Pre heat in BJ74

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M

Mick

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Oct 28, 2004
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My pre heat light in my BJ74 has not come since I got the vehicle. Someone mentioned that it usually stays on for about fifteen secs, so I have been waiting 15 secs and the engine starts just fine when it's not below -5. I have installed a plug in circulating heater which is a necessity for any vehicle here in Sask at this time of year when I use this it starts fine at any temperature. Today I installed a new bulb, hoping to see it light up when I turned on the ignition, but it did not. I started the engine immediately without any attempt to pre warm ( plug in was used as it was -28 last night ) and it fired up straight away.

My question is, would my engine start up at -5 if the pre heat system was not working ?

Thanks

Mick
 
Mick:

My BJ74's pre-heat also doesn't come on very often. It did a couple of times when I was in Kelowna and it hit -15 C, but it hasn't since. The problem is that between 0 and about 4 C, my truck doesn't start too smoothly, acting like she needs a little bit of pre-heat. So, I've added a manual over-ride to trip my pre-heat whenever I want, as initially described here by Mike (Stickboy) in this thread: https://forum.ih8mud.com/showthread.php?t=24480. Works great, and easy to do! Now I can add a little bit of pre-heat (about 5 seconds) when it's 0 to 4 C outside and she starts smoothly and with minimal smoke. :beer:
 
Thanks Stone , I now know what I need to do. It's good to know that the problems I have had are nothing out of the ordinary. BTW What exactly is a "momentary NC switch " ?
 
Mick: That's a Normally Closed switch where the contact is momentarily interupted when you push on the switch. You're essentially fooling the glow relay into thinking that it's very cold out. Use a good heavy-duty NC switch.

The way it's hooked up, you push and hold on the switch before you turn the key to "on". Once the key turns to "on", you should see your pre-heat light light up. Push and hold onto the switch as long as you need the glow screen on...for a maximum of 14-15 seconds. When you let go of the switch it will close the circuit and the pre-heat system should shut off. you can then turn the key to "ign" and proceed as usual. Cheers.
 
Morning Stoney,
i modified your (and Stickboy's) design slightly. i used a toggle instead of a push button and it works great. up, full glow cycle, down normal glow cycle..
my customers have loved the results.
thanks for the idea guys.
 
I have found with my HJ61 that I need to cycle the key to fool the truck into turning on the glow screen. This morning it was -10, I turn the key to "on" and I get no glow light. I cycle the key back and then on again and the glow light lights up.

It has worked well so far...

Even if the glow light doesn't come on, something is going on, as my voltage is in the toilet for the first 15 sec or so when it is cold outside...Not sure if the glow screens have a dual stage operation or not.


I have found that my truck smokes a little black on start up (every time hot or cold) but it only lasts a couple seconds and I would think it is due to the overinjection for starting. My 3B and 2H don't smoke at all when warmed up.
 
Radd Cruisers said:
Is a momentory switch or push button style switch more desirable as you could forget to turn the toggle off?

Could you burn out the glow screen if left on for to long?
Click to expand...

no chance of burning anything out. what the toggle does is set the system at the cooldest setting and even if you do not shut the switch off the system still shuts down accordingly. that is the nice thing with this setup no chance of damage...
 
wayne,
the only issue i'd see is if someone leaving the full glow cycle (circuit open) on would after awhile cause a large drain on the batteries. If someone is well educated when to use the full glow and when not to that'd be ok. Particularly if you do a lot of city, off and on, driving would i be concerned. My alternator takes about 2-3 min to recover from the momentary glow cycle i use around freezing. education is the biggest factor i see, 14 sec of glow (full cycle) regularly could have a large impact on the health of your batteries over time. I see a draw of about 50-53 amps at 24vdc with my system. It takes that puny 25a alternator a bit to catch up....

a little off topic but with my swap (13bt into a Fj60) the biggest issue so far is electrical. Nothing is wrong it's just that you should be congnisant of your useage. Surprisingly the wipers are one of the biggest impacts on voltage in the system. If you have a cold night and start the truck, turn the high beams on, wipers going, and the front/rear heaters on, you'll be in the negative amperage category.
bigger alternator would be good here....

my .02
mike
 
Stickboy said:
the only issue i'd see is if someone leaving the full glow cycle (circuit open) on would after awhile cause a large drain on the batteries. If someone is well educated when to use the full glow and when not to that'd be ok. Particularly if you do a lot of city, off and on, driving would i be concerned.

my .02
mike
Click to expand...

That's what I was thinking too, Wayne. I personally still like Mike's NC switch for that reason...everything is "stock" if you leave the switch alone.

I did the exact same mod for Greg's 74, and he is able to still kick in the glow for a few seconds AFTER the engine is running! I was wondering if maybe he has a lazy relay or something? Anyone care to guess why his can do this? Thanks.
 
i wired the system with the toggle instead of a push (we could not find a push that broke the conection, all the ones we found slosed the loop). that is a good idea, i will get some instruction stickers made up. i tried firing the glow after the truck was running and the glow did not turn on. once it is running the glow does not come back on. i don't know what is up with Greg's setup. wired there should be no way of firing the system by pushing the button/flipping the switch.

cheers
 
crushers said:
i wired the system with the toggle instead of a push (we could not find a push that broke the conection, all the ones we found slosed the loop).
cheers
Click to expand...

Here you go, Wayne...from Home Depot. Fairly good quality, not very expensive ($5.98/ea). Normally closed, momentary interupt. Brand: Gardner Bender (GB). Model Number: GSW-23. Barcode: 032076890230.
NC_switch.jpg


The one that I have used on my truck and on Greg's is a lot more heavy duty, but probably overkill for this application. I purchased it from Lordco, and I believe my final price was something like $23/ea or more. It looks more like a marine grade switch...unfortunately, I've thrown out the box and receipts, so I don't have the brand and model number off hand. I can find out for you if you like. This is what it looks like:

manual_glow.jpg
 
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I could not find myself a NC switch either so I bought a toggle switch, it does not matter which I have in my case as I can not get the pre-heat light bulb to light up no matter what. I tried removing the green plug at the water temperature sensor but nothing happens. I reconnected the plug and cut the wire ( I think it's the right one, the black one with a thin yellow stripe) but no sign of life.

Any ideas ?
 
thanks Stick and Stoney. i looked higha nd low but never thought of Home Depot...
 
Mick: Do you have an FSM?

The temp sensor is the one with the large green square plug that has clips in order for you to remove it...so it sounds like you have the right wire...but I wouldn't have cut it there. The other single wire with the white slide on connector should be your temp sending unit for your dash temp gauge.

I would check to make sure that the glow relays and timer are receiving power. If they are, maybe it's a bad timer? Are you local? Maybe G&S Cruiserparts have some kicking around.
 
I have a service manual, it is not as detailed as I would like, it's a Max Ellery's one. I did not cut the wire by the green plug, I cut the one under the dash that conects to the pre heat screen bulb. Electrical problems are really not my thing.

I live in Sask.
 
Stone said:
Oh...um, if I recall correctly the proper wire on the glow timer harness was Yellow.
Click to expand...


Mine ain't :) I cut the wire as in the diagram posted by Mike.

I assume the "glow screen" that I have seen mentioned here, is in fact the pre-heat ( it has pre heat written on it ) plastic thing under the other plastic thing that has " filter " written on it on the right hand side of the steering wheel. ( the big round turney thing that I hold on to when I am driving) :confused:
 
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