Overheating?

BADK5

MEMBER
CHEVROLET BLAZER

I have a 1987 k5 Blazer with a 5.7 TBI. It has about roughly 100000 miles is auotmatic and does has 4 wheel drive. The problem I am having is my Gauge always reads 210 even when I first start the truck in the morning then after about 10 minutes goes in the red to 260. I have checked the resivior when this happens the water is not boiling, the radiator is not hot to the touch and both the radiator hoses feel the same temp. I have drove it like this for a half an hour with no problems. I have replaced both senors the one by the water neck as well as the one on the head. I have also repaced my thremostat with a 160 one as well as flushed and filled the cooling system. My questions is, is my gauge telling truth if so what is wrong and how can I fix it.

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Have it block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.

Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.

If the block and pressure test passes check the following: Thermostat, Pressure test the Rad. Cap, Clogged radiator, Fan clutch, Radiator electrical fan, collaspe hoses, water pump.