Engine/Transmission (1994 - 1998) Cold shoulders

[Mundgyver]

All right Oo. I see my first clue here to what I think is your problem with getting heat into the cab. I say you have a flow issue. I see in the picture that both heater lines from the cab run forward to the front of the engine. I see one going to the pump side and one to the top of the block either just below the thermostat or above it. On my 2001, my intake line to the heater core comes off the back of the engine between # 5 and #6 cylinder on the head and my other line runs forward to the return side of the pump. I get a good differential pressure and get the heat off of the entire head assembly with the flow from the heads. What I see in the picture posted leads me to believe that you do not have enough differential pressure for a good positive flow. I would take your input to the heater core and connect it at the back of the engine head around the #5 or #6 cylinder. The output would be the return to the pump intake side. I could have the flow direction reversed and I am sure someone will chime in if I do. Does this make sense to you. You can get a standard clear liquid graduated flow meter from a good heating and cooling company that deals with industrial apps. They will be graduated in gallon per minute and will give you a good idea of our volume that you are pushing.

 

[Mundgyver]

Let see if this pic gets in of a flowmeter. With both your lines at the very front of the engine, I think I can see why you not getting alot of heat, because your are just cyling the fluid at the very front vice through the entire engine for flow to the heater. Does this make sense

 

[Mundgyver]

Let see if this pic gets in of a flowmeter. One of these will tell you what is going on.

 

[JoshPeters]

Great idea and all... . but you have a 24v and he has a 12v. I have not seen an elbow between the 5 and 6 cylinders just floating around on a 12v. I haven't even seen a pipe plug or a place where you could force/press fit an elbow in. This does not seem to be an option on a 12v. I do like the way you think though! The differential of pressure isn't like an A/C system. You need a constant flow of coolant through the heater core. The heater core acts like a radiator when trying to heat. If there is slow/no flow, you will get no heat. If you have high flow or a larger area, you should get higher heat. BUT, if you have a larger area, and not enough flow... . you will be in the same boat as before. Now the coolant has cooled off WAY before it has heated the air properly.



Josh

All right Oo. I see my first clue here to what I think is your problem with getting heat into the cab. I say you have a flow issue. I see in the picture that both heater lines from the cab run forward to the front of the engine. I see one going to the pump side and one to the top of the block either just below the thermostat or above it. On my 2001, my intake line to the heater core comes off the back of the engine between # 5 and #6 cylinder on the head and my other line runs forward to the return side of the pump. I get a good differential pressure and get the heat off of the entire head assembly with the flow from the heads. What I see in the picture posted leads me to believe that you do not have enough differential pressure for a good positive flow. I would take your input to the heater core and connect it at the back of the engine head around the #5 or #6 cylinder. The output would be the return to the pump intake side. I could have the flow direction reversed and I am sure someone will chime in if I do. Does this make sense to you. You can get a standard clear liquid graduated flow meter from a good heating and cooling company that deals with industrial apps. They will be graduated in gallon per minute and will give you a good idea of our volume that you are pushing.

 

[Mundgyver]

You are right, as there are differences between the 24 and 12 valve models. I have no experience with the 12 valve, but I would think there must be a pipe fitting somewhere on the head torwards the back or maybe on the block. These engines are used in other rigs with different setups for the plumbing and such so there has to be some alternative. I just think he does not have enough flow. Heck if worst came to worst, use the dang heater as a oil cooler for the engine oil Engine oil runs about 10 degrees hotter than the water anyway.

 

[ABorchard]

The differential pressure on a 12 valve comes from having a line on each side of the thermostat. When the stat is closed all the flow should be going though the heater core.



Sucks that you don't have the recirc position, didn't know any 12s came that way. I know that's the problem as I would have the same too with no recirc. My feeling living in the north is you could remove the entire radiator for the winter and not overheat, the heater core would be enough to cool the engine.



Have you ever noticed better heat when the vent intake at the front of the window is plugged with snow?



Might want to check out this http://www.ventechlhg.com/

I emailed, they will be availible for Dodge Cummins this summer for around $375 USD

 

[Hammer]

Tim. .

