Poor cab heat

[CATMAN]

I doubt that changing timing is going to do much for coolant temperature. If they choose to advance the timing, then the engine becomes ever so slightly more efficent, thus to maintain idle rpm(say 700 rpm) the governor tells the fuel injection pump that it requires less fuel delivery to the fuel injection nozzles for that rpm. Less fuel equals less BTUs(heat), BUT by advancing the timing, you give the fuel more overall "time" in the combustion chamber to burn BEFORE the exhaust valve opens and the remaining heat goes out the exhaust system. Allowing this extra overall "time" in the combustion chamber might allow a little addtional heat BUT remember it takes ever so slightly less fuel(BTUs) with advanced timing. Probably no difference. I will say this about advancing the timing within factory guidelines; it does help for white exhaust smoke complaints when engines are first started in colder weather AND it helps reduce that annoying raw diesel fuel smell while the engine is warming up to its operating temperature=if you give the fuel more "time" in the combustion chamber, then it has more time to finish its burning process before it exits out the exhaust system.

One might ask; Why don't diesel engines manufacturers all advance their timing?​

Anytime combustion chambers temperature go above 2500 degrees F, than nitrous oxide is formed, and the EPA requirements/restrictions come into play. Over the years, diesel engine mechanical compression ratios have had to be lowered(high comp ratio=more heat) and injection timing has been steadily becoming more and more retarded from what we had seen on earlier years of the same engine model.(Retarded timing= less "time" in combustion chamber BEFORE the exhaust valve opens and releases that heat and possibly unburn fuel into the exhaust or the turbo)Retarding timing helps control overall combustion temperatures inside the cylinder. Note: It does tend to spin the turbo faster because of the addt'l heat(expanding gases) with retarded timing, but the overall affect is a less efficient engine. You want the most amount of heat to stay in the cylinder to push down on the piston and not go out the exhaust, BUT then keep combustion temperatures below that 2500 degree threashold UNDER ALL OPERATING CONDITIONS as best as possible to pass EPA requirements to sell engines in the USA/Europe. This takes compromises when dealing with a mechanically operated fuel injection system as I see on JD parts for the 3720 tractor. Todays' engineers have it pretty tough to get good fuel economy but must pass EPA quidelines to sell engines. Sorry radman1 for getting long winded and a little off subject, I thought maybe some others might be able to use a little more indepth information on the timing issue.

Personally, I don't have a lot of hope for the timing adjustment, but I would like to see your JD dealer adjust the intake and exhaust valves. If the exhaust valves are too tight, then they open too soon on every cycle and let heat excape out the exhaust system. They will probably tell you that this is considered "preventive maintanence" and the cost to do this is at owner's expense, BUT under your situation, the JD rep may cover the cost. It won't hurt to ask. Note: it would take the valves to be extremely tight to be your one and only cause of this overcooling complaint, so don't get overly excited about this possibilty.​

 

[gemini5362]

When you buy the chips for diesel trucks such as duramax, fords or cummings. One of the things you have to worry about is exhaust temps getting to high. Do those chips not change engine timeing and pulse durations to the injectors along with turbo charger boost. Would that not affect the heat in the engine.

 

[dirtworksequip]

Radman, just a thought. What would you do to fix the problem IF your tractor was not still under warranty? Just curious as to what fix you would come up with?

 

[radman1]

Radman, just a thought. What would you do to fix the problem IF your tractor was not still under warranty? Just curious as to what fix you would come up with?

If I didn't have a block heater, I would directly route the return hose into the engine block on the left. There is a block plug there for the block heater. Unscrew the block plug and put in a fitting for a 5/8" heater hose. I could just remove my block heater and go this route. This would be and easy and hopefully quick fix.
2nd try to find a fitting to fit the opening where the oil filter cooler return water line goes into the water pump. Probably a "T" fitting to allow both the heater return hose and oil filter cooler line to both come into the same port on the water pump. I don't know if such a fitting exists or if there is enough room next to the engine/water pump.
3rd attempt would be to connect the return heater hose closer to the water pump on the radiator hose. The existing fitting could be moved about 6-8" closer to the water pump and thus further from the radiator. NAPA also has a heater hose fitting that can be directly placed into the radiator hose and mount this closer to the water pump - hopefully with in a few inches of the water pump.
4th try would be try to find a temp controlled fan blade clutch. This would require trial and error to find a part that would fit, more labor and cost.

Currently, I am using a vise grip clamped to the return heater hose to shut off the flow. Run the tractor for 10-20 minutes and remove the vise grip. Once everything is warmed up and the thermostat opens to heat the radiator water, I seem able to maintain the heat with the hotter thermostat. However, this works if the temps are in the 20's-30's and may not work if it gets really cold. I haven't tried this with temps below 25.

 

[Kahuna]

It appears you have a problem most do not experience with a cab and have made repeated trys in trying to fix it. Time to trade.

 

[hankus]

I see a lot of diesel vehicles that travel in colder climates, use front covers on their radiators to reduce cooling/maintain heat. I also saw this was the solution for Labrat in his post on 12/04. With the additional cooling capacity that the cab models' heater core provides, I would think that reducing the radiators cooling capacity in this manner would be an accepted practice.

 

[dirtworksequip]

radman, if it makes heat with the return hose clamped with vise grips shouldn't it make heat with the temp control knob set on OFF? I would start by checking that value. Part 31 is a water valve next to the heater core. Has anyone checked it? Are you getting any water flow thru the heater core?

Is there anything I can check out on my 3520/cab that would help you out?

 

[radman1]

radman, if it makes heat with the return hose clamped with vise grips shouldn't it make heat with the temp control knob set on OFF? I would start by checking that value. Part 31 is a water valve next to the heater core. Has anyone checked it? Are you getting any water flow thru the heater core?

Is there anything I can check out on my 3520/cab that would help you out?

From what JD told me, there is always some flow through the heater hose even when the heater valve is turned down all the way. The heater valve has been checked. Once the engine gets hot, the heater puts out more heat than I can handle. That would mean there is definitely flow through the heater core. The problem is getting, and if it gets colder, keeping the engine hot. There is a splice on the incoming heater hose near the cab. I bought a shut off valve to shut off the line so I don't have to pinch off the heater hose with a vise grip. I also figure since there is always flow in the heater hose, I can shut off the heater hose feed line in the summer when it gets warmer. Should help with cooling the cab by not having hot water circulating through the heater hoses. I do this on my 1978 corvette to help with cooling when I changed AC to R134 refrigerant from R12 (freon). R134 is about 20% less efficient than R12.
See my earlier long post with all of the temperature readings. Some of these were with the valve off, on and with the hose clamped off. Hottest engine temps are by far with the heater hose clamped off (170F).

 

[gemini5362]

since you have the valve in there have you tried just turning it so that you reduce the amount of flow through the heater and leaving it at that position all the time. I know the temp control valve does that but if there is water going through the heater core all the time maybe it is too much water even with the valve closed

 

[radman1]

gemini5362
I bought the valve last week but haven't installed it yet. Your idea maybe a good one, although I have tried to partially clamp the hose with a vise grip and it didn't seem to work well. However, the valve will let me do partial closer more precisely.

I got some crazy news today. My JD dealer is going out of business as of Jan 1. My tractor warranty issues will be reassigned to another dealer a little farther away. Employees were notified 1 week ago of closing which surprised all of them. Currently, they have my tractor but haven't changed the injector timing yet. They hope to do it tomorrow, but I figure they may just say forget it and let someone else deal with it. Feel kind of bad for the employees now looking for a job. Now I get to start all over again with someone else.