cooling crossover mod question

[lifespeed]

Dumb question here, but what do you do with the water outlet for the rear crossover, plumb it into the heater core? What happens to the outlet in the back of the water pump? Tee? Tee seems messy and not really necessary, but I could be missing an important detail. Like the heater won't warm up until the thermostat opens :)

It looks like the intake manifold has to come off thanks to the casting flash on the intake manifold over the passenger freeze plug. Should have thought of that before I installed the intake manifold.

Is the Cobra Engineering kit (http://www.cobraengineering.net/cooling%20mod.html) the best way to go? It isn't the cheapest, but it lets you use AN fittings to the heads so as not to revisit that awkward location. Obviously connecting to the heater core won't be AN fittings.

Edit: From Cobra Engineering: "This will not fit in the driver's side with the EGR tube. You have to either delete the EGR or modify it". Is this a Mustang reference, or does this thing really interfere with the EGR tube? Modifying the EGR tube sounds like a major hassle I would prefer to avoid.

[Spectragod]

I deleted that line off my COT, I used a set of Jerry’s stainless COT’s with that line deleted.

My heater works just as it always did. The water pump goes into the heater core, just as it does now.i used the Cobra engineering kit, the intake did not have to come off, I did mine from underneath on a lift, could have just as easily removed the wiper cowl and done it from up top.

I don’t have an egr tube, but I would bet that reference is for a mustang, but I would call and ask.

Even if I had to modify it, it would fall in line with everything else that’s been touched, every time I have a thought about this POS, it’s either a lot of money or a lot of modification or both.

That’s hot rodding....... so I’m told.


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[Blown3.8]

Yes run the Mod into the heater core. The heater core outlet goes to the back of the WP, leave that alone. Remove the pipe and hoses that run down the passenger side of the engine that feed the heater core now and plug the nipple coming off the COT.

Don't get that full cobra engineering kit. It is made to go on the backside of the heads not the top where the intake is. If you could just get the fittings that go into the head with the NPT thread that would be nice. Then you could just run some NPT hose barbs into them.

[Blown3.8]

Get cobra head fittings only, MIP(male international pipe thread) in whatever size is correct for the cobra fittings(probably 3/8npt), with a 3/8 barb. Then get this PEX "T" https://www.lowes.com/pd/SharkBite-1-2-in-dia-Brass-PEX-Tee-Crimp-Fitting/1000183099 to convert the 3/8 hose out of the heads to 3/4 hose to go into the heater core.

[lifespeed]

Get cobra head fittings only, MIP(male international pipe thread) in whatever size is correct for the cobra fittings(probably 3/8npt), with a 3/8 barb. Then get this PEX "T" https://www.lowes.com/pd/SharkBite-1-2-in-dia-Brass-PEX-Tee-Crimp-Fitting/1000183099 to convert the 3/8 hose out of the heads to 3/4 hose to go into the heater core.

I'm usually more of a AN guy than PEX, especially back where it is difficult to access. Besides, my aesthetic consultant Lowndex wouldn't approve it. I appreciate the thrifty suggestion.

[lifespeed]

Yes run the Mod into the heater core. The heater core outlet goes to the back of the WP, leave that alone. Remove the pipe and hoses that run down the passenger side of the engine that feed the heater core now and plug the nipple coming off the COT.

Don't get that full cobra engineering kit. It is made to go on the backside of the heads not the top where the intake is. If you could just get the fittings that go into the head with the NPT thread that would be nice. Then you could just run some NPT hose barbs into them.

Some important details, thanks. I was looking at the freeze plugs in the top of the head, but there are plugs in the rear. It would seem connecting to the outlets in the top of the heads is preferred for the Marauder? What secures the fittings into the smooth bore freeze plug bores? The Cobra Engineering kit has plates that bolt to the back of the head and engage a groove in the fitting.

[lifespeed]

I deleted that line off my COT, I used a set of Jerry’s stainless COT’s with that line deleted.

My heater works just as it always did. The water pump goes into the heater core, just as it does now.i used the Cobra engineering kit, the intake did not have to come off, I did mine from underneath on a lift, could have just as easily removed the wiper cowl and done it from up top.

I don’t have an egr tube, but I would bet that reference is for a mustang, but I would call and ask.

Even if I had to modify it, it would fall in line with everything else that’s been touched, every time I have a thought about this POS, it’s either a lot of money or a lot of modification or both.