I know its not a cheap option what I am going to tell you about but its a very viable option for someone like you who lives in a area,Central NY, where once the cold air drifts in its trapped and you endure cold spells for log times. Why not look into a Webasto or Espar heater system for your ride as it will preheat and warm the fluids of the truck at intervals you can choose. There a bunch of owners here who use them and love them for the cold climate areas and would ease the amount of idle time you truck will see. It will also allow you to not have to plug your truck in for the colder,harsher winter months as the heater is timed and runs off your engines fuel system. Do a search here for either of them and you should find plenty of info on them. Hope this helped some... ... ... Andy

 

[JoshPeters]

. My feeling living in the north is you could remove the entire radiator for the winter and not overheat, the heater core would be enough to cool the engine.

I have a feeling your right!



Josh

 

[vssman]

I too used to suffer with poor heat during my 13 mile commute. I ran one entire winter without a fan - much better. Would go up to 190 and stay there, especially with the winter front closed. As long as your running empty, you can run fanless until at least 50 degrees unless your in stop & go traffic the entire commute. I finally went to electric fans and it works great. As noted before, the cummins t-stat if much better. According to one of the major t-stat mfgs, top hat style t-stats tend to be more reliable than witches cap style (look at a side profile and you'll tell the difference).

 

[TWafer]

Well, I did some more research today. This may be a long post!



Mundgyver

I too like your ideas and what your saying does make some sense to me. If I understand correctly, when the thermostat is open coolant is drawn from the lower radiator hose (since the coolest water is at the bottom) into the engine. The heater (return) hose is also connected where the lower hose enters the pump so some of the flow would be through the heater core.

It is then pumped into the block and circulated up through the head and through the open thermostat back to the top of the radiator. The heater core inlet line is tapped into the top of the head just before the thermostat.

If the thermostat were closed the major circulation would be through the heater core.

You are suggesting that since the inlet and return for the heater core are both tapped into the front of the engine that the coolant doesn’t have the opportunity to pick up sufficient heat since it isn’t forced to flow through the entire block and head. Have I grabbed the basic concept you are trying to get across to me?

If so I now have several more questions maybe some of you could clarify for me.



Wouldn’t # 6 cylinder run hotter than # 1 as a general rule if this is the case or is it insignificant?



Myself and several others including two diesel mechanics searched the engine for another port to tap into on the 12 valve but found none. Does anyone know of any we missed?



I also discussed the 190 vs. 180 degree thermostat question with them and a Dodge dealer since I never got a definitive answer whether the 190* would even fit in the 12 valve. I still don’t have a definitive answer but the general consensus is that it would NOT fit. Given that answer, I went ahead and ordered the new updated 180-degree thermostat for the 12 valve.



We also looked over a 1993 12 valve that was there to compare it to mine. It is also a 5 speed but the owner claimed he has super heat in it. It is plumbed into the block in exactly the same spot as mine. However we did notice one significant difference. Mine has a small (maybe 5/16” or 3/8” ID) bypass hose that goes around the thermostat. It connects next to the heater inlet hose just before the thermostat and the other end goes into the elbow just beyond the thermostat. (you can see it in the above picture of my engine) The 93 had a plug in this hole which looked factory installed to us. No port at all for the other end.

Seems to me this bypass would substantially reduce the flow to the heater core. Could I plug it or at least put a ball valve in it to shut it off in the winter? What’s it real purpose?



I'd like to get one of those flowmeters just to see what actually is going through the core. Any ideas as to what would be a reasonable amount of flow at say 160* in order to get sufficient heat?



ABorchard

How does this thing work? http://www.ventechlhg.com/

Sure looks interesting and sounds like a possible answer but I didn’t understand the basic principal of how it makes heat.



Thanks for everyone’s input so far!

Tim

 

[JJW_ND]

Something is wrong....

Tim, my 96 5sp has always ran cool on the gauge (160 - 170) but blows plenty of heat. Even on days as cold as you talk. I do run with the fan removed, and a winter front.



The small hose to speak of on the front near the Tstat is a "jiggle" valve. It is there to help bleed trapped air. I does need to work and not be suck open or this would case excess circulation of the little warm antifreeze you have.



