Prius Mods part 3.4 – DEFA SafeStart finally installed!

I have finally installed the DEFA SafeStart permanently.  We left the story at Prius Mods part 3.3 – DEFA SafeStart WarmUp cable installation with the cable attached to the coolant overflow bottle with a cable tie.  To warm the engine I had to open the bonnet (hood) to fit and remove the power cable.  Not ideal.

I just finished fitting a lower grill block (See Prius Mods part 4 – later) when I decided to fit the cable once and for all.  I was going to have to find a way to route the cable from the upper grill (necessitated by blocking the lower grill) to the EBH.

Note: The official DEFA fitting instructions for the Prius put the socket in the lower grill, but don’t indicate how to route the cable.  My  method doesn’t leave much slack in the cable, but it isn’t stretched.

DEFA Connector Cable with fasteners. Note that “A” will be on the outside, there’s no O-ring and fastener “F” will be fitted backwards.

Step 1: I had to remove cable from EBH.  Fortunately, I could reach over the engine and down to the back of the block to remove the cable.  YAMV (Your Arm-age May Vary)

Tools: Pliers, Kincrome panel levers, Supatool 10mm socket with ratchet handle and ratchet wheel, pearl catch
Pop panel pins to remove cover. There’s 9 more pop pins and two bolts hiding under here.

Step 2: Remove the 3 pop pins and the front cover.  Underneath you’ll find 9 similar pop pins and two 10mm bolts holding the top of the bumper in place.  When finished, you should be able to separate the front panel far enough forward to slide your arm between the radiator and the grill.  If not, get a small urchin to help you.

Some things unclip to make replacing a headlamp bulb easier/possible. For this job, remove the lot.

Step 3: Make space.  Remove this lot and you’ll have adequate.

  1. Unclip the hose from the coolant overflow bottle (not shown)
  2. Remove the 2 x 10 mm bolts from behind the airbox
  3. Remove the 10mm bolt holding the airbox and clip
  4. Unclip the hose from its bracket
  5. Remove the airbox by twisting slightly and pulling to the left to separate it from the air-cleaner housing.

Step 4: The socket will not fit through the grill, so you’ll have to feed it in from the outside.  Fit part “A” (three pins facing out) to the cable.  Slide the cable into the grille; it will bulge a little.  Feed part “F” backwards, so that the thread will register, and tighten.

Step 5: Finding the gap around the radiator is not easy.  You think you’ve found it and then you’re blocked by a plastic bracket in front of the radiator.  Hint: Lift the inverter coolant (?) hose and feed the pearl catch or similar tool through the gap.

Looking from the rear – The gap between the radiator and body is just big enough for two

Step 6: Attach the cable to the pearl catch and gently pull the cable through the gap.  I used some 13mm pipe insulation to protect the cable.  A bit of fettling and it’s in place.

Cable run, protected by 13mm pipe insulation passes over an A/C line and the engine mount.  Earth lead is temporarily taped to the negative charging terminal

Step 7: Run the cable down the right-hand-side of the engine. (“Right” as seen from the rear of the car.)  I used another length of pipe insulation to “attach” the cable to the engine mount.  Note: Check as you go that you aren’t twisting or stretching the cable.

Step 8: Attach the cable to the EBH.  I could do this by reaching over the engine from above.  Hint: The earth cable is at the bottom of the plug and should line up to the bottom of the socket on the EBH.  Of course, you can always see better from under the car.

Step 9: Put everything back where you found it.  Note: I use the 10mm bolt that attaches the airbox to the engine mount to attach the earth lead.

DEFA SafeStart socket mounted in the upper grill – Prius NVW30


Prius Mods part 3.3 – DEFA SafeStart WarmUp cable installation

The engine block heater installation went remarkably well.  Compared to the installation of the Toyota Canada EBH from the top, which could involve removal of the wipers, windscreen tray, various brackets, lots of wiring and some skin, the DEFA installation from the bottom is a breeze.  (There is a way of installing the Toyota EBH from the bottom, but the top-down method seems to be the most popular.)  If my previous post didn’t convey the ease with which one may slide under a car, remove those pesky plastic push-pins holding the undertray and pop something onto the rear of the engine block, then please re-read; you’ve obviously missed the message.  Or the irony.

