Jump to content
HybridZ
sac_Z

Deleted heater core. How to plug cooling system?

Recommended Posts

**UPDATE** I have a 280ZX I'm not using, so I pulled its coolant inlet port off and installed it on the 240Z. I've learned that the later L-series engines have a threaded inlet port. I've plugged it with a 1/2" pipe plug and installed the Lower Radiator hose.

 

Note: If you choose to do what I did, the lower radiator inlet port from my '81 280ZX is slightly pointed more engine-side than the original 240Z port. So watch out for the lower radiator hose touching your alternator. What I did to fix this problem was to twist the lower radiator hose at the bottom of the radiator to clear the alternator. Well, it doesn't completely clear the alternator, but as long as it's not touching the fan blades, I'm fine with that.

 

** I've completed plugging my cooling system. Thanks, HybridZ. Your input was very helpful. **

 

Hi Hybridz.

 

First off, I'd like to mention that I removed my heater core. So no coolant flows through the interior. I'm trying to bypass that and apparently there are two popular alternatives to that: "looping" or plugging. I'm convinced that plugging the cylinder head outlet is the most logical way to go, since all that looping does is move cold water from around the left side of the block/cylinder head and back into the water pump inlet. Since I've deleted the heater core, the cylinder head coolant outlet is no longer necessary.

 

Also, my engine is stock. I found a popular thread pertaining to cooling on L-series motors for racing purposes, but I feel that for stock motors that advice doesn't apply.

 

With that said, I'm having a tough time searching on hybridz advice on how others deleted flow to the second inlet. Maybe it's so easy to do, that it goes without saying, but I'd like to know what people who have plugged their systems have done in order to delete their loop.

 

This is what I'm going to do:

 

Thermostat housing => intake manifold plug

 

Intake manifold plugs (front and rear)

 

Cylinder head coolant outlet plug by the #6 cylinder

 

And here is where I'm stuck. The water pump inlet is branched into two, one for the lower radiator hose and one for the heater core hose.

 

Should I tap the second one and then plug it with an npt plug?

Edited by sac_Z

Share this post


Link to post
Share on other sites

We plug all the holes for the heater and manifold heating. The only flow path is in at the pump and out at the thermostat.The engine is stock and we have a 3-row brass radiator. We use the car on the race track and have not experienced any overheating problems.

Share this post


Link to post
Share on other sites

dexter72,

 

I'm not sure if I'm understanding you correctly. Are you saying cut off the hose a few inches from the inlet port, put a pipe plug at the end of the hose, and then seal both ends with hose clamps?

 

If that's so, I might just do that. Have you tried that?

 

Has anyone used that method and run into any problems? I'd imagine the plug accidentally getting sucked in by the pump, or water leaking from the hose where the plug is clamped. But then if I use a big-enough plug, it couldn't go through the smaller orifice if it were to come loose.

 

However, I like the idea of having it tapped and plugged. It would be sturdier.

 

edit: sturdier

Edited by sac_Z

Share this post


Link to post
Share on other sites

I would be very mindful of the mix of coolant you run if you do that. An improper mix can eat up that thin walled port, especially if you take material away when you tap it. Tap only as deep as your plug! I only converted because the one I had (just like yours) was almost completely eaten through.

 

I would just find a threaded one here, there is a lot more meat to them. With as many people parting out cars as we have, you should be able to find one in no time.

Share this post


Link to post
Share on other sites

I would be very mindful of the mix of coolant you run if you do that. An improper mix can eat up that thin walled port, especially if you take material away when you tap it. Tap only as deep as your plug! I only converted because the one I had (just like yours) was almost completely eaten through.

 

I would just find a threaded one here, there is a lot more meat to them. With as many people parting out cars as we have, you should be able to find one in no time.

