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Still overheating

Tiny
MARY CORDRAY STROUGH
  • MEMBER
  • 1989 CHEVROLET 2500
  • 5.7L
  • V8
  • 4WD
  • MANUAL
  • 260,000 MILES
My water pump blew out. So I picked up a new water pump and installed it. No problems with the installation. We filled it up and let it idle to operating temperature to make sure it ran right.
It made it to operating temperature and kept climbing until it was almost into the red and then went back down. We figured a air pocket but it has a vented reservoir so it should burp itself. It starts climbing again and this time it goes to the line before the red and goes back down.
We decided to get a new thermostat and gasket. We replaced those with the fail safe and higher end gasket. After that we noticed a leak near there but saw that it was coming from the upper radiator hose. So We replaced that as well.
We filled up the hose and finished installing it. There was no more leaks on the ground or on the engine.
Here is where it gets confusing. We decided to drive it a little to maybe help it burp. As I'm hitting the gas the temperature goes up slowly until the light comes on and it is overheating. I stop to the side of the road and it immediately goes back down. I even changed out the fan clutch. I am at a loss at why it is still overheating like it is.
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Sunday, August 25th, 2019 AT 2:42 AM

17 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

I would start by getting and infrared gun and take the temperature of the radiator. Take the temperature of the upper part of the radiator when it is hot and then the bottom. There should be around a 40-degree difference. If there is, then I would have a leak down test done to be sure a head gasket has not failed from the overheating.

https://www.2carpros.com/articles/head-gasket-blown-test

If the temperature change is not there, the radiator is clogged and needs to be replaced.

https://www.2carpros.com/articles/how-a-radiator-works

Roy
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Sunday, August 25th, 2019 AT 5:23 AM
Tiny
MARY CORDRAY STROUGH
  • MEMBER
  • 11 POSTS
I didn't have a radiator problem before my water pump quit. Is it possible that I received a faulty water pump? I did spend extra hours putting on a water pump before I figured out they gave me one for a 2wd instead of a 4wd. Apparently, it hooks up perfectly until you put the fan on and then the bolt pattern is just slightly off.
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Monday, August 26th, 2019 AT 1:12 PM
Tiny
ASEMASTER6371
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No, I doubt it. There is no difference between 2 wheel and 4 wheel.

From the overheating, debris may have got into the radiator and clogged it up. Do not dismiss this. It needs to be checked.

Roy
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Monday, August 26th, 2019 AT 1:21 PM
Tiny
MARY CORDRAY STROUGH
  • MEMBER
  • 11 POSTS
You are incorrect on the water pump. There is a difference on the water pump between the 2wd and the 4wd. They both hook up to the engine the same but the bolt pattern for the fan and fan clutch is slightly different but different enough that it will not install. You, unfortunately, will not figure that out until you try to put the water pump pulley on.
I'm not going to dismiss what you suggested. I was merely asking a question if that was possible.
I have been told by many mechanics that just because the part is new doesn't mean that it is good so never rule that out either.
I was also wondering how do you know which fan clutch is the right one. At the auto parts stores they show 3 different types and it says that they have different stamps but doesn't say what is the difference?
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Monday, August 26th, 2019 AT 10:38 PM
Tiny
ASEMASTER6371
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Okay, first, I have researched both 2 wheel drive and 4 wheel drive. The only manufacturer that lists a different number is AC Delco. The diameter is the same for both pumps on the pulley. There is no difference between the other 5 brands of pumps. They are the same for both 2 and 4 wheel drive.

As far as the clutch, yes, you need the rear axle ratio for the correct one. That is based on load. I would just get a heavy-duty clutch listed. There are reverse or clockwise and counterclockwise rotation but that depends on how the belt is routed.

There should be a part number on the old clutch that the parts store can match.

I did this for 50 years and never had an issue with these pumps. Yes, you could get a bad new pump but I doubt it. I doubt the pump is even your issue.

Remember, parts people sell parts and are not technicians. They do not work on vehicles as we do all day long.

Roy
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Tuesday, August 27th, 2019 AT 2:22 AM
Tiny
MARY CORDRAY STROUGH
  • MEMBER
  • 11 POSTS
I didn't say the diameter was different just the bolt pattern. I actually bought a AutoZone and not a AC Delco part.

