Jump to content

1938 Radiator Flow Specification


EmTee

Recommended Posts

I have been looking for the coolant flow specification for a 1938 Century (Model 61) radiator, but haven't found anything.  Does anyone out there have a catalog or other source that contains that information?  I want to flow test my radiator, but need to know what the design flow rate is.  Thanks!

  • Like 1
Link to comment
Share on other sites

One of the checks is to use a remote indicating IR thermometer.    (Harbor Freight - Chinese )  I Use that to see how the temp  shows across  the surface of the radiator.   left to right and top to bottom.  When  able, do the front surface.   I have a 60 series  radiator in my 40 series 38-46s.   The standard 60 series radiator is 3" thick and the standard 40 series radiator is only 2" thick.    So the 60 series radiator has the better cooling capacity vs the 40  series.   In Florida we need as much as we can.    We also put a 'pusher fan' in front of the radiator.   I usually get a 25* drop from the input temp to the output temp.   So if you have a consistent temp drop across the radiator with no hot or cold spots,  your radiator is doing its job.   If thats not enough,  replace the core with the best you can fit on your old upper / lower part.    Cast Iron blocks take time to warm up and conversely take  TIME to cool down.   Once it gets over 212*,  you need to be moving to cool things down.    We suffer with long red lights and HOT BLACK TOP SURFACES.    Buick designed their cooling systems to operate with a 45 - 50 mph  and nominal outside temp.    + 90* outside temp's and slow / stop and go traffic does not make for a reasonable operating environment.    Today we have aluminum blocks and dual cooling fans with fan shrouds to control our engines.     Now - the block needs to be CLEAN.   With the remote  IR temp unit you can see if you have any hot or cool spots that show blockage with rust and crap that won't let the engine cool as Buick needed.   Fix that as necessary.   (also leaking valves ).    Been there, done that.    BTW,  I designed my own fan shroud for better cooling on my '35-58'.   I will find out how much better it is but that will be next summer.   Right now its only getting into the low to middle 70's.    So,  I'll wait !    Cooling can be a long trip to solve in keeping our engines operating in normal ranges.      

  • Thanks 1
Link to comment
Share on other sites

Figure a flow rate of 35 gpm as a working number. 
 

Buicks of the 20’s and 30’s NEVER ran hot. Cars that run warm or push water are simply not right. Plugged or restricted flow through the radiator, rust and scale in the block, poor circulation from a crappy or worn pump.......timing off, incorrect recore, the list of problems is long and expensive to deal with.  I drive our V-16 Cadillac in 105 degree weather in southern Florida on 95 at 75 mph and the car runs in the low side of the normal range and the shutter opens at the correct 140. By 1930 there were millions of cars on the road....none of them overhead or ran hot, as it was very simple engineering. 

Edited by edinmass (see edit history)
  • Like 1
  • Thanks 2
Link to comment
Share on other sites

My radiator looks to be original.  It was 'checked' when the car was refurbished.  Best I can tell, it was pressure tested and it doesn't leak.  I've only put about 300 miles on the car since i received it at the end of September, as i have been sorting out bugs.  The last outing I purposely drove at a steady 55 ~ 60 mph to verify fixes made to resolve what felt like a surge or miss at speed.  Good news was it ran well, no surge, but temp started climbing above 180 after 6 or 7 miles at 55 mph.  When I pulled into the driveway I left it idling as i went in to open the garage door.  After opening the door, I see coolant dripping onto the driveway under the car.  I shut it off, opened the hood and saw coolant dribbling out of the overflow tube.  That wasn't too surprising, but then I noticed coolant dripping from the trialing edge of the RF fender and the front surface of the RR fender was wet  - beads of coolant on the paint...

 

My theory is the sustained highway speed was running high volume through the water pump, discharging into the radiator.  The radiator isn't able to accept the higher flow, so coolant filled the upper tank until it was forced out the overflow.  I wondered how the pump was able to keep pumping high volume with a restricted radiator, but then I realized the excess was going out the overflow and the rest was going back via the bypass valve.  Anyway, i suspect a partially blocked radiator.  I had to add about 1/2 gallon to replace what had been expelled through the overflow.

