The radiator in my car is damaged. One tube has a severe gash in it. I need to drive the car about 100 km before I can get a replacement radiator installed and coolant drains too fast to reasonably refill the cooling system every so often (with water of course, I'm not going to be leaking antifreeze all the way!)

Can I, e.g.

  1. rip out some of the cooling fins around the damaged tube and crimp it shut on both sides of the gash or
  2. fill the gash completely with a high-temperature sealant

in order to (hopefully) dramatically impede the loss of coolant?

Will doing one or both of these things only cause the radiator to lose efficiency due to no flow going through a single tube, or will completely blocking the flow of one tube stop all coolant from flowing through the system?

I.e. are the tubes of a radiator run in series: enter image description here

or parallel: enter image description here ?

I imagine they are run in parallel and these are safe temporary fixes.

  • $\begingroup$ If you want to try this idea, leave the radiator cap off. Pressurizing the cooling system is almost guaranteed to "uncrimp" your attempts at a repair. $\endgroup$
    – alephzero
    Commented Jul 10, 2020 at 2:12
  • $\begingroup$ Done and noted! Thanks! $\endgroup$ Commented Jul 16, 2020 at 20:26

2 Answers 2


All (car) radiators are parallel, it is the only way to get the flow rate and reduce the fluid velocity in each tube sufficiently to allow the time for heat transfer.

However, some radiators are series parallel where each section is in series and the section has the small tubes in parallel. Not seen that in a car though.

If you can carefully « extract » enough of that damaged tube to put a small clamp on it that might help. But if the tube is copper/brass you can solder it reasonably easily, but most radiators are aluminium now which is more challenging.


Parallel, each tube just opens into the end-cap or top/bottom chamber ( On those I have seen, which is a bunch ,but they were all old copper/brass types).

  • $\begingroup$ Thanks very much for your answer! $\endgroup$ Commented Jul 16, 2020 at 20:27

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