Author Topic: Cooling Conundrum  (Read 6101 times)

Offline quinn.goode

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Cooling Conundrum
« on: September 21, 2017, 01:23:55 PM »
Greetinf from Houston! First time posting here because I'm in a real bind. Lately I've been having issues with my 1984 c20 overheating. It has the original 350 that has had no major issues thus far. The truck will max out the temp guage with a simple trip around the block and I couldn't keep her cool.
So far I have:
-plugged all leaks and changed freeze plugs
-new water pump
-new thermostat
- and several flushes between those changes and burped the system each time.

I've noticed severe lag when trying to accelerate when she's reading hot. At idle the guage will get up to about 210 and driving only makes it worse...any suggestions on what to try next?
 

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Offline zieg85

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Re: Cooling Conundrum
« Reply #1 on: September 21, 2017, 01:51:44 PM »
New "wrong" water pump might be to blame.  The newer style runs in reverse although from the outside they look the same...  My $.02
Carl 
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1986 C10 under construction
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Offline Irish_Alley

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Re: Cooling Conundrum
« Reply #2 on: September 21, 2017, 02:02:37 PM »
did you just get the truck? what/when started these problems? are you sure its not a faulty gauge or sensor? is it an aftermarket sensor or gauge?
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Offline Irish_Alley

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Re: Cooling Conundrum
« Reply #3 on: September 21, 2017, 02:07:54 PM »
for testing the gauge http://forum.73-87chevytrucks.com/smforum/index.php?topic=25339.msg300093#new
for testing the sensor http://forum.73-87chevytrucks.com/smforum/index.php?topic=29996.0 (its for the ecm, but it should have about the same outcome with the ohms raising)
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

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Offline bd

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Re: Cooling Conundrum
« Reply #4 on: September 21, 2017, 02:12:24 PM »
And check the exhaust for excessive backpressure.  When an exhaust becomes restricted it can cause an engine to heat up rather quickly and overheat under load, depending on the severity of the restriction.  Make sure there isn't a restricted muffler or catalytic converter and that a double wall exhaust pipe hasn't collapsed internally.

Edited for clarity.
« Last Edit: September 21, 2017, 06:01:40 PM by bd »
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
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Offline quinn.goode

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Re: Cooling Conundrum
« Reply #5 on: September 21, 2017, 04:39:53 PM »
did you just get the truck? what/when started these problems? are you sure its not a faulty gauge or sensor? is it an aftermarket sensor or gauge?
I've had the truck a few years now. It's been my daily driver and the cooling issue just started up about a week ago.

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Offline quinn.goode

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Re: Cooling Conundrum
« Reply #6 on: September 21, 2017, 04:43:23 PM »
New "wrong" water pump might be to blame.  The newer style runs in reverse although from the outside they look the same...  My $.02
The old 350s used a clockwise rotation pump I believe and that's what I out back  on.

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Offline quinn.goode

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Re: Cooling Conundrum
« Reply #7 on: September 21, 2017, 04:44:31 PM »
for testing the gauge http://forum.73-87chevytrucks.com/smforum/index.php?topic=25339.msg300093#new
for testing the sensor http://forum.73-87chevytrucks.com/smforum/index.php?topic=29996.0 (its for the ecm, but it should have about the same outcome with the ohms raising)
Could I just use a multimeter to check the resistance coming from the sensor and if so what sort of resistance should I expect to see

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Offline VileZambonie

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Re: Cooling Conundrum
« Reply #8 on: September 21, 2017, 06:29:35 PM »
Just to clear up the water pump differences, the pulleys do not interchange. The hub flange and bolt pattern were changed when they reversed rotation.

When you say leaks were "plugged" that means what exactly? T-stat was replaced? Upper and lower hose gets hot?
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Offline quinn.goode

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Re: Cooling Conundrum
« Reply #9 on: September 21, 2017, 06:40:44 PM »
Just to clear up the water pump differences, the pulleys do not interchange. The hub flange and bolt pattern were changed when they reversed rotation.

