Yesterday I noticed a pool of coolant under my truck . I had no idea where it came from. After tightening the radiator hose and the hose port on the radiator,I started the truck. Didn't see a leak .

Today morning I drove to work and I noticed the coolant pool again.it seems to come from the radiator hose. . Does this mean it is a bad hose and needs to be swapped or is there an another place I need to look ?.

The truck is a 1989 Chevrolet S10 Blazer (2wd) with a 4.3 l V6 tbi engineenter image description here

  • If the hoses are original from the year 1989, it means you should change them now. No, I mean, you should have changed them yesterday, as a preventative maintenance. If you continue to drive such an old truck, do expect all kinds of rubber parts to fail. Including radiator hoses, gas lines, CV joint boots, power steering seals, belts, etc. It is either rubber or rust that determines the economical lifetime of a motor vehicle, and your truck is way past the expected lifetime. Fortunately, rubber is easier to fully repair than rust, usually.
    – juhist
    Jul 17, 2017 at 15:11

1 Answer 1


Cooling systems build pressure as they get hot.

You will need to isolate where the leak is coming from. Here are a few scenarios that could be in play.

  1. Radiator cap is not holding pressure and allowing overflow/discharge
  2. Radiator hose has a leak
  3. Radiator hose clamps may be corroded and unable to hold properly
  4. Water pump is leaking

If the hoses are very old (OEM), or bulging, they should be replaced as means of preventative maintenance.

Note: You may be able to rent/borrow a cooling system tester from your local parts store. This will allow you to apply pressure to the system without running the engine.

  • After I parked the vehicle I noticed there were two clear streams of coolant from the hose. I am going to go buy a new top hose for the radiator.. I was wondering, when replacing the top hose , do I need to drain the coolant ? Or wait till the engine is cold and then swap out the old hose with the new hose ?
    – goodcat
    Jul 17, 2017 at 20:43
  • It is so weird because my temp gauge still shows a 100 C which is the operating temp
    – goodcat
    Jul 17, 2017 at 20:47
  • @AllanVarkey if you don't want to make a mess, drain the coolant. If you don't drain the coolant or if there isn't a petcock on the radiator wait until it cools off.
    – Ben
    Jul 17, 2017 at 21:33
  • Just because the hose is leaking does not mean the cooling system is not working to cool the engine. It indicates the leak is small at this time and the system is still able to build pressure. It won't stay that way. I see from the image you added that the hose is bulging. If the other hose is of similar age/condition, I would suggest replacing both hoses while you have it drained.
    – CharlieRB
    Jul 18, 2017 at 11:26

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