Automatic and A/C (not currently working) I purchased this last August. I have two GS400 convertibles, one auto one 4spd. Specifically the Automatic car. I flushed the cooling system, changed the thermostat from a 195 to a 160 and replaced the fan clutch. Still it runs hotter than I'm comfortable with. Once it warms up it hovers around 200 and higher coming off the highway, especially at times of low airflow through the radiator. In you guys(gals) experience, would a new T/A aluminum radiator get the temperature where I want it?
Check your pulley diameters to make sure they are correct for the year. Was the water pump replaced? Replacement pumps all appear to be 5 vane, original was probably 6 vane. Original head gaskets? The ones in my Dad's sporty were rusted through in several locations so the coolant wasn't being forced from the back to front of heads as Buick intended. It was going from the block into the heads and out.
A lot of factor in play here. Could be Rad, type of coolant used and mixture, fan clutch and shroud. Timeing can cause over heating. .
Timing is spot on Coolant is new Fan clutch is new Shroud is has a small strip missing on the bottom, otherwise intact. Thermostat is a new 160 The radiator is original as far as I can tell This is why I'm thinking a new T/A aluminum
The head gaskets I'm not sure. I did have a compression test done. The water pump appeared original when we installed a new T/A double roller chain and gears.
A new large tube aluminum radiator will provide a lot more cooling capacity then an old brass/copper style one. There are many options for this, I have never purchased one. TA is great. but that listed price looks kind high. I know there are other options that provide a quality piece for less $. With a 160 degree thermostat installed, it shouldn't go higher than 165ish if all is working correctly. Double checking the actual temp with a IR thermometer is nice also.
You say timing is "spot on", is that initial? What is your timing at idle with vacuum connected, warm, in gear and what is the RPM? I would make sure the vacuum advance pulls the correct timing, and then pull/plug vacuum line, then dial back 30-34 and take it to 3000 RPM and verify mechanical range is functioning. Then calculate where vacuum curve is and if it matches the manual. (advance at idle not working correctly can make it run hot. Same for mechanical and or advance affecting cruise. Late timing) Is this something that has come on suddenly, gradual or as you got the car?
careful on replacement radiator WIDTH .. 68/69 core support (bottom support for rad) and top cover brackets (top support) were only designed for 3-core width. I did fit a wide aluminum 2 core (equivalent to a 4 core brass) into my 68 SportWagon 400 but had to butcher the rubber inside of the top brackets and get creative with the bottom.
The temperature issue came up after after I installed a new Auto Meter temperature gauge and I saw what it's running at. Prior to the cooling system flush, it would sometimes spew coolant out the over flow after parking but not always. It never loses coolant now. I'm going to discuss all of your thoughts with the tech I'm working with. Lots to consider and I appreciate all the responses.
Personally, I would record the existing radiator to keep it stock, or at least flush the bejeebers out of it. Bottom passages could well be permanently clogged. My GN started running hot about 6 years back. Recorded. the radiator and it cooled off like never before.
Also, check your radiator cap. It should be holding 16psi. It will keep it from boiling over as easily. I always checked my temp at the thermostat housing with my IR thermometer and confirmed it was what it should be. I also used a Champion 2x1"-core aluminum radiator and it was very reasonably priced. It was an AE161 and is $239.98 at Champion.
Both good points. Start simple first before chasing your tail. I had an erroneous Auto Meter temp gauge once, it was reading up to 210 at idle. I remembered what my Dad, a career A&P mechanic and machinist, would say, start at the point of least trouble / cost first. I checked temp with an IR thermometer gun, it read 185. Changed out the temp gauge, read about 185 at idle warm. So, yeah, do / check the simple low cost items first before breaking out the CC and draining your bank account.
Hefe you considered using the plastic/ aluminum 96 park ave rad? They're cheap as dirt and they say it fits like a glove
I did as well when I put my Dewitt’s radiator in. Before you jump on buying a high end radiator I would definitely listen to what trunkmonkey has to say because I had similar issues to what your explaining and all the money I threw at the cooling system was not helping much at all. It may have helped a bit but, I believe what I thought was correct for how my car was tuned from my builder played a bigger part. I still have some tinkering to do.
Not to high jack the thread but why is it always the 68/69 400 cars that always seem to have threads on heating issues and timing is really finnakey (spelling). At least it seems like when you search the forum.
Did you say "70"? I have a 70 455 GS Skylark that had a serious high temp problem. After trying to figure out WHY the temp was high, our conclusion, the previous owner installed KB high compression pistons. We changed out the following items in the cooling system. 1. Fan clutch. 2.Thermostate. 3. TA's high performance water pump 4. 4-core cooper/brass radiator. 5. Evans waterless coolant. None of the above worked. I'm crying in my Beer. Larry the Wizard tells me to buy the most Bad Ass 2 core with 1" tubes, Griffin Aluminum radiator. So I did. 6. Problem solved. Thank you Larry. I agree, seems high compression has a lot to do with generating a lot of heat. Vet
Double check this! There were different sizes with vanes combo. It could mean your setup spins 40% slower than it should. I had that issue and choose to correct it with a new TA waterpump. See thread for more info: https://v8buick.com/index.php?threads/cooling-issue-on-idle-waterpump-combo.381933/#post-3349499
Honestly I don’t think the compression has much to do with running hot. Two years ago when my 350 was at 11.1 to 1 it ran at 170* now with a tad more compression 11.7 to 1 it still runs at 170* BUT I DO NOT run a 50/50 mix of antifreeze/water it’s more like 20% antifreeze/water