Which way for the cable?

Since the Toyota EBH is towards the top, it makes sense to route the cable up and to the left.  (By convention, “left” is when viewed from the rear of the car.  So an Australian car is Right-Hand Drive and an American or European car is Left-Hand Drive.) The cable terminates in a simple earthed plug, which is coiled up against the wing when not in use.

So, do I snake through the high voltage lines and exhaust manifold from the left (right in this picture) or dice with A/C and brake lines on the right (left in this picture)?

Since the DEFA EBH will fit about a dozen cars with similar engines, the instructions don’t specify a single route for the connector cable.  The instructions merely warn to keep the connector cable away from Air Conditioning and brake lines.  Taking that somewhat literally, I tried to find a path to the left of the engine, the opposite side to the A/C and Brake lines.  If I could only get under the exhaust manifold and support the cable far from it, I should be right from there.

Adding to the fun is that the cable has a large, weatherproof socket at one end; read, non-detachable socket at one end.  So I started by feeding it through the grille first and then back to the EBH (somehow).  There was a nice gap in the foam surround on the left of the radiator too.  I reached up from the fog lamp access flap to direct the cable up.  But there was just too much cabling from there and no real sight-lines and since my pearl-catcher on a stick was missing, there was no easy way to feed the cable down to the rear of the block.  I spent an hour or more trying various permutations of origin, fastener and route but none seemed to work.  The one that seemed to be out of contention was from the right-hand side on account of the A/C lines attached to the front of the radiator.  Getting late, I tidied up and waited for another day.

Bonus: I found the fog lamp adjustment screws and turned them so that the light actually goes in front of the car instead of below it!

DEFA socket test fitting in the bottom grille. The left-hand side seemed to be the best option at first.  Would have been a nice spot, I thought.  Then I thought, “why are all those pebbles jammed under the grille?”

New day, fresh start.  (Or should that be SafeStart?)

Next day I decided to fit the cable no matter what, even if it was a temporary fix accessed by opening the bonnet (hood).  I could play around on top of the engine as long as I wanted and only needed to pull apart the bottom for the relatively easy part of plugged the cable into the EBH once the route was determined.

Here’s where the belt-less engine design goes from merely being a technological wonder to become a really nice idea.  The right-hand side of the engine has a good 120mm of clearance between it and the inner wing.  The DEFA instructions that warned of not touching the A/C lines were actually telling me which route to take.

Back under the block and looking from many angles, the amount of space to play in became obvious.  Without a 3D model to work with you don’t realise that there’s a good armful of space.  Yes, there’s a steering column (RHD car) and the crank pulley (belt-less) to contend with, but they are far away.  I fed the cable down from the engine mount… and suddenly discovered the ideal earth mount close to the negative battery charging terminal. (There are no other holes or bolts small enough to attach the earth wire at the bottom of the engine.) From underneath I attached the cable to the EBH and checked the clearance.  HEAPS! There’s a clear run from the bottom with a lot of space between it and the A/C and brake lines.  What was I worrying about?

Looking up: View from the right-hand side of the block upwards, shows a lot of space for the cable. Bonnet (red) is in the bottom right and crank pulley (belt-less, remember) is in the bottom left.
Looking down: Lots of space. A/C lines run horizontally on the right (left of picture) avoiding the cable by a wide margin. Engine mount at bottom of picture.
The final, temporary fitting. Cable zip-tied to engine mount, earth lead attached near negative battery charging terminal (bottom right). Cable looped around coolant bottle and zip-tied for some degree of fastening. Dreaded A/C lines (centre) appear close, but are clear.

The final, temporary fitting is not ideal, but it works.  I have to open the bonnet to access the plug, but at least it is out of the weather.

