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1966 429 heats up very slowly at idle

Started by TJP 440, September 15, 2019, 01:19:56 PM

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TJP 440

Just wondering if anyone else has fought this same battle.  66 429 Deville, fresh engine trans, water pump, radiator, (4 row desert cooler) etc.  It's all new. The problem is the temp keeps climbing when idling  :(

I am using a thermocouple probe to measure the actual temp. in place of the factory sending unit.  The probe and meter are accurate to a .1 of a degree.
The temperature increases very slowly at idle in gear on a 80 -90 degree day. After 20 minutes or so it is still climbing and at about 210.  Putting the car in neutral slows it down but it still climbs.  Raising the RPM to 1500 or so will cause it to drop pretty quickly. This to me indicates a lack of airflow through the radiator at idle.

Going down the road it runs @ 175 or so regardless of ambient temps.
If I were using the factory gauge it may not be as noticeable.  However I do not want to torch a brand new engine should I get stuck in traffic for an extended period on a 100 degree day. The car does have the correct pulleys, a factory shroud, with a 2" or so spacer and the outside edges of the shroud have bee sealed to the radiator. I have tried the factory fan as well as and aftermarket flex fan.

The timing is currently set a 10 BTDC and the vacuum advance was moved to the manifold as opposed to ported.  Every change seems to help a bit but not enough.  ANY SUGGESTIONS ???
Thanks in advance
Tim

TJ Hopland

Have you tried different thermostats?    If not I would get a few from hopefully different sources and put them all in a pan of water and see how they operate.   Your symptoms are almost like not even having a thermostat installed.

I'm also assuming you are seeing this behavior after several full heating and cooling cycles so you know its not just air bubbles working their way out after having the system open. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

67_Eldo

My '67 Eldorado generally exhibits the same symptoms. I haven't inspected the problem as meticulously as you have, but when I let the car idle for a while, the temp slowly increases. If the air conditioning is on, the increase isn't quite as slow. My "solution" has been to not let it idle for an extended period. :-)

I cleaned out the cooling system with Thermocure, getting rid of lots of accumulated rust and dropping the normal operating temperature considerably. If your engine is new, you've probably already cleaned out the cooling passages one way or another. So Thermocure probably won't improve your situation.

Ultimately, I figured that there is a heat-soak issue with the design itself. A cast-iron block takes quite a while to heat up, but even longer to cool off. And 50+ years of oxidation doesn't help anything either.

So I figured that if I anticipated facing an extended-idle situation, I'd go out and add an auxiliary electric fan to push more air through the condenser/radiator at lower speeds.

35-709

210 isn't too hot if the radiator pressure cap is working properly at the correct pressure (16 lbs?) and you are using a 50/50 anti-freeze/water mix.  20 minutes at idle, in gear?  When will that ever occur under normal circumstances or even abnormal?  If you are stuck in traffic that long put it in neutral and rev it up just a little.  It seems like you are trying to force it to overheat, a fresh, tight engine will tend to run hotter anyway.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

TJP 440

We have tried different thermostats.  If it would stabilize at 210 I would be fine with that but it doesn't, it keeps climbing.  Part of the problem is I may not be the one always driving the car and that is the concern.  I really don't want to go to an auxillary fan and shouldn't have to but that may be the only solution. Myself I'm suspecting the quality / efficiency of the "DESERT COOLER" radiator core is likely at the root of the issue.  Anyone else ??
Thanks

67_Eldo

My radiator is the original 4-row model, re-cored with copper. You can't get much better than that, as far as 1967-Cadillac radiators go.

One other angle I was considering was adding either an oil cooler or using a double-capacity oil filter. The increased amount of oil would offer additional cooling.

But at this point, I don't think my heating issue is bad enough to go that route.

67_Eldo

Two more ideas:

* Try some sort of water wetter. I wouldn't expect miracles, but some folks say it can chop off a few degrees.

* Check to see that your carb isn't running too lean at whatever RPM seems to be the most problematic.

"Cadillac Kid" Greg Surfas 15364

Try running the distributor vacuum advance directly off manifold  vacuum  and see if there is a difference.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

russ austin

R.Austin

Big Fins

Quote from: "Cadillac Kid"  Greg Surfas 15364 on September 15, 2019, 04:19:44 PM
Try running the distributor vacuum advance directly off manifold  vacuum  and see if there is a difference.
Greg Surfas

QuoteThe timing is currently set a 10 BTDC and the vacuum advance was moved to the manifold as opposed to ported.

;)
Current:
1976 Eldorado Convertible in Crystal Blue FireMist with white interior and top. (Misty Blue)
1969 Fleetwood Brougham in Chalice Gold FireMist with matching interior and top. (The Old Man) SOLD!

Past and much missed:
1977 Brougham de Elegance
1976 Eldorado Convertible
1972 Fleetwood Brougham
1971 Sedan de Ville
1970 de Ville Convertible
1969 Sedan de Ville
1959 Sedan deVille

TJP 440

#10
Quote from: russ austin on September 15, 2019, 05:01:46 PM
Carb running lean at idle.

Doesn't appear to be but worth a check.  Mixture was adjusted for highest idle/vacuum plus 1/2 turn.  Everything that we've tried has helped about 2%,  I'd like 20% to be comfortable  LOL.

I should comment that it does seems to respond favorably to more advance and I may try that as well as it's not pinging yet.  I've also thought about an oil cooler as well as an auxiliary trans cooler but once again it shouldn't need it ::)
Thanks for all the suggestion  any more ???

