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Water Pump/Thermostat Help ('99 XX)


Zero Knievel

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1 hour ago, RXX said:

I took a bunch of shit to the dump in my old pickup today. Only about 3, maybe 4 miles. It was pretty full, since I left the key on last month and the battery was dead. I tried to charge it last week, but the charger I grabbed had crapped out on me last year. Never got rid of it, just bought an exact replacement. Well, SIL had taken the good one without letting me know. Threw the junk one in the back of the truck.

well, finally charged it. With all the shit in the back, there was no room in the back for the 2-5 gallon (yellow) diesel cans I was gonna fill up with off-road diesel so I threw them in the cab.

fucker started overheating on me halfway there. I killed the engine and coasted when possible. When I threw all the junk out, I grabbed the cans to throw them in the back.

 

And uncovered a (yellow) empty antifreeze jug sitting in the floorboard. Fuck me. I forgot that happened to me LAST time I went to the dump. So I borrowed a gallon or so of water from the dump and went on my way. I will try to fix it over the next few weeks, without as much drama as the OP.

 

My question to you Nicolas Carnot wannabees is, did it make diddly-squat difference coasting with the engine killed? Why or why not? Atmospheric conditions pretty much STP. Low humidity, low 80's. V8 FI, not running AC (cause it's broke). Windows down, side vents wide open, sliding glass rear window open. No dogs, no beer. 

No dogs or beer, that's why you ran into trouble.

 

Humidity doesn't matter in this case (I think but Ill let mikesail correct me as I have no formal education on this shit).  High humidity makes you feel hotter because you rely on evaporation for cooling, a non-leaking engine cooling system has no evaporation cooling so it's just a heat exchange between the radiator and the air.  If done right the coasting technique can be very effective, I've done it several times.  The problem is that while coasting there's no coolant flow and if you have to power up hard to regain speed you put a rush of heat into the motor/coolant then stop the flow again when you shut down.  At the least the engine is going to experience some amount of thermal shock, but it'll be better than a melt-down.

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9 hours ago, jon haney said:

Actually, the speed of the water does make a difference.  You're assuming the temperature loss going through the radiator is the same as the temperature gain going through the engine.  This would be true for the given designed flow rate of said engine and radiator.  However, as the flow rate increases beyond the design window, less BTU is transferred to the air in the radiator.  Same thing happens in the engine, except for the fact that the metal of the engine will continue to get hotter and hotter, increasing the temperature differential between it and the water.  This increased differential means more BTU is transferred despite the flow rate.  Same goes for the radiator.  The big difference is that the radiator is transferring heat to the atmosphere, which unlike the engine, remains a constant temperature.  In other words, the rate of BTU exchange for the radiator is now less than the rate of BTU exchange for the engine.  Result:  Over-heating

If the pump was cavitating, wouldn't that slow the flow rate?  And yes, a flow-rate slower than the design window would also allow over-heating (but at a faster rate), because of too much pressure in the cooling system due to water boiling in the block and pushing past the radiator cap.

Water speed absolutely does make a difference, the faster it flows the more it'll cool, it has nothing to do with assumptions.  If the coolant is flowing though the radiator really fast it will return to the engine hotter than if it were moving slowly, but it's also moving through the engine really fast which means it can remove more heat more quickly.  Too much pressure in the system will not cause an over heat, the more pressure it can hold the higher the boiling point will be and the higher the boiling point the better.

 

It's no different than fan speed; a fan on low will remove xx amount of heat, on high it'll remove more heat.

 

Pump cavitation will slow the flow, and has nothing to do with the missing thermostat and the 'too much' flow theory.  The only possible relationship is that a restriction, like a thermostat, can increase the negative pressure at the pump and increase the odds of cavitation.  Keeping lots of flow to the pump and minimizing it's negative pressure will decrease the chance of cavitation.

