I wasent happy with my factory block heater on the realy cold below zero days so I instaled a 1500 watt Kats circulating tank heater. I am sucking the cold coolant out of a port on the block rite behind the oil filter and dumping it back into a port on the top of the head. It gets it warm enough to open the thermostat and start warming the radiator. When I get in it and turn the key on the temp gauge shows 180 so its more than warm enough. The grid heater dont even cycle. What I cant figure out is when I start it it acts troubled or strained to stay running for the first second or so. I dont know how to explain it other than it almost acts as if it is under a heavy load at idle and just cant quite get up and going smothly emidiatly after starting it. After a second or two it smoths rite out and is purring like a kitten. The one thing I cant quite figure out is that even though you can feel the engine is realy good and warm and even the radiator is warm and the heater hoses are warm I dont get any heat for a while. Shortly after starting it the temp gauge goes back down to around 140-150 wich should still be plenty for heat but it only blows luke warm. My main concern is the weird startup, the heat is not such a issue. The only thing I can think of is that there is a temp sensor somewhere that is still reading the cold temps and giving the ECM mixed signals for the first few seconds till the coolant is circulated and everything kinda levels out. I would think that if that where the case though it would do the same thing when starting it while its still semi-warm on a cold day. It definatly is caused by the coolant heater though cause if I use the block heater it dont do it.

Any Ideas???

 

Just a few thoughts, nothing definite.

Sure sounds like the most of the tank heater output is is bypassing the engine and heating the radiator.

Try placing the tank heater low so the hot side outputs uphill to the engine block and then the cool side of the tank heater draws on the head connection. That should establish positive flow through the engine and heater core too.

Some of the tank heaters used to have check valves in them. See if yours does and that it is set to flow in the right direction.

There is always some bypass to the radiator, but it should not be the main path.

As far as the starting I think you identified the probable cause. Sensors are hot in the system and the engine is still relatively cold due to poor circulation. I think fixing the tank heater installation will fix the starting too.

 

thats opposite to the convection required to make that baby work. you must draw cold low and dump hot up high. and ideally the heater body is the lowest point in the system.

but the odd starting, sounds more like a fuel issue than heat.

 

As far as most of the hot watter bypassing the engine and going to the radiator I had thought of that as well but you can touch the engine and heater hoses and they are all nice and hot. The one mistake I know I made was dumping the hot back in at the front of the head rite behind the thermostat so I paln to move it to the back of the head. I dont think its a fuel isue as it only does it if i use the tank heater. If I use the block heater it starts and purs like a kitten it just dont have any heat.

 

Oh that was your loop over output line? I saw that in another thread. thats not good at all for making a convection system work. you understand there is no pump in these units. it operates entirely on convection.

you can do what ever you want, but drawing high and dumping low is entirely wrong.

1500w is pretty massive. tons of output. returning to the heater core inlet line would have been your best scenario. tag the heater core 1st then into the back of the head, down through the water jacket completing the loop.

 

I am drawing low and dumping high. I thought it threw and decided that reversing flow as suggested wont work. I realize the loop is less than ideal but it flows real good yet. I get the coolant from the block and dump it in the head there. You can hold the hose and feel the coolant rushing threw it.

Returning it to the heater line wont work. if ya look in the pic you can see I had already tryed that and had to splice the hose back together. It would not flow. Before you ask, yes I had the HVAC in teh heat position and as soon as you turn the key off it stops flowing. There must be a electric hot water valve in there that closes as soon as the key goes off. It wouldent flow backwards into the head from there either. must be a one way check valve in the metal line comeing off the head that the heater hose hooks to. The hoses would get hot till it tripped itself out then back on after it cooled but wouldent flow.

 

You might have had the heatercore vapor locked? they can be ignorant sometimes. but installing at the back of the head is the next best option. try to get that loop out of it. I'd suggest get the heater lower, a short 3" NPT stand pipe in the head port, to a 90* then a nipple straight out the side. that'll keep the geometry of the circuit nicer.

 

I wonder if the startng issue has to do with the grid heater not coming on? Seems to be the only other variable...

 

Not likely. The grid heater only comes on if the air in the intake is below 60 deg. Starting it warm with the tank heater should not be any diferent than starting it while it is still warm after running it. If I shut it off after it is fully warmed up and then restart it a little latter the grid heater dont run either cause the engine heat keeps the air in the intake above 60 deg. I think I may move the outlet to the back of the head away from the thermostat so it is not so fast to open. In my way of thinking it almost has to be a confused ECM caused by conflicting sensor readings. I just cant figure out why if that was the case it dont do it with the block heater as well cause that leaves even more cold spots in the system.

 

Been following "bkrukow's'" thread on the Kat's for a while and will be installing it this week.................I hope. I currently just use the block heater and if left plugged in all night, the grid heater doesn't come on at all. If I start and run it for 3-4 minutes then shut it down to lock the house door, the grid heater will cycle, but in both cases I have no starting issues. The one thing I was looking at in the pics is the location of the Kat's input and output connections. The output is almost directly above the input. Could this be causing a hot spot and only heating a small area? I have to assume there is a thermostat in the Kat's so if the pattern of hot coolant is localized then the heater will shut down once the area meets the cut off temp. That would leave almost everything behind cyl 2 out of the loop but convection may still heat the grid sensor enough to fool it into thinking all is OK! The rest of the engine may be stone cold or close to it. Next time you have it plugged in, feel the head and block back by cyl 6 and the fuel filter. Let me know because I intend to use the coolant port at cyl 5 with a brass 90 degree street el to keep the loop low and coolant flowing.

 

The engine sits butt low, so any hot coolant flows up. God, my Science Teacher would be proud...............for a split second anyway

 

When I initaly instaled it in the heater core feed I was wondering abought how well it would work cause the heater core dumps into a metal line that runs back down the length of the block and then into the water pump. The hot coolant would have to travel that full length and then threw the pump and into the block. I figured it would loose lotsa heat in that time and require longer running time to heat the engine.

As far as getting coolant from the heater line, unless I splice into the steel line on the side of the block(not happening) all the ruber lines are up higher than where I am getting it now, and way higher than where the heater is mounted. Rite now the heater is sitting just above shock tower abought rite in the middle of the flow so it should be in an ideal spot hight wise for convection pumping. I just need to eliminate the loop when I move it to the back to help make it a little better.

 

Ya I have done the feel around test and everything including the heater hoses are warm if not hot. I to am thinking that it almost has to be a isue of dumping the hot coolant in directly on top of where i am drawing it out of causing the front of the engine to be hotter than the back but I dont see how that causes the weird starting isue i have. A sensor has to be sitting in some cold coolant some where. When I feel the engine I cant feel any noticable diference in temp from front to back so its not like one part is 180deg and the rest is stone cold. I leave it pluged in at work for up to 12 hours(free electricity) on this heater when its realy cold and as few as 2 when its not so cold like now.

 

Except for the fact that you already said that it was different. The temp guage drops after you crank it so obviously there are still cold spots in the engine, but the ECM is being fooled into not running the grid heater. You don't have a good heat soak like you would if the engine is run and the turned off.

Pull the little wire off the grid heater solenoid on the p/s battery tray. Plug the truck in with the stock heater and if it does the funky start up then it because the grid heater wasn't on.

 

Ya I have always asumed the temp gauge droping was from the thermostat being open and it pumping the cooler water out of the radiator back into the engine. But there may be some cold spots with my less than ideal routing of the top hose.


I am gona have to rerout my top hose and eliminate the loop but its gona have to wate a week till I have time to go up to my budies heated shop and mess with it.