Mishimoto Radiator Install

All-aluminum radiators are a popular choice for race applications and cars with modified engines. My daily driver with stock m20 motor fits neither category but I’ve been diagnosing the common jumpy temp gauge and wanted to make sure my radiator is flowing freely and providing maximum cooling. Also, the super clean appearance of aluminum radiators appeals to my sense of aesthetics so I basically convinced myself to do this upgrade.

My criteria for the replacement radiator was improved cooling and OEM fitment. I set on the Mishimoto e30 / e36 radiator after recommendations from friends and finding only positive reviews in online BMW forums. Mishimoto offers a lifetime warranty which is comforting.

e30 Mishimoto radiator in box

However, my decision shouldn’t be taken as endorsement and I haven’t run this radiator long enough to provide a real product review. After I installed this my close friend and local e30 expert Eric Berger told me that he knows several people who have had these radiators fail. In some cases the failure resulted in motor damage: it’s “buyer beware” as always. For the record Eric recommends Behr.

Because of Eric’s emphatic warning I’m going to monitor this radiator very closely especially as it approaches the first year of service. I did some further internet searches and found few reports of failures with the Mishimoto products. Mostly I found complaints about fitment. The few cases I found of failure were related to running straight water (no coolant) for long periods of time and in some cases not even using distilled water. Since coolant lubricates the moving parts of the cooling system and iron in water reacts with aluminum I blame careless owners for those failures I read about. I’m not sure what the issues were with the other local guys who had failures.

IMG_9789

Build Quality and Fitment


I found the quality of the Mishimoto radiator to be good and I would rate it a 9/10. It loses points for two reasons. Firstly, some of the fins were bent and a couple near the top were sheared off out of the box. Radiators are delicate but I’d expect it to be perfect on arrival. There’s a tool that can fix bent fins so I guess I’ll buy one.

Secondly I found fitment to be imperfect. One of the support posts was angled slightly outward. From post edge to post edge the radiator should be 26″ across but because of this defect my Mishimoto radiator was 26.15″ across. The solution was to cut down one of the rubber radiator mounts so that it would still seat to the radiator support. I don’t like this solution as it looks sloppy and failure due to a weakened mount is a concern.

Not necessarily a show stopper but there’s no fan shroud for a mechanical m20 fan that fits on the Mishimoto. I mean, you can throw one on but there’s no where to zip tie or clip it onto the rad. I’m still researching that.

mishimoto e30 radiator mounts wrong fitment

Above: This post for the radiator mounts is angled incorrectly which caused improper fitment.

mishimoto e30 radiator fitment adjusting mounts with knife

Above: Cutting the passenger side rubber radiator mount for fitment.

Installation Notes


  • Installation was easy. It took 30 minutes to remove the hood and old radiator and another 45 minutes to install and reconnect the new radiator including the time it took to solve the problem with the radiator mounts. From start to finish including bleeding it took me 3 hours. I ran into no problems because my hoses are all fresh and flexible. Older hoses may cause more problems.
  • Don’t forget to buy high temp teflon tape for your fan switch. The radiator ships with an aluminum delete plug for the switch port.
  • The Mishimoto drains directly from the bottom of the rad. Draining will splash coolant off the radiator support and make a big mess. Some kind of petcock with a 12mm x 1.5 would help but there’s not much room to fit it.

Mishimoto radiator installed in my late model 1989 BMW 325i e30
Mishimoto radiator installed in my late model 1989 BMW 325i e30

Above: Mishimoto radiator installed in my 1989 BMW e30.

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October 5, 2014 mechanical, repairs