Question about Cars & Trucks
Overcooling isn't a common problem. The usual cause is coolant bypassing the thermostat, either because the thermostat isn't seated correctly or a seal has been omitted, because the thermostat valve is poor quality and not completely stopping the flow or because the degassing system is too efficient perhaps because the restrictor (if fitted) has been lost.
Some designs of cooling system place the thermostat near the water pump but conventional designs place the thermostat at the top of the cylinder head at the connection to the top hose. Most designs of this type are usually fairly simple to test. When starting from cold the top hose should remain cold throughout the warm up period and then become hot with a rush as the thermostat opens.
Any significant warming of the hose prior to the main opening indicates coolant is bypassing the thermostat into the radiator and can provide enough cooling to prevent a proper warm up cycle.
The cylinder head gasket of a high compression engine doesn't provide a perfect seal and some bubbles of combustion gas occur in the coolant and to prevent them building up and disrupting the thermostat operation many modern engines have a degassing system to move bubbles rapidly to the top of the degassing chamber (or coolant bottle). The vent orifice is very small and is often provided by an insert into a hose or hose spigot. Designs vary but if the insert is lost too much coolant will flow.
Posted on Aug 16, 2020
Though it could be either in feeding of data or gauge itself but most likely the gauge would be faulty. I assume it to be mechanical gauge
Posted on Aug 16, 2020
SOURCE: temp gauge
The sensor you replaced was the ECT (engine coolant temp)? Check your coolant level and air in the lines. Do a coolant pressure test to make sure the cooling system holds pressure, If it doesn't, you may have a head gasket problem.
Posted on Jun 11, 2008
Firstly - DO NOT run engine, when guage reads hot, as this will cause costly damage to head gasket & alloy engine head.
The fact that guage takes 1min to read HOT, would confirm the guage IS working properly.
So, other components which are likely to cause hot readings (in this order) are:
- lack of coolant (or leakage somewhere): is there sufficient green coolant at the correct level? Top up mixture to correct level. Repair any leaks.
- collapsed radiator hose: when engine is cold, start engine, then quickly watch both upper & lower radiator hoses to see if either begins to flex inwards (collapse). Replace if either hose is collapsed.
- bad/incorrect thermostat rating : when replacing thermostats, you must ensure it is of the SAME temp rating (they all differ).
- Incorrect Temp sensor rating: the ratings of this sensor must be within manufacturer's spec's.
- bad waterpump: the engine relies on the waterpump to distribute the coolant throughout the entire system. If waterpump is faulty, coolant will not flow quick enough, causing overheating.
If you still believe all of the above components are OK, then have your cooling system "pressure tested". This test should be done, before looking further at other electrical components.
"if this has helped you in any way, please rate this solution"
Posted on Jan 27, 2010
SOURCE: 1999 volvo s70 overheating
Well My car I changed the head, and the head gasket. The gauge says the engine is overheating, but it is not true, the coolant is perfectly normal and no hose is inflating or whatsoever but the fan is always running.. You can blow your head or head gasket because the sensor is faulty ???!!!! Please I need an answer because I'm using my car for a couple of days even if it says its overheating ( It is not really overheating there probably is a faulty sensor.. ) but i'll stop using it if you can blow you head gasket because of a faulty sensor... !!!
Posted on Jun 29, 2010
SOURCE: my temp gauge goes to
CHECK COOLANT FAN FUSES AND RELAYS. CHECK COOLANT LEVEL.MAKE SURE ITS NOT TOO LOW BECAUSE IF COOLANT TOO LOW . BY NO COOLANT AROUND OR COOLANT SENSOR NOT SUBMERGED IN COOLANT COOLING FANS WONT TURN ON.MAKE SURE YOU HAVE 50/50 ANTIFREEZE AND WATER. CHECK FOR CLAPSE RADIATOR HOSES.CHECK RADIATOR HOSE AT WATER PUMP.IF HOSE LOOK CLAPSE REPLACE IT AND BLEED COOLANT SYSTEM.IF EVERY THING HAS BEEN DONE YOU NEED ENGINE BLOCK FLUSHED OUT.HEATER CORE ALSO COULD BE STOPPED UP.A VERY HIGH MILEAGE ENGINE WILL OVER HEAT.OLD ENGINE LOSES COMPRESSION AND HORSE POWER.PUTTING MORE LOAD ON THE OLD ENGINE WILL MAKE IT OVER HEAT.IF COOLANT LEVEL IS LOW.BLEED COOLANT SYSTEM.START THE ENGINE LET IT IDLE FEW MINUTES WATCH THE COOLANT TEMPERATURE GAUGE.WHEN TEMPERATURE START RISING.TURN OFF THE ENGINE LET IT SET FOR 20 MINUTES.TAKE A LARGE RAG PLACE OVER RADIATOR CAP ON COOLANT EXPANSION TANK SLOWLY OPEN RADIATOR CAP JUST A LITTLE TO RELEASE A LITTLE PRESSURE AT A TIME.DONT OPEN CAP RAPIDLY OR YOU WILL GET SCALDED.ONCE THE RADIATOR CAP REMOVED.IF COOLANT LOW ADD MORE COOLANT IN THE THE COOLANT EXPANSION UNTIL YOU GET TO THE COLD MARK.REPEAT THIS PROCEDURE START ENGINE LET IT RUN UNTIL TEMP GAUGE START CLIMBING A BIT DONT LET CAR RUN TO OVER HEAT JUST IDLE UNTIL TEMP JUST START TO RISE.THEN YOU TURN OFF ENGINE. WAIT 20 MINUTES.THEN USE LARGE RAG OPEN RADIATOR CAP LITTLE AT A TIME. DO THIS PROCEDURE UNTIL THE COOLANT IN THE EXPANSION TANK STOP DROPPING. THEN ALL THE AIR IS BLEED OUT THE COOLANT.WHEN COOLANT LEVEL STOP DROPPING, WHEN YOU DRIVE CAR AROUND.AND TURN OFF ENGINE.WHEN ENGINE OFF CAR SET FOR A WHILE KEEP CHECK ON THE COOLANT LEVEL IN COOLANT EXPANSION TANK. THE COOLANT LEVEL SHOULD BE AT THE COLD MARK IN THE EXPANSION TANK.MAKE SURE COOLANT IS IN THE EXPANSION TANK.IF NOT AIR WILL DRAW IN COOLANT SYSTEM. CAUSING ENGINE TO OVER HEAT.IF BLEEDING AIR OUT THE COOLANT SYSTEM DONT HELP AND COOLANT FANS DONT TURN ON YOU HAVE PCM PROBLEMS.
Posted on Apr 22, 2011
Tips for a great answer:
Sep 06, 2018 | Cars & Trucks
Mar 16, 2018 | Cars & Trucks
Mar 12, 2018 | Cars & Trucks
Nov 04, 2016 | Volkswagen Polo Cars & Trucks
Sep 26, 2016 | Volkswagen Polo Cars & Trucks
Mar 26, 2014 | 2002 Volkswagen GTI
Sep 05, 2012 | Volkswagen Polo Cars & Trucks
Jul 27, 2012 | Cars & Trucks
Aug 08, 2009 | 2002 Volkswagen Jetta TDI
22 people viewed this question
Usually answered in minutes!