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Blazer Eagle
04-27-2011, 07:05 AM
so after an engine swap from a non-ac blazer to an ac truck...how do i hook these darn heater core lines up?

the original trucks (ac) motor has two lines from the heater core, one from the radiator and one from the top of the block...im not really srue how they were hooked up

the new motor has an extra fitting on the water pump, where should all of these hoses run? i believe the heater core leaks because i think it was blocked off...ie capped hose - how should i go about recapping everything? yes i know pictures would help, along with a better description but thatll come tomorow when im awake.....


as a recap....where the hell do all of my cooling lines go?

Ahays000
04-27-2011, 07:21 AM
One should go to the top of the water pump and the other to the front of the intake manifold, plug the thermostat housing with pipe plugs... this is my setup without any hoses, but you get the idea.
http://i829.photobucket.com/albums/zz216/ahays000/0128001627.jpg

b~lazer
04-27-2011, 08:20 PM
You should block off the one on the new motors water pump. One of the lines should run to the intake and the other to the radiator. If your not going to hook the heater core up then cap the three holes you have with screw in caps. The one on the radiator might be alittle tricky to cap though. Could just run a hose off of it to the intake and cap the pump?

70-K5
04-27-2011, 09:04 PM
This is how my 70 is run, pretty easy to see what is going on.

http://i948.photobucket.com/albums/ad329/c-code71/1970%20K5%20Blazer/IMG_1211.jpg

I think that is a plug on the top of the water pump.

70-K5
04-27-2011, 09:08 PM
And the 86 is run off the radiator and manifold, all the fittings on the water pump are plugged.

http://i948.photobucket.com/albums/ad329/c-code71/86%20K5%20Blazer/IMG_1469.jpg

Biggs Chevys
04-28-2011, 02:41 AM
70.... any reason the hoses are routed differently on the 2 rigs?

the 86 is correct and the 70 is incorrect..... anyone see why?

Blazer Eagle
04-28-2011, 04:13 AM
biggs gave me the answer so i cant tell...

the previous set up after looking at pictures was a hose from the top of the intake to the radiator(to bypass heater core), should i keep this and plug the pump?

Biggs Chevys
04-28-2011, 04:52 AM
its a matter of personal preference and also depends on what the engine/application wants....

running from the intake to the radiator causes the engine to warm up slower and run a hair cooler because you will have a thermostat bypass.....

if the hose is run from the intake to the water pump, it recirculates through the engine allowing the engine to warm up faster and relies on the thermostats operation within the cooling system controlling flow to the radiator....

70-K5
04-28-2011, 04:56 PM
70.... any reason the hoses are routed differently on the 2 rigs?

Never thought about it I guess... I just repeated how the hoses were in the first place!

I've been googling trying to get an in/out diagram of all the ports and am coming up blank... Help me label this picture...

http://i948.photobucket.com/albums/ad329/c-code71/Waterpump-1.jpg

Biggs Chevys
04-29-2011, 12:59 AM
it is not as complicated as one would think, as they dont really have names just intended uses....

yes manifold port 1 is intended for a heater hose, however you dont have to use a heater....

port 2 and 3 are intended for temp sensors and senders, like you have with your mechanical temp gauge (can use these to activate an electric fan).... each head should have a port as well (between exhaust ports 1 & 3 - and between 6 & 8 (SB))....

h20 port 1 and 2 serve the exact same functions, heater hose return.... this keeps the the heater cores coolant circulating through the block...

from radiator, is the coolant supply source from the radiator.... no names that i know of, as there is no other intended use...

radiator return is refereed to as the water neck or thermostat housing....

left and right pump to block ports.... same thing as only a water pump can be mounted there... otherwise the material around the coolant chamber within the block heads and intake are also refereed to as a water jacket...


as for the heater hose routing, after market fittings and heater cores change things a little, but.... pumping coolant into the lower heater hose port allows the system to purge any air much faster than the feeding the coolant at the top port....
it is much easier to push air up than down....
coolant going into the top port can drip/flow past an air pocket in the heater core, this makes for an inefficient heater core.... in some applications people have installed a "purge cap" in the return hose from the heater to the engine because these air pockets can be more of an issue than most people realize....

70-K5
04-29-2011, 02:08 AM
I got what you were after... why the routing is "wrong" on the 70...

Because the input is routed to the top fitting on the heater core, thus more likely to have air trapped in the heater core...

I know I've got 3/4 and 5/8 heater hose, I just matched the hoses to the fittings... heater core has two different size outlets.

Funny thing is the heater in the 70 works awesome and the 86 is like somebody is rubbing two sticks together...

Biggs Chevys
04-29-2011, 02:15 AM
any debris restricting air flow through the heater core? its amazing how much crap can work its way in there....

70-K5
04-29-2011, 02:31 AM
I don't know man... My home garage has turned into a *no work* zone due to the HOA bitches... Plus my garage is half packed up.

At least the summer is only a few months away, it was 60* here last weekend! Won't need a heater soon...

Biggs Chevys
04-29-2011, 03:13 AM
not like it is a critical repair.... it can wait until you have time....

Just-speed
04-29-2011, 08:54 AM
Yeah its no big deal.....