That’s hot rodding....... so I’m told.

Are your fittings connected to the rear of the heads or the top? I guess rear could interfere with EGR, I'll check tonight.

[Spectragod]

Are your fittings connected to the rear of the heads or the top? I guess rear could interfere with EGR, I'll check tonight.



I’m on the back of the heads, with AN fittings as well, because even though I can’t see it, I know it’s there. Remember..... anything worth doing is worth overdoing.


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[Blown3.8]

AN is fine too. Just have to decide how to connect the AN hose to the heater core nipple. I prefer AN too. Didn't know how elaborate you wanted to get.

[Zack]

I have only found one negative to routing the cooling mod to the heater core and leaving the COT out of the equation.
When it’s stupid cold out, the blower motor/heater core will actually become the radiator and fan. Meaning, I can drive 14 miles to work and the thermostat will never open. I logged temps and it never gets to 170. This is extremely bad for fuel mileage.

[Lowndex]

I’m on the back of the heads, with AN fittings as well, because even though I can’t see it, I know it’s there. Remember..... anything worth doing is worth overdoing.


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Thank you for that, because I way over did it!

[Lowndex]

I'm usually more of a AN guy than PEX, especially back where it is difficult to access. Besides, my aesthetic consultant Lowndex wouldn't approve it. I appreciate the thrifty suggestion.

Go AN or go home.

[lifespeed]

I have only found one negative to routing the cooling mod to the heater core and leaving the COT out of the equation.
When it’s stupid cold out, the blower motor/heater core will actually become the radiator and fan. Meaning, I can drive 14 miles to work and the thermostat will never open. I logged temps and it never gets to 170. This is extremely bad for fuel mileage.

I'm glad you brought that up, I was trying to envision how this still works correctly during engine warm up. The factory setup, like all cars, pumps a lesser volume through the engine and heater core with the thermostat closed. It sounds like the cooling mod, as typically implemented by hooking the cylinder head outlet to heater core inlet, allows excess flow around the thermostat through the heater core before the thermostat opens. While not a huge flaw, it isn't strictly correct either.

More plumbing, kind of a PITA. Maybe that ON3 COT delete up front would be more amenable to accepting a return from the cylinder head instead of using the heater core.

[Zack]

It’s only bad when it’s below zero

[Spectragod]

How cold does it get in California? And.... I hardly ever have my car out below 60degrees, I would guess everyone’s application would be different.


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[Zack]

On my turbo car, I have a water line that exits the COT, flows through the turbo and enters the radiator. When I drove it to Kentucky one year it was 40 degrees for a few hours of the trip. On the highway, the engine ran at 135 degrees!!!!

[lifespeed]

How cold does it get in California? And.... I hardly ever have my car out below 60degrees, I would guess everyone’s application would be different.

In keeping with your previous comment, "anything worth doing is worth overdoing", my preference would be to retain full thermostatic control rather than bypass some portion through the heater core. If this can be done reasonably, great. Temperatures in California vary widely, it gets cold in the mountains.

Clearly the "standard" hookup using the heater core works, but if it is just a matter of connecting a hose to the COT location while the engine is easily accessible, and I'm making new hoses anyway, I'll give it a try.

[lifespeed]

On my turbo car, I have a water line that exits the COT, flows through the turbo and enters the radiator. When I drove it to Kentucky one year it was 40 degrees for a few hours of the trip. On the highway, the engine ran at 135 degrees!!!!

At some point it is more than just fuel economy, piston (and other) clearances assume an operating temperature.

[Lowndex]

One of the coldest places in the US is Summer in San Francisco. :)

"The coldest winter I ever saw was the summer I spent in San Francisco."
Attributed to Mark Twain

[Joe Walsh]

I'm trying to remember how I had originally routed my rear cooling mod hoses, when I did the I install back in early 2005.
But...I definitely had a problem with not enough heat in the heater core.
I re-did the hose routing and got my cabin heat back.
I'll take a look this weekend to see how I have it set up now.

[TooManyFords]

Remember..... anything worth doing is worth overdoing.

That's my motto!

[fastblackmerc]

In keeping with your previous comment, "anything worth doing is worth overdoing", my preference would be to retain full thermostatic control rather than bypass some portion through the heater core. If this can be done reasonably, great. Temperatures in California vary widely, it gets cold in the mountains.