 

If the coolant boils pushing past the cap that's a whole other problem, one that won't be caused by not having a simple thermostat like the one in the bird.  There are some systems where the thermostat also controls a by-pass route for the coolant and in those a missing thermostat can cause an overheat because it allows the coolant to recirculate within the engine rather than being forced to go to the radiator.  In some engines there's a 'restrictor plate' (I don't recall it's proper name) to handle that function instead of relying on the thermostat and I know first hand that a missing one can cause overheats at high RPM; my Ford 351C being one of those.

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14 hours ago, superhawk996 said:

 

 

If the coolant boils pushing past the cap that's a whole other problem, one that won't be caused by not having a simple thermostat like the one in the bird.  There are some systems where the thermostat also controls a by-pass route for the coolant and in those a missing thermostat can cause an overheat because it allows the coolant to recirculate within the engine rather than being forced to go to the radiator.  In some engines there's a 'restrictor plate' (I don't recall it's proper name) to handle that function instead of relying on the thermostat and I know first hand that a missing one can cause overheats at high RPM; my Ford 351C being one of those.

Bird does have a bypass thermostat, at least for the redbird and the 2003.

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I think 97 doesn't have that, might be the only year, and that's the one I was thinking of.  You're right about the majority of birds for sure, I forgot they'd changed in later models.

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On ‎10‎/‎31‎/‎2016 at 5:12 PM, mikesail said:

Sorry but not true. Should I call UCLA and give back my engineering degree? The heat flow relationships are true regardless of velocity, the part that changes is the delta temp in the parts of the system. At zero water flow all the heat stays where it is generated and the radiator is at it's coldest. At infinite water flow all parts of the fluid are the same temperature, this temperature being set by the thermal resistance of  the entire system and the heat source/sink temps. At any water flow between zero and infinite there will be a temperature gradient across the radiator as well as a gradient across the engine block. This gradient is proportional to the flow rate of the fluid. It likely is true that one might measure a difference in heat transfer as the water turbulence changes, but that is outside of our discussion topic. None of these concepts change as you go over or under the design flow rate until the flow slows to the point where boiling occurs, then it becomes a different system.

 

For those who believe that the flow rate affects the heat transfer I ask you this. How fast would the water need to flow before you could hold a metal pipe with 200 degree water in it? Do you really think that the pipe magically stays cool?

 

Yes, pump cavitation means that the flow rate drops and lessens the heat flow capability. We all agree there.

How is water turbulence "outside of the discussion topic"?  Unless you are referring to Zero's specific issue.

Fluid dynamics has everything to do with the proper design of a fluid cooling system for any engine.  I'm not a very good writer, so maybe something was lost in my explanation, but I've seen a lot of dummies remove thermostats and wonder why their engines over-heat.  Can you explain why that is, if faster water flow doesn't matter?

 

FYI, my engineering degree is from Oklahoma State University.  Not sure if that wins me the dick measuring contest, but it appeared to be important info in your post.  IDK. 

Edited by jon haney
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9 hours ago, jon haney said:

How is water turbulence "outside of the discussion topic"?  Unless you are referring to Zero's specific issue.

Fluid dynamics has everything to do with the proper design of a fluid cooling system for any engine.  I'm not a very good writer, so maybe something was lost in my explanation, but I've seen a lot of dummies remove thermostats and wonder why their engines over-heat.  Can you explain why that is, if faster water flow doesn't matter?

 

FYI, my engineering degree is from Oklahoma State University.  Not sure if that wins me the dick measuring contest, but it appeared to be important info in your post.  IDK. 

I'm not in any contest here, just trying to make clear what the real issues are, sorry that I came off that way.

 

Turbulence of flow is a given in any of these cooling systems, if the flow were laminar then the heat transfer might lessen.

 

Regarding the missing thermostat, I have read (from a water pump manufacturer) that the pump in this case will cavitate and thus lose pumping capability. Have not seen this myself but the story is quite reasonable. Certainly with a bypass thermostat missing you would have a serious problem just due to the bypass circuit being open.

