Removed heater core - loop or plug?


I just pulled the heater core out of my new-to-me SpecE30. I hear there’s a block-off plate for the back of the head, which I may consider if and when I pull the head for a refresh. For now, I just want to get the system back together.

So, should I plug the hose ends or loop them?

I found a Jim Levie post from a while back advocating plugging them:

I tend to take things Jim says about the E30 at face value. That said, a little due diligence never hurt. How did you all do it?


Did a little more reading here and it looks like plugging is the way to go. Searched for 1" PEX plugs at the local Lowe’s and Home Depot, but no luck. I have them on order.

I have the “late” cooling setup. Just to be sure, I just need to plug the two lines which formerly went to the heater core, yeah?

Stole somebody’s image there.

Out of curiosity, what does the metal gizmo do that is in between the head / heater core and the T?


Plug the line to the right of the “T” in the picture. Plug the back of the head.


Thanks for the reply, Chuck. It looks like it’s a real pain in the butt to access where the head should be blocked off while it’s in the car. That’s why I was thinking to defer it until I had a reason to pull the head. Does that sound reasonable?

In the meantime, would I be good to go by just plugging the hoses that originally went to the core, like so?

What the heck is this gizmo?

Once I do get around to blocking off the head, would it make sense to plug it here and remove all of this?


I would go ahead and block at the “T”, and run a short hose off the back of the head and block that. “If it does not look like a race car, take it off” Tom Mcguire.


Ah, embarrased that I didn’t think of the “short hose off the back of the head.” That makes sense.

As far as the tee goes, if I block it off to the right of the tee (as shown in this picture) does that not potentially leave two hoses unplugged? The one that used to go to the head, and the other one that used to go to the heater core. Why wouldn’t I just take the tee and everything that used to be between it and head out of the picture?


You can use one hose from the T housing to the reservoir, or plug to the right of the T.


Yes, putting a block off plate on the back of the head is a pita if the head is installed. An alternative is to just plug the AL hose barb that comes off of the head. Clean the scale out of the inside of the barb with some rotary thing, then find a big-ass bolt that will thread inside by barely cutting it’s on threads in the soft AL. Then slap some JB Weld on the bolt and thread it in.

The same idea works on the tstat housing.

With both those ends plugged, all the hoses in your pics go away.

Be sure to install a coolant pressure switch in the system to warn you if something goes south. Easy way to do this is to grab an OEM pressure switch and thread it into the block where the barb is for the throttle body hose. That barb can be hard to get out tho. Soak it in Liquid Wrench over night, then use a breaker bar with a tall 24mm? socket.

Later edit. Oops, I see now that you have a late model reservoir. That changes things a bit. I’ve not done this on a late model. Maybe you don’t block off at the tstat after all because that has to go to the reservoir?




I think maybe I made the wrong assumption about what “T” we were talking about, hence my confusion about your answer. I was thinking it was the smallish T closer to the right side of the picture where there’s lots of little hoses.

Are you talking about plugging it off right of the big-ass “T” more towards the middle of the picture? If so, I think I follow you now. I’m a little slow. Perhaps crayons may have helped me grasp the concept more quickly.


Yes, by the large T.