 

Note that it had been running 180* with no coolant loss up to this point, where I was driving 40 ~ 50 mph with short bursts of 55 ~ 60 mph.  So, I want to either confirm or rule-out a radiator blockage.  Core plugs were removed and the water jacket  was rodded and pressure-washed when the car was restored (about 400 miles ago).  I flushed the engine and radiator with water a couple of weeks ago when I installed the antifreeze.  The plain water that came out was orange-ish, but all fine particles; no flakes or chunks.  Likewise when I back-flushed the radiator.

Link to comment
Share on other sites

I'm thinking of connecting a 5 gallon bucket to the upper tank and plugging the overflow and lower hose port.  I'd fill the radiator and bucket to the 5 gallon mark.  I'd pull the plug from the lower hose port and measure the time to drain 5 gallons from the bucket.  Using Ed's ballpark of 35 GPM, the time should be 8 ~ 9 seconds.  I'd plan to run several trials (e.g., 4 or 5) and average the times.

  • Like 2
Link to comment
Share on other sites

@EmTee, That is kind of a valid test. However, flow rate is a function of area, friction AND PRESSURE! With your test the pressure portion of the equation is very low.  I have no idea what to expect with your test. I would lean to a simpler test... Simply leave the cap on the radiator and secure a garden hose with good flow (check the flow with the 5 gallon bucket and timer) to the upper hose port. Turn on the hose to full flow and see what happens. What I would want to see is the whole flow come out the bottom port and NONE being pushed out the overflow. If this test passes I would look at other possibilities for the heating problem starting with timing and especially vacuum and mechanical advance. The breaker plate in the 37 and 38 and maybe others is known for warn bearing balls and sticking so the automatic advance fails. Just my $.02.  Good luck.

  • Like 2
Link to comment
Share on other sites

Ok, not trying to be difficult, but a car that was restored should always get a new radiator. That said, it’s expensive, time consuming, and difficult. This tells me a few other things. The motor wasn’t done......just cleaned out the water passages. So, it’s a refurbishment, not a restoration. Not being critical........but we need to speak on the same wavelength to make sure we understand each other. You probably have multiple issues.....and pushing water at speed is typical of a car that wasn’t totally done over. Now.......what is the fast, easy, and cheap fix. Ready?

 

There isn’t one. Now we are left trying to fix shortcuts that can be very difficult. Take it one step at a time. My first recommendation is entirely drain the cooling system and fill it with evapo rust. There are many postings here about using it. I sort of started using it and posting about it ten years ago and often times it will get you across the finish line without taking everything apart. It’s not cheap per gallon, but doing the math it’s a bargain. You can buy it on line, at harbor fright, Walmart, and others. Run it straight......do not cut it with water, and drive the car for a few weeks with it circulating. Don’t speed or make it push out......the trick using this is to thermo cycle the car often.........it works better with heat, and thermo cycling the engine breaks it lose and allows it to do its job. Sometimes you need to do the treatment three times......and yes, it will cost 150 bucks each time. Much cheaper than a radiator, labor, and paint repair. Look up the process in detail here from other postings........and PM me if you need additional help.......and be sure NOT to let the car FREEZE during the winter, as evapo rust does not offer protection from a cracked block!

 

PS- pushing water out is ALWAYS a flow issue.........always. Then you may have other areas or issues to deal with, start with the flow restriction.

Edited by edinmass (see edit history)
  • Like 4
Link to comment
Share on other sites

3 hours ago, Bloo said:

Is this a non-pressurized system? What kind of coolant? What type of water pump, sealed or packing gland?

It's a non-pressurized system.  I'm currently running 50/50 green ethylene glycol.  It's a 'modern-type' pump, mounted to the front of the engine and belt driven by the crankshaft pulley.  The restoration blog states that the pump was rebuilt by a third party.  One other thing to note is that when I installed the antifreeze I also removed the valve mechanism from an old thermostat and installed just the empty body (basically a restriction plate).  I have the original 160* thermostat and will test that in a pot of hot water to make sure it's opening properly before re-installing it.  I'm going to call a large, local radiator shop next week and ask them whether they have the means to perform a 'real' flow test.  If not, then I'll proceed with my backyard test, just to establish a baseline.

