2002 blazer ls, 4.3l - i know i have a coolant leak, havn't been able to tell where. main concern right now is when its started up from cold, it idles at 1,100 rpms for about 5 min then slows to a normal idle at about 650 rpms. i have heard that the thermostat opening to soon before its up to temp could be causing this. any suggestions. also anyone know what website i could go to to find all the specs on the thermostat to check what temp rating im supposed to have on it.

 

Thermostat is 195 degree model. If you are absolutely sure there is no external coolant leak, but are losing coolant level, you probably have a leaking intake manifold gasket (fairly common with the bad design gasket GM used on some engines). Have you looked at your oil (and its level on the dipstick) to see if it looks like coolant has turned it to milkshake?

 

havn't checked oil yet but it is due up this weekend anyway. i know that there is a leak, replaced the intake manifold gasket and waterpump seals, still leaking. i think it is the gasket that is lower than the intake (head gasket maybe?), little piece of it is sticking out. going to pressure test it tonight to double check and find out. when i did the water pump seals i replaced the thermostat just in case, not knowing how long ago it was done, and i think i might have got the wrong temp rating. it never idled faster on startup before the changed thermostat.