Coolant circulation?

[Hounds]

Hi Folks,
I've just added a heat exchanger and in-tank heater to my 300SE.
Question is where do I attach the coolant lines? I've got them in the heater core lines right now just to see if it works, which it does nicely.

But, I can't have the heat on all the time; so do I need to add ports to the block and if so, will they circulate all the time? If I were to keep them there and leave the heat off in the car, it doesn't get enough heat right?
Thanks

[dieseldan44]

Originally Posted by Hounds

Hi Folks,
I've just added a heat exchanger and in-tank heater to my 300SE.
Question is where do I attach the coolant lines? I've got them in the heater core lines right now just to see if it works, which it does nicely.

But, I can't have the heat on all the time; so do I need to add ports to the block and if so, will they circulate all the time? If I were to keep them there and leave the heat off in the car, it doesn't get enough heat right?
Thanks

First off, I really hope you mean 300SD and not 300SE.

It depends on how the system is plumbed. Typically you T in before the heater core and then after the mono valve, but before the Aux water pump.

When the heat is off, the monovalve is closed and water will circulate through the in-tank heat exchanger.

When the heat is on, the monovalve is open and water will circulate through both.

Since the Aux water pump is only on when the heat is on, it is customary on MB conversions to wire the Aux water pump to be on all the time.

[Hounds]

THanks DD, YES I meant SD, not SE. lol

[dieseldan44]

One other point I think needs to be made is that your WVO injection temperature drops when using the in-cabin heat because you are adding more heat exchanger area to the cooling circuit.

Bundle up in the winter to keep the heat on the fuel. My car's occupants know not to put the cabin heat on until the WVO fuel temp gauge is greater than 175.

[biopete]

Originally Posted by dieseldan44

One other point I think needs to be made is that your WVO injection temperature drops when using the in-cabin heat because you are adding more heat exchanger area to the cooling circuit.

Bundle up in the winter to keep the heat on the fuel. My car's occupants know not to put the cabin heat on until the WVO fuel temp gauge is greater than 175.

If you're worried about that, I think you could put the T on the other side of the veg circuit -- the return side from the heated tank so that the water goes through the veg heaters first and on its way back can go through the heater core or T out to where you return your veg circuit now . Know what i mean? Basically as you have it you are sharing hot water with your heater core if heat is on. But you can make it so hot water always goes through veg circuit first. Then if heat is on it will go through heater core and return back to area by the aux water pump. Either way, hot water is being split off before heater core . So try splitting off on return side of veg circuit rather than the supply side. Hopefully that works.

[dieseldan44]

Originally Posted by biopete

If you're worried about that, I think you could put the T on the other side of the veg circuit -- the return side from the heated tank so that the water goes through the veg heaters first and on its way back can go through the heater core or T out to where you return your veg circuit now . Know what i mean? Basically as you have it you are sharing hot water with your heater core if heat is on. But you can make it so hot water always goes through veg circuit first. Then if heat is on it will go through heater core and return back to area by the aux water pump. Either way, hot water is being split off before heater core . So try splitting off on return side of veg circuit rather than the supply side. Hopefully that works.

I hear what you are saying. Only problem with the 'series' arrangement is that I can't shut off heat to my system entirely without shutting off cabin heat :-/

I have a valve at my FPHE that shuts coolant flow off to the system when I am city driving. I dont want to 'cook' the oil and invite poly when it's not being used.

I really wish I could find a true 83C thermostat instead of 80 or 87. Then my problems would be solved. That being said on the highway in the winter with the radiator blocked I can still maintain 180F WVO temps with the heat on low.

[biopete]

Originally Posted by dieseldan44

I hear what you are saying. Only problem with the 'series' arrangement is that I can't shut off heat to my system entirely without shutting off cabin heat :-/

I have a valve at my FPHE that shuts coolant flow off to the system when I am city driving. I dont want to 'cook' the oil and invite poly when it's not being used.

I really wish I could find a true 83C thermostat instead of 80 or 87. Then my problems would be solved. That being said on the highway in the winter with the radiator blocked I can still maintain 180F WVO temps with the heat on low.