30 second ebay search. Problem solved.

http://www.ebay.com/itm/70-78-DATSUN-240Z-260Z-280Z-LOWER-WATER-INLET-HOUSING-/321148687894?pt=Motors_Car_Truck_Parts_Accessories&hash=item4ac5f41616&vxp=mtr

Share this post


Link to post
Share on other sites

We used a short piece of heater hose, a plug, and hose clamps. See the attached photo. Not the most elegant solution but it has been reliable for several years. Threading the housing will not work well. I think the next level up is to cut off the nipple and weld it closed.

post-4054-0-66467000-1372707427_thumb.jpg

 

Share this post


Link to post
Share on other sites

As i was replacing what I thought was a leaky hose, I discovered the water outlet elbow was actually missing 3/4 of it's length (car is new to me, so I'm not asking questions). 

 

If I'm reading correctly, i can just unscrew that elbow at the back of the block and install a plug there, and then remove the long hose running along the block to/from the other end of the heater core, and plug that line at the thermostat cover?  ('75 L28)

Edited by Wheelman13

Share this post


Link to post
Share on other sites

The rubber cap may be best so you can keep the thermostat bypass line on the pump intake. Should have the big hose from the radiator, big hose from the heater core, and then a little hose from under the thermostat (as shown in the ebay auction). Although, I am unaware why some intakes only have a place for a heater core and a radiator, without the thermostat bypass, as shown on post #14 by Beermanpete. Perhaps some engine blocks had an internal bypass and some didn't? I don't know.



Better go read all 10 million pages of the coolant FAQ on this board.


For what its worth, I just looped the back of the head around to the intake of the water pump, without the heater core. I didn't run the thermostat bypass. That is apparently the wrong way to do it, and I wouldn't do it that way again. Regardless, the motor ran fine as a daily driver for years. :wc:

Edited by josh817

Share this post


Link to post
Share on other sites

15 second McMaster-Carr search:

 

http://www.mcmaster.com/#silicone-caps/=nflkro

 

 

:-)

 

BAD John BAD! :P

 

These dry rot over time and can pop at high pressure... leaving you with an over heated engine. Its actually best to connect the back of the head back to the radiator outlet, but we've ran it plugged (threaded outlet) for years with no problems. 

Share this post


Link to post
Share on other sites

BAD John BAD! :P

 

These dry rot over time and can pop at high pressure... leaving you with an over heated engine.

This was why I recommended the $25 threaded pump inlet off ebay - just unscrew the hose barb and replace with an aluminum 1/2 npt plug and you are done.

 

 

 

 Its actually best to connect the back of the head back to the radiator outlet, but we've ran it plugged (threaded outlet) for years with no problems.

BAD Cobra_Tim BAD!  This has been shown conclusively (with data even) to be the opposite of the best way to do it.  You are just byassing the radiator and running hot water back to the pump inlet when you do this.  (I am assuming that when you say "radiator outlet"  you mean the port on the radiator where water comes out, which is the same as the pump inlet.)

Edited by TimZ

Share this post


Link to post
Share on other sites

This was why I recommended the $25 threaded pump inlet off ebay - just unscrew the hose barb and replace with an aluminum 1/2 npt plug and you are done.

 

 

 

BAD Cobra_Tim BAD!  This has been shown conclusively (with data even) to be the opposite of the best way to do it.  You are just byassing the radiator and running hot water back to the pump inlet when you do this.  (I am assuming that when you say "radiator outlet"  you mean the port on the radiator where water comes out, which is the same as the pump inlet.)

xDvzdjv.jpg

Something like that OP, if you get the threaded water pump intake and you plug the heater core side like TImZ says.

 

If don't have a threaded water pump intake, and you just use a rubber cap on the heater core intake, you may be left with a smaller intake and the radiator intake. Radiator intake goes to the bottom of the rad obviously and the smaller intake goes to under the thermostat. You could plug that too though, if you wanted to.

 

To illustrate what I mean by that:

rKXzkOk.jpg

 

If you don't have the threaded version as shown in the ebay auction, you can plug the Red and keep the blue. Or plug the blue as well as the red.

Edited by josh817

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...