Block Heater Question

[GM0406]

Ok, I don't know how good these pan heaters are, but there is one on my '04 that George Thornhill installed.  There has been no cracking or any indication that it is falling off.  To me a crankcase heater makes more sense than a block heater, simply because you want the heat as low as possible to allow fast rpm when starting cold.  The rest will take care of itself as the heat of compression is substantial.  But I don't have enough experience with this and that is hopefully why we post here and share information.  I understand that some people who have posted here got bent out of shape and withdrew sulking because they were right and the rest here were wrong!  To me that attitude doesn't make sense and the day you decide you can't learn more is the day you are done as far as I'm concerned.  Now I don't know whether pan heaters will cause cracking or be inadequate under certain conditions that others may be very experienced to be able to testify.  I hope I am not going to be driving over stuff that comes close enough to the bottom of the pan to knock the heater off!  It seems that you would have to do a lot of damage before you get to the pan? 

I am impressed with simplicity and if a pan heater installed properly (not quite sure how?  epoxy? )  can work, then to me it is easier and simpler than a block heater.  Perhaps someone who installed one and uses it could instruct us here.  Thanks to those who contributed so far. 

Bill T.

[Lin]

I like the idea of the pan heater simply for ease of installation, but I really prefer not to crack the oil pan.  Mostly, I will be dealing with temps above freezing, but the 20's could be possible.  Since the pan heater is only about 1000 watts, it certainly will not get the pan hotter than it gets from the hot, circulating oil on a running engine, especially in summer. 

JR,
Does the danger of cracking come from the bottom of the pan being hot while bolted to a cold block?  If so, does it mean that the lower the temp, the greater the risk?  Thanks

A little update: I just came across this site, http://www.tejascoach.com/index.html.  It has a bunch of info on maintaining DD's.  Some of you probably are already familiar with it.  Anyway, in one section they mention that magnetic oil pan heaters can cause the pan to crystallize and crack.  My question would be then, is it the magnetic field or the heat that causes the crystallization?

[Paso One]

   And, avoid units that circulate water thru various hoses.  Stick with the correct DD recomended unit.  They are cheap to buy.  May be a PITA to install.  You'll have to drain the coolant.   Have fun!   
HTH, JR

My Webasto also circulates the water thru the heater hoses.  They both work the same principle IMHO    except the circulation heater is $1600.00 cheaper.   If I only  could find an extension cord long enough I could get rid of the Webasto when on the road 

[NJT5047]

Lin, my understanding is that the heat from large pan heaters 'heat cycle' the area to which they are attached. 
Oil pan pads get hot.  Cummins does not recommend magnetic pad pan heaters on their oil pans.
Also read that they've been known to catch fire.  This must be rare and I'm not familiar with any fires related to pan heaters.
The damage most pan heaters suffer is related to ice on winter roads.  Small ice chunks will damage the pad. 
Add this all up, and you still return to a coolant block heater that heats both heads for quicker starts. 
You generally must leave a pan heater on all night to heat the oil.  And the oil will flow well, but what makes the engines start is combustion temp.   There's obviously a relationship between cold oil and cranking speed. 
One thing's for sure...the pan heater would be much easier to install. 
That's all I know about block heaters.  I use a 4 bolt coolant heater in my 6V92.  It will warm the engine from 20* to above 100 degrees in only an hour of use. 
Anyone using a bus in extreme cold probably should consider dropping to 30wt oil.  This would be in Arctic conditions.  DD recommends 40wt under all conditions as long as the engine can be started. 
Most of us don't use our coaches in bitter cold weather.  Not often enough that a pan heater or coolant heater would make a noticeable difference.  Either would be satisfactory. 
Still, if you get the temps below freezing on a worn turbo engine, you may, or may not, get it started without the aid of a block heater.
Non-turbo engines have higher compression ratios and usually start quicker in cold weather...if they're not worn out.
HTH, JR

[84bluebird]

As one who inhabits the Great White North, I would take a block or circulating heater over a pan heater any time. The block or circ heaters only require a couple of hours before eng start is required, pan heaters cannot raise the temp as fast as an element submerged in water, therefore are more efficient. Also there are available diesel preheaters that are used to maintain block temparature when electricity is not available, these run off of diesel from the tank and heat a water source. In a pinch the old tiger torch in a piece of stove pipe works, but not advisable for everyone.

[PP]

Speaking of block heaters, is it normal not to see an increase in the current draw from shore power if I switch the block heater on when it's above about 40 degrees.  In other words, does it have a built-in thermostat that keeps it from coming on when the outdoor temp is not low enough to need it?  I'm trying to figure out whether or not mine is working.
Thanks
Dennis

Dennis, I tore into mine today and discovered that the connections at the plug on the block were fried. There is a hard rubber type plug that goes over 2 prongs sticking out of the heater element (looks like a water heater element) that from use and abuse corroded until they fell off. I fabricated a new plug to push onto the prongs and insulated the whole thing with hi-temp silicone and it works great. It draws so much juice that it tripped a breaker at the end of a 50' 16ga extension cord. When I plug it into the engine compartment outlet it works fine, even with heat on in the coach (50Amp hookup) and no, I found nothing to indicate a thermostat-it appears to be all or nothing 
I realize this is an old post and with winter on us you probably have already answered all your questions about block heaters, but I am just so tickled that this repair didn't cost me anything but a little time and fun working on my beast-took a break from the sanding since it's so nice out today  Good luck, Will

[wvanative]

Hey guy's, for what it's worth, I read somewhere that the magnet type pan heaters will cook the oil where it's attached. Not sure if this is true as I don't know just how hot these thing can get, but it's sure something I would want to know before I would put one on my expensive engine. It would be sad to know you ruined your engine because you removed all the protection of the oil by burning it.

WVaNative

[busshawg]

For what it's worth my opion
- cool weather, -15C or 5F and warmer block heater only is lots good enough
--15C or 5F to -25C or -13F block heater with oil pan heater is good although the block heater should do it but the with the oil warm it is easier on the engine.
-25C or -13F and colder a webasto is the way to go. Block heater should start it but the webasto provides better heat with easier starts

Have Fun

[NJT5047]

For what it's worth my opion
- cool weather, -15C or 5F and warmer block heater only is lots good enough
--15C or 5F to -25C or -13F block heater with oil pan heater is good although the block heater should do it but the with the oil warm it is easier on the engine.
-25C or -13F and colder a webasto is the way to go. Block heater should start it but the webasto provides better heat with easier starts

Have Fun

Does a Webasto light easily in sub-zero weather?   
JR

[busshawg]

absolutly, that's what their designed for

[buswarrior]

On a lot of the new highway coaches, the cold weather strategy is to plug in the factory equipped BATTERY CHARGER, and set the timer on the diesel-fueled coolant boiler, whether it be Webasto, Espar or Proheat.

A lot easier on the electricity bill, to be sure!

happy coaching!
buswarrior