gs72

(So I put a plug on the overflow just to test) and it's still not building pressure.


If you did that as you said. Then all the radiator caps you will try will not change anything. I am in the "there is probably nothing wrong" crowd. More than likely your new radiator works so much better than your old one that the system sheds the heat enough to not build much pressure. You also have to take into account the cold ambient air (I think I remember you mentioning it was cold there) blasting through your radiator while driving.

jpc647

I was thinking about something like this. I found a slightly deeper cap from a 1980's firebird. Should be here wednesday, I'm going to try it.


I don't know how to better explain this. But the gasket on the spring of the radiator cap seals air in the radiator. It prevents air/coolant from coming out of the radiator into the overflow nipple. Is my Radiator cap isn't sealing, air will definitely keep going into the overflow.

I'm also weary of my car running right at or 5* under the thermostat rating, but thats a separate issue to address when I find a fitting cap.

Fun71

New cars typically run at or slightly above 200º so the heater will feel hotter.

oldcutlass

Can you post a pic of you squeezing the upper hose when the engine is up to temp and ran for a while? I would not worry that the thermostat is maintaining a temp of 5* less than the rating. There is a tolerance % of plus/minus within the gauge and the thermostat and it is well within that. Have you called the radiator manufacturer?

76olds

[QUOTE=jpc647;993113]I was thinking about something like this. I found a slightly deeper cap from a 1980's firebird. Should be here wednesday, I'm going to try it.


Let us know if you give it a try and it works, this thread will certainly help someone else if the cap is the issue with that Radiator part number.

Eric

MDchanic

So you're saying that you got a pressure tester, connected it where the radiator cap goes, pumped it up, and it held 18psi, and made the hose feel hard?o get it to rotate

i've got to say, that pretty much rules out a problem with the radiator, including a problem with the cap sealing surface.


If you have to press the cap down to get it to rotate and tighten, then it is protruding deep enough into the opening to seal.


Because the pressure tester did hold pressure, this does sound like a cap problem, though.

- Eric

76olds

I didn't see the post where he got a pressure tester and tested it to 18psi. I wonder what kind of pressure the caps held?
I hope he sorts it out, He really needs it to hold pressure or it will be overheating for sure in the spring and summer.

Eric

jpc647

Yup. They use Stant Caps for company tests. The Stant 10231 or the Stant 10331 Caps(The same as 10231 but with the pressure relief lever) which is what I'm using.



I pumped it up to 16psi. It holds 15 1/2 psi. It comes down a little from whatever you pump it up to.
The caps are bottomed out. I'm sure. They don't wobble, and they are tight.

It's a depth issue. The gasket attached to the spring on the cap isn't quite tall enough for the deeper neck of the new plastic tank radiator.




I didn't test it to 18psi. I pumped it up to 16 psi, it held steady at 15ispsi. No noises. Let it stay there for 5 minutes or so.

76olds

Happy to hear you got it figured out and have no leaks anywhere else . Especially not another heater core haha.
Put-r-ther,
Eric

Supernaut72

Probably depends on heater core/case design, too. Not quite "new cars" anymore, but for example, two of my friends' early 2000s Cavaliers with 195 T-stats have always had far inferior heat to any of my old cars with 180 T-stats. In both cars, the heater has never really been able to keep the smaller interiors adequately warmed up even after a couple of solid hours of driving and blasting the heat on chilly nights. The interior just gets "warm" and stops there, the heat has to stay on full hot in order to not be shivering. Old car, I'm sweating after ten minutes and have to tone the heat down. Even my '95 Buick w/ LT1 doesn't heat up all that well, and that's after flushing the heater core and putting in a working thermostat.

Anyways, glad to see that the issue's resolved. Regarding the 175 degree temp reading, if it was taken at the radiator then no issue, just means everything's cooling well. If you were getting 175 at the intake manifold sensor, I'd investigate a thermostat staying open more than it should.

MDchanic

Typically, the radiator pressure testers have a "Test" mark for each standard pressure about 2psi higher than the rating, so the test line for 16psi would be at about 18psi.

