Car running hot and cold, needle all over, coolant okay? Sort of- read on. Thx

SDSWEIGART

MEMBER
2003 SUBARU FORESTER
1.5L
4 CYL
4WD
AUTOMATIC
136,000 MILES

I will tell you know- I don't know anything about cars including what a coolant fan is or radiator fans. Please help. Yesterday, engine light went on and needle went all the way to red hot zone. Driving about 10 miles on major highwat, 75 mph. Quickly got off. Coolant full. Asked gas station guy what to do- he looked & said belts etc all running, maybe drive it around awhile & see if it stops. ( I was on a commute to work). I took some side roads & it flipped hot and normal- no rhyme or reason. Nervous wreck. Drove it back home half hour- took to meineke- they said water pump @ timing belt, and my coolant was empty- but it wasn't 10 min. Before I got there. They said $850.00. Took it back to dealer- they had it for 2 hours& showed me they had put in a new water pump etc whe n I bought it 1 year ago. They didn't see a leak. They put in a new thermostat and if that didn't do it - radiator fans or something- and to take it to mechanic. (No warranty). Car fine today, but drove home from work and it ran hot hot then normal. Couldn't discern pattern w/ highway driving, sideroads, air on- really didn't know what I was doing with air. Got it home on hot. Stopped every 5 miles and it would go back to normal for 10 miles. What can I do? What might this be? I don't have $$ for repair this week. Freaking out big time. Help! Thank-you Susan S.

5 Replies

CAR-MAN145

MECHANIC
321 POSTS

Well I will try to help. First of all the coolant fans are made to work at lower speeds to cool the car at stops and the air blowing into the radiator cools at higher speeds. So if it is over heating at 75mph the I would not think it would be the cooling fans. With that said I believe you may have a clogged radiator if you are not low on coolant. One way to check this is to very carefully when the cars warn feel the top of the radiator and the bottom of the radiator to see if they are both the same temp.

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Sunday, October 11th, 2015 AT 12:20 AM

SDSWEIGART

MEMBER
3 POSTS

Thank-you. So, if the top and bottom of radiator feel about the same- the radiator could be plugged. How does one unplug? Can I drive the car- would it be at a slow speed with air on? Trying to read what others did w/ driving- heat on, high speed etc.

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Sunday, October 11th, 2015 AT 6:05 AM

CAR-MAN145

MECHANIC
321 POSTS

If the radiator is plugged then the top will be hot and the bottom will be cooler and if so then you must replace the radiator. If you continue to drive the car and over heat it you will do more engine problem and will cost a lot more to fix it.

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Sunday, October 11th, 2015 AT 6:12 AM

SDSWEIGART

MEMBER
3 POSTS

Thank-you!

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Sunday, October 11th, 2015 AT 6:17 AM

THIS IS MIKE

MECHANIC
686 POSTS

Caradiodoc
Oct 10, 2015
Expert

Based on the combination of symptoms, I'd start by having a chemical test performed to check for a leaking cylinder head gasket. That involves drawing air from the radiator, while the engine is running, through a glass cylinder with two chambers partially-filled with a special dark blue liquid. If combustion gases are sneaking into the cooling system, the liquid will turn bright yellow.

Those combustion gases can pool under the thermostat and cause it to not open. Thermostats have to be hit with hot liquid to open. Hot air won't do it. If that test is negative, any other cause of overheating is going to much less serious.