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Is it Hard to Change Radiator? (avoid these expensive mistakes)

Replacing your vehicle radiator isn’t the worst job, and with a little knowledge and the right tools, a home DIY mechanic can easily master it. That said, it is possible to mess this up badly, don’t panic. We won’t let that happen. I’m a mechanic, and I’ll walk you through the process.

Changing a car radiator is well within the scope of the home DIY mechanic; however, pay particular attention when adding coolant. Incorrectly bleeding the coolant system can result in overheating, head gasket failure, and engine failure.

In this post, you’ll get a flavor of what it’s like to change a car radiator. You’ll learn what tools you’ll need, and you’ll learn to avoid some very expensive mistakes.



Dangers of Changing Car Radiators

Yes, the headline is clickbait, but it’s all true. Messing up a radiator swap can have serious consonances for your engine and your wallet. I think you should know this right away before you begin. I don’t say this to discourage you; I do believe most owners of regular-type family cars can swap out their radiators.

If you own a top-end luxury car, sports car, or a big diesel pickup, forget about it. These types of vehicles are so compact under the hood you’ll be pulling your hair out 10 minutes into the job; best to bring it to a garage.

For everyone else, keep reading.

Ok, so how can we mess this up?

Engines are cooled in three main ways – the oil system, which carries heat away, airflow across the engine that helps remove heat, and finally, the coolant system. It’s critical and does all the heavy lifting when it comes to controlling engine temperature.

It consists of various components, all of which have a major role in the cooling process.

When working on a cooling system, it’s important to get a few things correct, and here they are:

  1. Fluid level
  2. Coolant strength
  3. Bleed procedure
  4. Fan operation

We won’t dwell on the negative, but we’ll quickly point out the four common ways working on a coolant system can go wrong; that way, we can simply do the opposite.

Fluid Level

Running the engine with insufficient coolant risks overheating the engine and possibly blowing the head gasket or, worse, the engine. A small leak at a coolant hose clamp is enough to start a domino effect.

Low coolant level

We’ll pay particular attention to coolant levels for a few days after the repair and check the garage floor for possible signs of coolant leaks.

Coolant Strength

Most coolant comes premixed, so you can’t get this wrong, but if you opt for the concentrate, you can mix the coolant too weak and as we know, come winter, our coolant may freeze and possibly crack the engine block. Ouch!

Bleed Procedure

This is the one most novices get wrong, and I can’t blame them. Some engines are difficult to bleed. Bleeding refers to the process of removing pockets of trapped air inside the coolant system. The problem with air pockets is that they prevent coolant from circulating in the system, so the engine overheats. I’ve seen this one claim a few engines.

We’ll pay particular attention to the bleed technique, and I’ll share a few mechanics hacks and a top tip for knowing when your system is bubble free.

Fan Operation

This is another simple mistake, forgetting to plug in the fan. No fan means when you hit peek city traffic, your temp gauge will climb and climb and hit the red, and you know how this story ends.

Yep, we’ll make dame sure your fan works because we’ll check it before we call it good.

That’s it, now let’s get stuck in!

What Tools do I Need to Change Radiator

The tool list isn’t huge. Some really useful tools make certain tasks a ton easier; I’ll list them in case you want to go pro. But I’ll give you the alternative tool recommendation also.

Here goes; you’ll need the following:

  • Remote hose clamp remover – really useful tool for those hard-to-reach hose clamps; otherwise, use suitable channel locks or pliers
  • Flexi hex head driver clamps – flexible jubilee clamps for hard-to-reach hose hex head jubilee or use a screwdriver or wrench set
  • Catch tray – for catching the old coolant, or just use an old basin
  • No spill funnel – Really useful tool to help minimize air locking coolant system when filling with fresh fluid from empty otherwise, just do a thorough job bleeding the system

You’ll find all these tools listed here on the “Coolant tools page.”

Removing the Radiator

This step will vary according to your vehicle. Stating the obvious isn’t ever helpful, but here it is anyway. Some vehicles will be trickier than others. I’d YouTube your particular model to get the heads up on the actual process before commencing.

Some vehicles may be too involved for the DIY mechanic; some may require removing the A/C condenser, for example, which isn’t practical as you’ll need a refringent recovery machine.

