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98 Regal still overheating

Linika

New member
2
1
3
Buick Ownership
98 buick regal
I am working on my Grandmas car..
my family bought a crazy cheap car for her grrr...

So I have already changed the
water pump
Coolant temp sensor
thermostat
belt
re-wired the coolant temp sensor connections because they were fried

before all the work it was overheating fast, mostly when at stop lights and idling.
if the vent is on and driving fast the temp came down but not a lot.

now after all the work it lasts longer.
I took it to test while driving today and it was doing really well. then the Temp rose fast and when I turned it off coolant flooded out of the reservoir

radiator fans do turn on
there is also some brown sludge under the radiator cap
I also had added blue devil head gasket sealer when refilling the coolant after changing the water pump..

also note tomorrow I take it into dealer for a recall service for the valve cover leaking oil onto the manifold. Not sure if that is connected

I have no idea what to look at next :(
 

97PA

Member
34
18
8
Buick Ownership
1997 Park Avenue
I would look at your problem being a flow issue with the radiator, given the age (assuming its the original radiator), the typical DexCool sludge and the added Blue Devil treatment. I just posted a few days ago to another member with a 2004 Regal with overheating problems and it looked like after he checked over the things I suggested we both concluded the radiator was most likely the problem. I haven't heard back from him if the radiator replacement solved his problem. Before replacing the radiator, run the car to temperature and feel the bottom hose. If the radiator is plugged, the lower return hose will be noticeable colder than the top hose which connects to the thermostat housing. I use a cheap Harbor Freight non contact IR temperature gun (Ames) and take readings at several points on the radiator and at the hoses to better diagnose a plugged radiator but the suggestion I gave you about checking the lower and upper hoses will give you a good idea. I would also replace the radiator cap or get it checked, as this could cause overheating. Also make sure the cooling system doesn't have any air by following the air bleeding procedure (I loosen the 7mm bolt on top of the thermostat housing and run the engine until the air is released and coolant starts to flow). It can take a couple of bleeding cycles to completely remove the air, especially if you've replaced the water pump.
 

G-308713

thank you.. Yes I have done 2 bleeds.. yesterdays was better

the radiator is not original. at least that is what I was told.
The lower hose gets hot but I had wondered about a clog somewhere but not sure.

was thinking of doing a flush.. I did not do that after water pump change.

Car is at dealer now getting the recall service done for leaky valve cover
 

Linika

New member
2
1
3
Buick Ownership
98 buick regal
@97PA

Thank you
I have bled the system 2 times..

I was told the radiator is not original
I just picked it up from the dealer where they changed the front valve cover and gasket for free as part of a recall.
its super hot here today and it did overheat on the way home only 4 miles. it was 98 degrees out.
when I got home and turned car off it was 2 white dashes from red and coolant over flowed the reservoir
also both upper and lower Radiator hoses super hot

the fans come on but I was reading another thread where someone talked about a higher speed.. How can I tell if maybe the fans are not turning on at the right speed ?
also I was running it with the heater on.. should I have been doing this with AC and not heat ?

I was thinking of doing a flush with something to clean it all out.
I did not do a flush after water pump change.. I think I should have but I didnt

also curious how to tell if radiator is blocked somewhere
______________________________
 
Last edited:

97PA

Member
34
18
8
Buick Ownership
1997 Park Avenue
You should have a high speed fan speed when commanded by the PCM when it detects a high temperature via the coolant sensor's ohm reading. I would run it with the AC on and no heater and see if the fan speeds change and whether it overheats when idling. On some Buick models it's the left side fan which goes to high speed during overheat and the right stays at the standard speed. One other way to test the fans is to unplug the coolant temperature sensor connection in put in a 130 ohm resistor in the plug harness. This will simulate an overheat condition to the PCM and command the fan(s) to high speed. You could still have a restricted radiator and cap, so after doing the fan check you need to consider these items. Another way to test a radiator is to empty out the coolant and disconnect both top and bottom hoses and then put a garden hose into the top radiator port and look at the flow rate at the bottom port. It should flow pretty freely and without restriction.
 
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