Prius Mods part 3.2 – DEFA SafeStart WarmUp engine block heater installation

A model wearing infection control goggles
Photographic proof that wearing eye protection does not make you look silly. (Photo credit: Wikipedia)

Epic.  First the epic adventure of sourcing and buying the thing, now comes the fitting.

Step 1. Eye Protection.  When you’re going to be under a car, wear eye protection.  I can’t stand those car restoration shows where no-one wears protective equipment and then someone cops an eyeful.

Step 2. Jack and stands or ramps?  I forgot to collect my ramps from Newcastle when I had the chance on Wednesday.  However, when I looked at a new pair at Repco, I found that I couldn’t drive the car onto them because of the very low front spoiler.  Jack and stands then.

Step 3. Remove the undertray.  If you count the pieces under the bumper, there’s three undertrays to help direct the air under the car.  The two front pieces and held by bolts mostly and the rest by push fasteners.  (When putting it back together, I left the dodgy fasteners near the outside so that it will be easier to replace them.)

You really only need to remove the rear-most undertray.  In fact you could probably install the EBH through the flap that gives access to change the oil.

However, removing all of the undertrays lets you inspect the whole engine bay and see any leaks, etc.  I found a lot of pebbles, rocks and broken glass in mine, but no leaks.

Step 4. Get to the back of the engine to find the rear of the engine block.  The place to fit is almost visible and accessible from either side of the drive-shaft.

Aim between the middle bolt and the exhaust pipe in the centre

Step 5. Offer up the heater and bracket.



Remarkably, the heater was happy to stay hanging in a vertical surface because of its shape.

Step 6. Clean the surfaces.  I just used window cleaner as there was just a bit of dirt.

The ridge that fits the heater is clearly visible. The bracket will attach to the bolt hole in the bottom right corner. Not much cleaning required.

Step 7. Cover the heater with supplied heat sink compound.  PC Overclockers may be shocked to see how much goop I’ve put on, but it will squish a bit.


Step 8. Fit the heater and offer up the bracket without tightening.  The bracket came with a 17mm bolt, however the instructions require reuse of the original bolt; here’s why…

DEFA bolt (left) was 17mm but original with dual-width thread was 14mm. Kincrome nut size tool invaluable

… the original bolt has two threads.  Here’s the finished installation


Tighten the bolt slowly so that you don’t damage the thread.

All that was left was the puzzle of how to wire it up.

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