circulating block heater on BJ74

[Malahki]

Im about to install a Zerostat circulating block heater into my BJ74 with 13BT and would like some input. As per the heater manufacture's instructions: the inlet side on the tank is to come from the lowest possible point on the engine, such as a frost plug. Or from the lower rad hose heater. Either way the unit needs to be mounted lower then this point. I am opting for the lower rad hose and mounting the unit to the frame.

The outlet or upper connection is what I am not sure about. It say's in the instructions its to be connected to the highest point possible on the pressure side of the cooling system. So if I tee'd into the hose on the back left side of the motor that runs between the engine block and rear mounted cab heater would this be correct? Does the rear cab heater get its pressure from the block or return into the block?

Here's a couple pics to help display the hose I am talking about. Its a little hard to see but in pic #1 the bent hose on the far right of the pic connects into the block....... Pressure side???

On pic #2 and 3 the hard line that runs over top of the manifold from front to back on the motor, connects between the lower rad hose and is the other line running to the rear cab heat, it also tee's into one of the main cab heater lines running through the firewall...... return side correct??

Thanks in advance for any help or opinions offered

 

[Malahki]

Thought I should also add a pic of the circulating block heater I am installing.

 

[ForealBoreal]

I am looking to do one on my 1hz
Pics would be very nice

 

[Mark W]

It is not really all that important that it be the highest point on the highest hose. Just the highest connection on the block itself. Heater hose into the head is the best place to hook up the highside line.

Use the block drain point for the inlet (lowside) connection. Just replace the plug with a 3/8 npt pipe/nipple.

This will yield the ideal convective circulation pattern and keep all of the flow inside the block (except for where it must pass outside to get to the heater of course).

If you can get a freeze plug heater, go that route. Applying the heat internally is much more effective than externally. And it makes for a much cleaner install with less likelihood of future leakage/failure.


Mark...

 

[Malahki]

Thanks Mark W,

A couple things though. I made a mistake on my original post, the hose I was referring to in the first pic actually goes into the head. So I guess this is going to be a good point for the upper connection.

I am wondering about the block drain point you referred to? Is their one on the 13BT? and if so do you know where is it located?

In theory isnt a circulating heater going to be more effective at warming the entire block and coolant then a typical frost plug block heater?

 

[wongtsenhin]

I am looking to do one on my 1hz
Pics would be very nice

JDM should have this

 

[Mark W]

Thanks Mark W,

A couple things though. I made a mistake on my original post, the hose I was referring to in the first pic actually goes into the head. So I guess this is going to be a good point for the upper connection.

I am wondering about the block drain point you referred to? Is their one on the 13BT? and if so do you know where is it located?

In theory isnt a circulating heater going to be more effective at warming the entire block and coolant then a typical frost plug block heater?

The "circulation" is simply convective. The heated fluid pushes upward out of the heater, drawing fuid in from below to replace it. Hot fluid flows to the top of the block and cold fluid drops down and flows to the heater.

When you put a freeze plug heater in you get the same effect.. Heated fluid rises, cooler fluid drops and you get a circulation within the block.

Just like if you put a heating element in a bucket of water... all the water is heated.

When this is all done inside the block, you are not dumping heat into the atmosphere to nearly the extent that you are when it is an external tank heater and hoses moving the coolant from the bottom to top of the block.

I have used both types in different situations... I have used both together in extreme cases. I like the external style heaters for use as intake manifold heaters on 2fs with headers. But prefer freeze plug heaters otherwise.

An external tank heater like this will work of course. I doubt that you will be dissatisfied so long as you get a clean installation (I have used exactly that model unit a couple of times).


Mark...

 

[northernrighty]

I was under the impression that they are actually circulating the coolant with a pump? I was just about to install one! Now I wonder?

 

[Malahki]

I installed My circulating block heater yesterday and I am quite pleased with the results. First I made a bracket out of 1"x2" rectangular tubing and positioned the aluminum bracket from the kit onto it. I then mounted it to the frame using the existing threaded holes that were part of the PTO shaft hangers.

I also had this fitting made up to tie into the lower rad hose.

 

[Malahki]

Because of the close proximity of the heater to the lower rad hose I had to find a 5/8" heater hose with a very specific bend in order to make a clean connection without restricting flow.

The upper connection was a simple tee

 

[Malahki]

I added a small L bracket off of the battery box and secured the upper hose to it with two rubber insulated clamps

 

[Malahki]

This is how it looks mounted. As you can see the existing hole in the skid plate fits around the tank body nicely and allows the tank to be mounted low enough that proper flow into the tank is achieved.

The only thing I dont like is how much of the heater tank is exposed inside the wheel well and may consider adding a guard to it if I start to notice it getting beat up.

It does however clear all suspension and steering components even with the suspension fully articulated

 

[2rivers]

Nice. Timely thread. Just to clarify your Zerostart model does not have a built in pump, just an element correct? Offhand I think I have a Temro 400W - shaped like a 500ml coke bottle sort of.

I too have something like this on my HJ61 but need to re-visit the plumbing around the thermostat housing b/c I think it is not circulating as well as possible.

Regards,
John

 

[Malahki]

No it does not have a pump but does seem to work quite well so far. The true test will be at -30

I had a 750w zerostat on my BJ71 that was installed by the previous owner. It was mounted too high and did not circulate very well. They should definitley be mounted as low as possible as the tank is gravity fed.

If it is working correctly the inlet hose should remain relatively cool at all times compared to the upper outlet hose which will be quite warm to the touch

 

[John Galt]

That's a lot of extra work when one considers that a simple lower rad hose heater does the job just fine, even at 30 below zero.

 

[Phil in BC]

I also have a lower rad hoe heater. Works pretty slick, in fact I have it plugged in just now. Damn winter crap.....

 

[northernrighty]

The unit I got from NAPA does have a pump. 1000 watts and about $125.