Cadillac 500 auxiliary radiators

[wschimberg]

So I have a car that may have a few go fast parts on it and I have trouble in the summer keeping it cool.  I made sure timing and everything is set properly and it was still getting hot.  I have a huge radiator in it with 4000 cfm of fans pulling air through it.  It doesn't get hot at a stop, just while under load.  I can't reasonably put a bigger radiator in the thing but I could put 2 smaller roads in.  I was wondering if I could hook 2 heater core to the water outlets on the heads of the 500 that the heater core would normally hook up to.  My only concern would be disrupting the natural flow of coolant in the engine and making the issue worse. My second question would be where would that water then return.  And would just looping the hoses to the place for the return help circulate water better and decrease my heat issue.  The last thing is also my exhaust is a little restrictive for my engine but I don't know if that would be enough to make an engine run 230.

[TJ Hopland]

Do you have the proper thermostat with the lower valve on it?  The proper stats have a different amount of open area than a typical stat plus they have that lower valve that blocks the bypass when fully open.  That bypass is like a 3/4" hole so that's a decent amount of coolant to not go through the rad if its open all the time.

What sort of radiator are you running?   There are a lot of pretty much crap radiators out there especially when you get into the all aluminum ones. They look pretty but have zero actual design going on.

For going down the road it sounds like maybe your fans are restricting things?  I have seen setups with louvers that open up to allow more flow as well as some sort of active management of the fans so they are not also slowing things down.  I don't think its as easy as not powering them. 

What sort of car is this in?   Stock cars have lots of seemingly unimportant little flaps and seals in various places to control the air flow.  At higher speeds missing one of these features can really change the way the air flows so maybe you have something going on that just isn't allowing enough air to flow.

[V63]

What compression ratio do you have?

 Seems like 230 is about where these engines should run?

["Cadillac Kid" Greg Surfas 15364]

"It doesn't get hot at a stop, just while under load."
Under load is when you are actually doing some work and compression pressures and temperatures go up. As V-63 says, these motors were designed, for thermal efficiency, to run warm. 195-210 degrees is what they were intended to run at with 220-230 not being "worrisome" (to the engineers at least).
An issue with additional "radiator" devices might be exceeding the water pump's ability to pump effectively
Greg Surfas

[The Tassie Devil(le)]

One question I have is "is this engine in a Cadillac"?

What you are describing sounds to me like the engine bay where this motor is in does not have sufficient ability to allow the air to pass through, as in letting the used air out.

A build-up of air pressure within the engine confines will stop air passing through the Radiator, no matter how big the fan is.   At idle, there might be enough outlets to get air flowing, but increasing speed, with more air trying to get in, if it cannot get out, then the pressure in the engine bay will stop the air from coming in through the Radiator.

This happens a lot when people do engine changes, like Hot Rodders and Custom Car Builders, then try to cover every hole or gap to make everything look neat and tidy.   Sticking a larger engine in a place where a smaller engine came from, and not opening up the air-escape holes to allow for air to depart, is asking for trouble.

Bruce.

[wschimberg]

So to start answering questions, it's a cadillac 500 in the 1970 body.  There isnt a whole lot of air flow through the engine bay.  It's a nice aluminum radiator with a shourd that has fans that pull enough air and has the little rubber flaps that let the air through once it up to speed.  Most everything in the engine bay is still stock but I don't know how to get more air flow through that engine bay.  My only thing that I will have to check is if the thermostat is the right one.  I know I have a 180 in it but I have to make sure it's the right cadillac one.

["Cadillac Kid" Greg Surfas 15364]

William,n I might suggest you look for
There re "tens of thousands" of 1970 Cadillacs with standard radiators, correct fan shrouding, and a mechanically driven fan (7 blade is the best) running around successfully cooling in all climactic conditions.
I've got enough "go fast" parts in my (73) to make it almost UN-streetable, and I am using a stock (HD) radiator.
If you are unable to keep the coolant temperature in line (195-220 degrees F) then I might suggest you look for the source of the problem. If you are not using a Cadillac specific thermostat then the bypass circuit remains open recirculating hot coolant without it flowing through the radiator.
Greg Surfas

[TJ Hopland]

So to start answering questions, it's a cadillac 500 in the 1970 body.  There isnt a whole lot of air flow through the engine bay

The 1970 body?  Meaning you have 1970 Cadillac that would have originally had a 472 that has been swapped for a 500?   That should not really make a difference.   Or is this 1970 body not a Cadillac?     

[35-709]

The correct thermostat will look like this, note the flange on the bottom that closes the bypass circuit.  These thermostats only come in 185 and 195 degree iterations (not 160 or 180).  Other "standard" type thermostats will fit but will not perform properly as Greg Surfas has pointed out.  Cadillacs came with 195 degree thermostats form the factory, the 501 series engines (472/500/425) and their cooling systems were designed to run warmer than what some may be used to on older cars.

[TJ Hopland]

There was a series of John Deere engines that used the same stat.  I'm not sure what temps those were available in.  At one time those were regarded as the best quality stats but I assume like most things what ever those fit got old enough that JD didn't care anymore so those too became junk. 

I now do several test cycles on any stat I install in anything.   I also don't ever replace one just because. I will test it if I suspect a problem and want to be sure its the problem.

[J. Skelly]

If you have the correct thermostat, the shroud is designed specifically for the new radiator, and the timing is correct, one issue that hasn't been mentioned is the cooling passages in the engine block.  Some guys on the ACCA forum recommend pouring a gallon or more of Evapo-Rust full strength in the radiator for weeks or months to dissolve deposits - even in antique cars that had been parked for decades. 

