I finally got my car 95% together and am having an issue I cant solve. When I drive the car the temp on the gauge (it is new but it's a junk brand so I am in the midst of changing it to an autometer)is never higher than 160 degrees, but when I shut the car off the radiator boils over. background of what I have I will get pics up in a couple of hours. - Originally I had a 195 stat in it, It now has a 160 stat with a 1/8th inch hole for bleeding. - the radiator is an aluminum with 2 10" electric fans. - the schroud is a solid piece of 20 ga aluminum with the 10" holes cut out from it. - the fan control is set at 160 and seems to cycles correctly. - I originally installed a 15lb rad cap but the rad blew off, as I said, last week I installed a 15 lb closed system cap and a resivour. I filed it like the posts have said and the jar stayed half full for 2-6 mile drives in 85 degree weather, dont ash me why but yesterday I syphoned the fluid out of the resivour and put it in the radiator to see what happened thinking it would refill and be at a normal level, and after the 6 mile drive I turned the car off and it boiled over as it did before filling the bottle. After letting it sit for 2 hours and cool I checked it and the radiator had sucked all the coolant form the resivour. I am not very good at cooling problems so ideas would be greatly appreciated. thanks guys
If you are using a recovery bottle, are you also using a cap designed for recovery systems (mid '70s and up design)? FGFs did not use recovery systems but it is a common addition.
The fill line on the radiator is about 3" below the neck. If you fill higher, it will spurt out on shutdown. This is not the same as boiling over. A properly positioned recovery bottle and cap should be able to manage the flow.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching
If you leave the radiator cap at the first detent, so it's loose but not off, start the car up (engine cool). With the engine idling, and the water cool, take the cap off and look at the water level. The water should be still. Keep looking into the radiator, and when the thermostat opens up at 160 degrees, you should see the water moving. The water will pour from the radiator's internal fins like a little waterfall. On the Pontiac crossflow radiators, the water flows crosswise from the driver's side (upper hose) to the passenger side where the radiator cap is. If you see the water flowing when the engine is warm, your water pump is working, and your thermostat is opening.
Put the cap back on, and tighten it down. Pressure should start to build in a minute or two. Make sure the lower radiator hose is not collapsed. The lower radiator hose should have a spring inside to prevent collapse.
If the lower hose is ok, turn the car off. As pressure builds, feel the lower and upper hoses. They should be hard. Again, make sure the lower hose does not collapsed.
And yes, check the gauge. If the engine is hot enough to boil over the radiator, it sounds like you're at least at 230 degrees. At that temp, the engine will run rough (hot fuel), and it should be obvious the engine is hot.
Q: Does the engine run ok, everything seem normal, until you shut off the car off, then the radiator boils over?
Q: The coolant recovery system requires a coolant recovery radiator cap. Is your radiator cap correct?
You may indeed get some boil over the first time you fill the radiator. Water may dump into the coolant overflow bottle, then (as you said) the coolant will be drawn back in after a few hours. On these coolant recovery systems, you don't have to worry about the level in the radiator (other than the initial fill). The overflow bottle will handle the extra coolant, so you only need to add coolant from the coolant overflow bottle.
I can't get the timing set. When it's idling at 800 rpms it has a little shake every 2 -3 seconds and the timing on the damper jumps from 10 to 12 erratically. I am taking the hei to a friend that has a distributor machine this week.
1. I do have closed system cap. I opened the cap this morning and the radiator is filled all the way full.
now for Questions: 1. Should I remove the bottle and some coolant and put on the original 15 lb cap. and try the letting it heat up watch the flow? 2. Is a 2 row aluminum radiator enough for the engine?
The aluminum radiator should be enough to cool the engine, but not so sure about the electric fans. I would go with a mechanical fan, preferably a factory type clutch fan, and you definitely need a shroud. Electric fans are nice, but running electrics without a mechanical or a shroud just won't cut it.
When in doubt, go back to the way the factory did it.
As for timing, that could also be your problem. You should just be able to get it in the ballpark without a timing light. Just raise the idle to about 1500 rpm, then turn the distributor (advance) until the engine starts to miss, then back it off a bit, and tighten it down. That will get you close enough.
There's also a chance your factory balancer may have slipped, a common problem with the Pontiac design. The outer ring slips on the inner hub, and trying to set the timing with a timing light is impossible. You could be 10, 15, even 40 degrees off using a timing light (if your balancer is new, or you have an aftermarket unit, ignore the info above).
No need to remove the coolant overflow, just remove the radiator cap, and take a look at the flow as described above.
Ok so the engine RUNS good now i got the distributor checked and I only had 8 degrees of advance. after some fiddling and grinding I have 23 degrees that starts at1500 rpm and is all in at 2800 rpm with 15 degrees of vac advance.
BUT it still over-heated (light came on)
Before it over heated I let it warm up with the cap off and I could see the water coming out of the radiator coil when the thermostat opened.
next step I am going to remove the electric fans and install a 7 blade mechanical fan close to the radiator. the only problem is I dont have a schroud. but I think with a 7 blade it should cool.
There have been many many threads on this topic. A 19.5" 7-blade clutch fan is what you want. However, it will be basically worthless without the shroud, 400 X-fillers, lower baffle/filler, rubber fillers that direct the air through the rad not around it etc. ALL factory/stock cooling parts & pieces must be in place on these cars or they WILL run hot! Also, a stock 180* stat as well. If ALL of these components are in place and your timing is correct, good water pump, correct pulleys etc. you car will not overheat...
If you are using a recovery bottle, are you also using a cap designed for recovery systems (mid '70s and up design)? FGFs did not use recovery systems but it is a common addition.
The fill line on the radiator is about 3" below the neck. If you fill higher, it will spurt out on shutdown. This is not the same as boiling over. A properly positioned recovery bottle and cap should be able to manage the flow.
Exactly right. Have a rodney red and keep water 2" from top. Recovery bottle stays dry. Plenty enough in there to do the job.
The thing is, on FGF you don't need a recovery bottle if ALL stock/correct parts are in place. If a stock system is puking, it's because there is too much water/anti freeze in the system. Once it pukes out the access, you should be all set. I know in my bird, the water level was down 2-3" as stated above. If I filled it more than that, it would puke out what it didn't need and that was it....
Speaking as a person who just went thru the overheating mess. Find you a stock shroud, 19.5 clutch fan, spacer that puts the fan 50/50 in the shroud. It will be money well spent trust me... Also having at least the upper baffles will get you cooling down. Get as much air flowing thru your radiator as possible. Sure someone here has the items listed above for sale.
