Mystery of the Heat Gauge????

[mkarns]

Hello Experts,

 

You've helped me several times with you advice and I'm back with a problem I gotta solve.

 

Since I've gotten my '87 GL Turbo Wagon the temp gauge needle has run just a hair over center to hot side and the reservior cap has been missing. Once in a while the needle would go up alittle more but it would come back down.

 

I made sure the radiator was full and tried to keep the plastic overflow tank filled, but without a cap that was next to impossible.

 

I thought it would be easy finding a lid for it, but boy was I wrong.

 

So me and my bright ideas, over the weekend bought a tube of Bars and more antifreeze.

 

Before I left for work today (70 miles each way) I poured in the Bars and made sure the radiator was full and the overflow tank over filled, then I put cellophane over the plastic opening and sealed it with a rubber band.

 

On the way to work the needle went almost to the hot mark and stayed there. I was scared of warping a head but I made it to work. When I looked under the hood the plastic and gum band were gone and antifreeze from the plastic tank had sprayed out but its still over full.

 

I gotta get home tonite, as well as back tomorrow. What could be the problem? The thermostat isn't that old.

 

What dumb thing did I do wrong?

 

Thanks,

 

Mark

[ShawnW]

Is the radiator original to the car? Most of the guys with 80's Subaru's on here have replaced theirs in the last 2-3 years...age really seems to be catching up with the radiators lately.

 

Your radiator cap might be bad and not holding pressure.

[mkarns]

The radiator has been replaced in the mid 90's.

[Partsman]

Pressure test your cap (or just get a new one). Sounds like it's blowing back into the reservoir causing it to pour over, since it was already overfilled. Cellophane can't take the heat! You probably don't have a leak, so the Bar's won't do a thing (except maybe plug off some passages that were close to plugged, leaving you with reduced cooling capacity or heater ability).

[MaroonDuneDoom]

i drive without a well fitting cap on my reserve tank but just have it covered with a 1 litre soda cap and some duct tape.

?¿does the reserve tank need to hold pressure?¿

 

also, just replaced the radiator in my '88 gl wagon. the $120 was well spent. saved me all kinds of time, troubles, and headaches. and they run super-cool and efficient.

[Turbone]

I had a problem like this with my 86 GL10 Turbo wagon. After replacing the waterpump the problem was gone. You should be able to find a cap for the recovery tank at the JY.

[speedbump]

my car did the same thing after i cracked a head!

[Alexx]

Originally posted by MaroonDuneDoom

i drive without a well fitting cap on my reserve tank but just have it covered with a 1 litre soda cap and some duct tape.

?¿does the reserve tank need to hold pressure?¿

 

I'm of the opinion that the reservoir cap holds some pressure, but nowhere near as much as the radiator cap.

 

It's disappointing to hear someone say they kept driving their car even though it was hot. Really a dumb move unless stopping will endanger your life or job.

[Alexx]

I've never had a reservoir on my car, which now has 256,000 miles on the original engine.

So even if the reservoir cap is not on, if you have water spewing out of the radiator to the point that it is emptying the radiator, there is some source of internal pressure that is above and beyond normal. Even if you found the reservoir cap, it's quite possible it will pop off due to the extra pressure.

 

Hmmmm, if you could find a cap for the reservoir, and it blew off, then you'd know for sure you have a problem. Maybe that's how you lost the original reservoir cap?

 

A sticky thermostat, plugged up radiator, or a warped head may be in your future.

[mkarns]

WIth the old radiator cap the needle was between the middle and the red zone on the temp gauge.

 

I replaced the radiator cap today and topped off the antifreeze in the radiator and drove 60 miles to work. The needle stayed below the center the whole way, thought the problem was solved.

 

Coming home tonite the needle stayed in the normal zone right below the red zone the whole way, didn't budge.

 

What could have happened sitting in the parking lot for 8 hours at work.

 

I'm perplexed to say the least.

 

Help.......

[Turbone]

Ok, let me put it this way: How old is the waterpump?

[mkarns]

The water pump was changed about 7 years ago, but very few miles were put on it in those 7 years.

[Alexx]

If you want to check the water flow in your radiator, you have a couple of minutes from the time you start the car while COLD before it gets too hot in which to check. Have two hand cloths with you if you decide to try the following.

 

Here's a disclaimer. I am not a expert and what I am suggesting is based on my own personal experience. If anyone disagrees with it, say so and I'll retract or change it as needed.

 

-----------------------------

 

With the car COLD, COLD, COLD, the parking brake on, the car in neutral (if it is a stick shift, park for automatic transmission), and of course, parked in a SAFE, well ventilated area and preferably while with a friend, open the car hood and remove the radiator cap (the car must COLD) BEFORE you start the car. Start the car while the hood is up and the radiator cap already off (but not placed on the engine or in the engine compartment) of the radiator and watch and see if the water begins to circulate. Don't stick your face right up to the radiator cap opening just in case it could be temporarily plugged and gush on you! Just watch and see from a safe distance if it looks like the water is circulating.

 

If the water does not not begin to circulate within a short time, be careful because you could have an instant gusher. You should see the water begin to circulate within a minute or two. When you are done with your water flow observation test, and presuming the car has been on long enough to warm the water, (definitely well under 5 minutes) turn the car off and wait 30 seconds to see if the coolant boils over. If the coolant boils over it might mean you have a cracked or warped head or an improperly working thermostat. Put the radiator cap back on before closing the hood.

 

If anyone has additional advice on this technique please share it.

[mkarns]

This morning I replaced the new radiator cap with the old one and drove about 45 miles.

 

Temp gauge needle stayed just alittle over center, no where near the red zone.

 

This is really not making sense to me.

 

How can a new radiator cap cause the engine to run hotter?

[EmmCeeBee]

The overflow tank does not hold pressure. There's a small vent hole in the neck (just under the cap threads). Besides, it's linked to the radiator neck with a limp rubber hose -- how much pressure do you think that can hold?

 

You could leave the overflow cap off, and if the rest of the cooling system is working OK, it wouldn't make any difference (except for an odd leaf to fall in).

 

In my experience, Bar's Leak is death to Sub radiators. You might be lucky...... but chances are it'll coat the walls of the cooling system and -- worse -- plug up the radiator passages. It does indeed stop leaks, but at the expense of reducing cooling capacity. For me (yeh, I know, I learned my lesson), it was the first in a chain of events that led to a new radiator.

 

-- Mark

[Alexx]

I had a friend with a toyota corrolla who's resevoir cap blew off the reservoir. I had a country sedan wagon with a reservoir that used to boil over something fierce.

 

I seem to rercall they had a thin rubber hose attached between the radiator and the reservoir yet their reservoir's still built up pressure.

[MaroonDuneDoom]

Originally posted by Alexx

I had a country sedan wagon with a reservoir that used to boil over something fierce.

 

I used to have the same thing happen to my GL wagon while 4x-ing during the summer months. New radiator and a 180 t-stat solved that problem. I'm tellin ya, if you plan on owning many a soob in your days, a new radiator is one of the most worth while investments you can make.

[rallyruss]

if there is presure in our style over flow bottles its because of a bad rad cap, a blown head gasket, or a genuine overheating condition.

 

bars leak is not that bad a stuff. I have used it alot with good results.

 

has any one mentioned the T stat? its cheap,easy to chang and is supposed to control the temp. a sticky T stat could do what you describe. this is espically true if the car has sat alot and not had frequent coolant changes.

[xforxlifex]

I agree with russ. I had the same issue with my rx and i replaced the T stat and the problem cleared up. Like he said cheap and easy. You said that it isnt that old id still give that shot.