These cars were designed to run well with the stock radiator and water pump.  In fact, Cadillac overdesigned them to take just about any abuse an owner would throw at it.  The only time I ever had an overheating issue on one of my Eldorados was with a failed thermostat or incorrect timing.

[V63]

I have a friend with a Stock 500 ELDORADO that now has a "replacement" Direct fit ALUMINUM radiator.

With all other probables exhausted the aluminum radiator is simply NOT efficient enough. Ambient excessive at 110+ the engine Temperature getting to 250 and Then he shuts it down.

  I just sourced an original (tested) used Harrison copper/brass radiator for it and anticipate that should resolve its issue. 

Will advise

[The Tassie Devil(le)]

The reason I asked the question back in post No. 4, I was surmising that the car is not a Cadillac, but something a lot smaller, with a restricted engine bay.

He came back and said it was a 1970 Body, which sounds like he is trying to cover himself by not admitting what that 1970 body actually is.

Makes a whole lot of difference.

Bruce.  

[wschimberg]

Its a 1970 sedan Deville, so about one of the biggest cars that the engine could sit in, but then again it is still from fender to fender.  I had the wrong thermostat in it so I took it out and the new one had the flange in the picture but it made the problems worse today.  It looked like the water was moving slowly through the rad when I took the cap off of the rad, like dripping out.  Would this be considered a low flow situation caused by the smaller hole in the thermostat?  The Water pump looked fine when I did the engine rebuild about 20k ago so I don't think it is that.  Do they sell a high flow thermostat with the Cadillac provisions on the bottom or am I just running in circles at this point, or do I need to do a water pump?  Or with a stock pump and  4 core rad, will the water just flow through slower?  My only other thought is that the stock exhaust is too resitctive being about 50 years old and not completely round in places anymore.  It only get hot when it is about 70 out though so it isn't like my water pump gernaded or something, the system is working, just not to the best of its ability.

[V63]

I asked about compression ratio and that's because if the engine is 10/1 then the problem becomes running the correct octane fuel that is no longer available at the pump.

So to correct the low octane pinging... the trick is to retard the timing but this also increases the running temperature.

Other issues could be a vacuum leak or a lien fuel mixture, improper carburation  can cause over heating

Do you still have a mechanical fan on it ?

[wschimberg]

Im running at a 9.2 compression ration.  It has about 20 degrees at idle(Not a small cam) 34 total and 8 degrees vacuum so it doesn't knock, as far as I can hear.  So I don't think the timing is to far retarded.  With the wide band I have on it, It runs at 13 at idle, 13-13.5 at part throttle, 14 at cruise and 11-12 at WOT.  It is the stock Quadrajet and an edlebrock.  Would the cross over not being blocked off in the intake cause an issue with summer driving?  It has a derale fan shroud with 4000 Cfm of fans so I dont think air flow is an issue, Im more leaning towards flow.  I don't have a lot of experience with cooling systems but it barely dripping, and I mean barely drip unless I rev it up.  Maybe the 4 core is too much for the stock pump and a stock style thermostat.

[The Tassie Devil(le)]

Is the bottom radiator hose closing up when you rev it?  This can cause flow restrictions.

You didn't say why you changed radiators, but Aluminium ones have to be larger to do the equivalent to the originals.

Have you tried reverse-flushing the coolant system?

I don't suppose you have the fans turning in the wrong direction?

What is your timing with the Vacuum Advance off and plugged?

I have the crossover in my '72 completely blocked off, as I like cool petrol to gain the best combustion.

What is the actual temperature of the radiator?  Using a good IR gauge?  These things run hot.  Hotter than most, but are designed to run hot.

What is your Pressure Cap on the Radiator? 

Being an aftermarket radiator, is it designed for recovering excess coolant?  And if so, is the radiator cap the correct type, and pressure?

The size of the radiator will have very little bearing on the cooling system, so long as it isn't too small.  The proper thermostat will regulate the coolant flow.

One question though, is the Edelbrock Manifold designed to take the Factory Thermostat, or a basic one?   If the Factory one is not working, then this could bring up another problem.

Lots of questions.

Bruce.

["Cadillac Kid" Greg Surfas 15364]

Just a note. When I was having heating problems with my "warmed over" 500 I was looking into electric fans. I tried a couple of set-ups and they did not seem to do the job. I called and talked directly with the Tech dept at one of the major electric fan companies and his response was interesting. He said that ANY electric fans you could behind (r in front) of a standard sized radiator would not have the capacity as far as air flow was concerned that a properly cowled, 7 bladed mechanically driven fan would. Interesting.
Greg Surfas

[bcroe]

Step one on any car here is have a premium 4 row
brass and copper radiator made, minor mounting mods
may be required.  The old radiators never seem to
have 4 rows, and they do lose capacity with age.

No aluminum experience here, I keep reading they
are not as good.  I will not have one, to begin
with I cannot solder up any aluminum rad leak.

Some belt driven fans have deeper blades for moving
air.  They might use 5hp when the clutch engages,
no electric fan setup can claim that.  If they
could, it would draw some 250A, the alternator with
losses would use close to 10hp.  Anyway they are
for dealing with minimum speeds, road speed can
handle air flow.  Bruce Roe

[Dave Shepherd]

Also consider the impeller in the water pump has deteriorated where it does not move sufficient coolant.