Link to comment
Share on other sites

Jim Nelson's check method is valid.   Ed is correct.  Very LEAST I would do is pull the radiator and have it rodded out. New core is best. In the overall scheme of things, cheap.

 

  Radiators, even today, are sized with little excess capacity. Doesn't take much "plugging" to be under capacity.

 

  Bite the bullet. Pull the radiator.

 

  Ben

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

2 hours ago, edinmass said:

PS- pushing water out is ALWAYS a flow issue.........always. Then you may have other areas or issues to deal with, start with the flow restriction

Thanks, Ed - you're confirming my suspicion.  And yes, you're right again, I would say the car is 'refurbished', or partially restored; there are still things to be done and that's the list I'm currently identifying.  My thought right now is to determine the condition of the radiator and go from there.  The evapo rust is something that I'll probably hold-off until Spring, as I won't be driving much up here in NY and I definitely need freeze protection.

 

FYI, just poking around on the internet I see there's a shop near Buffalo that advertises they can fab an aluminum radiator for a '37 Buick for about $600.  All things being equal, I'd prefer a brass/copper re-core (if mine can't be saved) even if it's a 'modern' style and not a reproduction of the original.  Like I said, I'm going to make a call next week and ask them a bunch of questions...

  • Like 2
Link to comment
Share on other sites

EmTee…….please understand one thing, installing a modern aluminum radiator will significantly affect the cars value is a large negative way. Unfortunately, your going to have to work it all out one step at a time. 

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

You may have a foaming problem. I changed my antifreeze using the old green kind a week before leaving on a road trip, and though the car has always run a little hotter than I would like, suddenly I had a push/boil problem I didn't have before. I spent the rest of that week chasing the problem. Antifreeze formulas vary widely today, and the "old green" formula I recently had foamed horribly. It is an open system,and so the foamed coolant would push out the overflow at speed. When the overall level got low enough that there was foam in the head it would boil. If that is what is happening, you could try some Valvoline/Zerex G05. It is less prone to foam.

 

I don't want to discourage you from flow testing though. I'm really curious about the results, especially if you do it yourself.

 

Edited by Bloo (see edit history)
Link to comment
Share on other sites

4 minutes ago, edinmass said:

installing a modern aluminum radiator will significantly affect the cars value

Yup, that's the last resort.  (I'd never get rid of the original one if that happens.)  My goal with this car is to tour with it, so it needs to be as reliable as I can make it.  I'm not looking for shortcuts (within reason) and don't want to do anything that's not appropriate for the car...

Link to comment
Share on other sites

The proper way to service the cooling system…..is do EVERYTHING………..while it’s winter pull the pump and rebuild it, also check for the grease cup for a check valve to prevent it from sucking air at speed……another common problem that pushes water only on the highway.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

5 minutes ago, edinmass said:

...also check for the grease cup for a check valve to prevent it from sucking air at speed...

Yes - that was also something I am going to look at.  Bloo's foaming issue is also a possibility, however, I didn't see any foam being expelled; it appeared to be all liquid.  Next time I refill the system I will take Bloo's advice on the Zerex G05 (currently it's NAPA's green stuff).

 

Can I pressure (or vacuum) test the pump once I have it off the car to rule-out 'sucking air'?  The pump has to be removed in order to get the radiator out anyway...  The other thing I'm going to scrutinize is the coolant 'bypass valve', which the restoration blog notes has been modified.  I need to get eyes on what was done there to make sure it isn't part of the problem.

 

FYI, I've seen green foam being spit from my '64 GP on occasion.  That car will run hot on a hot day when sitting in traffic.  The issue with the Pontiac is it's a non-A/C car, so it has the basic 4-blade fan and no shroud.  It doesn't get enough airflow in that situation.

Link to comment
Share on other sites

Emtee,

While, I don't know the extent or method of the radiator shop's testing, they tested it and said it was fine. The water pump is also a new pump from Cars, Inc. I suspect antifreeze foaming might be your issue. Running straight water with water wetter (the source of the slight orange color) it did not have that issue. I would try a different antifreeze.  