Ralph Messina CLC 4937

Tim,

QuoteMixture was adjusted for highest idle/vacuum plus 1/2 turn

I'd experiment with a set up closer to factory specs. The carb adjustment with a vacuum gauge is highest idle/vacuum minus a quarter turn. I'd also bring the advance down to 5-7 degrees before TDC using the carb port.  Both my '66's ran with this setting and I never had an overheating issue. Your current settings tend to induce high combustion temperatures.

HTH
1966 Fleetwood Brougham-with a new caretaker http://bit.ly/1GCn8I4
1966 Eldorado-with a new caretaker  http://bit.ly/1OrxLoY
2018 GMC Yukon

busboys

I am curious... Is the "desert cooler" aluminum? If so that is nowhere as good as copper. Have you checked for trace amounts of exhaust gases in the coolant? Why did you change the location of the vac to the dist.??

The Tassie Devil(le)

G'day Tim,

One think in your observations, is how long does it take for the thermostat to open up from cold?

That is, when do you see the sudden rise in temperature as the engine is warming up, to the plateau of when the thermostat opens up, and the temperature levels off as the coolant is being transferred into the radiator.

Plus, no new engine should be let idle for any length of time, and it should be noted that whilst driving at speeds over 35 MPH, there is no reason for the engine fan to be working, as there is sufficient air flowing through the radiator at those speeds, except when travelling with a following wind/gale.

Bruce. >:D

PS.   You have an email from the Moderators that requires your attention.
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

savemy67

Hello Tim,

What is the highest temperature you have measured when idling the engine?  Are you running exactly 50/50 water/anti freeze?  What is the pressure rating of your radiator cap, and what is the rating of your thermostat?  Did you have the original water pump rebuilt or did you purchase a rebuilt unit from Rock Auto, NAPA?

At 15 pounds, a 50/50 mix has a boiling point in the neighborhood of 260 degrees F.  As 35-709 posted, a newly rebuilt engine may run hotter for a few hundred miles.  In '67, the 429 was designed so when the coolant temp reached 230 F, the vacuum would switch from the carb to the manifold, thereby inducing full advance at idle.

I don't want to dismiss your concern, but you may not have a serious issue.  Run the car for a few hundred miles.  Check again the temps when idling, and let the car idle for as much time as you think it might idle as if it was in stop and go traffic.  At some point, the temperature will level off based on the airflow through the radiator, and the water pump volume at idle.  If your temps approach 260 F, and you have set timing, and adjusted the carburetor correctly, then you may have a problem with your water pump or radiator.

If you partially block the radiator at idle, and notice no immediate change in the temperature, then the water pump may be delivering insufficient volume at idle, perhaps due to impeller clearances that are too large.  If blocking the radiator causes an immediate increase in temperature, your radiator may not be as efficient as it was advertised to be for your 429.

I agree, nobody wants to torch a new engine, so keep an eye on things.  However, these engines are pretty tough.  If the ported vacuum is designed to activate at 230 F, I wouldn't be excessively worried if your temps level off at 230 F.  Do you have a '66 shop manual?

Respectfully submitted,

Christopher Winter

Christopher Winter
1967 Sedan DeVille hardtop

67_Eldo

One more generic cooling "hotspot" that hasn't yet been mentioned: Make sure your lower radiator hose isn't partially collapsing.

Alan Harris CLC#1513

Not to insult you, but are you sure your fan is mounted properly? My Mark II Continental drove me crazy with heating up at idle and cooling down at speed. It turned out that the last guy to replace the water pump had put the fan on backwards!

Also, did 1966 use a fan clutch? If it did, is yours working correctly?

Julien Abrahams

Just my two cents worth: I also think that your advance is set a bit too early. Factory spec fory the '67 429 is 5 degrees btc with vacuum advance disconnected and plugged. I set the carb (Rochester) per shop manual: engine at operating temp, choke completely off and at base idle ,adjust the mixture screws one by one to get the highest idle,. Base idle according to the SM is around 500 rpm with transmission in drive. In '67 the ac cars had a fan clutch and 6 blade fan. Non ac cars had a spacer, no fan clutch and a 7 blade fan. According to my SM, the thermo valve thst switches from carb to manifold vacuum at coolant temperatures above 230 degrees is only used on Eldorado and the Fleetwood 75 (sedan and limousine).
Is your heat riser still in place and functioning properly (stuck closed?).
Lastly: did you check for vacuum leaks? Although unlikely on a fresh rebuilt it could make the engine run.
Good luck.
1954 Cadillac series 62
1967 Cadillac Sedan De Ville HT
1969 Austin Healey Sprite
1979 Opel Kadett

TJP 440

lots of comments to answer,
the advance was aset to 10BTDC as the temp readings indicated a slower rise in temperature.  Same reason the VA was moved to manifold vacuum.  I will repeat the tests today to confirm.
The fan is mounted correctly, good question though :)
Lower hose has a spring in it :)
Highest temp recorded while idling was about 220 at which time I aborted the testing.  This was on an 80 degree day. Water pump is a brand new unit.  Can't remember who I purchased it from right now.
No apparent vacuum leaks but will double check.
50/50 anti freeze,  cap is new and has been checked,  Brass cooper on the radiator.
To reconfirm, all is well until it idles at which time the temp just slowly climbs.
I will play a bit with the timing today and verify the mixture. I will also check for any vac. leaks.  They would have to be pretty small as I get good response from the idle mixture adjustments
Thanks to all for the suggestions.


"Cadillac Kid" Greg Surfas 15364

Not to chime in here so late, but ASSUMING your TDC mark is correct (it is possible to get a mix and match of timing covers, dampers (harmonic balances can be re assembled in correctly during rebuilding), I myself would put a few hundred miles on the motor, watching the temperature gage of course, and see what happens.  220 degrees during extended idle is within specs for these motors.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-