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Help, temp gauge pegged to top after shop visit


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Just picked up my 95 lsi wgn from shop tonite, timing belt, crank seal, cam seal, water pump, serpentine belt, flush cooling system, and 2 miles from shop the temp gauge starts rising and pegging out at "H". Called AAA to tow it back to shop for mechanic to fix tomorrow. What happened?? Any help would be greatly appreciated.

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Was there any signs of overheating?

 

It could just be a loose wire on the temp sensor, if the wire hits a ground and closes the circut it might cause the meter to peg.

 

Hope it's a simple fix like that. Good Luck.

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They have air in the coolant system and it is not pumping water. The car needs to be drained and properly serviced.

 

 

Jack the front as high as possible.

Open the Bleed on the radiator

Pull the top hose and fill the engine block slowly, I like to open the flush fitting I've installed in the heater hose.

When fluid fills the top hose and or is coming out the flush fitting put them back on.

Continue to fill the radiator until the bleed plug has fluid coming out.

Put it back in and fill the system.

 

Start the car and pinch and release the top hose it will help the air move. When the fluid starts overflowing the radiator cap, replace it and let the engine come up to temp.

Shut it off and let it cool. It should draw some fluid in from the overflow tank. Do this a few times and then take it off jacks. You should be good to go.

 

This is common, if the coolant system is not properly serviced. Many shops have the tools to pull a vaccum on the system. If so they can use it to pull the air out. It speeds the process some.

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It could be air in cooling system(search this forum for air bleeding), defective water pump, thermostat not opening or installed upside down, etc. But I agree first make sure it is really overheating and not a gauge/sending unit/wiring problem.

 

I had an alomost new 87 Aerostar as a company vehicle back when, and the guage itself(not sending unit) would go from a normal reading to slowly pegging to over hot. Of course I would pull off the highway NOW and wait for it to cool down for several hours, and then procced. I did notice one time that the engine was cold enough to lay may hand on and guage read pegged. Could smack the dash HARD and get it to read normal again, tested the sending unit it was OK. Another fine FORD product.

 

Let us know what they find out....

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I agree its air, I never seen this problem with others cars I have had, But it happens ever time with my Subaru when I have to refill my system with coolant. I have always been able to let mine cool and then add coolant till full, then start and idle with cap off and heater on and add coolant as it goes down.

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Good nipper, but be prepared for it to NOT be OK. There still may be a bubble in there, keep your eye on the tamp guage.

 

Also, historical data indicates that what happened to you is the trigger for later HG issues, the supposition is that the heat stress weakens the HG, and later on down the road, blooey a $1,500 bill.

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Now I'm a little worried over the HG possibility. I only drove it about 5 miles at 45 mph after the temp started to rise. Do I really have to worry about the stinking HG issue? The car has 163k and has been a real workhorse for me, no real issues in 10 years.

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Do a search (I can't my company firewall seems to block search functions).

There was a posting by a guy that was involved in Subaru aero-engine conversions that did a whole test series and data search that seemed to indicate that most HG failures could be linked to an overheat incident, often after a post cooling system change airlock. Sometimes, doesn't seem to happen for a long time, but I would find the thread and print it out for your meachanic, and your records for if & when.

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It may be a good ideal to document this as MTSMITHS suggested, however I know a lot of us here have learned about trapped air by getting our own cars hot, and I have not seen anyone post about trouble later. I did get a Dodge Colt so hot one time that it blew the head gasket.

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