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.

opps wrong thread.

dam so far it looks real professional .more pics more pics

Great post :)

I think your thermostat is upside down Tom... the little jiggly bit should go as close to "up" as possible to help disperse air bubbles.

You are absolutely correct and when I put it in finally, it was with the air release at the top which is actually very important which I should of mentioned. That pic was just taken to show the thermostat in the back.

On a side note and update, the reroute is great, but routing the heater return back to the rad after the thermostat does cause super slow warmup, and in the cold weather, I can't get my coolant above ~160F. While I'm sure that this will be awesome on a hot day at the track, I think I will probably modify my setup in one of four ways:

1) Run a radiator blocker in the cold weather like trucks do. (I think paul made one for his car.)
2) Put a valve in the heater core return to the radiator and almost close it off in the winter and open it for track days.
3) Put an inline thermostat in the heater core line (if they make one that small).
4) Take the thermostat out of the back of the head and put it somewhere after the heater return.

Not sure which path I'll take yet.

Was this a perfect fit? Therefore the thread of the stock sensor?

Thanks,

It was NOT a perfect fit which is why you need the included rubber washer to avoid any leaks. I think I have a 1.6L cover and if I can find it, I'll measure the threads.

fwiw- I used the exact same routing on my FE head and the heater works great. I overbored a small unused sensor hole at the top and threaded in a large barb fitting.

im in the process of doing my re-route, i was thinking about mating the heater line with the coolant line after the thermostat... any feedback/thoughts on it? turbo tim told me he wasnt sure but if i welded them together on a small angle theoritically it should create a suction...

also i think you said you were running 3/8" line for your heater but were going to run a shut off valve... does this mean you would recomend a smaller line?

The problem with that (and this has been reproduced 3x now, if not more) is not heater core flow (heater works fine), but when the heater coolant flow goes to the radiator AFTER the thermostat, there is too much flow into the rad since nothing blocks the heater return to radiator during warmup. Essentially this works like running no thermostat since flow out the back of the engine when the thermostat is closed goes thru the heater core and back to the radiator. Even though the heater core lines are small, it's enough that with a larger aluminum radiator, it is tough to get my coolant temp above 160 or so on a 50-60 degree day when driving (idle is okay since not much rad airflow) and even less on a cold day. So cold warmup is super slow and on a cold day very difficult. You'd think this would be a great thing for a track/turbo car, but I don't think low coolant temp are good for the engine in terms of thicker oil at colder temps/extra fuel dumped b/c coolant temp related fuel adjustment/etc... I'd imagine that over the long haul it'd be much better to have the engine at normal operating temp and normal oil pressures rather than like 100-120 on cold days with higher oil pressure.

So for you, I'd either try to put the heater return BEFORE the thermostat or put a serious restrictor into the heater core return line before it merges into the radiator return. YMMV.

sorry about that brg, i meant to say BEFORE. so you are saying its a good idea to do it before? because tim said he wasnt sure if it would work alright... to be honest, my temp is so high currently... on the track in 5 laps without the heater on the cars at 3/4 of the way over on the temp gauge... as soon as the temp passes half way all my power is gone... you have a Link... do you know of any way to help this/ tune the link because nobody can help me with it... not even the tune shops.

Before should be fine as long as you drill a few small holes in thermostat to allow just some small flow for some circulation before the thermostat opens. But your overheating issue sounds like it's caused by something else as the coolant reroute may make a few degree difference overall, but the main purpose is to even cooling across cylinders instead of giving cyinder 4, the hottest coolant. If you are overheating at the track is sounds more like your cooling system can not handle the extra heat load so you might want to look into a bigger radiator, look for clogs in the smaller coolant passages, make sure your thermostat opens competely, etc....

hmmm... i have an aftermarket rad.. its a 2.25" rad, not sure of the brand... dual core. i think its about 5yrs old, drained it last year. im not exactly a genius when it comes to radiators or the cooling system so where can i find/unclog the small passageways? just ordered an inline t-stat housing and 180* t-stat from shore motorsports. I am going to work on the car either tomor or tuesday, im going to bring my camera to take pics

> The radiator is a dual core unit, available from Bill Cardell. It should have twice the cooling capacity of the OEM unit.

^^^^Thats from my uncle, he bought it and installed it.

nice setup brgracer, I'm gonna add it to my page of coulant reroutes. It's been a while since I updated the site, but a completely new site is in the works!

brg, what do you think about what 1fast said and about his radiator? i have something similar

don't you mean you two are one-in-the-same....:fawk:

Nice job, brgracer. What do you use for a coolant supply to the turbo? I used a J-shaped piece coming off the coolant pipe (green arrow in pic #1), but was wondering if there is a better place. Anyone else?

I've also turned the t-stat cap pointing to the intake side. My thermosensor is in a fitting I got from BEGi -- it's a nice billet piece that's tapped already, and fits inline with the larger hose that goes to the top of the rad.