There was no part number on the old clutch to match up with. They aren't listed by loads only stamp numbers which mine was not stamped. It also didn't list clockwise or counter clock wise.
I am going to check out the temperature on the radiator because that is what I was thinking. Maybe the new pump pushed something into the radiator to clog it.
The water pump was the first issue and now it just goes down to the next weakest link.
Some of the people at the auto parts places actually do work on their vehicles but you can tell which ones are full of it. One of the reasons I refuse to go to O'Riellys anymore.
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Tuesday, August 27th, 2019 AT 8:55 AM
Tiny
ASEMASTER6371
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That's what I said in a previous post about dirt getting into the radiator.

Roy
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Tuesday, August 27th, 2019 AT 8:57 AM
Tiny
MARY CORDRAY STROUGH
  • MEMBER
  • 11 POSTS
I changed the coolant temperature sensor.
I also checked the temperature on the radiator. While it is running there is very little difference between top and bottom and left and right in temperature but after we shut it off there is a huge difference from top to bottom.
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Tuesday, August 27th, 2019 AT 11:27 AM
Tiny
ASEMASTER6371
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Why did you change the temperature sensor? That had nothing to do with the overheating.

The temperatures are wrong. From your test, you need a radiator. The coolant is not circulating and being cooled down.

Roy
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Tuesday, August 27th, 2019 AT 12:47 PM
Tiny
MARY CORDRAY STROUGH
  • MEMBER
  • 11 POSTS
I just installed a new radiator and it is still overheating. The upper radiator hose is ice cold.
I'm at a lost at what to do.
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Tuesday, August 27th, 2019 AT 8:09 PM
Tiny
ASEMASTER6371
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Okay, the radiator may have been the root cause of failure for the combination of the overheating but you may have damaged the head gasket from the overheating.

You would need a leak down test done on each cylinder to see if compression pressure is leaking into the cooling system. This is a test the is done with the plugs removed. Shop air is injected into each cylinder, one by one, and watch for any coolant movement in the radiator with the cap off.

Roy
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Wednesday, August 28th, 2019 AT 2:06 AM
Tiny
MARY CORDRAY STROUGH
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I'm not losing coolant and there is no white smoke coming from the exhaust pipe.
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Wednesday, August 28th, 2019 AT 6:48 AM
Tiny
ASEMASTER6371
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Does not have to be leaking or smoking for the gasket to be bad.

When it is really bad, it will do both.

Roy
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Wednesday, August 28th, 2019 AT 8:39 AM
Tiny
MARY CORDRAY STROUGH
  • MEMBER
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Problem is fixed. I back flushed the block just in case something was blocking the flow. I also back flushed the heater core. I did do the pressure test which let me know the drain plug on the new radiator had issues so I had to replace the radiator again. It was completely stripped plug and hole.
I replaced the thermostat again since my vehicle overheated but the upper radiator hose was still cool. I slapped it all back together again. Burped it and now it runs like a champ. It is running slightly cooler than I am used to but better than ever. No more leaks anywhere. I also took the time since most of the things were taken off that I cleaned the engine very well.
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Thursday, August 29th, 2019 AT 11:00 PM
Tiny
ASEMASTER6371
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Good job. Glad it is fixed.

Roy
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Friday, August 30th, 2019 AT 4:32 AM
Tiny
MARY CORDRAY STROUGH
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  • 11 POSTS
Ran great for two weeks. It started to overheat and then it would cool back down and then do it all over again. I figured that the thermostat is failing so I replaced the thermostat. It did the same to that thermostat. I just went ahead since it was summer to just take the thermostat out. Now that it is getting colder I need to put it back in. I exchanged it out again to a fail safe thermostat and it overheated again. I have taken the intake manifold off and the valve covers. There is no evidence of blockage or any milkshake evidence. I returned the other thermostat and went to a different auto parts store to purchase a thermostat with a lower degree just in case it was a fault in the maker for that auto parts store. It only overheats if the thermostat is in.
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Saturday, November 2nd, 2019 AT 9:02 AM
Tiny
ASEMASTER6371
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You need to have the leak down test done.

Roy
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Saturday, November 2nd, 2019 AT 10:11 AM

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