Thank you, but as I have said, if my overflow reservoir WERE doing its job we would not have this thread. Thanks to all for the excellent suggestions. Jeff
One possible contributor to this problem that hasn't been mentioned yet is air in the cooling system. Whenever cooling system components have been changed (for example, replacing a thermostat or heater hose), the air that enters the system must be purged by running the engine with the radiator cap off until it reaches the temp. where the thermostat opens and begins circulating the coolant throughout the entire system. Then add water (distilled, of course) to the coolant flow until it tops off (level stops dropping in the radiator). The pressure rating of the cap allows that actual temperature of the coolant mixture to exceed what would be the normal boiling temp. for water (212*F). Or, said another way, raising the pressure in a system raises the boiling point of the liquid in the system (in this case, water and coolant). What the trapped air does is it basically raises the temperature beyond what the normal temperature of the coolant would be with a cap with a given pressure rating. Just my 2 cents on this. I'm not an engineer, so I can't write the formula for pressure and temperature as it relates to your system, but I had a '72 GTO a few years back that kept doing exactly what your Riv. is doing, and I purged the air and the problem went away. Easy and cheap fix... Hope that helps. --Chris
Did you actually watch the res empty out or was it empty when you checked on it. The water may have been pulled back into the radiator.o No: Bob H.
I've watched it three times so far, with the hood raised and watching the reservoir level rise and overflow. I could probably get you a video without too much trouble.
Well, back to topic:grin: Since we have already established that this is a 1972 Buick, and it has an overflow container stock, the radiator would always be full (if the system functions as intended), so there is no such thing as overfilling the radiator. The title of this thread is "Cooling Down The Boat", so that led me to believe that OP wanted the engine to run cooler. To that end, my suggestions were aimed in that direction. Now it seems that the overflow system is not working as intended, and I'm thinking the cap is bad despite it being new. Getting all the air out of the system is mandatory of course, and I've never had a problem doing that. I just run the engine with the cap off, until the stat opens, then fill the radiator as much as possible. I then raise the RPM to about 1200, and the level will drop another inch down into the radiator. I then add more coolant, and put the cap on. Done.
The 16 pound pressure cap held slightly more than 13 pounds when tested. The radiator itself held 16 with no problem, so I'm not seeing that as the issue. We're going to rig a temporary temp gauge as suggested to try and get a clear pattern of how it's behaving. I will keep you all posted and thanks for everyone's input.
Ummm.... isn't a 16 pound cap supposed to hold 16 pounds of pressure? I believe those 3 pounds could be the difference. Change the cap and then see what happens.
I was thinking along the same lines, but even at 13 psi with straight water it shouldn't boil until just under 250 F. The worst temp I've seen after shutoff was 230 F. It'll be interesting to see the results when the gage is installed. Devon
I asked that too, but my retired mechanic said it was ok. Just for fun we pressure tested the identical looking cap on my '65 Electra (installed last fall) and it held 12 pounds. Maybe I'm getting a bad run of caps? Temp gauge gets reconnected next week. Last time we rigged it, car was running about 200 degrees without a/c around town and highest seen was 235 on a test run of a steady hill climb. This was in Palm Springs with an ambient temp of about 100 degrees. Once the a/c was repaired I managed to boil the coolant on a 7 mile trip (116 ambient- no traffic) - that's when I had the block chem flushed and switched the thermo to a 160. Remember this car is Rip Van Winkle- it was in dead storage from 1991 to last October so the reawakening has been a bit challenging. First attempt to drive it I got about four miles before it blew an upper radiator hose, and that was the beginning of the fun. Can't wait to get the temp gauge back on it. Thanks to all and more to come.
First drive with gauge connected, 10.3 miles. Ambient temperature 105 degrees. A/C on but not recirculating. Operating temperature climbed to 235 in light traffic with a few stop lights, but no extended idling. Switched off the car and left the ignition on, gauge is only graduated to 240 but needle went to approximate position just over where 250 would be. Fluid mildly boiling in reservoir. Reactions?
Radiator cores are not all equal. Get the specifications on the one installed with your tanks. Then call www.alumitech.com and compare those specifications with one of their Harrison aluminum reproductions. Let's see what they say. You say the fan and the shroud are original? The fan should project into the shroud maybe 1/3 of its depth. Check for the chance that you have a bad thermostat even though I understand it is new.
The 1972 Engines with the exception of the 455 Stage1 were specified to use 4* BTDC as initial timing. That is retarded timing, and the engine will have a tendency to run hot from that alone. In addition, Buick used the TCS system on this engine. This resulted in no vacuum advance in 1st and 2nd gear, and normal vacuum advance in 3rd. Part of the system uses a thermo vacuum switch mounted in the intake manifold. When coolant temperatures reach 220*, the switch would supply full manifold vacuum to the distributor resulting in 14-18* of advance. That would speed up the idle speed and advance the timing to bring temperatures down. In all probability, the TCS system may not be working correctly on this engine. I asked the OP if the distributor in this car was original (1112110), but never got an answer. If that is the case, that distributor has no more than 18* of mechanical advance. That means at 4* initial timing, the total advance less vacuum advance would be no more than 22*. If this were my engine, I would total time the engine to 32*, which would probably raise the initial timing to 12-14*. I would then hook up the vacuum advance to manifold vacuum, and verify that it was working. I feel that these things would bring down coolant temperatures dramatically. Just my .02 You can lead a horse to water, but you can't make him drink.:grin:
