Wrong Waterpump?

[restricted]

Have a 1998 k3500 7.4 . Water pump went out, replaced it, overheated within 15min, replaced thermostat but didn't help. I took new water pump off and took plate off back of new and old to compare propellers , they were opposite, so took it back bought another, before i put it on took back off to make sure propellers were same, they were so i installed the new one. Overheated in 15min again, I know there is not an air lock . I do see that there is a heavy duty water pump available , wondering if I need to try this or there is something I am missing.

 

Thanks

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[markw8]

How do you know it's not air locked? Water pumps are simple. Maybe time to look at the radiator?

 

Mark

[restricted]

How do you know it's not air locked? Water pumps are simple. Maybe time to look at the radiator?

 

Mark

 

I have loosened all the hoses , flushed it did the whole cap off thing. It didnt start overheating till i replaced the water pump, only reason i had to replace water pump is because it was leaking around front seal, it still kept it cool and never overheated.

[markw8]

It still sounds like there's air in it. Try taking the t-stat out and see what happens.

 

Mark

[restricted]

It still sounds like there's air in it. Try taking the t-stat out and see what happens.

 

Mark

 

 

Did, wont get over 110.

[thebandnerd03]

From what i have found with the 7.4 if there is a heavy duty option available go with it.

[markw8]

I'd say the t-stat isn't opening. Either it's bad or air locked in frt of it and won't get hot enough to open. Try drilling a 1/16" hole in the stat to let it vent.

 

Mark

[restricted]

I'd say the t-stat isn't opening. Either it's bad or air locked in frt of it and won't get hot enough to open. Try drilling a 1/16" hole in the stat to let it vent.

 

Mark

 

 

This is the 2cnd t-stat i have tried, but i will try the hole. Thanks

[gmtech4]

fill it up with the t stat out ,when its full at the t stat ,put on a new one,continue filling,--done, no air at all

 

most t stats have a little vent dont they??

[markw8]

fill it up with the t stat out ,when its full at the t stat ,put on a new one,continue filling,--done, no air at all

 

most t stats have a little vent dont they??

 

Just put one in an s-10 that didn't. Ive seen em both ways.

 

Mark

[Zembonez]

It still sounds like there's air in it. Try taking the t-stat out and see what happens.

 

Mark

 

 

Did, wont get over 110.

 

This proves that it's NOT the pump. Sounds like a thermostat problem.

[Silverado4x4]

This might sound stupid and people often do this, are you sure you put the thermostat right you can put them in upside down.

[restricted]

This might sound stupid and people often do this, are you sure you put the thermostat right you can put them in upside down.

 

 

Its in the correct way. But dont see how it could be the therm when it was fine before i changed the water pump. Didnt no if the heavy duty water pump moved more capacity or was just built heavier.

[markw8]

For 8 bucks try another t-stat and be done.

 

Mark

[Silverado4x4]

Or throw the T stat in some water in a pot on the stove with a temp gauge and see at what temp it opens or if it opens.