"robby" wrote:

Hello, i am Robby from italy, sorry my english is not good.
I have a D6D SA (165 HP, engine 3306 PC pre-chambers unfortunately!!!!!) 6 gears Fw, 4 Rv, and D5B SA VHP (160 HP,engine 3306 DI) 6 Fw and 5 Rev.
D6 I have to purchase used from 2007 with 11000 hrs today’s 14000 and I have rebuild the motor, gear box, reducer and repainted,
D5 I have purchased new from Brazil and have 13000 hrs I rebuild to much the transmission and bevel (two times), too much power
Both to use to make plowing
The d5 is good (no good the transmission), the d6 I have make too power,3 spacer in the fuel screew, I don’t know how much is the power now,
but the problem is the warm temperature of the water engine when use in 3 th gear under stress in plowing. Have you any suggestion?

Hello Robby,
What happens when you drop down to 2nd gear? Could you tell us what lead up to your over heating problem? What is the outside temperature?
Bob

"edb" wrote:

Something simple to check is the thermostat outlet pipe--this is the cover that the top radiator hose connects to on top of the engine--Cat reduced the size of the hole to slow the water flow down thru the radiator so it could be cooled better. If the flow is too high the water is not in contact with the radiator tubes long enough to give up the heat efficiently. This smaller hole makes a big difference to the radiator efficiency.
Cheers,
Eddie B.



.

Hi ebd, I read this through a few times and decided that it didn't fit in with my (very basic) theories on thermodynamics! I did a bit of digging around and found why the restriction can have a beneficial effect on cooling - it doesn't appear to relate to the radiator per-se.

This is copied from an old news-group:

Mike wrote:
>
> The coolant has to remain in the radiator long enough to dissipate its
> heat. Removing the thermostat usually results in hotter temperatures,
> because the heat is not being efficiently transferred from the radiator to
> the air.

What some people will say in public. This is absolutely false, of
course. Try to conceive of blowing on something hot, say a spoonful
of soup, first slowly and then more rapidly. Which cools faster?
For extra credit, try imagining the same spoon with first slow and
then fast water moving across the bottom. Sheesh!

The issue with running without a thermostat is two-fold. The first
part is that the thermostat provides drag on the water flow. This
drag increases the backpressure the water pump and all of the engine
sees. This additional pressure, over and above the nominal 15 psi
static pressure the radiator cap sets, raises the boiling point of
the coolant. The reason this is important is that it suppresses
localized film boiling at hot spots such as around the exhaust
port. The transition from nucleatic boiling (bubbles of steam
originating from irregularities on the surface) to film boiling
(where the hot surface is coated with a film of steam) is called
Departure from Nucleatic Boiling or DNB. DNB is very bad, for steam
is a very good insulator compared to water. Once DNB occurs, the
area under the steam gets hotter because the steam doesn't remove
very much heat, adjacent metal which is still wetted heats from
conduction. DNB happens there. The process spreads until
substantially all the coolant-wetted surfaces are insulated by a
film of steam. The engine overheats. In addition, the buildup in
steam pressure forces the radiator cap open, bleeding coolant,
therefore making the situation worse.

The second issue is that of water pump cavitation and surge. If the
pump is operated at high RPM with insufficient head pressure
(provided by the frictional losses in the coolant passages and the
thermostat), there is a great likelihood that the pump will either
cavitate (localized boiling and/or degassing on the impeller) or
surge (an unstable flow regime). Either phenomena is destructive.
Cavitation's collapsing bubbles act like little sand blaster,
eroding away impeller material. Surge can do the same thing and in
addition, can vibration stress the impeller enough to break it.
Many times what looks like corrosion damage to the impeller,
especially when the housing is damage-free, is actually cavitation
damage.

The myth of velocity originated among those unschooled in physics or
thermodynamics, I suppose, because a common racer "solution" is to
press a fixed restriction into the thermostat housing neck when no
thermostat is desired. The conventional (but wrong) wisdom is that
the restriction "slows the water" as stated by the previous poster.
In reality, all it does is provide some more dynamic pressure in the
block by restricting the flow. The exact same result could be
accomplished (assuming the water pump doesn't surge or cavitate)
with a higher static pressure (cap pressure), assuming the system
could withstand it.

John




Regards Julian. (still a little confused:()

"bluox" wrote:

Hello Robby,
What happens when you drop down to 2nd gear? Could you tell us what lead up to your over heating problem? What is the outside temperature?
Bob

hello Bob,in the 2nd or 3th gear even when the engine is not 'under stress of instrument temperature is around half of the green, or so beyond. The outside temperature reaches 36-38 ° C day If the engine strains, instrument get near the red zone, just stand still a few minutes at 1000 rpm to make it back to mid-green of the instrument.

Is the fan blowing air forward? or back towrds the engine? For constant pulling, ag work, the engine will run cooler if the fan is pulling the air through the fins rather pushing it.

