Rear Exit Coolant Lines

jeffball610 · Post by **jeffball610** » Thu May 05, 2011 1:32 pm

I'm bringing this subject back since this is my current issue. I've seen some decent ideas like running a tube for the coolant from the rear of the motor from the stock thermostat housing forward. But I have yet to see a "clean" design that I think will work.
The front exit coolant looks nice, but drilling or tapping the head and opening up a MLS head gasket is not an ideal way in my opinion. What other options can we come up with? I don't think huge AN lines are a realistic option either.
I know I've just shot down almost every setup currently on the road, but this is the issues we face with custom cars. My first thought (before actually getting the motor in my car) was to run the coolant line from the rear of the head along the intake side of the block. However, the CAS is in the way and this does not look possible. I have no issues with running a pipe along the exhaust side of the block, but having it stick out above the exhaust manifold just isn't appealing to the eye.
My next thought is to run the pipe under the exhaust manifold just like the factory does, but I don't know that there will be room there with the water pump and alternator taking up precious real estate. Anyone have a better idea?
I know I seem to be making this difficult, but just like Bill, I'm trying to find a "bolt-on" solution that most anyone can do. The front exit is bolt-on, but how reliable is it? Many state they have been driving with one for some time, but what about race situations? Drag racing does not count, as it doesn't even challenge the cooling system. Please, please post some advice. I'm stumped.

Post by **AustinTSI** » Thu May 05, 2011 4:47 pm

The best I have come up with is the 4g37 thermostat housing. Then either front exit the water or eliminate the 1g CAS and go with the 2g CAS. For the 2g CAS check out the EDIS post.

1SloEvo · Post by **1SloEvo** » Thu May 05, 2011 11:28 pm

You could get an ALT relocation kit from Jay racing or someone else (or make one) and move it to the driver side if you removed the A/C. That would give you a little more room to go under the E/M. There was one I was that looked very nice on a Mighty Max. It was a pipe going across the top of the E/M, in front of the cam gears and across to the driver side of the radiator. Very clean setup. Solid pipe (no welds that I remember) with some good mandrel bends and just two couplers to connect to the T-stat housing and the radiator. That will probably be my setup if I have the space in my notchback Mustang.

JDOliver · Post by **JDOliver** » Fri May 06, 2011 3:44 pm

but drilling or tapping the head and opening up a MLS head gasket is not an ideal way in my opinion

There is what amounts to a freeze plug in the head at the front. It doesn't require drilling or tapping. You just pop it out and Jay Racings outlet in. If you just don't want to take the head off.

If you just don't want to drill the back opening in the head and the MLS, it's not that big of a deal if you have the head off. The location of the hole needed in the MLS is not near anything else, your not creating a week spot, pressure is not that high in the cooling system.

89coltgt · Post by **89coltgt** » Fri May 06, 2011 8:03 pm

You can run a rmote thermostat, I bought a housing from here to use on my other truck build. I had mine made with -16an male threads and it is anodized black, very nice piece.

http://www.ipsco.org/Pantera%20Parts/re ... ousing.htm

Matt Arruda · Post by **Matt Arruda** » Mon May 09, 2011 12:11 pm

89coltgt wrote:You can run a rmote thermostat, I bought a housing from here to use on my other truck build. I had mine made with -16an male threads and it is anodized black, very nice piece.

http://www.ipsco.org/Pantera%20Parts/re ... ousing.htm

This works great it is also what I use. It uses a standard common GM thermostat.

Bill Hincher · Post by **Bill Hincher** » Tue May 10, 2011 3:34 am

use both front and rear exits with 1/2 the single exit line diameter and mount the thermostate in the inlet side of the radiater
Its win/win
dont put your upper rear exit line over the exhaust manifold, keep it on the intake side, bring it forward to a resivour and tee the two exit lines in there, then exit a single upper radiater hose from the resivour to the radiater inlet at the top of the radiater, place your cap in the resivour and remove it from the radiater keep your lines lower then the resivour

Socjdqcer · Post by **Socjdqcer** » Tue May 10, 2011 6:19 pm

Bill Hincher wrote:use both front and rear exits with 1/2 the single exit line diameter and mount the thermostate in the inlet side of the radiater
Its win/win
dont put your upper rear exit line over the exhaust manifold, keep it on the intake side, bring it forward to a resivour and tee the two exit lines in there, then exit a single upper radiater hose from the resivour to the radiater inlet at the top of the radiater, place your cap in the resivour and remove it from the radiater keep your lines lower then the resivour

Any pictures or a write up on this set up... Im intrigued!

Post by **AustinTSI** » Tue May 10, 2011 7:46 pm

I'm not really convinced having the thermostat housing between the radiator outlet and the water pump inlet is that much of a benefit. Several times in my life I have gone to replace the thermostat and found that it had actually broken into pieces. Each time I found pieces at the bottom of the thermostat housing.

