trwebb26 Posted July 21, 2009 Share Posted July 21, 2009 For as much money as people spend on their L6 engines - I think there really should be a best practice for when you take the heater out of the circuit. I want to get to the bottom of it. I'm thinking about running a test of some sort on my engine using thermocouples and some kind of valve setup to measure flow rate. One datapoint will be how everybody have done it on their cars. So time for a poll - please participate and post any kind of experiences you have good or bad looping or plugging. Please also include what version of head you run. Here is a pic of my engine looped: Here is a post about the subject. http://forums.hybridz.org/showthread.php?t=107364 So do you loop or plug? Quote Link to comment Share on other sites More sharing options...
thetremendoustim Posted July 21, 2009 Share Posted July 21, 2009 +1 for Loop I grabbed a 1/2" 90* street bend copper pipe, a 1/2" MPT to Hose barb, and a couple feet of heater hose! So cheap yet so beautifully effective! Oh yeah, and a 3/8" brass plug for the Thermostat housing. head is a P90....standard L28et.... Quote Link to comment Share on other sites More sharing options...
janaka Posted July 21, 2009 Share Posted July 21, 2009 I have them looped on my LS1 swap (I know not L6 but still)... When I install my Flex-a-lite heater I'll un-loop and run them properly. no issues at all with having them looped. Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted July 21, 2009 Share Posted July 21, 2009 I have mine blocked off. No pictures of the motor together, but you can see the block offs in both of these pictures. P79 head F54 Block [Flat tops] Quote Link to comment Share on other sites More sharing options...
cockerstar Posted July 21, 2009 Share Posted July 21, 2009 My thinking behind looping the system was this: With the heater core in the circuit the coolant was able to flow the external route. Maybe this flow was only designated to provide heat to the cabin, but it might also serve to route coolant in the head. I wasn't exactly sure, but I knew that keeping the flow there wasn't going to hurt anything and I wanted to get my engine in asap. Can they be plugged without any adverse effects? Probably Quote Link to comment Share on other sites More sharing options...
Xnke Posted July 21, 2009 Share Posted July 21, 2009 DON'T loop them. You are creating a short path from the back of the cylinder head directly back to the inlet of the water pump, so you are recirculating HOT water, instead of runnning that hot water back through the radiator first. Quote Link to comment Share on other sites More sharing options...
woldson Posted July 21, 2009 Share Posted July 21, 2009 DON'T loop them. You are creating a short path from the back of the cylinder head directly back to the inlet of the water pump, so you are recirculating HOT water, instead of runnning that hot water back through the radiator first. Yeppers!!! This was covered in the head cooling tread that is a sticky now. You should read it, very facinating! Quote Link to comment Share on other sites More sharing options...
thetremendoustim Posted July 21, 2009 Share Posted July 21, 2009 So plugging off is a better alternative than looping? Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted July 21, 2009 Administrators Share Posted July 21, 2009 The pro's and con's have been discussed extensively here... http://forums.hybridz.org/showthread.php?t=125186 Quote Link to comment Share on other sites More sharing options...
thetremendoustim Posted July 22, 2009 Share Posted July 22, 2009 Yeah from what i understand from that thread, RTz, is that you can loop it as long as you use some water wetter, to increase the cooling abilities of the water. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted July 22, 2009 Administrators Share Posted July 22, 2009 It would take a whole lot more than Water Wetter to convince me to loop it. It's far to much volume to be bypassing the radiator. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted July 22, 2009 Share Posted July 22, 2009 Ron, I totally agree with you on that! Gawd, how hard is it to block the holes? It serves no purpose if there is no heater core. Even the external bypass from the thermostat housing back to the WP (via the intake manifold) had a mini thermovalve to stop the flow once operating temps were reached. The internal bypass in the head prevents cavitation at the WP at that point and ensures the thermostat is seeing actual cylinder head coolant temperature. Removing this path allows the thermostat to operate more effectively and stabilize temps. The heater, when used, also effectively removed some heat from the system. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 22, 2009 Share Posted July 22, 2009 The thought of 'the heater core allows flow' is incorrect. The heater core is BLOCKED! That is the purpose of the heater control valve. If the heater control valve is opened, allowing flow, the water is COOLED before reintroduction to the water pump suction port. I can't tell you how many OEM Radiatored 240Z's I have 'fixed from overheating' in So Cal simply by cutting that damnable looped hose, and installing two spark plugs and some hose clamps! Looping the hose is not recommended, and not proper. Period. It's blocked when not in use, just like (for SoCal at least) 95% of the time you are driving around without the heater on. By the time you need a heater, loss of cooling capacity due to inadequately cooled recirculated water is not an issue. Matter of fact, anybody notice the engine warms up slightly quicker when you turn on the heater, but don't turn the fan on 'high'? That kind of tells you something right there... Quote Link to comment Share on other sites More sharing options...
Megatherion Posted July 22, 2009 Share Posted July 22, 2009 Thanks for the info guys! I removed the heater from my Z and I didn't know what to do with those hoses. Quote Link to comment Share on other sites More sharing options...
dhp123166 Posted July 22, 2009 Share Posted July 22, 2009 Okay so I remembered wanting to do this for a long time. Then I forgot. Then I saw this thread and said " Oh yeah, I remember... Let's do it"!! Here's what I ascertained: (All temp. measurements were done with an Autometer water temp. gauge which has its' sensor right before the thermostat in the housing.) These are all preliminary observations as well. Plugging the holes seems to stabilize the temperature of the coolant. It seemed that the thermostat first opened at a higher temp. than it did with the heating hoses looped into one another. BTW I have a 180 degree F thermostat. The car also seemed to run a little hotter (3-4 degrees F) than it has been. But once the thermostat was open it stayed open. This is how I remember it working when I had a functioning heater. When the loop was in place the thermostat opened and closed alot in the course of normal vehicle operation. Aesthetically it cleaned up the engine bay a little more so that is always beneficial... Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted July 23, 2009 Author Share Posted July 23, 2009 From the looks of the poll - it is just as I suspected... lots of confusion about this topic. I'm nearly convinced to take out the loop... Is anybody else? Quote Link to comment Share on other sites More sharing options...
rturbo 930 Posted July 23, 2009 Share Posted July 23, 2009 From the looks of the poll - it is just as I suspected... lots of confusion about this topic. I'm nearly convinced to take out the loop... Is anybody else?Yep - I'll probably do it before I start the car for the first time (whenever that will be). Quote Link to comment Share on other sites More sharing options...
dhp123166 Posted July 23, 2009 Share Posted July 23, 2009 Okay, after removing my loop and plugging the holes my car operates... ...pretty much like it always has. But removing the loop takes a weak point and aesthetically unpleasing part out of the engine bay. That seals the deal for me... Quote Link to comment Share on other sites More sharing options...
cockerstar Posted July 23, 2009 Share Posted July 23, 2009 Nearly convinced? All it takes for me to be convinced is for Tony to say it's a good idea I'll be fixing this today. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 24, 2009 Share Posted July 24, 2009 I'd really be interested to see ANY objective evidence on looping being beneficial. I don't see confusion, save for the people looking to loop. Those who don't loop, aren't confused! pffft! Quote Link to comment Share on other sites More sharing options...
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