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What is the proper way to perform a coolant service for the Evo X?
My Evo X is close to 10 years old and even though the OEM SLLC coolant still appears fantastic for its age, I'm planning to have the coolant replaced and/or flushed. I may also replace the plastic OEM radiator with a Mishimoto aluminum one, the hoses with Mishimoto silicone ones, and the clamps with Mishimoto constant tension worm gear (CTWG) ones.
The Service Manual Group 14 (excerpt below) recommends using a coolant evacuation tool (CET) MB991871 to perform fluid replacement only, instead of a proper coolant flush. A quick search shows that Mitsubishi's OEM SLLC coolant is actually a "hybrid organic & phosphate type," which cannot mix with silicate type coolants, and cannot mix with tap water. The SLLC has to be with distilled water only, free from minerals:
Originally Posted by ace33joe
As far as I know Mitsubishi LLC (long life coolant) is hybrid organic & phosphate type, and it is not supposed to be mixed with conventional silicate type as they can make some deposits.
Also phosphate types are known to cause scales when reacting with minerals in hard water, that is why Honda/Acura sells pre-diluted coolant so that people won't be putting any water with minerals.
Although many Asian makers use different colors, they are all phosphate-based, and that is why I use Hyundai LLC with purified water (available from drug stores). (Mitsubishi parts/chemicals are not available locally)
[...]
Aftermarket coolant makers are using organic only formula to make it compatible to all kinds of coolant types, but I personally prefer to use OEM types as I am sure Mitsubishi used all the hose/seals compatible with Phosphate type coolant.
Should I...?
A) Follow the Service Manual and, with a CET, perform fluid replacement only, using 2 jars of Mitsubishi SLLC prediluted 50/50.
This might be the common thing that Mitsubishi dealers do. To me it seems cautious and conservative, but wouldn't the remaining deposits cause an overheating problem in the near future?
B) Drain the coolant, flush the cooling system with distilled water, and fill up the radiator with an aftermarket antifreeze+coolant concentrate (such as Prestone AF2000). Then replace the fluid with a CET, using 2 jars of Mitsubishi SLLC prediluted 50/50.
This seems over-complicated, and I have to bring a lot of distilled water.
C) Drain the coolant, flush the cooling system with tap water, fill up the radiator with an aftermarket antifreeze+coolant concentrate (such as Prestone AF2000), and call it a day.
This is a common way to perform the coolant service. Many Evo X owners here appear to do it in this way. By using a compatible aftermarket antifreeze+coolant, it avoids the problem of Mitsubishi SLLC causing scales when contacting the minerals in tap water.
Originally Posted by Yxd68
Yes - flush/rinse with water. Garden hose variety. And lots of it.
Then when you're changing hoses and other coolant-related stuff, you only get your clo9thes, tools, floor, interior ... wet with clean water.
If your cooling systme is like totally cruded up with deposits, which is unlikely for a car of only 3 or so years of age, then you might want to use one of those cooling system cleaners. Follow their instructions.
Then rinse it all out with fresh water.
Lastly fill with 100% coolant and test the SG of the coolant (using a coolant tester). Shooting for 50% ratio. Since it's not easy to drain the block, there will still be lots of water remaining in the block after draining the rinse water out of the radiator. The one time I changed the coolant in my X, I had to add 100% coolant to get even close to 50%
What do you think is the proper way to perform a coolant service for our Evo X? Feel free to post your experience and outcomes. My thanks to your input in advance!
Last edited by Lightsaber; Feb 27, 2023 at 12:38 AM.
Reason: typo
Alright. So after consulting subject matter experts, here is what I went with:
Drain the coolant, flush the cooling system with tap water, blow off most water with compressed air, and fill it up with Prestone AF2000 concentrate and slightly less distilled water, aiming for a 50/50 mix.
This way I get an OAT coolant + distilled water mix that won't corrode for years, at a reasonable price. The Prestone is unlike the pricey Mitsubishi SLLC P-OAT coolant that's not even available here as a concentrated version. That said, the stock SLLC is still possibly the very best for our cars. Assuming a pass range from pH=9.0 to pH=6.5 and a fail range from pH=5.0 to below, mine has stayed at pH=7.0~7.5 or so after 9 years of service.
Parts I provided for my shop:
1x Mishimoto performance aluminium radiator for 5MT Evo X (MMRAD-EVO-10)
1x Mishimoto silicone hose kit (MMHOSE-EVO-10)
8x Mishimoto constant tension worm gear clamps 1.26"–2.13" (MMCLAMP–CTWG–54GD)
2x Mitsubishi OEM lower radiator support insulator bushings (MB605173)
1x Mitsubishi OEM thermostat (1305A802)
2x Prestone all vehicles concentrated anti-freeze/coolant with Cor-Guard 3.78L
2x Distilled water 4L
My Evo's hood is secured with AeroCatch hood pins. Unfortunately the aluminum strike pins have corroded badly, so I have to order new strike pins (SKU 117-1053) from AeroCatch as the pins would be extracted to access the radiator.
I ordered the new clamps because the stock clamps sometimes fail if you re-use them:
Originally Posted by pistolpete69916
I just did my hoses.. no you don't need to take off the front bumper, thats just wasting your time. You jack it up, take off the under panels, drain that $h!t, etc, take off the hoses.
Replace with new ones.. Re-use oem clamps, but i recommend the 'better' ones. The LOWER RIGHT elbow hose is kind of a &!#ch, but all you need is a long socket to get it to the bracket that holds it on. (This is the part where you need to take off the undertray while under the car) Only one bolt, youre home free.
You're going to need about a gallon or two of coolant. Don't waste it on AMSOIL "performance" coolant.
Peak 50/50 at autozone is good enough. Better yet, use oem. Just dont get !#c&ing Dexcool.
Make sure you keep some extra coolant in your trunk just in case you run into a leak. I was stranded for two hours the other day cause an OEM clamp popped right off.
Mishimoto has provided excellent advice that radiator hoses should use constant tension worm gear (CTWG) clamps only. They maintain the required tension throughout every heat cycle.
I'm quite pleased with the end result. The engine idles very smoothly. After cold start up, the coolant temperate bar rises slightly later than before, so I remind myself to be light on the gas pedal when it's cold. There are no rattles from the Mishimoto radiator. I'm peacefully sleeping like a baby at night.
Photos:
The Prestone coolant uses Organic Acid Technology (OAT) and is sold at a reasonable price.
Distilled water can be bought at drug stores for cheap.
The original SLLC coolant after 9 years, still firmly at pH=7~7.5 or so. Super long life indeed.
Mishimoto silicone hoses.
Coolant system flushed, new radiator installed.
New radiator (MMRAD-EVO-10). I favor this over the Mishimoto X-line version because the X-line version is too thick and requires cutting. This needs no cutting and is still much beefier than the stock one.
Passenger-side elbow of the Mishimoto radiator.
Last edited by Lightsaber; Mar 18, 2023 at 01:27 AM.
Reason: grammar
No, I don't think, even though the shop does have a coolant evac tool (CET). For my 9-year-old Evo, my mechanic recommends flushing the coolant system to remove any build-up and clogging. With the pressure hose, he can flush only with tap water. Because I want to dilute the coolant concentrate with distilled water only, he simply blew off the residual tap water with compressed air before refilling.
Jan 26, 2023, 09:13 PM
What is the proper way to perform a coolant service for the Evo X?