On my truck, even with the gauge on 160 I get enough heat to back off on the heater temp. I big help to trucks with AC is to disable the AC in the winter... that does not appear to be applicable with your truck.



You should not have to put up with a "cool" truck.



I am sure you have made sure the heater temp adjustment is fully opening to give you 100% of the heat available.



I have found that intown (speed less the 50 mph) does not make much heat on the gauge but warm air should still blow. This is where no fan and a winter front conserve what little heat you can make under these conditins. The other things is run your idle pretty high (900 - 1000) in the winter. If you can do not run your heat fan speed very high. No need to push the heat like summer AC.



I can start my truck after setting in -10 and colder and with the idle kicked up to 1200 actually feel warm air after a period of time without driving it... . no fan, winter front!



I have a oil temp gauge and the oil temps barly get to 175 with outside temps are below -10. Coolant temps that warm or warmer are entirely a result of a blocked radiator or lack of air flow over the radiator.



I too wish there would be a TStat that would run up to 190 and stay there.



jjw

ND

 

[TWafer]

A couple more thoughts I’ll pass on since I’m sitting here thinking about it. I live at a higher elevation than where I work. This contributes to the colder temperatures but more importantly it’s mostly downgrade the 10 miles to work. I’ve always noticed that the diesel makes little heat until you put a good load on it. Its slightly better on the return trip but also I usually have used it during the day so it hasn’t had time to completely cool down.

Its my belief also that on a typical cold winter morning that the thermostat never opens on the way to work. It doesn’t matter if I plug it in or not. I base this on the fact that I never see the gauge get much above the 140 mark and can get to work, open the radiator cap and stick my finger in it and its ice cold.

Also if I decide to start it and let it idle before driving it, I’ve found that unless you let it run 30 to 45 (depends on outside temp) minutes you might as well not bother. It takes that long to defrost the windows. Even after that I don’t know as the thermostat would open on a typical drive in to work.

Tim

 

[Mundgyver]

You understand me correctly. If the inlet is right at the thermostat and the outlet is right at the pump, when do you draw hot water to the heater. You are getting minimal heat into the line, where is the circulation through the block to pick up the heat. That is the jist of my thinking.



Could you tap the head into the water jacket back by # 5 or 6. Food for thought here is all I am putting forward. If you move the line by the thermostat back to 5 or 6, my bet is you will have more heat than you thought possible. I don't see any down side for flow across the heads because you will be drawing the entire length of the head.



Thats my idea and I be a sticking with it I will be very interested in what the final fix will be.



-Wally-

 

[mechanic]

Well, I did some more research today. This may be a long post!



Mundgyver

I too like your ideas and what your saying does make some sense to me. If I understand correctly, when the thermostat is open coolant is drawn from the lower radiator hose (since the coolest water is at the bottom) into the engine. The heater (return) hose is also connected where the lower hose enters the pump so some of the flow would be through the heater core.

It is then pumped into the block and circulated up through the head and through the open thermostat back to the top of the radiator. The heater core inlet line is tapped into the top of the head just before the thermostat.

If the thermostat were closed the major circulation would be through the heater core.

You are suggesting that since the inlet and return for the heater core are both tapped into the front of the engine that the coolant doesn’t have the opportunity to pick up sufficient heat since it isn’t forced to flow through the entire block and head. Have I grabbed the basic concept you are trying to get across to me?

If so I now have several more questions maybe some of you could clarify for me.



Wouldn’t # 6 cylinder run hotter than # 1 as a general rule if this is the case or is it insignificant?



Myself and several others including two diesel mechanics searched the engine for another port to tap into on the 12 valve but found none. Does anyone know of any we missed?



I also discussed the 190 vs. 180 degree thermostat question with them and a Dodge dealer since I never got a definitive answer whether the 190* would even fit in the 12 valve. I still don’t have a definitive answer but the general consensus is that it would NOT fit. Given that answer, I went ahead and ordered the new updated 180-degree thermostat for the 12 valve.



