Radiator cleaning and fin straightening write-up. | SwedeSpeed

Hello everyone. I cleaned my radiator and straightened some fins which provided an indicated 3-5 degree reduction in temps so I figured it was worth a small write up. Environment: Southern USA: 90+ degrees most days here recently.

What: Cleaned radiator and straightened bent fins.

Result: 3-5 degree reduction in indicated temps (obd2 gauge.) noticeably faster temperature reduction when off throttle. Well worth the minor investment and time even if the difference is small.

Tools required: Small pick and toothbrush (for fins), water hose + flat nozzle, turtle wax bug and tar remover.

Time: 3-4 hours without breaks. I did it over a day taking my time.

Step 1: Remove bumper.

Step 2: carefully spray radiator and intercooler with water to remove any loose dirt, bug remains, debris. I let it sit for a few minutes to soften any debris and then sprayed again before progressing.

Note: you WILL damage/bend the fins if you are not careful. the fins are semi-fragile and bend relatively easily. However, they can take a decent amount of water pressure/spray from a HOSE. DO NOT USE A PRESSURE WASHER. (just up the pressure slowly and get a feel for how much is safe. avoid spraying at an angle – shoot straight.)

Step 3: Utilize small pick and toothbrush to carefully remove any small rocks and tougher bits and begin straightening fins. Use judgement but if a dent/set of fins looks too far gone, it is safer to leave it. We aren’t going for perfection, just improvement. The pick I used was a hypertough pick set from walmart, specifically the 45 degree bend one and only inserted it about half way down the tip to straight fins. (see image below) The fins are organized in an accordian style so it will be up-down-up-down and so on.

Step 4: Spray radiator and intercooler with turtle wax bug and tar remover. let sit for 5-10 minutes before spraying off. (optional but helped: utilize toothbrush before spraying water to remove grime. a soft – normal bristle type and brush up and down. it doesn’t take that long to do the entire part of the radiator we are accessing.)

Step 5: (Optional but advised): after rinsing again. re-apply turtle wax bug and tar remover again and then lightly and quickly spray the radiator. this is to push the product deeper into the radiator to loosen any debris that is deeper within. let sit for 5-10 minutes before spraying off.

(For improved results, repeat step 4 or 5.)

Step 6: Spray and do final inspection. Reattach bumper.

Note: There will be a decent amount of water collected in the bottom of the fan shroud so don’t freak out of you hear water splashing when you turn the car on as it will get kicked out by the fan.

Reminder: Be gentle. it takes very very little force to straight the fins. if you think “Man, this fin/set of bent fins is taking a lot of force to straighten/get the pick under” it is better to just leave it and move on.

Style of water hose attachment with flat nozzle I used. similar product probably sold at your local Walmart/hardware store:

For reference:2008 c30 with 207k miles. I would spray the radiator when washing to remove debris but have never done a proper cleaning. The amount of bent fins was not an unexpected amount for my cars age and miles but enough to be noticeable visually. Pre-cleaning my gauge would read 203-208 on the interstate with windows down no AC. Post-cleaning 201-204. 90+ degree’s 60-80mph.