*Anyone know what size threads I need for a pipe plug to plug the radiator inlet for the hose returning coolant from the heater core?*

I actually threw away a plug that was mistakenly left there to fix my previously non-functional heater core last year. If anyone cares why, it's b/c I already got rid of the HCV/hoses, but now I want to route the return line into the top of the water pump b/c my driver's side header occasionally vibrates against the solid fixed pipe that's screwed down behind it, ever since I did my cam swap, etc. (changed exhaust gasket to copper - thicker, I guess?). I went to do the simple changeover and realized I'd need a plug for the radiator... JPrevost, I read that you once wrote something about the necessary parts to do this, but your website link doesn't work. Thanks!

 

why would you need a plug for the radiator??? are you bypassing the heater 100%?? I took that steel heater line out. I cut a big part of it off and still have all the hoses conected to it. Its up on top of the AIR box that controls the AIR flow from the smog pump.

 

No, I already bypassed the HCV stuff when I did my cam swap - now I just have a short hose running from the back of my intake to the heater core inlet. Everything works nicely, except that my driver's side header now knocks against that fixed pipe (the one the hose from the core dumps into and the bypass hose from the valve used to dump into) because, I guess, the copper exhaust gasket I just put on is a bit thicker...

Soooo, I want to take out that pipe altogether and just run the hose off the heater core outlet, over the intake, and into that xtra inlet atop the water pump (w/the plug in it from the factory) so that I don't have to listen to that damn noise anymore (plus it's probably not that great for the header's longevity).

I just wanted to know if anyone knew the thread size for the plug I'll need to put in the radiator (where the hose from that pipe clamps on now) so that I don't have to spill coolant just to find out b/f I head to the store.

 

ok so insted of dumping the return into the radiator you want it to go to the water pump? I was planning on running a line from the heater outlet, over the valve cover/intake area, around the AC, and to the radiator. Auto part stores sell rubber plugs you can clamp on. That pipe isn't fixed you can take it off. I did. It was in my way when I was installing headers. Everything on that steel pipe was 3/4" heater line. The other pipe that goes into the radiator should be 5/8".

https://www.thirdgen.org/techbb2/sho...r+valve+delete

 

That pic you posted is exactly what mine looks like now (with the rubber cap clamped onto the "T" inlet where the HCV bypass hose used to run).

I hear what you're saying about running a hose over the valve cover into the radiator, but I think I'd rather drop it into the pump, keeps it out of the way a bit better for me.

 

I didn't know you could put it in the pump on our cars. Good idea. So can't you use your 3/4" rubber thing for the radiator after you take that steel line out? Do you think dumping it into the radiator might make the heater core cooler to keep inside temps down?

 

Maybe.... I'd feel more comfortable with a brass plug in there with teflon tape sealing the treads, but maybe that plug would work in the meantime - I might just do that.

I'm not sure it would make a noticeable difference, except that doing it my way is basically taking hot coolant out the intake manifold, through the heater core (where it cools a bit, but not nearly as much as it would via the radiator), out the heater core and, still somewhat hot, back into the water pump - basically putting hot coolant back into the engine; a small fraction of my coolant will now always be diverted from cooling via the radiator. I could see this raising the overall temp, what, maybe a couple degrees? More? Anyone care to comment on the impact this has on overall engine temp? Interior temp?

It also seems to me that by sending the heater core outlet to the water pump directly (rather than the radiator), I'll be greatly increasing the flow through the heater core via a pull from the water pump (whereas before it was pushed from behind and just fell out into the radiator). Is this the case, i.e., does the water pump "pull" fluid into its top inlet, or is the effect insignificant?

 

maybe you can swap the plug in the water pump for the outlet in the radiator?

I'm copying this to the new cooling board which I forgot about.

 

I looked at my pump and didn't see where it could be attached. Where is it?

 

There are a few reasons to have it just dump into the waterpump. One is that it cleans up the engine bay, heater seems to warm up faster (but if you have stock you need to put the heater on so as to let coolant flow into the h.core), and it prevents hot spots from forming in the engine. By having coolant always flowing through the block, heads, and intake, there won't be any chance for hot spots forming.
I do see your concern about the motor getting hot, I have a feeling that this is a likely reason why my car creaps up in temp very slowely on hot days. It'll get up to 220 at MOST but that was a 45 minute drive on a highway with construction and a light every 200 feet in rush hour. No overheating problems except for the creaping. I'm going to put a plumbing shut-off valve inline of the return line to the waterpump and see if that helps. If that doesn't fix it, try a stock style thermostat and last resort, rip out the radiator and clean it out (original with lots of miles = lots of build-up).
As for blocking off the return line on the radiator, just use that rubber stopper. Mine's over a year old and starting to dry out and crack, no leaks but it's just a matter of time.
My thermo right now is the robershaw 180 and it seems to be working fine because on a cool day the engine will get right up to 180 (slow but sure) and stay there. The thermo already has some holes drilled in it to let coolant out of the engine so as to lesson the chance of trapped coolant. It's only on a hot day that the temp will climb to 180, stay there for a while and creap up above 200.

 

okay i see the two heater hoses coming out of the firewall area, one on the drivers side one on the passengers side. they are right beside each other. which hose, drivers side or passengers side, is the inlet and which is the outlet to the heater core. and just to make sure i am correct: the inlet goes to the intake manifold and the outlet goes to the water pump?

 

Not sure about location but the larger fitting is the return and the smaller is the in. Yeah, just imagine how the waterpump sucks coolant from the bottom and pumps it through the block, up to the heads, and then through the intake manifold where the thermostat controls the flow.
I've got some interesting info that I dug up from my experience of ripping out my old engine. When I removed my intake manifold the rear coolant crossover was blocked off from the heads by the intake gasket. The gasket had a pin sized hole in it. This would restrict the volume of coolant that would circulate through the heatercore, enough to keep the majority of coolant going through the engine and into the radiator.

 

thanks. so the inlet(smaller hose) goes to the intake manifold? the outlet(larger hose) goes to the water pump?

1992 Camaro RS LO3/700R4
Holley 600 Double Pumper, Weiand Stealth Intake Manifold, Accel Distributor and Coil, Hedman Headers and Modified Hedman Y-Pipe(Ported and 3" Pipe), Straight-Pipe Cat, Flowmaster 3" 2 Chamber Race Muffler, 160º thermostat, 3.73 Posi, Boxed LCAs, Kumho 255/50s, Polyurethane Transmission Mount, Stewart Stage 1 Water Pump, and B&M SuperCooler.

 

I'd say the intake goes to the inlet (the pipe on the right, if you're standing in front of the car looking at the firewall) and the heater core outlet (the pipe on the left) goes to the water pump.

 

thanks