- Eric

jpc647

My olds doesn't heat up all that well. I do attribute it to only having floor vents, and in all honestly, I need to weatherstripping around the door glass. But on the highway, my heater in on high, and it's chilly in the car. Always been like that.

And my 175 temp reading is at the intake manifold through a cheap mechanical gauge. It used to run about 205 with the old radiator, and 195 thermostat. On the highway though, even if it's 40* out, that air coming into that radiator is pretty cold. Running 175, maybe isn't too unbelievable. I don't know what the car would have run with the old radiator on a 40* day on the highway, I never drove it when it was that cold.

Haha. Yea. The heater core was a pain. I still haven't put my glove box liner back in. Now I just have to find a slightly taller spring radiator cap, and maybe I'll be good to go until the next project.

rustyroger

Don't trouble with the radiator or cap any more. Fix the heater instead and you're good to go until the next project.

In all honesty I think you have overthought this one, and chased down a non existent problem.

Roger.

jpc647

There is a problem. The cap isn't sealing. Like I said above, I have a slightly taller one coming, now it looks like tomorrow. Or I can double gasket the one I have, but it's currently bleeding air continuously into the overflow and it shouldn't. We don't have pressurized overflows. If I did, this would be a non issue.

There's nothing wrong with the heater. The car itself if just drafty. The heater blows okay, it's "warm", it just only comes out the floor vents. That's just how it is.

Supernaut72

Hmm, well I'll admit I can't really speak for the heat in a '72 Cutlass (that's what you've got, right?), though Olds V8s do tend to put off lots of heat so lukewarm cooling doesn't sound like a limitation of the car's design. I'm sure GM would have been receiving lots of complaints from northern drivers if that were the case. Could be an issue with the blend door not traveling as far as it needs to, not sealing right. Full hot should redirect all of the cold incoming air through the heater core, which gets its coolant directly from the back of a cylinder head. Something to look into, perhaps.

Don't think the weatherstripping would help with the heat that much, I've got a '69 Chevy sedan with completely dryrotted, crumbly, destroyed weather seals and with a good working heater it gets downright uncomfortable if I leave it on full heat for too long. The sound of the wind leaks can become grating, though. Good luck with it, having fully working heat isn't crucial but it sure sucks when it isn't available.



Edit: I saw in another thread that you were running a 160 T-stat. Wasn't aware of that. With that 'stat, 175* would be normal, I was under the impression you were running a standard 180* stat. Keep in mind that from the factory, an early '70s car would've run either a 180 or a 195 thermostat, for emissions/economy reasons back then just as now. Granted, my only direct experience with early '70s cars is my Cadillac and the information provided by folks at the Cadillac/LaSalle Club forums regarding what temps it should be running at, but it's my understanding that an early '70s car getting up into the 230* range on a hot day was actually considered normal by the engineers, with a minimum designed operating temp way higher than 160* to meet those incoming federal standards.

Now, whether that's better or worse for engine longevity or performance, I won't get into it here, it's just the way they were rolling off the line originally. If you're running a 160* stat and you've got a brand new radiator that really sheds the heat, obviously you're going to have lower temps in the heater core, which could be part of the heat problem for you. Cooler isn't always better.

MDchanic

I've driven many sixties GM cars over the years, and I will agree that getting enough heat was never an issue.
The only time I found there wasn't enough was on a cross country trip in January, in my '72 Skylark convertible. I was driving through the mountains in Wyoming and began to wonder whether I was having a water pump problem or a coolant leak, as it was slowly growing cooler and cooler in the car, and it had never had inadequate heat in the past. I pulled into a lonely gas station in the middle of the inky blackness to fill up, and figured I'd pop the hood and see whether I could see anything wrong. The gentleman came out to pump the gas, stomping and rubbing his hands together.
I said, "Chilly, huh?"
He said, "Yeah, it's 25 below."
I said, "Ohhhhhh..."

Other than that, I always had more heat than I needed.

- Eric

Supernaut72

Ha! Guess you found its limitations. Even more wild to consider that it was a heater in a '72, after they'd raised the operating temps of vehicles to around what modern cars run.

