73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: quinn.goode on September 21, 2017, 01:23:55 pm
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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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New "wrong" water pump might be to blame. The newer style runs in reverse although from the outside they look the same... My $.02
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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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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)
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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.
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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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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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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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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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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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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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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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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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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.
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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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Did it run hot before you used the stop leak?
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Did it run hot before you used the stop leak?
Yeah. I feel like through the flushing and stop leak and flushing that I just moved a clog from one part of my cooling system to the radiator and that's why I've been having trouble pinpoint my problem area.
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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?
Sent from my SM-G950U1 using Tapatalk
I think the cooling was the least of my problems. Now fearing the worst...came home after letting the truck sit over the weekend. Started her up...barely ran...slowly overheated and after a few light revs to see if she'll kick into a decent idle I noticed water on the ground under the passenger side tail pipe. Upon further inspection the dark water had spewed from the exhaust and the part of the pipe up front by the starter was covered in blown out oil. She's started to smoke more since my cooling issues began and I believe I have a blown head gasket and or cracked block. It's obvious now that my cooling issue was just one part of a much bigger problem and just the most obvious seeing how the truck has always smoked a bit before it was warmed up. I have been fighting this possibility as much as I could but I don't think there is anything left to do. I think it's time for a new motor :((https://uploads.tapatalk-cdn.com/20170925/a273ff8f6e28bfd3d05bafba76f68a0c.jpg)(https://uploads.tapatalk-cdn.com/20170925/d37b0cc1a58900f7a5827cf96661b351.jpg)
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Are you still losing water ? If not I would replace the radiator and I agree any kind of stopleak is asking for trouble. If replacing the radiator does it . I would start getting estimates on those freeze out plugs you can't get to. BECAUSE the stop leak will eventually fail.
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Are you still losing water ? If not I would replace the radiator and I agree any kind of stopleak is asking for trouble. If replacing the radiator does it . I would start getting estimates on those freeze out plugs you can't get to. BECAUSE the stop leak will eventually fail.
chevy heart beat of America
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I didn't realize this went past one page. So for your trouble. Would love to see pics of your trucks.
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Are you still losing water ? If not I would replace the radiator and I agree any kind of stopleak is asking for trouble. If replacing the radiator does it . I would start getting estimates on those freeze out plugs you can't get to. BECAUSE the stop leak will eventually fail.
Yeah I was losing water like crazy. I think my problem is bigger because the engine kept chugging water from the radiator and began dumping it out of the exhaust pipe. My stop leak was only on for a day and was then thoroughly flushed. I ran the truck while filling the radiator and black oily water was just spewing from the passenger exhaust as fast as I could full the radiator.
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Sounds like a intake gasket or possibly a warped, cracked head or blown head gasket
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How hot did it get? If you got it real hot it very well could be a blowed head gasket probaly with a warped head. So when you take the head off you'll need to haverify it manifluxed to check for a Crack and have them check to see if it's warp. TI would go ahead pull intake and replace the intake gasket as well. Not alot of money (probaly around a 100 to 150 ) but will take you a couple days to do it.
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How hot did it get? If you got it real hot it very well could be a blowed head gasket probaly with a warped head. So when you take the head off you'll need to haverify it manifluxed to check for a Crack and have them check to see if it's warp. TI would go ahead pull intake and replace the intake gasket as well. Not alot of money (probaly around a 100 to 150 ) but will take you a couple days to do it.
I know a new head gasket is a relatively cheap fix but with all my other issues with the motor (oil leaks, blow by, head gasket, heavily corroded cooling channels, timing troubles, exhaust manifolds and gaskets) I think it's best to spend the 5k on a crate 350 and upgrade. I need a motor that's reliable and that I can count on for longer trips and occasionally hauling and everything between. Plus I'm looking forward to the extra performance and clean looks.
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