By having the housing in front of the water pump, isn't there an increased risk of metal getting into the pump? Or is the possible damage of metal fragments in the cooling circuit considered negligeable?

jeffball610 · Post by **jeffball610** » Wed May 11, 2011 6:16 pm

In my opinion, the thermostat cannot go before the water pump. At least not inline. There are more things going on here other than just routing water. If the thermostat housing is in the wrong place, then where will the water temp sensor go and how will you route water to things such as the heater core? The 4G63 will not run without a proper signal from the temp sensor.

It makes the most sense to me to keep the thermostat housing where it is, and find a clean way to mount the water lines. If the CAS wasn't there, it would be pretty simple to run the water lines out the intake side of the head forward.

It looks like (in my case) that I will be routing the water lines along the exhaust side. Mitsubishi did this in stock form, so I do not see the harm in doing it. However, it was the water pump lines going under the manifold, not the thermostat lines. I will mock up some tubing and see what I come up with, but this looks like the direction I'm going to head. There may be better ways, but I haven't really seen one in practice yet.

jeffball610 · Post by **jeffball610** » Tue May 17, 2011 9:56 pm

Did some quick mock up this past weekend, and think I have a solution. And a simple one. The stock water pipe that travels under the exhaust manifold seems to be the direction I'm headed.
The stock unit points down for the lower radiator hose and makes a nice bend from the block to the water pump in stock configuration. However, with just a little turn, the new direction would make one end point upward to the thermostat housing and angle up and over the water pump.
The small issues seem to be the stock water line that leads from this pipe to the heater core. I'll need to cut it off to get it to turn enough to test. Also, the stock mounting tab will need to be relocated. I have a bent pipe that should make a good mock up example. I'll see what I come up with and if this is a real solution. Pics to come.

Socjdqcer · Post by **Socjdqcer** » Wed May 18, 2011 12:20 am

jeffball610 wrote:Did some quick mock up this past weekend, and think I have a solution. And a simple one. The stock water pipe that travels under the exhaust manifold seems to be the direction I'm headed.
The stock unit points down for the lower radiator hose and makes a nice bend from the block to the water pump in stock configuration. However, with just a little turn, the new direction would make one end point upward to the thermostat housing and angle up and over the water pump.
The small issues seem to be the stock water line that leads from this pipe to the heater core. I'll need to cut it off to get it to turn enough to test. Also, the stock mounting tab will need to be relocated. I have a bent pipe that should make a good mock up example. I'll see what I come up with and if this is a real solution. Pics to come.

Awesome man! Please post pics. Im getting ready to drop the motor in and i need figure out what im doing with this lol

avandull · Post by **avandull** » Thu May 19, 2011 11:24 pm

This is my post taken from Austarion.
This is one option for a rear water outlet. I have found this setup to be reliable and tidy. I have made up a pipe out of aluminium from the rear outlet on the head, note the air bleeder fitting.(brass fitting at the highest point) The aluminium pipe comes out of the head, and under the intake manifold.

The pipe leads to a mid 80's corolla thermostat housing(AE82 fwd), Before it leads to the top radiator tank.

I have used the VR4 water pump, I made the pipe so that I can put the bottom radiator hose on. I still have a heater and thermostat, that is the function of small black pipe going below the exhaust ports. It feeds the low pressure side of the heater core, and also goes on to the bypass port on the thermostat housing. This is so that water circulates past the thermostat before it opens.

Socjdqcer · Post by **Socjdqcer** » Thu May 19, 2011 11:42 pm

DUDE! Where did you get that header! I have been searching for a top mount! i only found ones for $1250... and whos got that kind of money!

avandull · Post by **avandull** » Fri May 20, 2011 1:00 am

I made it.

I did some welding training at the local tech collage in the evenings after work. I purchased a TIG welder on Ebay for $1000.
I bought some steam pipe bends and the flanges and welded it up. It took me 6 days to make. Very time consuming.
It has been on the car over a year now and has not cracked.

avandull · Post by **avandull** » Fri May 20, 2011 1:22 am

Here is a couple of shots before I put the external gate on.

Socjdqcer · Post by **Socjdqcer** » Sat May 21, 2011 12:22 am

avandull wrote:Here is a couple of shots before I put the external gate on.

WOW Bro, IM not going to lie...IM TOTALLY Jealous! Im going to try to make my own too, I hope I dont hurt myself in the process.

jeffball610 · Post by **jeffball610** » Tue May 24, 2011 5:55 pm

Sorry I didn't post these sooner. This is the basic idea.

This is the stock configuration of the water pipe, but sitting on top of the exhaust manifold.

This is where the water will exit to the radiator. It will angle over the water pump.

This is the approximate angle the water pipe is at to send coolant to the stock thermostat housing.

A small bracket will need to be made, as it sits further away from the block than it does in stock configuration. I will also need a short piece of tubing to join the pipe and the thermostat housing.
Other reasons to keep the thermostat in the stock location include water lines for the turbo, heater core, and sensors associated with ECU function. I'm sure some will argue this is not the proper way to do things, but it makes sense to me. It will also look clean and semi-factory looking.