truck over heating

[arcticcat400]

hello everyone i have a 1997 chevy silverado 1500 that has always ran about 150-160 degrees well a week or so ago while out driving it i noticed it was blowing cold air out of the heat vent and the temp was around 210 after talkin to a mechanic we had the intake gaskets replaced because everytime we put antifreeze in it it would work fine for a while but then would do it again and be out of anti freeze but there was no antifreeze leaking underneath and none on the motor so we put in new intake gaskets thinkg it must be burning it and now it is still the same thing any one have any ideas on what might be wrong? head gasket maybe? any help is greatly appreciated

[Valv]

I would say head gasked too, definitely after running it at over 210. Does it smokes white even it's warm (tough to see this time of the year) and does exhaust smell like antifreeze ?

[Jeremy airjer W]

210 is nothing. Some of the early OBD GM's wouldn't even turn on the fans untill the coolant temp was 220F. As fae as where is the coolant going. Step one leave at a shop over night and outside. have them do a cold pressure test. More often than not A coolant leak will be more likely to show up with everything cold. I wouldn't be surprised if it was a slow enough leak to evaporate fast enough that it never hits the ground. but fast enough to show up in a couple weeks.

If that shows up negative have them put dye in the system and drive it for a couple of days. They then will be able to use a UV light to see where the leak is.

If that doesn't work then they need to "snif" the coolant with a four gas analizer (the most accurate measurement of hydrocarbons, IMO). In theory there shouldn't be any. If there is than the headgaskets have failed.

My guess is the water pump. Which usually starts to leak within a month after repairing the intake gaskets. It got to the point where we just include the water pump in the total price for the repair of the intake gasket.

[Macgyver55]

I concur with Airjer! I'd be surprised to hear if it turns out to be a head gasket. I have 55 Chev and GMC trucks in "my fleet" with this particular engine and to this day I have yet to replace a head gasket in ANY of them. I'm not saying it cannot happen but we just haven't seen ANY head gasket failures. Most of the vehicles have well over 100,000 and many over 150,000 some at 180,000 miles and some are as much as 10 years old. Thats probably well over 4,000,000 combined miles! Actually we see very few water pump failures too but they are not unheard of. Other than the intake gasket these are as bulletproof of an engine as you will find.

One of the more easily overlooked places to check is the small hose going to the coolant reservoir. If it leaks, when the engine warms it pushes coolant out and will leak only when hot. Then when it cools it cannot pull coolant back into the system because it just sucks air back through the leak. You won't find a leak here with a pressure test because it is not under system pressure. May not be your problem but its worth a check.