  • Like 2
Link to comment
Share on other sites

Problem is 99 percent of radiator shops don’t actually do a flow test, they eyeball it. Been there, done that. I have no idea who the pump builder is, but I can say that 80 percent of the pumps I do are being done over after tried and failed……..simple fact. Car had the block cleaned, radiator flushed, pump done over. All decent and correct for a car that sat and is getting back on the road. Since it’s still pushing water out……. There MUST be a short cut, poor workmanship, or someone missed something…………not pointing fingers, as lots of great shops have newbies doing component work and stuff makes it out the door that should not. My new guess as to what is wrong now we have all the new information…….sucking air first, restricted radiator seconded. I would run straight water with cutting oil in the spring after the freeze danger passes……..cheaper and easier to deal with while working on the system, and it will NOT foam with cutting oil. 

  • Like 1
Link to comment
Share on other sites

2 minutes ago, MCHinson said:

While, I don't know the extent or method of the radiator shop's testing, they tested it and said it was fine.

I did go back and look at that part of the restoration blog.  As you say, there's no mention of what was specifically done (other than mechanical repair of the support).  So, I'm going with the assumption they simply pressure tested it and soldered any pinholes.  It doesn't look like they removed tanks or 'boiled' it out.  Like I said in the beginning, the system was not leaking when my test drives were in the 40 ~ 50 mph range.  The last run with an extended period at 55 ~ 60 mph is where it was pushing coolant heavily out of the overflow tube (at the top of the upper tank).

Link to comment
Share on other sites

3 minutes ago, edinmass said:

My new guess as to what is wrong now we have all the new information…

Thanks Ed, I think we're on the same page and I really appreciate the input.  This is my first pre-war car, so although I'm generally familiar and have the shop manual, it's great to have this forum of experts to lean on...  -Tim  ;)

Link to comment
Share on other sites

2 minutes ago, edinmass said:

Problem is 99 percent of radiator shops don’t actually do a flow test, they eyeball it.

 

^^So much this. Admittedly they probably usually get it right, having seen so many, but if they don't then you still don't know anything. Ed's 35GPM is the closest thing to a target I have ever seen. I certainly never got any numbers out of a radiator shop. Testing it has to be the best way forward.

Link to comment
Share on other sites

I'm going to call the local shop (or better yet, I may just drive over there and look them in the eye) next week.  I'll pull the radiator and try to rig a backyard flow test unless the shop says they can provide me with a flow 'number' (i.e., GPH).  If nothing else, it will give me a baseline for comparison.

  • Like 1
Link to comment
Share on other sites

Use a plastic barrel and hook it up to the radiator and measure thirty five gallons of water and time how fast it drains. Also understand that it’s possible it had been recored in the past and flows too slow even if there is no restrictions……been there, done that.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

I do have a blue plastic barrel that I think holds ~20 gallons.  That would be better than several 5 gallon runs.  Another thing I'm considering before pulling the radiator is: (1) plug the overflow and (2) clamp a section of hose (preferably clear) to the filler neck.  I would run the car in the driveway at a increasing idle speed and monitor the level of coolant in the hose attached to the filler neck.  I expect that at some RPM (2000 or so?) I'll see coolant start climbing up the hose...

  • Like 2
Link to comment
Share on other sites

Just found and read your other thread......much more info than before. Overheating at 50 degrees ambient air temperature and pushing water is a indication of a cooling system not even functioning at 60 percent of potential......it’s probably less than half. While you need to look at everything......I expect a new core is in you immediate future. That said, shops get buried in the spring.......I would pull it apart now and get things going so you don’t lose 2/3 of the season next  year. 

  • Like 4
  • Thanks 1
Link to comment
Share on other sites

When I restored my '37, I sent the radiator out to a company called "Cap-A-Radiator" in NY.

I had the original Harrison radiator re-cored and it was money well spent.  

I found them very professional, great communication and nice work.

 

Now approaching 2500 miles, and driving on some 95+ degree days, she barely approaches 180. 

 

Overheating, boiling over, foaming, antifreeze on the paint, drips in the garage......... bite the bullet and enjoy that magnificent automobile!