Anyhow, here’s a flavor of what a regular rad removal process looks like:

  • Pop hood
  • Jack front of the vehicle and use axle stands to support
  • Remove lower engine splash guard
  • Drain the radiator using the rad drain plug if fitted; otherwise, remove the lower hose clamp and remove the hose
  • Remove top hose clamp from rad
  • Unplug the rad fan and remove caul fasteners and remove the fan assembly
  • Remove the top shut aesthetic panel to access the rad fasteners
  • Remove top rad fasteners
  • Remove rad by lifting it vertically from its rubber feet mounts.

That wasn’t so bad!

Fitting the New Radiator

With the old rad removed, check to be sure they are the same, and remove any additional fittings from the old rad, such as rubber feet mounts or plastic shields, etc.


The fitting process is just the reverse, but do take care with the new radiator, they are delicate, and the fins are easily damaged.

Lubing the rubber feet mounts ease’s the fitting process.

What Coolant Type

All coolant isn’t the same. Some vehicles have a preference. Coolant, as you know, helps keep your engine cool in summer, and the anti-freezing additives help prevent freezing in colder conditions. That’s why coolant is often referred to as antifreeze; while technically, they are different ingredients, folks are really referring to the same thing – Coolant with an antifreeze mixture.

But the story doesn’t end there; coolant/antifreeze has two more important functions it contains additives that help lubricate internal coolant system seals and also an additive to help prevent system corrosion.

Using too much water in your coolant (weak mix) promotes corrosion which eats away at head gaskets, killing them prematurely.

Best to use the recommended coolant type and mix it (if applicable) to the correct strength. That said, I use and recommend Valvoline premixed to 50/50, meaning you just pour; no need to add water. I like it because it’s safe for all vehicle coolant systems and ok to mix with all coolant colors.

Valvoline coolant covers 15psi systems (most systems) from -34°F to 265°F. You can check it out here on the “Coolant tols page.”

If you decide to use concentrate, the following ratios are a guide. Best to follow the on-container mixing instructions.

50/50 refers to 50% water and 50% concentrated coolant; such a mix typically offers the following protection -45°F + 240°F. It’s not recommended to mix at less than 30% coolant or to mix at more than 70% coolant. Doing so compromises frost and heat protection.

Bleeding the Coolant System

This is by far the most important part of the process. That’s because an incorrectly bled system is a silent killer. Your car may drive fine, and the temp gauge may read normal or cool, but in fact, she’s boiling her head off.

Coolant system info graphic

I don’t say this to scare the bejesus out of you; I do so to get your attention. We need to get this right!

It’s not difficult; you just need to be mindful.

The process is as follows:

  • Run the engine at 2000 rpm for 5 – 10 minutes to help move trapped air
  • Vehicle temperature gauge indicating normal, verify heater is hot
  • Shut engine off
  • Allow the engine to cool before topping up coolant again if needed
  • Open coolant bleed screw. Commonly found on heater hoses at the firewall.
Coolant cap
  • Remove the reservoir cap
Car coolant
  • Fill coolant system
  • Close coolant bleed screw
Coolant hose
  • Squeezing the hoses helps move trapped air through the system
Hvac temperature controls
  • Fit reservoir cap
  • Run the engine with the heater set to hot and fan speed at high
Modern car
  • Run the engine at 2000 rpm for 5 – 10 minutes to help move trapped air
  • Continually check vehicle temperature gauge indicating normal.
Top up coolant
  • With consistent hot air from the heater, shut off the engine
  • Allow the engine to cool before topping up coolant again if needed

Some vehicles are a real pig to bleed, especially some older minivans with rear seat heater controls. Large diesel engine pick-ups take forever to heat up. If your vehicle heater fails to offer you heat after 10 minutes, take the vehicle on a test drive (as per below) to help remove trapped air.

When you have good heat at the heater vents, the bleed process is successful.

Test Driving

My old foreman said a job wasn’t complete until after the test drive shakedown, and he was never wrong. Before test-driving, check your coolant level. On the test drive, pay attention to the temp gauge and heater temperature. I like to drive a test circuit route close to the workshop instead of driving in one direction.

Other points to note:

  • A test drive should take more than 10 minutes to generate sufficient heat at the heater (if it does, return to the workshop and check the coolant level or for leaks)
  • Drive the vehicle as normal, avoid overstressing it
  • After the test drive, park the vehicle on level ground
  • Check fluid level again; if it needs a top-up, allow the engine to cool for ten minutes. (DO NOT Remove Coolant Cap on a Hot Coolant System – It will scald you)
  • Idle engine until rad fan operates (could take 15 to 30 minutes)
  • Check for leaks under the vehicle all the while
  • Finally, check the coolant level after the system has cooled

That’s it; nice work; job well done!

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