12H-t/HJ61 coolant diagram for Webasto

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Is it acceptable to drive with webasto running continuously?
 
As long as you have plumbed it the right way you can run it 24/7. Also under engine running conditions
 
I do that with the Eberspächer and it is running like that for the last 14 years.
 
Ok, I am home after another run, stop for coffee to consult with Rob, and run home.
I jacked it up and will let it cool one last time with the front elevated just to make sure no air in the system.

Conclusion, 12H-T runs cool. I bought one of those IR temp guns, and I have 3 temps that pretty much sum it up/.
At the thermostat housing after highway run - 158 F, right on top of radiator housing, ( where it is hottest ) 164 F
at heater valve 148 F. The thing just runs cool. Outside air temp is only freezing 32F / 0 C.

So I'm going to add a canvas radiator winter front to the radiator itself. I leave on Thursday or Friday for drive to Calgary,
so I'll see how it is with the front covered right up. And if it's below freezing I'll run with the webasto operating.
Thanks for all the help, and if anyone has any more wisdom, speak up. J
 
Question; how many kw heating capacity does your heater have?
I got an old Eberspächer rated at 4.5kw I am thinking of installing. Also have a 30kw webasto unit I just bearly could fit in my engine compartment. Very power consuming thought.
Just asking the obvious; have you bleeded air at the heatercore valve?
 
Webasto TSL 17 is 6.14 kW at full load input, 5.0 kW at full load output. 3.8 amps full load/2.6 amps partial load
I've done every thing to bleed air out. I have a bleed cap right at the heater input valve which I did check. I'm as certain
as I can be that there is no air in the system.
 
The 12H-t runs cool, I'll check how mine's plumbed again...
The reason I asked if the rear heater is functioning is it will help bring up the interior temp, Toyota wouldn't have bothered installing it otherwise.
Don't fear air bubbles, I have a leak at the thermostat housing, so I'm loosing coolant, I refill when I hear air in the heater core, the air is out in a few minutes...
Lasse mine's 5kW, 30kW is way too much, that's what a big bus or motorhome runs!
 
I think running both a water heater and air heater is overkill unless you build a camper rig where you sleep during -15ºC and below.
I know 30kw is way to much, but think of this. Instant heat in 5min!
Bought it used from a big diesel locomotive :cool:
 
Just reread your piping, sounds right... Your Webasto heats the cab and engine fine, right?
The issue is that you can't keep it toasty when the Webasto is off and the engine is on, right?
If the above is correct it sounds like you don't get adequate flow when the Webasto is off and the engine on. This could be because of the inherent resistance in the Webasto and pump. Water always travels the path of least resistance and the longer lines, bends, pump and the internals in the Webasto might reduce flow too much to produce adequate heat?
Your rear heater is plumbed like originsl, without added restrictions right? How hot it the air from that?
 
I think running both a water heater and air heater is overkill unless you build a camper rig where you sleep during -15ºC and below.
I know 30kw is way to much, but think of this. Instant heat in 5min!
Bought it used from a big diesel locomotive :cool:
I don't think it will be that fast a lot more water, mass etc. To heat up... You'd better just give it to me for my Volvo TGB 1314 camper project!
 
FYI, although I am not using a heater the photo gives you the flow direction.



IMG_0864.webp
 
Watrob, I hoped you get into this! Love that 12H-T 40!! Got me thinking of NOT putting the 13B-T I have for my '73 40 in now!

Thanks for the pic. That is how I have it plumbed.


Just reread your piping, sounds right... Your Webasto heats the cab and engine fine, right?
The issue is that you can't keep it toasty when the Webasto is off and the engine is on, right?
If the above is correct it sounds like you don't get adequate flow when the Webasto is off and the engine on. This could be because of the inherent resistance in the Webasto and pump. Water always travels the path of least resistance and the longer lines, bends, pump and the internals in the Webasto might reduce flow too much to produce adequate heat?
Your rear heater is plumbed like originsl, without added restrictions right? How hot it the air from that?

You are right on all counts above. I can only add, that before I added the webasto last spring I damn near froze to death driving home from a
winter trip when it got down to -25 C. I had to put on all my clothes, and stop for hot coffee to keep going! That is the coldest I've ever been in
a vehicle, and I've wheeled my FJ 40 with a 351W at -15C - without a roof!
The rear heater works quite well, I have to admit, not hot, but acceptable. Perhaps the rear heater is a bit higher temp as it come out of the rear of the engine instead of being piped along the top of the block from the front?
I will see how it is from here on in. I'm going to be up north, and I expect temps below -20. I am going to add a canvas cover to the inner rad support just away from the radiator, but it will be completely covering of the rad opening. I've got my camping gear all organized, so it will be interesting to see how it works out. J
 
If you where near dead last winter without the Webasto while on a long trip, the Webasto is not the only issue!
I've heard and found that the 12H-t is slow to warm up, and doesn't produce boot melting heat, but damn near killed you!?!?

My course of action would be to try to detemine the actual flow in the lines, I believe some obstruction is at fault, bad casting in the head ports, something in the lines maybe?

I flushed the entire cooling system on mine, the amount of rust and sediment was all the 27 years and 340.000 miles worth...
 
I had the whole system apart last year when I did the heater core and installed the webasto. It all seemed to be flushed out
and functioning. The only thing I haven't done is stick a brush down through everything.
 
Have you had the engine apart?
How did it look under the oil cooler cover?

An engine running without anti freeze for many years will eventually clog up and I know many living in warmer climates never care to add anti freeze to there cooling system.
My 12H-T heats up in no time and blow out heat from both my rear and front heater. My tuning of the engine of course helps on this.

Christian: Why don't you give me your Volvo so that my Webasto gets a deserving home?
Look around and wait for a good deal. I bought mine from a guy in Alaska parting out overstock "trash" (old units changed out for no reason) and paid only about 1.000,- NOK for it incl. shipping. He had more and I regret today that I only bought one. Webasto Thermo 300
 
I'm not about to tear it all apart now, but the possibility of it clogged up hadn't really entered my mind. That would be a major
undertaking I expect without clear proof. I'll look at peripherals to see if it is going that way.
Certainly going to wait until I get home from this trip.
 
Yeah, a serious undertaking. As you drive it up north in freezing temperatures I guess you use about 50/50 antifreeze and tap/battery water?
Do you know the engines history?
Taking of the oil cooler cover often tells you the story, if it is clogged up it definitely shows here.

But then again if it is clogged up, then you possibly should notice it by overheating, if not the water, at least the oil.
 
Why not put a piece of clear tube in the system, possibly with a piece of string on the inside so the flow is visible?
 
Or get a few of those cheap Ebay digital thermometers with the probe, tape them to the different hoses, I.E. to and from the heater and monitor the temperatures while driving.
I bought 5 for less than $10...
 

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