Hi Team,
Cat engineers worked out that full thermostat opening allowed the coolant to flow too fast in the 3306 system. They determined the best size orifice for the outlet and modified it as needed.
I had a overtaxed Gen Set and experimented with Cat's orifice size and could not improve on it. By going larger or smaller in size caused the cooling system to overheat sooner from the coolant flowing too fast or too slow thru the system.
The problem the Gen Set had turned out to be a re-cored radiator with less fins and tubes as per Cats; Specification for the Part Number tag on the core. So the core was under capacity for the engine application even though it was tagged with the correct P/No tag !!!
As others have said other factors can effect the cooling system's ability to reject/transfer heat.
BUT, as I originally said in a post above that an EASY THING TO CHECK is the orifice.
If the orifice is in place then we can take it from there, if NOT then maybe modify the pipe and see what you get.
We are finding that Robby is being confused by all the "Technical Talk" that is taking the theme of the thread away from the "simple checks" to get to the bottom of his problem.

Next thing might be is it really overheating, is the gauge accurate?

Here is the Thread from the Acme BB on this subject. Regardless of what the thermodynamics pundits say I have proven in practice that the orifice size in the 3306 cooling system is critical, all from experiments I have done on the job at The Dealer for Cat.


www.antiquecaterpillar.net/ACF_v2/showth...?t=9178&page=1&pp=10

Below is one of my posts from the above thread.

The orifice in the T/stat housing outlet from memory is about 1.1" It is used to slow down the coolant flow at full T/stat opening. It was found that the coolant was not in the radiator long enough to give up the majority of its heat, so leading to gradual system overheat at full loads.
I did experiment, at the Dealer, with orifice sizes and blocked open thermostat, on an over taxed genset running in high ambient temps. but could not improve on the standard size for flow rate and hence optimum cooling effect.
From this you can see that removing the T/stats from an overheating engine--depending on cooling system design and capacity-- can cause worse overheating and engine damage.
It turned out that the Rad. core had been recored with a low ambient capable core in England (cold climate) and the original Part No plate re-attached to the lesser core. After checking the fins per inch and number of tubes for the P/No core we got to the bottom of the problem. The genset was a low hour import. There were other problems with the enclosure--restricted air flow, unlagged exhaust-- etc.

I could go on about doing an Ambient Capability Test for the system but, we have not checked enough "simple/easy things" in a logical order to go that far yet.
Cheers,
Eddie B.

Speaking of "simple checks"...Has the thermostat been changed out? (if it has an oil cooler thermostat, check that too)

I had overheating problems on my D6c too. (powershift 10k model)
- The rad core wasn't very good so I replaced it....still had heating problem.
- I brazed in a washer in the upper rad tube as mentioned (1.1" diameter)...had no effect.
- The fuel may have been turned up since the machine seemed to have quite a bit of power....more power than it had traction.

The cure came after doing 3 things at the same time so I'm not sure which did the trick:
- Turned down the pump by changing shims.
- Removed the restriction in the upper rad. tube.
- Replaced the thermostat (which I should have done first)

Most of the time the temp runs in the middle of the green...maybe a little higher if working hard on a hot day.

The other thing that makes a lot of difference is if the rad gets full of dust....temp will start to climb. Blow it out with an air hose and it cools right off.

Robby, you said the gauge gets NEAR the red zone? Near the red is not overheating, I've seen engines that run a little hotter than others, but as long as it's not IN the red, & it shows no other signs of overheating, like boiling, you may be OK...if it rises to a certain level, then stays there, that might be your engine's "happy spot"...the gauge might just read a little higher than the gauge on your D5, gauges do vary. try comparing the temp of the 2 machines with a temp. gun, at the thermostat outlet or radiator inlet...

WOW, lot of good input but so far all the definitive data to work with is:
1. The engine has been rebuilt in recent past.
2. The rack settings appear to have been tweeked.
3. The radiator core has been changed.
4. Statement that it appears to run hotter under 3rd gear load.

Need some real temperature reading data to determine if in fact there is a problem.

"ROME/KG" wrote:

Is the fan blowing air forward? or back towrds the engine? For constant pulling, ag work, the engine will run cooler if the fan is pulling the air through the fins rather pushing it.

yes, the fan is blowing air forward.

Hello everyone, I am now really confused.
I found the temperatures:
external environment, 38 ° C.
tube that goes from the radiator thermostatic valve at the top, 85 ° C.
Water pump inlet pipe which is near the radiator at the bottom, 77 ° C.
Today I worked on soft ground, the instrument has always marked a little more than half of the green.
I calculated the flow section of the valve thermostatic, corresponds to the section of the washer to be applied to the pipe (hole 1.1 ").
The valve is new and opens to 80 ° C, the pump is ok, the radiator is new, filled with water and liquid anti-corrosion appropriate.
The oil coolers are clean. The belt does not slip.
The instrument for measuring the temperature is new

Confirmed that the phase of the injection pump, if it is not just a place can contribute to overheating the engine? 13.75 deg BTDC is correct? (I checked)
Thanks to all