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SUVs Chevrolet Blazer Chevrolet Blazer Thermostat Replacement
23 messages, Last post on Jan 28, 2009 at 6:41 PM
You are in the Chevrolet Blazer Forum. Your Hosts are steve_ & tidester
I have a 2001 Blazer ZR2 4x4 and need to know how to replace the thermostat. Any help would be appreciated! Thanks!
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First, you must determine if you really need to replace a thermostat. Many thnermostats are replaced by someone who want to controll a overheating problem. Doing that will seldom, if ever, will solve a overheating problem. A thermostat will only control what temperature the engine reaches before coolant will flow through the engine.A 190 degree thermostat is normal for modern engines. To remove a thermostat for whatever reason require the following steps: 1.) Remove two bolts from the thermostat housing located at the end of the return hose (top hose) on the radiator. 2.) Pry out the old thermostat with a screwdriver. 3.), Scrape the thermostat locating lip clean on the manifold. 4.) Install the new thermostat in place of the old one. 5.) Apply some Locktite High-Tack sealer to the gasket surface of the thermostat housing. 6.) Clean the thermostat mating surface on the intake manifold. 7.) Place the thermostat gasket furnished with the new thermostat to the Loctite High-Tack sealer you applied to the thermostat housing mating surface and align the two holes in the gasket with the holes in the housing. Do not apply sealer to the manifold side of the gasket. Let the gasket set for fifteen minutes for the gasket sealer to cure. Never use silicone type sealers anywhere on an engine. 8.) Install the thermostat housing and gasket over the new thermostat. 9.) Reinstall the two bolts only finger tight to make sure they are not cross-threaded. 10.) Tighten the two bolts with a socket and ratchet wrench alternately and carefully to 24 lb. torque in 8 lb increments. . 11.) Start the engine let it warm to the operating temperture of the thermostat and look for leaks around the thermostat housing. Sometimes a minor leak will be seen for a few days until the gasket swells and seals. 12.) If a leak is seen after a few days, tighten the bolts again evenly and carefully up to 1/8 turn or a an additional 2 lb. torque. Overtightening can break the thermostat housing.
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Replying to: duntov (Oct 26, 2008 10:10 am) |
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It is seldom the thermostat that causes heater problems. If your engine is running at the correct operating temperature, the heater core will also be hot if it is properly connected to the engine with an in and out heater hose. The problem may be bad heater fan motor and can be tested. If the fan motor is good, it is a kinked or a disconnected vacuum line, a disabled heater control switch or it could be that the linkage that opens the register (heater door) is disconnected. The register is located inside the heater plenum and the vacuum lines and controls are located under the dash If the fan is operable and if the register in the heater plenum does not open, warm air from the heater core cannot enter the pasenger compartment. If the heater core has recently be replaced, the person who did that work accidentally disabled the register controls.
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Replying to: duntov (Oct 29, 2008 8:27 am) |
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Whenb the engine is warm, does the heater blow cold air? If it does, the heater fan os OK. After the engine warms up to operating temperature, turn on the heater and feel around on the heater plenum under the dash and see if it is warm. If it is warm, the hot air from the fan through the heater core is being blocked by a closed register. You must find out why the register is not opening. Eith vacuum line is disconnected or the switch to the register linkage is binding.
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Replying to: duntov (Oct 29, 2008 9:59 am) |
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| The plenum is the plastic air box that is under the dash that has heater outlet vents and is attched to the heater fan and core assembly that is located on the engine side of the firewall.It contains directional doors that are controlled by the vacuum diaphrgams and those are contriolled by the heater contol switch. | |
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Replying to: sheps47 (Oct 25, 2008 5:55 am) If both feed and return are hot, you have a baffle not operating in the duct work. Haven't worked on these before, but there are others on the maintenance and repair board that have. Good luck,
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Replying to: jlflemmons (Oct 29, 2008 12:05 pm) Thanks again.
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