Problem solved

[SquareRoot]

Well I guess that exhausts all options. The intake bypass must be plugged. If it worked before and now it don't and the only thing that changed was an engine swap, that leaves you in a conundrum. Pull it apart and see if you find the proverbial missing 10mm socket.

 

[MikeB]

By "no circulation" what do you mean -- no heat or no air flow?

 

[SirRobyn0]

Ok I'll toss out a couple ideas. Sometimes a completely plugged core will prevent any circulation, still you should get coolant flying out of the intake nipple with the hose off. I have seen water pumps fail in weird ways that cause little to no flow such as impeller fins rotted off. Lower radiator hose collapsing down, is a pretty rare thing these days, but can happen and will restrict flow.

The thing is almost all of those issues will also cause overheating.

 

[MikeB]

If you have a non-factory A/C truck, your heater core may not be wide enough for the housing. I had this problem with my 82. Check out the photo. The heater core on the left fits snugly into the housing, whereas the one on the right lets cold air bypass it. Both part numbers were listed for an 82 non-AC truck. My symptoms were warm air (not hot) when the truck was sitting still, and cool air when it was moving.

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This picture shows how outside air takes the path of least resistance around the thinner heater core.

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This picture shows how the wider heater core seals off the "bypasses" on both sides.

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[matt4426]

You should remove the thermostat and make sure the coolant passageway under it is clean and open to the (2) 1/2" NPT plugs on either side of T-stat housing and the (1) 1/2" NPT plug on front of manifold. If that coolant passage is open and clear, run your heater core return line to the 1/2" NPT port on top of your water pump.

Big block trucks had the heater core coolant return to top of the radiator. Big block cars had the heater core coolant return to the top of the waterpump. Either will work fine.

 

[Ontheboulder]

sometimes they get an air lock, needs to be burped. they can be frustrating to get out. I have parked my rig with the nose uphill and sometimes that will work

 

[triplel43762]

Thanks for all of the responses! New water pump and thermostat. Started it today and coolant came out of the intake hose so I put it on the heater core and the heater worked fine, BUT I took it for a drive and it ran pretty crappy and never got above 160 but heater was hot. When I got home, went to pop the radiator cap while running about 160 and got a SHOWER!! Really thinking it blew a head gasket!!!

 

[Craig Nedrow]

If you have a head gasket leak, it can be from a few bubbles, to blowing all the water out when the radiator cap is off. With the cap off and the engine warm, idling, are there bubbles? when you up the RPM's, are there more bubbles or does it blow the water out? In any case, there should be no air bubbles in the system. If an increase in RPM's bubbles more, a cylinder is leaking into the cooling passage of the engine, so cracked head, block, bad gasket. The oil will eventually show water contamination in the engine oil fill as a milky gray sludge. If so, this will eventually ruin the engine.

 

[AuroraGirl]

Is this a factory 87 intake?

Tsb from gm about cleaning and breaking up blockages in them from poor practices to make ‘em

 

[AuroraGirl]

Thanks for all of the responses! New water pump and thermostat. Started it today and coolant came out of the intake hose so I put it on the heater core and the heater worked fine, BUT I took it for a drive and it ran pretty crappy and never got above 160 but heater was hot. When I got home, went to pop the radiator cap while running about 160 and got a SHOWER!! Really thinking it blew a head gasket!!!

YOU POPPED THE RADIATOR CAP AR TEMP WHAT DID YOU EXPECT

IT has a WARNING DO NOT OPEN HOT CONTENTS UNDER PRESSURE or similar.

But I don’t think your truck is dead and can you post pics and did you bleed it

 

[SirRobyn0]

Ya, @triplel43762 Not to say that it couldn't have a head gasket issue, but when an engine is warm there is suppose to be pressure in the radiator. Your lucky you didn't get seriously burned.....

There is a TEST for head gasket issues. A test kit at your local auto supply store is about $20.

 

[triplel43762]

I have NEVER had an issue taking the radiator cap off while running within normal operating temperature. It has an edelbrocj intake on it. As far as bubbles, the thing doesn’t seem to be normal all the time. Some times as it warms up, it does have bubbles and when the thermostat opens everything seems normal except the lack of coolant at the intake nipple AT TIMES???!! Something definitely going on, been busy and haven’t messed with it but going to tear into it this week.

 

[triplel43762]

can’t someone with experience back me up??? Can’t you take the radiator cap off while it is running as LONG as it is normal operating temperature??

 

[Ricko1966]

You are not supposed to take the cap off a hot radiator,I do it all the time but I put a rag over the cap so I don't get sprayed and I take it off slow so it can vent.

 

[Ricko1966]

can’t someone with experience back me up??? Can’t you take the radiator cap off while it is running as LONG as it is normal operating temperature??

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