Cooling system pressure problem

MYCHICADEE

MEMBER
1999 JEEP WRANGLER
4.0L
6 CYL
4WD
MANUAL
96,000 MILES

I did a cooling system overhaul and replaced the thermostat and gasket, water pump and gasket, radiator cap, and upper radiator hose (because it had a small indentation). And I did a radiator flush as well. After doing this the lower radiator hose started blowing off. At first I put it back on and made sure it was tight with the clamp. Well after it blew off two more times I replaced it too and another radiator cap. And on the very first drive it blew off as well. I also want to say that there was several days in between the first three times. What could be causing this to happen?

5 Replies

DANNY L

MECHANIC
5,648 POSTS

Hello, I am Danny.

Let me ask you a question first. Did you have the actual radiator pressure tested? Sounds to me like it is plugged up! If the radiator is not flowing enough CFM your new water pump will keep sucking the lower hose right off! However, It is possible you bought a defective thermostat. I can help you diagnose that too. Hope this helps and let me know your feedback.
Thanks for using 2CarPros.
Danny-

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

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Monday, October 15th, 2018 AT 4:18 AM

MYCHICADEE

MEMBER
5 POSTS

No, I did not have a pressure test done on the radiator. It is possible it could be clogged. I have had my Jeep thirteen years and I have only put a little over 50,000 miles on it. When I replaced the radiator hoses both of them had what looked like a rust coating inside. I flushed the radiator several times. I also opened the plug and put the water hose in the top and flushed it that way too. The water coming out was also a rust color. What can I do to make sure there is nothing else in the radiator clogging it up? Also when I put the new thermostat in I did not know that the little hole needed to be at the top. I have since fixed that.

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Monday, October 15th, 2018 AT 8:51 AM

KEN L

MASTER CERTIFIED MECHANIC
42,895 POSTS

Nice work, I agree with Danny the radiator could be plugged the only thing you can do is replace it. Also lets check for a blown head gasket.

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

This guide will walk you through the steps on how to replace the radiator:

https://www.2carpros.com/articles/how-to-replace-a-car-radiator

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.

Cheers, Ken

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Wednesday, October 17th, 2018 AT 11:25 AM

MYCHICADEE

MEMBER
5 POSTS

Here's an update. Since I made sure the thermostat was installed correctly (about a week) I haven't had any problems with the lower radiator hose. Until yesterday. Out of nowhere it ran hot. I pulled over immediately and lifted the hood. I could see and hear the water literally boiling in the overflow. I let it cool down and checked it. The water was not low. Both of the hoses were hot. The top one a little warmer than the bottom. From what I understand that's how they are supposed to feel? Im thinking your advice of a new radiator is the next step. If that doesn't solve the problem then maybe a for sale sign! Lol

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Wednesday, October 24th, 2018 AT 7:56 PM

KEN L

MASTER CERTIFIED MECHANIC
42,895 POSTS

It really sounds like the radiator is the issue. Here is a guide to help you step by step and diagrams below to show you on your car.

https://www.2carpros.com/articles/how-to-replace-a-car-radiator

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

Cheers, Ken

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