 

Faster water flow is really no different than faster air flow, they are both fluids on opposite sides of the radiator. Heat transfer is set by temperature delta alone, the fluids velocity does not change how it conducts/radiates heat.

 

I'm a terrible writer myself, so I actually enjoy forcing myself to learn how to express thoughts correctly. As you point out the thermostat fallacy is common, hopefully this will help correct that.

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I've thought about this some more (too much), and have a hypothesis (just as an alternative to the cavitation thing) .  A fluid running down a tube, such as those in a radiator, has an average velocity across the cross-sectional area, with the velocity being slowest where the fluid touches the walls of the tube, due to friction.  As flow rate increases, the velocity down the center of each tube should be increasing at a faster rate than the fluid that is touching the sides.  So the volume of fluid that is actually releasing heat as it goes through the radiator is slightly reduced.  I know this isn't much, but it doesn't take much of a temperature rise above normal for a cascade effect to ensue.  Of course, this is assuming a laminar-type flow is maintained in the tubes.  A turbulent flow would actually help heat dissipation.

????

 

Edited by jon haney
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2 hours ago, jon haney said:

I've thought about this some more (too much), and have a hypothesis (just as an alternative to the cavitation thing) .  A fluid running down a tube, such as those in a radiator, has an average velocity across the cross-sectional area, with the velocity being slowest where the fluid touches the walls of the tube, due to friction.  As flow rate increases, the velocity down the center of each tube should be increasing at a faster rate than the fluid that is touching the sides.  So the volume of fluid that is actually releasing heat as it goes through the radiator is slightly reduced.  I know this isn't much, but it doesn't take much of a temperature rise above normal for a cascade effect to ensue.  Of course, this is assuming a laminar-type flow is maintained in the tubes.  A turbulent flow would actually help heat dissipation.

????

 

I totally agree that laminar flow would lessen the heat transfer. I'm confident that any engine coolant is well up into the turbulent flow region due to velocity, and it would take some very special plumbing to achieve laminar flow  even at a much lower flow rate.

 

I think you are stretching to find a "cascade" effect, until some non-linear phenomenon occurs all effects are proportional. I'll try to see if I can find a reliable reference for the cavitation issue. I can tell you about a  very high powered turbo motor thirty years ago that we pressurized to 30 psi in the cooling system because of the pump issue. I was not the designer but I can tell you that we had a pump that moved 50 gal in about 4 seconds as I recall. Trust me the coolant circulated very fast.

 

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Laaminar flow would be impossible in any case.

the layer intimate to the wall, as it absorbs heat from the wall, is comprised of molecules which will become more energetic, and since the molecules cannot vibrate or move in every direction, can only move away from the wall. The temp delta, would of course determine the magnitude of the movement. Actually there would be a plethora of these deltas, as the excitation of the molecules would be mitigated by not only the less energetic molecules in the adjacent layer, but also, in the absence of Maxwell's demon, there will be a "pull" of molecules to fill the new voids created by the exit of the recently excited and highly mobile molecules. 

And pressurizing the system, shit that just mucks it up even more, doesn't it?

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Quote

Low speed flows of air and water have been analyzed with a wide range of heat transfer rates. In addition to the mean velocity profile characteristics, variable viscosity and density terms in the stability equations also have considerable influence on the results of the stability and transition analysis.

 

What does you little Chevy pump attain, 5~15 GPM?

 

Quote

Keywords

Flow instabilities; Boundary-layer heat transfer; Laminar to turbulent transition

 

I'd worry way more about the insulating properties of the calc buildup and other crud that's mixed into the coolant over the years myself...

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Retention time in the radiator reduces its coolant temp, leading to cooler temp coolant being let into the engine when the thermostat opens, lowering the engine temp, and closing the thermostat, The speed of the water flow is set by the thermostat. The pump speed is set by the engine speed, and is bypassed when the thermostat is closed.

 

 

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6 hours ago, jon haney said:

I take it back,  I have not thought about this too much, but RXX sure has. LOL.

 

 

 

I sort of made all that up, based on my 1 year of teaching high school physics 35 years ago.