I just noticed this... Heat to the floor is normal, nothing's broken about that. The idea is, since hot air rises, the traditional way to heat a compartment is to blow the hot air down low, along the floor pan so it rises and mixes evenly with the rest of the cabin air. If you want to see a neat trick, put the climate control to "Vent" and move the temp slider to "Hot". There's your mid-level heat, it just might not heat the cabin as evenly.

jpc647

[QUOTE=Supernaut72;993461]Hmm, well I'll admit I can't really speak for the heat in a '72 Cutlass (that's what you've got, right?), though Olds V8s do tend to put off lots of heat so lukewarm cooling doesn't sound like a limitation of the car's design. I'm sure GM would have been receiving lots of complaints from northern drivers if that were the case. Could be an issue with the blend door not traveling as far as it needs to, not sealing right. Full hot should redirect all of the cold incoming air through the heater core, which gets its coolant directly from the back of a cylinder head. Something to look into, perhaps.

Don't think the weatherstripping would help with the heat that much, I've got a '69 Chevy sedan with completely dryrotted, crumbly, destroyed weather seals and with a good working heater it gets downright uncomfortable if I leave it on full heat for too long. The sound of the wind leaks can become grating, though. Good luck with it, having fully working heat isn't crucial but it sure sucks when it isn't available.



Edit: I saw in another thread that you were running a 160 T-stat. Wasn't aware of that. With that 'stat, 175* would be normal, I was under the impression you were running a standard 180* stat. Keep in mind that from the factory, an early '70s car would've run either a 180 or a 195 thermostat, for emissions/economy reasons back then just as now. Granted, my only direct experience with early '70s cars is my Cadillac and the information provided by folks at the Cadillac/LaSalle Club forums regarding what temps it should be running at, but it's my understanding that an early '70s car getting up into the 230* range on a hot day was actually considered normal by the engineers, with a minimum designed operating temp way higher than 160* to meet those incoming federal standards.

Now, whether that's better or worse for engine longevity or performance, I won't get into it here, it's just the way they were rolling off the line originally. If you're running a 160* stat and you've got a brand new radiator that really sheds the heat, obviously you're going to have lower temps in the heater core, which could be part of the heat problem for you. Cooler isn't always better. [/QUOTEe

I am running a 180* thermostat. The parts store accidentally gave me a 160* and I debated on using it. But I had to go back for something else, so I swapped it. My issue was when the coolant temp was running 230* the fuel in the carb gets so hot, that it starts to boil, you can actually hear it sizzling/boiling. Trying to bring all the temps down a little.

Good to know about the heater though. My windows stay open 3/4" because the weatherstripping is bad and the windows rattle. So on the highway, there's a lot of warm air leaving the car. I'll have to look into the blend door, and see if it's an "easy fix". I'll first check the wires under the dash, making sure the levers in the panel are fully opening everything as they should. Since I've owned the car, the heat was never great. I just thought it was how it was.


Good info. Thanks.

rustyroger

Are you losing coolant?.

Roger.

olds 307 and 403

I have decent heat in my 70. The main issue is leakage at the fresh air vents. One was totally screwed, leaked cold air bad. When I drove the car home, the heater on full blast barely kept up at just above freezing. I blocked that one completely but the other one leaks slightly and keeps the car decently warm. Glad to hear you are figuring this out, my 70 ran right around 175 max with the 260, will see with the 350.

jpc647

I'll have to look into that. Why'd you block the vent completely? Don't you need the vent?

Supernaut72

Oh okay, when I searched around I saw that you were running a 160* stat at some point, didn't know if that was still the case or not. Regarding the fuel line, I took others' advice and insulated it last August, as I found I had a heater return hose that brushed right by the steel fuel line and was heating it up to a boil. Right now it's just clean shop rags clamped around it, but I'll be looking into more proper insulation before summer really hits again. Proper or not, it's worked a charm.

