there is someplace for the liquid to drain out, and it might just disolve and flush enough of the grease way to prevent future fires.

I had a good friend who had this issue with his '72S. he owned it bewfore his finances allowed him to fix things on a timely basis. Once in awhile, he'd jump out of the car, give the heat exchanger (in flames) a shot from his fire extinguisher, and jump back in. Maintain an even strain!

Three lessons from him: 1- leave enbough $ left over to fix things
2: Always have a fire extinguisher
3: if you break rule #1, carry a bigger fire
extinguisher and a tow strap.

Rob McKibbon · 09-22-2003, 07:06 PM

Don't talk to me about fire.... I'm from the interior of BC
Fire Capital of the World

kpfoten · 09-22-2003, 07:14 PM

Quote:

Originally posted by Roger 911
For clarification, I disconetced the hoses from the fan housing to the heat exchangers. These constantly blow air over the header pipes. With these disconnected, the pipes are encased in the exchanger housing with no airflow whatsoever, not even ambiant airflow. This will make them real hot. I'm not sure it would be a problem by itself, but if anything does leak onto them, there would be an increased chance for ignition.

Would that be the accordian-style hose that runs up to the blower motor? (I'm assuming the '72 and '77 are similar in that respect).

That's pretty interesting. I didn't realize that that that air was constantly going to the exchangers. I'll have to hook all that stuff back up!

lateapex911 · 09-22-2003, 07:28 PM

Yes....and I think the other end of the casing around the exchangers goes to the 'flapper boxes'. Thes are controlled by a cable from in the car. When you close them, I think they vent to the underside of the car, and when they are open, they vent into the rocker boxes and eventually into the interior.

For those of us in the cold climes, it's important to make sure that the fumes in the engine compartment are clean!

RoninLB · 09-22-2003, 08:58 PM

Quote:

Originally posted by Rob McKibbon
.. I'm from the interior of BC

yeah, cool..
What's happening SE of Prince George in a town called Barkerville that sits on Spectacle Lakes, state forests..
in other words if I was in that direction looking for coffee would I find it there? I want big beautiful forests..
I bet a lotta Bald Eagles would head up that way.......Ron

Rob McKibbon · 09-23-2003, 09:37 PM

I've always got a hot cup of cappucino for any Phead in my area, anytime, especially my buddy Ronin LB!

Bald eagles sightings are a regular occurance.
The local natives have a belief that if you see a bald eagle in flight, it will bring you good luck all day. My family spots 'em like they spot Porsche's.

RoninLB · 09-24-2003, 07:04 AM

So Rob.. the Barkerville forest area is a good shot.. and I couldn't find your lake area on the map..

I did go as far north as I could N of Edmonton a while ago. 40 mi on a big logging dirt road, then a small dirt road that a bulldozer cut to a lake. I don't know what it's like now.

And thanks for the hospitality, really..............Ron

Rob McKibbon · 09-24-2003, 07:17 AM

Hi Ron,
Our lake is called "Shuswap Lake" and it's a small "H" shaped lake with over 1,000 miles of shoreline. We're located 4 hours North of Vancouver, 1 hour East of Kamloops or 1 hour North of Kelowna in the interior of BC.
The area we live in is very touristy and resortish; absolutely gorgeous. When you've found the lake, we live in a small town called Sorrento, which is on the Southern tip of the bottom left part of the "H" shaped lake.

The worst fire was the Kelowna fire which took out over 200 homes in one of their estate areas. There were over 600 forest fires in BC this summer with approx. 90 straight days of heat and no rain.

Let me know if you find it on the map?