Fire Detector replacement for engine bay

[Jeff Bayley]

I power washed the leaking oil preasure gauge in the engine bay a few weeks ago to try and see where it was leaking and afterward an alarm started going off in the cockpit. I posted the issue here and within an hour someone replied with the answer. The fire alarm in the same vicinity (mounted to the roof of the engine bay) had gotten wet and closed the circuit making the alarm go off. I disconnected it, would up taking it out seeing that it was corroded and ordered a new one from Prevost. They don't make the round style (photo below) anymore. They make the tiny replacment (pictured) instead. About $55 I recall. This could be a good prevenative maintainence part to change or at least check especially if your bus is 10 years old like mine. It's simple to change and comes with simple instructions.

I ran across this on Ebay: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=400053542719&ssPageName=STRK:MEWAX:IT

Described as a "Fenwal Series 27000 Detect-A-Fire" Horizontal Units New

If you prefer to keep the original part this MIGHT be it. If absolutley appears to be the same but I can't find a model number on my corroded unit to confirm and the company may make several models. Prevost Parts could not report if that was the correct model. I can tell you that my old one says 500 degress on it which seems to me to be a bit high. I would think it should alarm at no more than 300 degress. Maybe mine was changed at some point by someone with an incorrect thermostat setting. They say you can test it by putting a blow dryer on it and seeing if your alarm goes off.

For the extra $30, it's probabley not worth the time to research it to see if the Ebay one is correct but I might want one for my generator bay since I already have an audiable alarm installed inside the coach from the fire supression system that failed (and is not longer in place), but the alarm and wires for it are there. I'll test it with the new one I'm about to install this morning and report back wha happens and if the blow dryer works. I have a heat gun I'll use instead actually since it's hotter.

Anyway, you might want to do the blow dryer test on your unit or if it looks like mine, just replace it for good mesure. Cheap insurance.

The small one with wires is the replacment that has two holes and self taping screws to put in the firewall.

[Jon Wehrenberg]

The new one is a simple thermodisc with wires attached. $55 is a bit steep for a $3.00 switch, but the plug must cost a lot. NOT

The 500 degree temp is not a bad temperature. The engine exhaust can get over 1000 degrees, the transmission oil at the outlet to the intercooler can hit 300 degrees and pulling a steep hill heat soaks everything to the point that it is conceivable if you pull over at the top of the hill and shut down the heat radiating from everything could set off alarms.

Jeff, your biggest problem is corrosion protection and remediation. That looks like you've been parked on a beach. I hate to think what other electronics look like.

[Jeff Bayley]

Jon- Understood on the 500 degree being correct then. But does the heat gun test work ? Does a heat gun get to 500 degres to set the alarm off for testing purposes? I'll find out here in a bit. I was out there messing with my inverters issue (still).

Jon- Don't I at least get an honorable mention for cautioning people to check their fire device ? I really need you and am glad you are on this site and I thank you for putting up with my idocricy. Regarding the issue of corrosion, what should I use to bathe the electronics like this in ? Silicone spray ? WD-40 ? I use battery corrosion inhibitor on the batteries but how about the Vanner, the alternator(s), the over the road air ? What do you or others do for preventative maintaince to soak this stuff ? Inquiring minds want to know.

I'm folding up and heading to the tech in an hour or so but I did manage to get the AC1 In LED to come on and have power going to the inverter (and out also). All seems normal on the remotes and testing at the inverter leads itself but still.....the same symptoms and equipment don't work (outlets, microwave and even W & Dryer NOT on the inverter). The W & D has me stumped. Could a lightening strike or surge have taken out the microwave and/or the W&D ? W&D weren't on of course.

Also, after further testing, I'm positive the wiring from the batteries is wrong after the battery change. I should have done it myself instead of letting my mechanic buddy do it. If you want a job done right.............. Reason I know is that when I disconnect the jumper going to the 350amp J Class fuse, the inverter remotes don't go off !!! They MUST go off. When the fuses have blown in the past the remotes go off. So the fuses are being bypassed and I've got a headache from looking at all the jumpers and figuring out which terminal block should get what so instead of making it worse by trying to play musical chairs I'm finally going to the tech (taking him some aspirin by the way).

The needle meter separate from the inverter remote was showing a draw from the inverter in questino ! What the %$&^ ?? There's nothing on from that inverter to make a draw unless the charger was working. Maybe the transfer switch inside the inverter ?

[Jon Wehrenberg]

Roger (the King) beat you to the alarm issue. He posted that quite a while back.

Corrosion is insidious. Once it starts it is like a cancer. In aviation there are products designed for corrosion protection. I can't remember their names, but a Google search should turn up several. Do you think your inverter/electrical problems may be the result of issues like you have with the alarm?

If so you really need to get after the corrosion.

[JIM CHALOUPKA]

Corrosion X is one product. Search POG for discussion on the topic and product mentions.
There is no one cure all, constant vigilance and attention to maintain proper conditions is what is necessary, ie. stay off the beach or be willing to pay the consequences.

Corrosion X, and others may stop the corrosion, but their use can cause a build up, as they attract dirt and dust.

JIM

[Jeff Bayley]

Hey Jon- I haven't installed the new style fire detector yet but I remember seeing some OEM information on the unit. I might need a magnifying glass to read it but I'm going to see if I can Google and see if I can get it for way less. I have to return some stuff to Prevost Parts anyway.