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  • 3 weeks later...

Well...here's the latest....

 

Replaced thermostat (as a precaution). 

 

Replaced fan switch sensor (new one tests okay, couldn't get old one to test). 

 

Drained and let sit a week or so with hoses disconnected (just was too lazy to get around to working on it). 

 

Radiator tested negative for ground.  I wired in a redundant ground wire to a working ground.  Now circuits will ground to the radiator...this should fix any problems with the sensor not turning on the fan, but I put my manual switch back on with it wired in parallel...just in case.

 

Put in the Evans prep fluid.  Bought 1 gallon.  Not even 1/2 gallon went in.  Capped it and started it up.  Engine revved for a while.  Temperature finally started going up.  Got close to H then suddenly dropped down to midway (thermostat must have opened up.  Slowly worked it's way towards H, but never quite got there and held steady.  Fan never came on.  Shut it down and let it cool so I can put in more of the prep fluid (working out air bubbles).  I'm not sure how much more went in, but I added some to the overflow tank and started it up again.  Bike eventually worked its way towards H.  FAN CAME ON BY ITSELF!  So, that's one problem fixed.  This is just with the prep fluid.

 

There's not a lot of instructions to follow on the label.

 

How long should I let the prep fluid say in the motor (to do its job)?

 

How much do I have to tear down the coolant system to get all of it out before putting in the Evans coolant?  I expect draining the whole system plus open the lower coolant hose to get what sits there, but the manual says the XX has drain holes at each cylinder.  Do I have to do those too?  I'm guessing the prep fluid is glycerol-based and won't evaporate if I let the system sit for a couple weeks with the cap off.

 

If I have to "blow out" the prep fluid, where should I do it from?

 

Thanks for the help.

Edited by Aunt Zero
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First,

I haven't done a complete drain, just a flush pulling the water pump drain and a lower hose.

 

My 01 manual shows .84 US gallon capacity.

Thats allot more than the .5 you say that you drained. Not a big deal for flush, but my reading on Evans says that you need all the coolant out.

 

 

image.jpegI would remove the radiator cap, to eliminate pressure build, and then warm up the bike to open the thermostat.

 

You can then drain the coolant, and prevent it from being trapped behind the thermostat.  I would probably remove a lower hose, and one to the wax unit too. 

 

 

image.jpegYou are correct, the manual talks about a block ( cylinder) drain.

The picture sucks.  Do us a favor and post a good picture when you find it.

 

I would reach out to Philip, or others who have done this before finishing.

 

Now I'm going for a ride to see how mine does with a new fuel filter.

 

 

Edited by redxxrdr
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I see no need for an auxiliary fan...not now that the fan is working as it should.  Indeed, once I "topped off" the prep fluid (got some more air out), the fan came on at a lower temperature.  So, air in the system will fuck up the fan doing it's job...it won't turn on as soon as it should (or ever).  Granted, it's in the 40s outside, but it's good to see the parts working together as they are supposed to for a change.

 

Here's a picture of the ground setup.  Don't know where the OEM ground to the radiator is, but at least now it's there.

IMG_3345.jpg

 

I painted a mark on the fan so I could easily see it spinning.  Tapped in to run a redundant fan switch.

IMG_3346.jpg

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Man, that header is close to the radiator.

 

Sitting in traffic on a decently hot day on the bridge in Sualt Sainte Marie watching my temp peg was no fun. Then having my stator go TI was icing on the cake....

 

It was probably already weak, but the heat did it in - IMHO.

 

You went to the trouble to put in a manual switch. It will be interesting to see how well it works. That would be easier than mounting a whole 'nother fan.

 

 

 

 

 

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1 hour ago, XXitanium said:

You went to the trouble to put in a manual switch. It will be interesting to see how well it works. That would be easier than mounting a whole 'nother fan.

 

Well, the switch was already there because the fan wasn't doing it's job.  I didn't want to remove it, so I wired it in parallel so should the need arise, it's still available.

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