(They do heater cores also.  It's worth a conversation with them.) 

 

1644010867_ScreenShot2021-11-27at1_08_27PM.png.203d2a4284c0a611bc96ad2dea06e964.png

 

1730121803_ScreenShot2021-11-27at1_06_51PM.png.b7e1692fd96e62bebd653c67b2e5736b.png

 

  • Like 3
Link to comment
Share on other sites

Thanks Gary - I did see their web page when I was poking around yesterday.  As Ed suggested I plan to pull the radiator as soon as I make a couple of related checks.  With things as they are these days I expect a re-core will take 2x as long as it would have 2 years ago...

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

34 minutes ago, EmTee said:

Thanks Gary - I did see their web page when I was poking around yesterday.  As Ed suggested I plan to pull the radiator as soon as I make a couple of related checks.  With things as they are these days I expect a re-core will take 2x as long as it would have 2 years ago...

 

 You won't be sorry.

 

  Ben

  • Thanks 1
Link to comment
Share on other sites

I took the car for a short ride on Monday (11/29).  When I pulled into my driveway I was leaving a dribbling trail of coolant, though temperature was still 180.  With the car idling in front of the garage I removed the radiator cap and the neck was full of foam!  Not only that, but there was liquid running down the right side of the inner surface of the core.  Up until this point, the radiator had not been leaking (I hadn't needed to add coolant until the episode last week where it was pushing coolant out of the overflow).  I pulled the car inside and shut it off.  After it cooled a few minutes, the foam subsided and the level was low, but the bottom of the neck was still wet.

 

Yesterday (Tuesday) I decided to try to figure out whether the foaming was simply due to the now leaking radiator, or something worse (e.g., head gasket).  I topped-off the radiator and removed the fan belt to disable the water pump.  With the radiator cap off, I started the car and ran the engine until it warmed up while looking into the radiator neck.  I ran the engine at a fast idle and saw no foam and no sign of air bubbles.  Following that check, I let the car cool down (~100*) and then drained coolant from the radiator and removed the upper radiator hose.  Next, I refilled the radiator until coolant was about 1-inch below the top of the hose connection on the thermostat housing.  (Note that I have been running the car with a 'gutted' thermostat [basically a restrictor plate] since I added the antifreeze a few weeks ago.)  I then repeated the previous test, running at a fast idle and watching the coolant in the thermostat housing.  Aside from a couple of 'burps' as the coolant warmed up, the result was similar to the first test; no foam and no bubbles in the coolant.

 

So, my conclusion at this point is that the radiator core is obviously leaking now, so it is likely the source of air that is being whipped into the coolant.  There is a chance that the water pump could be to blame as well, so my next test will be to pressurize the cooling system (sans radiator) to 4~5 psi and see whether it holds.  Following that, I will remove the water pump and the radiator...

  • Like 3
Link to comment
Share on other sites

I emailed the radiator shop that Gary W identified above (Classic Radiator) in Farmingdale, NY.  John at Classic Radiator got right back to me via return email and answered all of my questions.  It's obvious these people know antique radiators and I intend to send them my radiator.  Thank-you to Gary for the recommendation.  They're equipped to handle anything from cleaning and repair to core replacement.  When I asked him about how they verify a repaired core is 'good' he told me they flow test the radiator.  That sold me.  ;)

  • Like 1
Link to comment
Share on other sites

Depends...  He said a repair could be as little as $150 and take a week.  Re-core could be ~$1000 and 2~3 weeks.  I'm bracing for the worst and hoping for the best.  Above all else, i want it fixed right.

  • Like 1
Link to comment
Share on other sites

On 12/1/2021 at 5:45 PM, EmTee said:

...so my next test will be to pressurize the cooling system (sans radiator) to 4~5 psi and see whether it holds.  Following that, I will remove the water pump and the radiator.

Today I performed the cooling system pressure test that I mentioned yesterday.  The plan was to pressurize everything behind the radiator, since I already know that the radiator is leaking.  My objective was to see whether I may have issue with the water pump, heater core or head gasket in addition to the radiator.  I went to the hardware store and bought some hose adapters, cap and plug to allow me to cap the radiator hoses where they would otherwise attach to the radiator.  I modified the pipe plug at the upper hose to accept a tire valve stem.  I used my air chuck to pressurize the system and my tire gauge to check the pressure.