Oh, that sucks. Yeah if you have to have the windows open to avoid rattling, that'll interfere with the heat to some degree even if it's working as intended. The blend door should still be cable-operated but don't quote me on that, if it is it should be pretty easy to hunt down the cable by its black sheath, then observe the end of its steel core for proper movement when you move the temp slider. Depending on location, might even be able to disconnect it to move the blend door's stud by hand to make sure the door isn't binding up in the heater core housing, or to see if the cable is moving it all the way on its own. Good luck!


No problem The older cars certainly have some eccentricities when one's more acquainted with modern cars, but a lot of little things haven't really changed all that much, apart from the odd effects aging can have on a car's functions.

jpc647

No problem, I'm happy to answer questions in the pursuit of solutions! Really, just like a regular red shop rag? Got a photo? Is it zip tied on? When it gets hot, it might be worth doing it, and taking a ride just to see if it would help the problem.


I may take a quick look tomorrow or friday(the weather is supposed to still be warm) and I'll follow the cable to make sure the end connected to the door is fully operating, and like you said, not getting stuck. I did have it all apart, who knows, maybe it wasn't put together right when I got the car.



Very True. I did replace the heater hoses that were in the car, but those only were for the fresh air vents. They were very brittle and dry rotted, so I bought flexible hole approx the same size and replaced it. I didn't notice a difference, but I felt better, haha.

Supernaut72

Currently it's one of those blue lint-free towels but it's kinda grungy, one of those red towels would look better, might even insulate a little better. Had zip ties but the underhood heat did away with them pretty quick, they got brittle and fell apart. For now it's wrapped and then pinched in place between the fuel line and heater hose, though I did get some large twist ties with my front parking brake cable segment so I'm thinking of using those with my next insulation.

Before wrapping the line I had major, major issues with fuel percolation, so it did seem to make an impact. Since the weather cooled off I haven't messed with it anymore but I'll be contacting an HVAC supply shop for suggestions before it heats up again. Don't have any pics handy, sorry, but I can try to snag one next time I'm under the hood!


Regarding your cable, since that stuff's been out of the car it could be as simple as a busted retaining clip on the cable sheath, I had that happen on mine sometime between removing and re-installing the ductwork. The sheath would attempt to move with the cable and the cable was hardly moving the blend door as a result. Nothing a good glob of epoxy couldn't cure. Hopefully it's just something small like that.


And yeah, replacing dryrotted rubber pieces and hoses in an old car is always satisfying, no matter how little it changes. "Okay, there, don't have to worry about that for another couple of decades, onto the next item". Haha

olds 307 and 403

The rubber was mangled, probably where the mice got in. I shoved a rag and duct taped it up. There is two, the other one provides plenty enough air in the summer.

jpc647

Gotcha. What are running for a carb? What motor, specs, etc? Just to settle a little curiosity. Are you running a heat spacer between carb and intake?

I'm hopefully going to have time to look at it soon.

It did make me feel better. I did lose some of the insulation under the dash, but otherwise all was well.

Supernaut72

I'm running the stock 9:1 compression 2-bbl 425 that the car was born with, Rochester 2GC carb on top. Stock 180* thermostat, can't remember what brand but it's nothing fancy, Spectra Premium 4-row radiator. Also have a Hayden 2747 heavy-duty fan clutch, which makes a bit more noise taking off from a light, but does very well at keeping the temps from getting out of hand. Don't have a spacer, though I'd thought about trying one when I first heard fuel percolating, before I noticed the heater hose making friends with the fuel line.

I feel your pain regarding the dash insulation, been tinkering under the dash of my car lately and every time I wind up with clumps of yellow insulation all over the floorpan. I figure I'll do something about it eventually, if it becomes an issue. At least the firewall insulation is still intact.

jpc647

Gotcha. I discovered a couple of the rows in the OEM radiator (2 row) were crushed, and by a couple, I mean 4 or 5. I recently installed a clutch fan(don't know the brand) and I'm hoping the 4 row equivalent 2 row radiator and 180 thermostat help to mitigate some of the temps under the hood.

The spacer doesn't seem to do much for me, although I have an Edelbrock carb.


I'm glad I'm not the only that makes a mess everytime I thought something under the dash.