Water Pump Questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

phanatic32212 · 05-29-2005, 03:53 PM

I am trying to diagnose my overheating problem. It won't boil over but it runs at about 210. The rad is cool to the touch while the engine is running. I just replaced the cap and the thermostat with a 180 degree but it still runs hot. When I check the pressure on the upper rad hose, it seems like the only pressure I get back is from the rubber hose pushing back. Water pump maybe? How much pressure should be on the top hose? Also what is the measurement for a short and long water pump? Thanks in advance.

**john** · 05-29-2005, 04:50 PM

Here is the diff between long and short pumps. I would check the temp with a thermometer , guage could be off. Also if you dont have pressure check the rad cap. John

fastwillie 696969 · 05-29-2005, 04:59 PM

i would check the radiator is the lower hose cold or hot ? possible plugged radiator and do you a fan clutch on ? are you using a shroud ? electric fan works great too
how many rows is the radiator ? hope this helps ya

Fred T · 05-29-2005, 06:24 PM

Sounds like a thermostat issue, or a broken impeller on the water pump. Is the thermostat right side up? Pointed side goes up. Another possibility is a collapsed lower radiator hose. With the radiator cap off you should be able to watch water flow through the radiator once the engine is warm.

phanatic32212 · 05-29-2005, 08:20 PM

I went out and checked the hoses and other stuff as you guys suggested. Here's the rundown: lower hose is hot, I guess I don't have a fan clutch, as the fan spins all the time, I am using a shroud, and I think I have a single maybe 2 core radiator (it's only about 1 1/2" thick), thermostat is good it don't kick in until 180. I can see the coolant level go down once the thermostat kicks in. The pump shaft spins pretty smooth by hand, with no noise or anything. Any other suggestions?

**VetteVet** · 05-29-2005, 10:15 PM

Quote:

Originally Posted by phanatic32212

When I check the pressure on the upper rad hose, it seems like the only pressure I get back is from the rubber hose pushing back. Water pump maybe? How much pressure should be on the top hose? Also what is the measurement for a short and long water pump? Thanks in advance.

The manual says you should feel the hose pulse back when you squeeze it if the pump is good. Like Fred says, pull the radiator cap and look for water flow. You can see the vertical columns of cores in the radiator,so just count them from front to back to see how many core rows you have. yours sounds
like a 2 core.

GloryHound · 05-29-2005, 10:34 PM

Just a little Caution note that was not mentioned that could easily be forgotten remove the cap while the engine is cool. boiling hot coolant and skin do not mix. You probably already knew this, but I've heard of people doing stupider stuff who you thought would have known better!

Now as for the problem: The upper hose should be hotter than the lower hose since the upper hose is your return. If it is not then you are having circuation problems. Also are you using a good mixture of coolant to water, sounds dumb but pure water or pure coolant will not cool an engine as efficently as coolant and water at the right mixture for your area. Also what does the coolant and water mixture look like. If it has a heavy rust color you could have to get the engine and radiator flushed to remove the rust deposites that could be blocking passages not only in the radiator but the engine also.

phanatic32212 · 05-29-2005, 10:59 PM

The coolant looks fresh (no rust or brown color), the pressure on the top hose is not as much as I think it should be. I guess I'll get a water pump tomorrow. Also, when I changed my gauges to the autometer ones, I didn't use the supplied sensor with the gauge, I just used the one that was already there. Could this be a problem? A sensor is a sensor, right? Thanks for all the help.

GloryHound · 05-29-2005, 11:41 PM

A sensor is a transducer that converts your 12V signal into a voltage that can be read by the meter for a given temperature. Nomally they are simular enough to use on all meters but also your old sensor could be bad and as I said normally they are interchangable, but who ever you bought the guage off of should be able to answer that question with thier tech support. Or you might just want to put the new sensor in and see what happens. They aren't hard to change on these trucks and the newer styles probably have a tighter tolerance if nothing else.

**VetteVet** · 05-29-2005, 11:43 PM

Quote:

Originally Posted by phanatic32212

The coolant looks fresh (no rust or brown color), the pressure on the top hose is not as much as I think it should be. I guess I'll get a water pump tomorrow. Also, when I changed my gauges to the autometer ones, I didn't use the supplied sensor with the gauge, I just used the one that was already there. Could this be a problem? A sensor is a sensor, right? Thanks for all the help.

Very possibly because the sensor is nothing but a variable resistor to ground. The hotter the coolant gets the less resistance to ground. The gauge may be calibrated to the autometer sensor.

70GMCer · 05-30-2005, 08:47 AM

I would most certainly try that sensor before taking the water pump off.......

phanatic32212 · 05-30-2005, 01:53 PM

I changed the temp sensor this morning...and VIOLA, gauges reads 180. Good thing I changed that before I chaged a water pump.

Lesson learned: Change out all parts supplied with the part you get.