Clearly the "standard" hookup using the heater core works, but if it is just a matter of connecting a hose to the COT location while the engine is easily accessible, and I'm making new hoses anyway, I'll give it a try.

I have a D.R. installed rear cooling mod and I have never had a problems with heat. Last year I changed out the plastic fittings for brass fittings.

[Lowndex]

I'm trying to remember how I had originally routed my rear cooling mod hoses, when I did the I install back in early 2005.
But...I definitely had a problem with not enough heat in the heater core.
I re-did the hose routing and got my cabin heat back.
I'll take a look this weekend to see how I have it set up now.

Picture of the setup, please.

[Lowndex]

I have a D.R. installed rear cooling mod and I have never had a problems with heat. Last year I changed out the plastic fittings for brass fittings.

Picture of the setup, please.

[lifespeed]

I'm trying to remember how I had originally routed my rear cooling mod hoses, when I did the I install back in early 2005.
But...I definitely had a problem with not enough heat in the heater core.
I re-did the hose routing and got my cabin heat back.
I'll take a look this weekend to see how I have it set up now.

I looked at the ON3 COT delete kit, and notice it has a port for coolant return from the rear cylinder head mod. This would leave your cooling and heater system flow path and thermostat functioning as original. Just a few hundred dollars in AN hoses and hours of hose fabrication. Anything worth doing . . .

[fastblackmerc]

Picture of the setup, please.

I'll see if I can get some.

[Svashtar]

I have a D.R. installed rear cooling mod and I have never had a problems with heat. Last year I changed out the plastic fittings for brass fittings.


I have the same mod and (until my latest blend door issues) have always had no problems getting heat.

I thought about following your lead and changing the fittings to brass, but clearance is such a ***** back there I just looked at it and had another beer.

I should have just done it the last couple of times I changed out the BMSC module and had to move those hoses around anyway. Maybe someday.

[tbone]

I can't remember how I routed the On3 kit and cooling mod nearly 4 years ago but I can say it all works together flawlessly.

[lifespeed]

I'm trying to remember how I had originally routed my rear cooling mod hoses, when I did the I install back in early 2005.
But...I definitely had a problem with not enough heat in the heater core.
I re-did the hose routing and got my cabin heat back.
I'll take a look this weekend to see how I have it set up now.

Pics would be great.

[lifespeed]

Just got an email from James at Cobra Engineering. He didn't go into detail, but apparently has some broken equipment and won't be machining these for the foreseeable future. ON3 (http://www.on3performance.com/shop/on-3-performance-coolant-crossover-delete-2-port/) sells the rear head cooling mod fittings, but they're NPT instead of -10AN. Not the end of the world, a right angle AN adapter goes in there anyway.

[Joe Walsh]

Pics would be great.

Sorry, my Marauder is stored at my brother's house right now.....30 miles away.
May be able to get over there this weekend....

[lifespeed]

Dumb question, but my engine is out so this isn't obvious. Where does the heater core tube that runs alongside the passenger side of the engine connect to the engine? COT?

[justbob]

Heater core (doesn’t matter which side, mine is opposite of stock) to the nipple on the COT.


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[lifespeed]

So the stock flow path is:

pump output ->
COT ->
passenger side heater tube->
heater core in ->
heater core out ->
under intake heater tube ->
pump in

If I understand correctly this may bleed a limited amount of heat from the engine block during warm up, but the heater flow path doesn't really included going through the engine block and heads. It is mostly just in/out of the water pump, although obviously there is engine flow path heated water going through the pump as well.

If you connect the rear cylinder head cooling mod to the heater core you are flowing all the heater core water through the block/heads without thermostatic control, which could conceivably over-cool the engine.

[Chevyguy]

On my turbo car, I have a water line that exits the COT, flows through the turbo and enters the radiator. When I drove it to Kentucky one year it was 40 degrees for a few hours of the trip. On the highway, the engine ran at 135 degrees!!!!

The COT supply is NOT controlled by the thermostat, but it does have a stepped down fitting size, plus the supply tube running along the engine should work as flow restriction.

The 2V has the supply for the heater core directly piped into the intake, and some end up using a restriction to the heater core feed hose, like found in my old 5.0 Mustang. That should help with the overcooling issues.

I gotta ditch the COT heater supply as the metal pipe has sprung a few leaks, and I got all the cooling mod stuff waiting to go in....

[Lowndex]

https://www.youtube.com/watch?v=2dyPfWWwPTc