Blew up a heater core

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I think GM makes a flow restrictor/ pressure reduction valve for heater hoses so it doesn’t get the full force of the cooling system rushing through it. Perhaps your cavalier could use something like this if high RPM possibly caused the failure.
I replace the original hearer core in our 65 4-4-2. Pain in the ... I did not know about the restrictor. Blew the new core in no time. Sheesh.
 

brianl703

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I replace the original hearer core in our 65 4-4-2. Pain in the ... I did not know about the restrictor. Blew the new core in no time. Sheesh.

I looked up heater hose restrictors and I find some that are made for the Mustang fox body, they are an aftermarket part, does anyone know of a GM part number for one of these or another aftermarket equiv? Think the inlet is a 3/4" ID hose.
 
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I looked up heater hose restrictors and I find some that are made for the Mustang fox body, they are an aftermarket part, does anyone know of a GM part number for one of these or another aftermarket equiv? Think the inlet is a 3/4" ID hose.
Start by checking with dealerships. Lemme know what you find.
 

brianl703

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If your Cavalier regularly sees 4K+ shifts and the heater core is all you’ve had happen I’d say that’s a bulletproof vehicle.

Peak HP is 88HP @ 4800RPM, and with the short gearing that this thing has (almost 4000RPM at 85MPH), I'd say it was probably designed for that sort of shifting. Such shifting is probably necessary just to keep up with traffic in some places.
 
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Heater core was one of the many repairs I had done on my ‘85 Buick Skyhawk with this same engine.
 

brianl703

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I would measure the outlet pipe on the heater - 3/4 sounds large for such a small and old car.

The heater core specs say 3/4 for one pipe and 5/8 for the other. But the replacement heater hoses all say 5/8. And one pipe does look larger than the other in the picture, but I will measure it when I get it.
 
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Peak HP is 88HP @ 4800RPM, and with the short gearing that this thing has (almost 4000RPM at 85MPH), I'd say it was probably designed for that sort of shifting. Such shifting is probably necessary just to keep up with traffic in some places.So why would the factory heater core not handle the RPMS as “designed “?
Rock on. Why would the heater core need modifications if this engine/vehicle is designed for 4,000 RPM shifts? Maximum torque is at 2,400 RPMs. So it takes 4,000 RPMs to move it along…..? I bet you have a fart can muffler on it!
 

brianl703

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Rock on. Why would the heater core need modifications if this engine/vehicle is designed for 4,000 RPM shifts? Maximum torque is at 2,400 RPMs. So it takes 4,000 RPMs to move it along…..? I bet you have a fart can muffler on it!

Stock exhaust, complete with catalytic converter. Doesn't always take 4K RPM shifts to move it along, but when you're dealing with an 88HP engine in a 2300lb vehicle, it could be necessary, such as when passing or merging onto a highway.
 
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Nice thing: early GM vehicles (the plain ones, at least) had fairly simple dashboards and therefore the HVAC components aren't buried. I've replaced heater cores on a Fiero, an SL2, and for you Ford guys, my '88 F150. The F150 was easiest: drop the glove box, pull the hoses off under the hood, 4-6 screws to remove a cover, and the core slid right out.

That was back when things were simple. I'd be willing to bet that 90%+ of vehicles made in the past 20 years require at least some amount of instrument panel removal for access, easily a 6-10 hour task.
 

brianl703

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I got the new heater core. Copper/brass Spectra Premium, made in the USA. Bet it's been sitting around for a long, long time..no date on the box that I could find.

I looked and it appears that I just need to remove the ductwork that runs along the front bottom of the dashboard, and I should be able to remove the bottom panel of the HVAC plenum, which should give me access to the heater core.

Not having a center console makes this job easier.

EDIT: I think this is the only USA made part I've bought for this car so far, other than an oil filter....
 
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