: 97 deville cooling system



jerimage
02-24-05, 03:32 PM
It all started a few months ago. First the water pump was replaced. 4 weeks later it was the lower hose. 4 weeks again and the pulley and waterpump belt was replaced. In the meantime the vehicle still was overheating at speeds greater than 65 mph. All the above was done at my friendly cadillac dealer. One last visit to the dealer who kept the car for 3 days and could only find that the radiator cap needed replacement. He could not find anything else wrong. I took it out on the highway and it overheated as before. I brought it to a highly recommended repair shop and they replaced the thermostat and the radiator. Things looked ok till I took it up to 75 mph. Overheat again.
ANY SUGGESTIONS PLEASE?

BeelzeBob
02-24-05, 03:56 PM
One thing to check is the vapor vent line. Look at the pressurized surge tank. Find the 3/8 hose attached to it coming from the engine. When the system is cold, disconnect the hose from the nipple at the surge tank. Coolant should stream from the nipple from the coolant in the tank if the nipple is unobstructed. Start the engine briefly. You should get a stream of coolant from the hose flowing toward the surge tank with the engine running. If not, find the obstruction in the hose. If the hose flows freely then the vapor vent circuit is fine.

If the stat is OK, rad is OK, water pump belt and drive is OK and the vapor vent line is unobstructed.....then....you have to start thinking of head gaskets....

Lots in the archives on this topic if you use the forum search feature in the forum tool bar above and type in "overheating" or "head gaskets" or "timeserts" or such.

jerimage
02-25-05, 10:07 AM
One thing to check is the vapor vent line. Look at the pressurized surge tank. Find the 3/8 hose attached to it coming from the engine. When the system is cold, disconnect the hose from the nipple at the surge tank. Coolant should stream from the nipple from the coolant in the tank if the nipple is unobstructed. Start the engine briefly. You should get a stream of coolant from the hose flowing toward the surge tank with the engine running. If not, find the obstruction in the hose. If the hose flows freely then the vapor vent circuit is fine.

If the stat is OK, rad is OK, water pump belt and drive is OK and the vapor vent line is unobstructed.....then....you have to start thinking of head gaskets....

Lots in the archives on this topic if you use the forum search feature in the forum tool bar above and type in "overheating" or "head gaskets" or "timeserts" or such.
I will check the vapor vent line, today. If I were losing coolant thru the headgasket or anywhere else, wouldn't I get a low coolant warning before the overheat?

Ranger
02-25-05, 09:49 PM
Yes, the surge tank is the highest point in the cooling system so it would go down first and you should see a low coolant message.

jerimage
02-28-05, 10:35 AM
vapor vent line ok. will replace fan relays today.
This is mind-boggling. any one else have this problem?

zonie77
02-28-05, 11:12 AM
Yes, check the headgasket info.