 

image.png.4dc1aec3254682eb9871976a469819e7.png

 

image.png.a8b376b539b44ad79461377f9b03d064.png

 

By the way, here's a picture showing the active leak in the radiator.

 

image.png.934ed039bc57db59aba86017e7353630.png

 

With the hoses plugged, I pressurized the system to 7 psi.

 

image.png.ca06a97dad60bb4cddd24b0ee3944a47.png

 

After chasing a couple of leaks in my test setup, the system maintained 7 psi for 30 minutes (I figured that was long enough).  I now feel pretty confident that the radiator is the root of my cooling problem.  With the pressure test complete, i removed the water pump/bypass valve assembly to allow removal of the radiator.

 

image.png.daed23f4cfac0688563f93bec126854e.png

 

The radiator is pretty heavy (even for its size) and it almost feels like it has jello in it (if that makes sense).

 

image.png.d4036a34d9efab16b860265a1db6ecce.png

 

 

 

The core is 3-inches thick.  Does anyone know if that's correct for this car?  Before I crate it up and ship it to Long island, i want to try to perform a 'gravity-dump' flow measurement.  Like I said above, I strongly suspect that its packed full of rusty sludge...

  • Like 5
Link to comment
Share on other sites

A 3 inch thick core is right for a 38 320 engine. Same as my 37. I had to have mine recored as it was full of pinholes. My recore cost $1000 about 6 years ago so the price you were quoted seems fair. Another thing you could try after your flow test is to turn the radiator upside down and ,run a garden hose in the bottom, now top, port and see if anything flushes out. It will not "repair" anything, but it might give you some information.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

18 hours ago, 37_Roadmaster_C said:

run a garden hose in the bottom, now top, port and see if anything flushes out.

Sure, that would be interesting.  I did attempt to backflush the radiator with the garden hose when I installed the antifreeze.  I didn't really see anything but orangeish water come out (no flakes).  I would expect turning it upside-down will loosen more crud.  It looks like Sunday will be decent, so hopefully I'll be able to mess with it then before crating it and shipping Monday or Tuesday...

Edited by EmTee
typo (see edit history)
  • Like 3
Link to comment
Share on other sites

Today I rigged-up a gross gravity-powered flow test for my radiator.  I modified a spare 5 gallon bucket that I had using some leftover plumbing fittings so that it would dump into the radiator's filler neck.  There was no good way to dump into the upper radiator hose nipple because the opening is below the upper tank.  I used my pressure test caps to block the upper and lower radiator hose nipples.  I also blocked the overflow tube.  I sat the radiator on the ground against a scrap piece of plywood leaning against my truck's tailgate.  The bucket was supported by the tailgate with the output plumbed into the filler neck.  A picture of the setup is provided below.

 

image.png.699ad9ce4bfc90ac81d322d1548ce03e.png

 

I filled the radiator and the bucket to the top with water, pulled the hose off the lower radiator connection and measured the time needed for the bucket to empty (~5 gallons).  Four trials ranged from 31 to 35 seconds.  Two were close to 32 seconds (as best I could measure).  I also ran a check of how long it took for the bucket to empty without being connected to the radiator.  It took about 15 seconds for the bucket to empty when dumping directly to the ground, so the radiator was definitely restricting the flow from the bucket.

 

image.png.52a1dabf7ec6c29e1aa19fd5eddf1ad3.png

 

Using Ed's flow guesstimate of 35 GPM as the benchmark, it's obvious that my radiator flow falls short.  Based on my measurements the radiator is only flowing about 10 GPM, or roughly 1/3 the expected value.  (Note that the setup is only capable of providing about 20 GPM to the radiator.)  Finally, I attempted to backflush the radiator with it turned upside-down.  Other than a little orange-ish water with a few rust flecks, there wasn't much of anything exciting to report.

 

Next step is to crate the radiator and ship it down to Classic Radiator in Farmingdale for assessment and repair.

  • Like 2
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...