I see. Hmm. Is it just a one way ball valve or something? Make that valve a three way and you got it .

[dieseldan44]

Originally Posted by biopete

I see. Hmm. Is it just a one way ball valve or something? Make that valve a three way and you got it .

It's a standard one way ball valve.

Three way valve would make the plumbing a lot more complex (than it already is) indeed.

The time has past for this conversion, maybe I'll rethink the next one for series operation with the option of shutting off heat to the system.

I think shutting off heat to the system is critical if you city drive a lot (like I do) and dont need the system. I am told idling or city driving on VO is not best practice.

[funola]

Originally Posted by dieseldan44

I hear what you are saying. Only problem with the 'series' arrangement is that I can't shut off heat to my system entirely without shutting off cabin heat :-/

I have a valve at my FPHE that shuts coolant flow off to the system when I am city driving. I dont want to 'cook' the oil and invite poly when it's not being used.

I really wish I could find a true 83C thermostat instead of 80 or 87. Then my problems would be solved. That being said on the highway in the winter with the radiator blocked I can still maintain 180F WVO temps with the heat on low.

What's the magic about a 83C tstat? Wouldn't a 87C or even a 92C one be better?

[dieseldan44]

Originally Posted by funola

What's the magic about a 83C tstat? Wouldn't a 87C or even a 92C one be better?

With the 80C stat I run about 87C on the temp gauge. My WVO temp runs around 170 with the heat on - I need 3 deg. C more heat.

With the 87C stat I run near 95C, but it has longer warm up time. If I block the radiator to reduce airflow, I'll overheat.

I guess I should just use the 87C in the winter and be done with it.

Is there any disadvantage to running hotter all the time? (Provided all of the other cooling system parts are in order)

[biopete]

Originally Posted by dieseldan44

It's a standard one way ball valve.

Three way valve would make the plumbing a lot more complex (than it already is) indeed.

The time has past for this conversion, maybe I'll rethink the next one for series operation with the option of shutting off heat to the system.

I think shutting off heat to the system is critical if you city drive a lot (like I do) and dont need the system. I am told idling or city driving on VO is not best practice.

Yeah. I agree. At least for the direct injection. I have experience idling those on veg with bad results. I used to jump cars with my veg tdi and let it idle for 30 minutes sometimes on veg until i knew better. After about 10000 miles of veg use , it started to get a harder to start.

The Elsbett manual says that for the Direct injection engines keep Rpms between 2000 and 3000 and avoid idling. For the indirect injection like MB, they pretty much just say drive it and don't worry about it. But definitely if your stuck in traffic regularly for hours a week, i would switch over to at least a blend. At least until i got tired of paying for fuel.

Don't you wish they had a diesel hybrid?

[funola]

Originally Posted by dieseldan44

With the 80C stat I run about 87C on the temp gauge. My WVO temp runs around 170 with the heat on - I need 3 deg. C more heat.

With the 87C stat I run near 95C, but it has longer warm up time. If I block the radiator to reduce airflow, I'll overheat.

I guess I should just use the 87C in the winter and be done with it.

Is there any disadvantage to running hotter all the time? (Provided all of the other cooling system parts are in order)

I think it is better to run a diesel engine hotter (within safe limits) for better thermo efficiency. A hotter stat should get you better fuel economy.

Have you verified the accuracy of your cluster temp gauge?

Strange that the 87C stat has a longer warm up time than the 80C stat. I would have expected the opposite. Have you looked at design differences between the 2 stats?

170 F VO is fine. Let me ask you this: Do you feel a difference in how the engine runs with 170F VO vs 180F VO? I doubt it.

[dieseldan44]

Originally Posted by biopete

i would switch over to at least a blend. At least until i got tired of paying for fuel.

Don't you wish they had a diesel hybrid?

I cant complain. I get about 125-150 miles-per-diesel-gallon in my 85, and i do a lot of city driving where the system is totally off.

Diesel hybrid is something ive heard talked about for so many years but theres not enough demand and no company seems to want to bring it to market.

Im actually somewhat anti-hybrid. I'd rather have a small TDI or an all-electric than involve all the electronics and batteries for both fuels.