Thanks for all of your help.
Jake

05-29-2005, 03:53 PM	#1
phanatic32212 It's Done When It Runs!! Join Date: Sep 2002 Location: Jacksonville, FL (Orange Park) Posts: 220	Water Pump Questions I am trying to diagnose my overheating problem. It won't boil over but it runs at about 210. The rad is cool to the touch while the engine is running. I just replaced the cap and the thermostat with a 180 degree but it still runs hot. When I check the pressure on the upper rad hose, it seems like the only pressure I get back is from the rubber hose pushing back. Water pump maybe? How much pressure should be on the top hose? Also what is the measurement for a short and long water pump? Thanks in advance. __________________ Or Give Me DEATH

05-29-2005, 04:50 PM	#2
john member #16 Join Date: Dec 1999 Location: Yuba City Ca. Posts: 3,618	Here is the diff between long and short pumps. I would check the temp with a thermometer , guage could be off. Also if you dont have pressure check the rad cap. John Attached Images __________________ john http://67-72chevytrucks.com/vboard/showgroups.php board vendors http://www.flickr.com/photos/1745471...7602865984234/ Last edited by john; 05-29-2005 at 05:14 PM.

05-29-2005, 04:59 PM	#3
fastwillie 696969 ~Rest In Peace~ Join Date: May 2005 Location: CALIFORNIA NOR CAL Posts: 9,707	i would check the radiator is the lower hose cold or hot ? possible plugged radiator and do you a fan clutch on ? are you using a shroud ? electric fan works great too how many rows is the radiator ? hope this helps ya __________________ is it fast ? it has a lighting bolt donut? B___H please, I can remove 90% of your so called "beauty" with a kleenex

05-29-2005, 06:24 PM	#4
Fred T Cantankerous Geezer Join Date: Aug 2002 Location: Bel Aire, KS Posts: 6,264	Sounds like a thermostat issue, or a broken impeller on the water pump. Is the thermostat right side up? Pointed side goes up. Another possibility is a collapsed lower radiator hose. With the radiator cap off you should be able to watch water flow through the radiator once the engine is warm. __________________ Fred There is no such thing as too much cam...just not enough engine.

05-29-2005, 08:20 PM	#5
phanatic32212 It's Done When It Runs!! Join Date: Sep 2002 Location: Jacksonville, FL (Orange Park) Posts: 220	I went out and checked the hoses and other stuff as you guys suggested. Here's the rundown: lower hose is hot, I guess I don't have a fan clutch, as the fan spins all the time, I am using a shroud, and I think I have a single maybe 2 core radiator (it's only about 1 1/2" thick), thermostat is good it don't kick in until 180. I can see the coolant level go down once the thermostat kicks in. The pump shaft spins pretty smooth by hand, with no noise or anything. Any other suggestions? __________________ Or Give Me DEATH

05-29-2005, 10:34 PM	#7
GloryHound Working on a Nova. Join Date: Nov 2002 Location: ## Posts: 506	Just a little Caution note that was not mentioned that could easily be forgotten remove the cap while the engine is cool. boiling hot coolant and skin do not mix. You probably already knew this, but I've heard of people doing stupider stuff who you thought would have known better! Now as for the problem: The upper hose should be hotter than the lower hose since the upper hose is your return. If it is not then you are having circuation problems. Also are you using a good mixture of coolant to water, sounds dumb but pure water or pure coolant will not cool an engine as efficently as coolant and water at the right mixture for your area. Also what does the coolant and water mixture look like. If it has a heavy rust color you could have to get the engine and radiator flushed to remove the rust deposites that could be blocking passages not only in the radiator but the engine also.

05-29-2005, 10:59 PM	#8
phanatic32212 It's Done When It Runs!! Join Date: Sep 2002 Location: Jacksonville, FL (Orange Park) Posts: 220	The coolant looks fresh (no rust or brown color), the pressure on the top hose is not as much as I think it should be. I guess I'll get a water pump tomorrow. Also, when I changed my gauges to the autometer ones, I didn't use the supplied sensor with the gauge, I just used the one that was already there. Could this be a problem? A sensor is a sensor, right? Thanks for all the help. __________________ Or Give Me DEATH

05-29-2005, 11:41 PM	#9
GloryHound Working on a Nova. Join Date: Nov 2002 Location: ## Posts: 506	A sensor is a transducer that converts your 12V signal into a voltage that can be read by the meter for a given temperature. Nomally they are simular enough to use on all meters but also your old sensor could be bad and as I said normally they are interchangable, but who ever you bought the guage off of should be able to answer that question with thier tech support. Or you might just want to put the new sensor in and see what happens. They aren't hard to change on these trucks and the newer styles probably have a tighter tolerance if nothing else.

05-30-2005, 08:47 AM	#11
70GMCer Senior Member Join Date: Apr 2005 Location: Joppa, Maryland Posts: 4,408	I would most certainly try that sensor before taking the water pump off....... __________________ 1997 GMC Sierra Ext 1965 Mustang

05-30-2005, 01:53 PM	#12
phanatic32212 It's Done When It Runs!! Join Date: Sep 2002 Location: Jacksonville, FL (Orange Park) Posts: 220	I changed the temp sensor this morning...and VIOLA, gauges reads 180. Good thing I changed that before I chaged a water pump. Lesson learned: Change out all parts supplied with the part you get. Thanks for all of your help. Jake __________________ Or Give Me DEATH



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