We also looked over a 1993 12 valve that was there to compare it to mine. It is also a 5 speed but the owner claimed he has super heat in it. It is plumbed into the block in exactly the same spot as mine. However we did notice one significant difference. Mine has a small (maybe 5/16” or 3/8” ID) bypass hose that goes around the thermostat. It connects next to the heater inlet hose just before the thermostat and the other end goes into the elbow just beyond the thermostat. (you can see it in the above picture of my engine) The 93 had a plug in this hole which looked factory installed to us. No port at all for the other end.

Seems to me this bypass would substantially reduce the flow to the heater core. Could I plug it or at least put a ball valve in it to shut it off in the winter? What’s it real purpose?



I'd like to get one of those flowmeters just to see what actually is going through the core. Any ideas as to what would be a reasonable amount of flow at say 160* in order to get sufficient heat?



ABorchard

How does this thing work? http://www.ventechlhg.com/

Sure looks interesting and sounds like a possible answer but I didn’t understand the basic principal of how it makes heat.



Thanks for everyone’s input so far!

Tim

The thermostat is at the "adverage hottest" point in the system. It has to be to do the job. The coolant flow is through the block to the back,#6, then up into the head and forward to the front and out through the thermostat. This routing, with some minor variations, is the basic routing of all the conventional type cooling systems I have encountered in 40+ years of servicing vehicles. Some of the newer systems are different, but the B series is not one of them.

I would check the air handler doors under the dash to see if they are closing off the incoming cold air duct when set in max heat postion.

Also check if your heater hoses are the same temp or if the return is cool and the supply is hot. If the supply is hot then the return should be cooler, but not cool. This would indicate flow problems. If is is as hot as the supply, it would indicate an internal bypass in the heater core or a lack of air flow over the core. Either problem is not uncommon.

VW has a glowplug type assist on their TDI models. (At least some of them) It would be easy to install on one of the trucks. And if the price is to high, you could make one out of a heavy wall pipe two heater hose nipples and some glowplugs. Install it in the supply hose then all you would need is a relay and related circuit to power it up. Might be worth a try.



I just looked at the "ventech" referred to by Art Borchard. I would bet that it operates on the principle of a fluid coupling which is a torque converter without the stator. The coolant would be circulated through the coupling and to the heater. The difference between it and a fluid coupling would be that the driven member is stationary, so it would make a lot of heat-quick. Depending on the price, it could be a very good solution. Good find Art.

 

[TWafer]

My conclusion

After reading through everyone’s suggestions and spending some time researching and thinking about this whole problem I’ve come to the following conclusion.

The heater simply sucks! :{

Now that it’s the end of March and temps are normally well above zero the heater is perfectly adequate. However in the dead of winter with temps well below zero it simply isn’t. I think that even though a pickup cab seems smaller than a car interior to me, that the heat loss on a –20 day is substantial and the heater simply can produce enough heat to overcome the loss at those temps. It might be if you could get the engine temps up to 180* consistently but under normal (for me) driving conditions that’s apparently impossible.

I have felt the heater hoses and now in 30-40 degrees above zero they both seem hot. Again in sub zero temps they seem warm at best. There is a slight difference between the inlet and return at both times. But the temp gauge seldom rises above 140- 150 degrees at sub zero temps unless I’m pulling a trailer or under some other load. If you drive 50 –60 miles it may warm enough to open the thermostat but soon as the cold water in the radiator is allowed into the engine the temps again plummet. I think the heater core is sufficient to keep the engine cool during normal (again for me) situations at sub zero temps.

I sent an email to Ventech and below is there response.



“Tim



Thanks for your email.



The device produces heat by converting energy from the crankshaft

(horsepower) to heat in the coolant, by means of hydraulic friction.



We are preparing after-market self-install kits for the GM, Ford, and

Dodge full-size diesel pickups. The product will be available for the

winter of 2005.



We will soon be launching a new website where the kits can be ordered.

The kit price is anticipated to be in the $500 - $600 range.



If you would like, I can put you on our mailing list to notify you when

the kits are available?



Many thanks for your interest in the Ventech Liquid Heat Generator.



Sincerely



Jeremy J. Sanger

Ventech, LLC”



I think my best solution would be either this or one of the Espar heaters. The more I think about the Espar type heater the more I like the idea. That should solve the whole problem. I'll have to start saving my pennies either way.



Tim