My spacerless hotside coolant reroute.
 

First a caveat, I had the head out of the car so I do not think that you can drill/tap what I did without removing the head but YMMV.

PICTURE #1:
- back of the stock 1.6 head for reference
- green top plug is the coolant temp sensor for the ECU
- red arrow is the pipe for the heater core send line
- yellow arrow is lower coil pack bolt (more on this later)
- blue arrow is temp sensor for the dash
- green arrow is a unused water port aka the cursed water plug

PICTURE #2:
- front of head with thermostat housing removed and 30mm freeze plug inserted ($0.73 at Advanced Auto Parts)

PICTURE #3:
- unused water port nipple cut off and drilled and tapped for ECU thermosensor (tap 12mm x 1.5, drill 13/32)
- no that's not blood in the pic (though I did cut myself)

PICTURE #4:
- ECU thermosensor in place (will not interefere with thermostat if you choose to put it back here as I already checked)

More to come, I'm waiting for parts that should be coming in soon!

this is massively awesome. Thanks. I'm going to end up following your example.

I've also recently done the coolant re-route and so far have had no problems.

I tackled it a little differently though.

Swapped the front thermostat housing cover to the rear of the engine, and blocked off the sensor plug.

Used the (rubber capped) coolant outlet below the dash gauge sender for a 5/18 hose, and had a brass adapter made up to join the small hose from this outlet to a larger hose which fits the heater core inlet.

Used a suitable diameter and shaped aluminium tube section around the exhaust side of the motor to feed to the radiator top hose. See here:

Attachment 216000

Made a blanking plate for the top of the front thermostat housing out of 5 mm aluminium plate and relocated the ICU temp sensor to here, along with the thermofan sensor.

So far it works, cools, and operates the thermofans and heater core perfectly, and the temp still reads perfect. Much easier than drilling and tapping the head, and can be done simply with the head still attached to the engine, and even probably with the engine still in the car. The hardest part was making the blanking plate, and extending the wires to the ICU sensor.

Update
 

Pic #1:
- Tapped the other side of the heater outlet with a 3/8 NPT for the heater core line (before the thermostat so the heater core gets flow all the time)

Pic #2:
- 3/8 NPT to 5/8 hose fitting for heater send (from Pepboys $2.99)
- M14 x 1.50 oil drain plug with washer for thermostat cover (from Pepboys $1.99)

Pic #3:
- heater core fitting attached to head (I used the longer fitting that came out to be about the same length as the original heater core send barb)

Pic #4:
- thermostat in place in the back of the head (note: I will later post about my coil pack mod to make removing it easier for thermostat changes)

Way to go, Tom:bigtu:

More pics for the update
 

Pic #1:
- original 1.6 front thermostat cover with already mentioned oil drain plug in to block front thermosensor hole
- note: I use my Megasquirt to control the fans so I do not need the front thermoswitch, if you are using the stock ECU, you'll need to plumb a port for the front sensor somewhere as it will not fit back there by the firewall

Pic #2:
- 1.6 thermostat on the back of the head
- note: you can orient it either coldside or hotside, mine is pointing hotside/driver's side...heck, I may end up going coldside, but we'll see...


Pic #3:
- added small 90 degree hose pointing forward
- I plan on wrapping this hose as well as using a hardline for the portion under the exhaust manifold to avoid hose problems from the heat.

From here all you really need to do is run a combo of hose/hardline to the radiator and you're done.

More pics to follow as the project progresses...

damn that's easy enough...wish you posted last week.

Looks great Tom! I like the idea of the thermostat in the head.

You'll get your hard line this weekend, maybe even tonight. I'll call.

I vote for the return on the intake side. Nice documentary. :D

How hard would it be to mount the housing so if pointed at the intake side and when under the intake manifold instead of the exhaust manifold???

BTW thanks for the great write up Tom, this will be very very useful in my future.

Keep up the good work.

You can rotate the thermostat cover 180 degrees and it will point to the intake/passenger side without any modifications. In fact, I believe that most people route it this way. It would take all of 10 seconds. :)

Any updates...Im eager to hear how well it worked out for you!

Sweet, now the question is, how come your routing yours by the exhaust manifold?

Why is this re-routing needed? Is this to make more room for IC pipes

Thanx

It reroutes the flow so that the coolant flows through the head from one end to the other instead of just flowing around it. Supposed to increase cooling efficiency by allowing all cylinders to be cooled equally. Whereas cyl #4 is usually the hottest.

#1 To be different. :)
#2 Because I have a ton of space on that side from the PS/AC removal
#3 (and most important for me) I plan on doing something a little different with the heater lines for a touch more cooling...working on it with pics to follow.

now you have my attention again..:bigtu:

can't wait,

Another update
 

Pic #1:
- No, it's not a stainless bong :gay:
- Reroute hardline made by TurboTim
- Smaller pipe coming off is for the heater return which allows you to remove the hardline attached to the exhaust manifold that is going back toward the front of the engine (the one with the flange that bolts on top of the exhaust manifold)
- So, instead of the hot coolant from the heater return going back to the mixing manifold -> water pump -> front of the engine, it will go to the radiator and only cool coolant will enter the engine from the water pump (more pics to follow later)
-In theory, this should provide a bit more cooling since the hot heater flow is not recirulated into the water pump/engine, but it may take longer for the car to heat up in the cold

Pic #2
- Hardline in place for reference under the exhaust manifold area
- I may be able to go above the exhaust manifold instead, but will have to see for fitment after the head goes back in the car.

Pic #3
- Cut the bottom flange of the coil pack where the difficult coil pack bolt attaches to the head
- This way the bottom bolt is tightened to hold the coil pack in place, but when you need to remove it, instead of having to loosen the difficult to reach back bolt, you just need to remove the two top bolts and pull the coil pack up and away! :)

I wouldn't have done this since there is a chance that your heater will get no flow after the t/stat opens along with engine warm-up taking a long time. You may find that as the t/stat opens and closes that you will get random circulation to the heater core.

I did worry about that but talked to a few peeps that did a variation of this with good results. I may stick a restrictor in the heater return line just to make sure that there is a pressure differential for flow as well as not too much flow to the radiatior, but I think I'l run it full flow first and see what happens.