On another note, for those of you wo have removed the t-stat neck, how do you route coolant to/from the air valve on top of the intake manifold?

The lines that comes to a "T" under the thermostat can be just be connected to each other to complete the circuit.

olderguy: doesn't make sense because they both have coolant coming OUT of the thermostat neck (since it's a tee). Am I wrong in this thinking? It's been awhile since I've looked at where those hoses go/come from in an OEM application. Anyone have a diagram of where they go? I can't figure it out from the diagrams on the m.net/garage parts index.

Tom, have you test fitted the head on the block in the car yet? curious as to whether that oil drain plug you got will clear. Had originally gone with something similiar on mine but before installing it changed to a threaded insert plug instead for fear of clearance issues and I just didn't like the look of it(extra weight!)

pics with big bolt plug and the more better threaded insert.

http://www.miatamx5.com/coolantreroute/reroute-001.jpg

http://www.miatamx5.com/coolantreroute/reroute-004.jpg

It clears OK on a 1.6

Yes it fits on a 1.6L with probably like ~1-1.5 inches to spare. I was running this in the brg for the past year without any problems, and of course you ask me this right AFTER I removed the engine so I can't even measure now.

Bumping an older thread because this weekend I'm going to attempt a spacerless re-route. I like brgracer's layout from a "most optimum" standpoint. I'm just trying to work up the courage to drill holes in the head.

And I like Uncle Arthur's idea from a low-impact standpoint, except for one thing- relocating the ECU's CLT sensor to the front water neck seems like it would give an artificially low reading, since there's mostly cool water fresh from the radiator hitting that spot.

Thoughts?

Regarding heater core flow and warm up. In this pic, could you drill a 1/8in hole in the thermostat, then plumb the heatercore off the location you have the big bolt in? I think that would allow a little flow to the heater core during warmup, but not enough flow to cause long warm up times. Am I completely wrong?

Stupid question, why is there a drain plug on the aluminum coolant reroute hardline?

Is it to burp air from the system?
http://http://www.miatamx5.com/coola...eroute-004.jpg

With only a 1/8" hole through the thermostat, the measly amount of coolant flowing through would probably take the path of least resistance and just go to the radiator, and you'd have very little heater operation until the thermostat opened.

My current plan of attack is a hybrid- take the heater feed off the Cursed Water Plug nipple, and fab an inline adapter to put the CLT sensor in that line. I may drill that nipple out and install something larger, like a 3/8" HB. I'm trying really hard not to have to drill a big hole on the other side.

Probably. Looks to me like that pipe is now the highest point in the system, instead of the radiator's top tank.

So, if it was lower that burp plug wouldn't be needed?

It was never really intended to be a burp plug. It was just on the pipe Paul found that fit in that position.

Later, when Paul had the piping re-done by Tim, this pipe ended up on another members reroute and was used to keep the heater core in use by running one line here(before the thermostat the pipe in question fed in the front) and leaving the other heater core hose going through the hardline under the manifold to the stock waterpump inlet location.

Thanks OG for clearing my head.

If you got rid of the heater core and did this type of coolant reroute, what will happen to the water pump when the car is warming up and there is no where for the coolant to flow until the thermostat opens? Will there be any damage to the water pump? This is assuming that the mixing manifold only gets water from the radiator and all other ports on the mixing manifold is blocked off.

Should not be? The pump is continuously flooded with coolant, and it is an impeller type pump, not positive displacement.

Forget about damage to the water pump. Zero circulation means uneven heating, probably localized boiling, no heat passing through the thermostat housing means it'll take longer to open... Not good.

You need some circulation through the engine. Always. Period.

Ok, so there should always be some sort of flow through the engine even when warming up.

Heater core circulation for the reroute is best; however, small holes drilled in the thermostat flange allow for some circulation and get heated water to the thermostat so that it can see temp rise and open.

How big of a hole on the Tstat flange can provide sufficient circulation , OG?

One 3/16" hole will move a lot of water. I would start there if I had it to do again. It is really a balance between getting flow and taking forever to come up to temperature in cold weather.

Thanks OG,

Since I just got my Tstat out of the car, I could make any hole to acommdate. OG, I am not running any Heater core, so water is pretty much all going thru to the Tstat at the back. From the photo on the OEM Tstat, there is already some relieve hole with a small metal plug measured at around 1/8. I'll have it enlarged to 3/16.

Also, does it matter if the hole be rotate on top or bottom? If it goes on the bottom will I be needing another hole at the top to let air pass?

I would put the hole at the top, but it really doesn't matter. Once the tstat opens, it will purge out most of the air.

Tom, first of all thanks for this thread! :bigtu:

Can you please post a pic of your engine bay with the reroute in place?

Thanks