Block heater troubles

[Christian Rokhgar]

I installed a diesel powered engine heater which brings the coolant almost to operation temperature.
The problem is that this results into hard starting and after some cranks more the engine fires up with a lot of grey/white smoke but than keeps runing fine.

I thought preheating would help the 6.5L in coold winter days. Is there any influence to the starting procedure ( f.e. coolant sensor, glow plugs )?

Any idea?

Thanks,

Chris / Austria

[john8662]

How cold is it when you are having hard starting? It would seem if you get the engine water temp warmer and you are still having starting issues you might have a problem. Couple of things come to mind, how fast is your starter turning, and have you checked the glow plugs. You are right in considering your temp sensor, but only if your "glow time" is short. on a cold day you could get a long initial glow cycle of about 11 seconds. I don't think that preglow before starting helps getting it started. The best way is to crank it immediatly after the light goes out, that way the plugs are still red-hot and you can get fire. Letting it cycle, the plugs will be cooler, as the second cycle is shorter, and harder to start. If you miss your opportunity, turn the key off for at least 1 whole minute, then try again. Some smoke at startup is normal, but rough running and missing after the start (if it doesn't smooth out after about 10 seconds) isn't good.

[Christian Rokhgar]

The preheated engine makes less troubles when outside temperatures are moderate ( 5 degrees celsius ). Anything below results into really hard starting.

I think the glow plug system is confused. The glow plugs may not be hot enough because the temp sensor sends warm engine but the block itself isn

[john8662]

I see your point, the heater is actually making the coolant hotter than you need hence confusing the temp sensor, because the coolant is hotter, but not the combustion chambers. So from what you're saying, you will see shorter glow time plugged in because of the warmer coolant than if you had just left it unplugged and bone cold. I think a resistor can been added inline on the temp sender on the thermostat crossover within one wire to change the temp value to the PCM. Changing the temp value will give you longer glow time, and more timing advance at startup. This won't affect your gauge readings inside the cab for engine temp, as this uses another sensor. Use the search feature on the forum to see what comes up, I am not sure what post that was.

[Christian Rokhgar]

John,
Would it make sense to install a switch to disable temperature readings from sensor to the PCM?

[john8662]

Unplugging the temp sensor will make the PCM assume the absolute coldest temp. You'll get ALOT of advance and a long glow time. You could put a switch to turn off while starting and turn back on when the engine warms up a bit. I would only unplug (or switch one of the wires) for troubleshooting because of the timing advance used, it'll be pretty grumbly!

[BuffaloGuy]

Tell us about the diesel fired block heater. Sounds neat.
Ken

[moondoggie]

Good Day!

Others here on the Page have done what you are suggesting: Put a switch in line with the coolant temp sensor that feeds the PCM (the gauge has a separate sensor). Then flip the switch to open the connection before turning the key to run, & flip the switch back right after the engine starts. Yeah, she'll rattle pretty good while that switch is open, but I doubt it will hurt anything. In any case, as soon as the engine fires the switch can be flipped to restore the temp sensor connection.

Boy, am I jealous. I'd REALLY like to have those heaters on my trucks, but they sure are expensive! :eek:

Blessings!

Brian Johnson, #5044

[BigMikeO]

Does this heater also circulate the coolant throughout the engine? if not than the block could still be quite cold until the coolant starts getting pumped thorugh.

[jjbouwens]

I drive a 96 Winnebago with a P30 Chassis and a F engine. This RV has an engine coolant line to a heat exchanger in the back and to the boiler. A specialist installed a diesel fired coolant heater (Webasto)for me. A similar one is Espar which is sold in the US and Canada. Apart from the back heater I have three addional radiators and since the engine coolant is heated the dash heater is hot as well and the dash fan exhausts warm air into the motorhome (provided you have set the dash temperature control on "hot"and switched on the fan). The whole thing is controlled by a thermostat and by the heater itself (it shuts of at 70 or 90 degrees celcius engine coolant temp.) Therefore the radiator thermostat never opens otherwise you would start heating the environment.Furher there is a clock so you can start the heater in the morning by the clock or by a phone call. I never noticed a different starting behavior in the summer or in the winter, but I must say that the starting performance of the engine improved considerably after I changed the control of the electric fuel pump as suggested by some of the members. Now the PCM and the OPS operate a relay instead of the pump directly. So I am not sure whether the engine coolant sensor really senses a warm coolant and changes the glowing time in the winter because I really never sensed a warm engine but next time I will check that a little more closely. There is an article by Todd Smith that describes how to influence the glowing time by temporarily adding a resistance in the circuit. But again I did not notice a difference in the starting behavior except for the change in the fuel pump control.

------------
1996 6.5l TD/El.boost controller/mod. fuel pump control/ K&N Air filter.

[jjbouwens]

Hi Christian:
I still though about the hard starting. There is a downside with the diesel fired heater: it uses a lot of battery juice: glow plug for starting, fuel pump, water circulation pump plus combustion air fan. My heater runs on the coach battery (not the starter battery) and also I am practically always hooked up with the grid. In your case I assume that you use the starter battery. If the starter battery is not 100% and it is cold and the heater has been on .Well you can figure out that may be the battery is contributing to hard starting. Just a thought.
John

96/P30/ 6.5L TD/Gauges/JK el. boost/mod.el.fuel pump control/K&N filter/relocated FSD with home made heat sink.

[Kennedy]

Try unplugging the ECT sensor prior to starting once. This gives maximum glow time and advanced timing with faster idle sped.