When you say leaks were "plugged" that means what exactly? T-stat was replaced? Upper and lower hose gets hot?
Then I defiantly have the correct pump. I did drop in a fresh thermostat and both hoses do indeed get hot once engine gets up to temp. For the leaks I pulled the started and replaced the leaky freeze plug I could get to. The other leaky one was underneath a motor mount and pulling the motor is beyond my garage capabilities. So instead I poured half a can of leak stop in and let it do it's thing. That plugged the drip fro m the freeze plug and then I reflushed the system with heavy duty cooling system treatment. None of those changes had any effect on the fact that the truck still gets just as hot just as fast. I believe the guage readout is correct because there is some obvious lag and lack of  performance when the guage is showing higher temps

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Offline quinn.goode

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Re: Cooling Conundrum
« Reply #10 on: September 21, 2017, 06:42:36 PM »
And check the exhaust for excessive backpressure.  When an exhaust becomes restricted it can cause an engine to heat up rather quickly and overheat under load, depending on the severity of the restriction.  Make sure there isn't a restricted muffler or catalytic converter and that a double wall exhaust pipe hasn't collapsed internally.

Edited for clarity.
I'll check the pressure but I don't think that's my issue. The truck has a set of flowmaster duals and no cats to worry about and they both seem to be blowing fine.

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Offline VileZambonie

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Re: Cooling Conundrum
« Reply #11 on: September 22, 2017, 05:49:21 AM »
Sounds like you need to take it to a shop and have those core plugs replaced. You probably have a clogged radiator if you used leak stop.
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Offline quinn.goode

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Re: Cooling Conundrum
« Reply #12 on: September 22, 2017, 07:31:47 AM »
Sounds like you need to take it to a shop and have those core plugs replaced. You probably have a clogged radiator if you used leak stop.
Replacing a radiator seems pretty straight forward. I can try it but my issue from the beginning hasn't changed at all. It still runs and heats up exactly the same as it did prior to any leak stop or new parts.

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Offline bd

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Re: Cooling Conundrum
« Reply #13 on: September 22, 2017, 09:02:15 AM »
Inspect the front of the radiator for flattened fins that obstruct airflow.  Straighten bent fins as needed.  If the fins exhibit evidence of disintegration, replace the radiator or have it recored.  Start the engine and bring it to operating temperature.  With the engine running, place your hand against the driver side (left) front of the radiator and drag your hand toward the passenger side.  You should feel a gradual decrease in temperature with no "cold spots" as you drag your hand across.  Repeat this process across the entire front of the radiator.  If you feel an uneven change in temperature (cool spots) the radiator is plugged and needs to be rodded and repaired, recored or replaced.  There should be a net drop of about 20° F between the radiator inlet and outlet.

Remove the fan shroud.  Using a high flow air nozzle connected to a +120 PSI air source, methodically blow the accumulated bugs, feathers and crud out of the radiator fins being careful not to flatten any fins.  If the vehicle has A/C, remove the upper radiator support plate to reveal the gap between the condenser and radiator and use a 36" long air wand to blow out the fins.  Repeat the process on the condenser.

And, I agree...

Sounds like you need to take it to a shop and have those core plugs replaced.  You probably have a clogged radiator if you used leak stop.

Replace the core plugs and followed by a thorough flush.  Stop leak in a compromised radiator exacerbates overheating issues.  It may not be the primary cause, but adding constipation sauce makes a bad situation worse. 
« Last Edit: September 22, 2017, 09:10:36 AM by bd »
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline quinn.goode

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Re: Cooling Conundrum
« Reply #14 on: September 22, 2017, 11:27:15 AM »
Inspect the front of the radiator for flattened fins that obstruct airflow.  Straighten bent fins as needed.  If the fins exhibit evidence of disintegration, replace the radiator or have it recored.  Start the engine and bring it to operating temperature.  With the engine running, place your hand against the driver side (left) front of the radiator and drag your hand toward the passenger side.  You should feel a gradual decrease in temperature with no "cold spots" as you drag your hand across.  Repeat this process across the entire front of the radiator.  If you feel an uneven change in temperature (cool spots) the radiator is plugged and needs to be rodded and repaired, recored or replaced.  There should be a net drop of about 20° F between the radiator inlet and outlet.

Remove the fan shroud.  Using a high flow air nozzle connected to a +120 PSI air source, methodically blow the accumulated bugs, feathers and crud out of the radiator fins being careful not to flatten any fins.  If the vehicle has A/C, remove the upper radiator support plate to reveal the gap between the condenser and radiator and use a 36" long air wand to blow out the fins.  Repeat the process on the condenser.

And, I agree...

Sounds like you need to take it to a shop and have those core plugs replaced.  You probably have a clogged radiator if you used leak stop.

Replace the core plugs and followed by a thorough flush.  Stop leak in a compromised radiator exacerbates overheating issues.  It may not be the primary cause, but adding constipation sauce makes a bad situation worse.
Okay I'll give it a try. Thanks for the suggestions!

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