Bob wrote in rec.autos.tech
Ok, somehow it seemed like you were the one that was having a problem understanding. Sorry, but perhaps the post helped some lurker understand his car a bit better.
Couple of thoughts..
First, I was always under the impression that the temp of the thermostat indicated when the thermostat would be *fully* open.. ie, a
195 thermostat is fully open at 195. It's flowing coolant at a lower temp, but it's not fully open until the indicated temp.Second.. on engine driven fan equipped vehicles I don't see much temp change once the vehicle has come up to operating temp.
On electric fan equipped engines though.. when I'm moving, the temp stays pretty much in one place. When sitting still with the AC compressor going (which forces the electric cooling fan to run) the temp still stays in pretty much the same place.
If I let the car idle without the cooling fan on, the temp will slowly increase to about the 'L' in NORMAL, then the cooling fan will come on and the temp will drop.
Normally, the temp stays around the 'N'.. so I'd say that I'm riding the thermostat most of the time (also watching the engine temp on the scan tool).
If you're running over the thermostat temp while running down the highway I'd say that there's a problem.. I wouldn't rely on the temp gauge to give me an accurate temp though; I use it more for trends.
Regards,
Jim
PS. No coffee yet this morning.. I HAVE written more coherent posts. .
But doesnt it have a temperature activated hydraulic clutch on the fan? Steve B.
I have both, two Jeeps.
One uses a temperature controlled hydraulic fan clutch 'with' an optional electric fan and the other uses a fixed fan.
I have managed to 'overheat' the temp controlled Jeep twice. Both times were off roading in 4 low in hot weather. Only enough for the red light to come on, not a boil over.
The first time was with the original fan clutch and the original radiator.
The second time was with a new radiator, t-stat and a new clutch for the rad fan.
My Jeep 'could' come with an optional electric fan to help cool things if it has AC in it. I have no AC, so no electric fan.
This means Jeep designed the radiator and the thermostat and the pump and fan all to 'just' be marginal for cooling. No freaking way were they thinking a 160 t-stat to run cooler 'or' an electric fan to run cooler. LOL, they use a 192.
If they didn't ride the line for overall flow and cooling, I would have an electric fan for that half of the radiator stock now wouldn't I?
They 'obviously' didn't think I needed that extra fan for cooling....
My CJ7 has a 4 blade fixed fan that sounds like a freaking airplane warming up with the choke on.
The fixed fan is just that, fixed. Go faster, it spins faster.
So that means it is always pulling the maximum through the rad. Wow, you would think a colder t-stat would make that one run colder for sure eh? Nope. Real life says the pump speed, rad and t-stat opening size are designed to keep it running at 210F.
Slow down and the fan and pump slow down, speed up and they speed up to match the extra heat pull off needed in theory.
I have a winch and Hella Black Magic driving lights on front blocking some air flow, so I can't run at or over 75 mph on a hot day for long, she wants to get up to boil over temps or 250F+ or so....
Slow down to 65 mpg and the temp drops back down low.
Again this is with a new rad and a new pump and any t-stat made for my engine....
I think I need to add a shroud to my fan now. It didn't come with one stock.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's"Mike Romain" wrote
My mistake! I keep forgetting that general automotive theory is based on what's happening with "your" Jeeps!
Ian
LOL!
Man I have a whole mess of friends with Jeeps and they all run at 210 too....
Gee, ya think that Nash, then Willys, then AMC and now Chrysler think the best temp for that engine just 'might' be 210 and they put the 192 or 195 t-stat in just to keep the thing hot?
I really find it funny that thermostats aren't understood better....
They just set the base line for the engine and the sensor needs. Engine demands are taken care of by extra fans, hydraulic heat clutches, etc....
How many engines have 2 fans? The Jeep 4.0 'does' for 'some' configurations.
Crap they can't need two fans if you just put a cold t-stat in right?
The engine 'has' to be this hot or it stays in choke mode and dumps gas into it, right?
Isn't that what this thread is all about? The snake oils sales guys saying run a colder t-stat, turn on the fans earlier, dick with the timing and get a nice punch in power 'in cold weather only' as it turns out because you keep it in choke....
What you said wasn't wrong when you 'qualified' it to a perfect rad draw as you well know.
Real life just don't work that way.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT'sshiden_Kai wrote in rec.autos.tech
How funny, Mike runs his jeep off road, which means low speed and little air flow, works the heck out of the engine, and then claims that the cooling system is marginal.
"Mike Romain" wrote
The only reason I had to qualify it is because you don't seem to understand plain english.
Ahhhh....."real life" = "what my jeeps do".
Ian
"Mike Romain" wrote
(laugh)....my goodness...you really do have no idea how this stuff works, do you?
Ian
This is what they claim the vehicle is designed for. If in fact it can't do the job it was designed for without overheating then the cooling system is marginal.
Steve B.
The cooling probably IS marginal for the way Mike uses it.. also, it ain't stock, and those lights and winch blocking airflow on the front might have something to do with it..
Regards,
Jim
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