Plug-in test

I used my Watts Clever power meter to check the power, which sat on 328W, slightly over the 300W specification and current was 1.37A at 240V (P=IV).

Temperature test

Since the Prius does not have a temperature gauge, I have to use my Garmin 2460 LT with ecoroute HD, which takes some 10-20 seconds for the gauge to display.  After 30 minutes, engine warmed from estimated 15°c to 30°c.  (The engine was running for about 10 seconds and read 32°c when the gauge appeared.)  Subsequent tests show a change from about 6°c to over 30°c in just under 2 hours.  I am yet to test from cold for the maximum 3 hours (the temperature does not rise after that) to see how hot the engine block can get.

So, why did I bother again?

The benefit on these cold mornings is that I can start-stop at the top of my hill and can use the heater earlier.  The difference in fuel consumption can’t be quantified without an OBDCII data logger tracking every variable.  A back of the envelop calculation suggests that 20¢ of electricity (3 hours) could save 15¢ of fuel (at Australia’s high electricity and fuel prices), which at face value seems silly.  But that simple maths doesn’t account for reduced emissions, less wear, easier start-stop, quick heater response and quick acceleration response.  Confirmation bias might skew my thinking of how quickly I’ll pay the AUD 280 back, so I shouldn’t comment… except to say that for the Saturday morning run to drop off Chikako at work and then to the dog park here’s the difference between a warm engine (30°c) and a cold one (10°c):

  • Before: 19.3km Cons: 3.8l/100km Avg: 40km/h (74.3 mpg(Imp) 62.2 mpg(US) 26.32 km/l)
  • After: 19.1km Cons: 3.1l/100km Avg: 42km/h (91.1 mpg(Imp) 76.2 mpg(US) 32.3km/l)

Any worries?

Removed what appeared to be several kilograms of debris, rocks, pebbles, grass, leaves and broken glass from the undertrays. Might look into the crash history of the car.

Read more:

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.

Prius mods part 3.1 – DEFA Engine Block Heater

Finally. After several weeks of postage (preceded by a month or two of umming and ahhing) I received the DEFA SafeStart engine block heater (EBH) I’ve been waiting for.

To recap, an EBH attaches to the engine and is plugged into the mains. Some designs attach to the oil sump or sit inline to a coolant hose. Originally used in extreme cold conditions to allow an engine to start at all, EBH are now being promoted to improve fuel consumption and emissions. For the Prius the particular advantage is that the car can move to a higher “stage” faster and therefore reach efficient operation sooner.

DEFA SafeStart engine heater, connection kit and loads of catalogues

Package arrived with two thick catalogues full of Waeco camping and car accessories. In total the cost was 214.45 EUR or about AUD280 at the time. (I wonder how much cheaper the 55 EUR postage would have been without those books? At least I didn’t have to pay 19% sales tax in Germany!) Since Waeco in Australia is synonymous with travel fridges and seat coolers, you can see why I couldn’t buy an engine heater from them and had to import one instead.

The parts list includes the EBH, connecting cables, brackets etc. and is very neatly presented.

DEFA SafeStart and PlugIn for Prius – Clockwise from top right: 5m lead; bracket and heatsink compound; engine heater; power cable with weather-proof connector, connector brackets; CEE 7/7 plug to AS/NZS 3112 adapter model’s own

You can possibly see how it all connects from the photo above: the EBH plugs into one end of the black lead. At the other end is a weatherproof socket that attaches to the grille or bumper; somewhat like a caravan socket. The green lead connects from the socket to the mains.

Toyota Canada market and fit their own EBH for a mere CAD249 on new Toyotas, though the same basic unit is available from PriusChat for USD59. The EBH is about the size of a lipstick and fits snugly within a hole in the engine block and runs at 120V 400W.

The DEFA SafeStart runs at 230V 300W, is much larger (100mm x 48mm and 40mm deep) and clamps to the engine. The instructions aren’t entirely clear on where it clamps, so I’ll be translating the various languages in the single paragraph to get clearer directions.

The installation process will need to wait until I have a good look.