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Foretravel Motorhome Forums => Foretravel Discussions => Topic started by: AC7880 on February 06, 2021, 09:46:36 pm

Title: Block Heater failed on ISM 450 - Question in bold below
Post by: AC7880 on February 06, 2021, 09:46:36 pm
We plan to move on Monday morning, departing from  I5 coridor Oregon state.  Checking all systems in advance, I turned on the block heater for a test  (with switch at end of bed, red light came on)  and checked amp pull on my Progressive display.  It was pulling around 10 or 11 amps when on.

It was on about 5 minutes when smoke and burnt smell came from engine compartment.  Went inside to turn off block heater as the only likely culprit.  Red light on switch was off, and breaker had popped (as it should with such a issue).

Turned switch off and unplugged cord under the bed.  The cord looks fine where plugged in and as far down as I can see.  Felt where cord goes into box/block, does not feel like burned insulation.  I had expected to see the cord or outlet melted given the burnt smell and smoke.

So the smoke and burnt smell must have been under where the block heater mounts (since cord and outlet look ok).

****  Question: could the burnt element contaminate the coolant, circulate in the coolant, and possibly harm the engine water pump?*****

We had several times in the past where the switch under the bed was turned on by a foot or the vacuum, so it was working in the past. Probably a year plus since I used the block heater.  I had put duct tape over ithe under bed switch  to prevent that from happening again (I know I could have just unplugged it under the bed as well).

We are in no hurry to replace the block heater.  We will use the aquahot to pre heat the engine night before departure (high 30s atnight here right now).

I did a search on block heater, saw the part and part number.  Bigger wrench than I carry. 

**** Just want to verify no damaged element pieces could circulate in the coolant and cause issues.

Part Number Collection (https://www.foreforums.com/index.php?topic=11472.msg194896#msg194896) 

3309188 - Fleetguard Service Part | Free Shipping (https://www.simplyfilter.com/Fleetguard-Service-Part-3309188-p/3309188.htm) 







Title: Re: Block Heater failed on ISM 450 - Question in bold below
Post by: oldguy on February 06, 2021, 10:15:02 pm
Shouldn't be a problem as the element inside the tube is what goes. I've changed one one in an 8.3 Cummins and drove a lot of
miles after it burnt out before I changed it.
Title: Re: Block Heater failed on ISM 450 - Question in bold below
Post by: ifixboats on February 06, 2021, 11:27:58 pm
You should be able to heat your engine with the AquaHot. At least that is what was explained to me. Turn on the engine and electric or diesel on the AquaHot panel to do so. I have a chassis battery charger/maintainer connected to my block heater switch and don't use the block heater.
Title: Re: Block Heater failed on ISM 450 - Question in bold below
Post by: Roger & Susan in Home2 on February 07, 2021, 09:29:18 am
Dan, use the AH.  Electric side probably won't keep up with the demand.  A couple hours with the AH on diesel will be enough unless it is really cold. 

Our coach, delivered in CA in 2001 never had a block heater installed. It was wired for one.
Title: Re: Block Heater failed on ISM 450 - Question in bold below
Post by: JohnFitz on February 07, 2021, 12:12:20 pm
Agree with others that it shouldn't harm the coolant at all.

But something smoked somewhere.  I suggest looking at the outlet that the heater plugs into; I had to change out mine due to age and weather. Polarity problem at home - Page 2 (http://www.foreforums.com/index.php?topic=41366.msg413046#msg413046)

I would also check the resistance across the plug.  For a 1500 watt heater should be around 10 ohms.
You could also check that there isn't any conduction to ground at each power leg of the plug.
Title: Re: Block Heater failed on ISM 450 - Question in bold below
Post by: JohnFitz on February 07, 2021, 12:37:12 pm
Oh, these covers over the switch will keep it from getting kicked on accidently:
Light Switch Guard Cover Plates Set of 4 - - Amazon.com (http://www.amazon.com/Light-Switch-Guard-Cover-Plates/dp/B078PPG44X/ref=asc_df_B078PPG44X/?tag=hyprod-20&linkCode=df0&hvadid=242041198988&hvpos=&hvnetw=g&hvrand=569341887877141916&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1016191&hvtargid=pla-403109062688&psc=1)