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Help me figure out this Odd Cooling Issue


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What will happen...

 

1. I start the car up in the morning and warm it up for about 10 minutes. The temp needle is still on the C but it's warm enough to run.

 

2. I start driving wherever I'm going (work or maybe my girlfriend's house). The temperature slowly rises to normal operating temp. I've always considered about 1/3 up the gauge to be normal temp, as that's where the engine runs.

 

3. The gauge will continue to rise, almost to the point where it is overheating, when suddenly the temperature will back down to operating temperature.

 

This sounds almost how a thermostat would work, except for how high the temp gets.

 

Let's say I'm leaving my girlfriends house for home. I warm the car up a bit and head to the freeway. The car is almost to operating temp when I enter the freeway, but once I get going (lots of accelerating up to speed) the temp will slowly rise.. and keep rising. the temp will keep going up until it's almost touching the red... then suddenly it will drop back down to operating temp, regardless of if my heater is on or not. I'm talking so hot that I almost consider pulling over to let it cool down. This has happened 3 or 4 times now.

 

Now this is sort of an odd part. If I start driving but dont go on the freeway, it wont get as hot before it cools down. When I leave for work in the mornings, I dont get to the freeway until about 20 minutes of driving. If this is the case, the temp will only go slightly above normal before dropping back down.

 

Like I said before, this sounds very similar to how a thermostat works, except that a thermostat wouldnt let it get this hot before kicking in!

 

I've been driving the car since summer, and have had no serious cooling issues to date. The car will sit in Stop&Go traffic for hours with no complaint, but since winter started it has started acting up. Even today... after it does its almost-overheat-then-cool-down act, the cooling system will work fine and the car will remain at a good temp.

 

 

Do you guys have any experience with this? Should I replace the thermostat?

 

 

Another really odd thing, is that about 5 minutes after I start my car, I get a coolant smell, REALLY bad, It reeks of coolant for about 2 minutes, and then suddenly it will go away and I wont smell it again until I shut down the car and then start it back up.

 

Before you ask, I know my car leaks coolant, but not sure where (as I havent seen any puddles). I've been topping off the radiator every couple days to make sure that my coolant level isnt the problem. I'd suspect a head gasket, but my oil looks fine when I change it.

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It would help to know how old and which model you have. However, two things jump out at me:

 

The sudden drop in temp could be due to a stuck thermostat allowing the car to start to overheat and then suddenly opening. Odd that the car normally goes only up to 1/3 on the temp guage. All of my cars are typically 1/2 or just slightly below. My Brat used to be 1/3 until I replaced the thermostat; turns out the unit that was in there was a "summer" thermostat that opened at a lower temperature and the car always ran cooler. Works fine now that I have the correct thermostat in the car.

Secondly, older Subarus has marginal radiators. With age they become less efficient and the car is prone to running hotter than normal. The typical symptom is that the car might run at normal temp at 40 or 50mph, but will run noticeably hotter at 60 (but not overheat); hotter still at 70 (maybe not overheating yet); when you slow down the temp will come back to normal by itself. Nothing helps this second problem other than replacing the radiator (easy job and not too expensive; I bought a radiator for my GL wagon for $120 from http://www.radiator.com and it took less than 30 minutes to install). Don't try a backflush on the radiator--waste of time and money. Take it from someone who spent $75 on various remedies on my wagon and finally fixed it once and for all with a new radiator. If I'd have been smart, I would have taken that $75 and put it to the purchase price of a new rad.

So, to summarize, I think you may have a stuck thermostat as well as an older radiator. Try the thermostat first, it'll be less expensive.

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Hey Ed, I dont think you'd recognize me, this is Jay. You've even seen the car, when you sold me that spare axle in Woodinville (it works great BTW)

 

Just for the record though, it's a carbed EA82 with about 216k in a 1985 GL Wagon 5-spd 4wd.

 

I suspect more the thermostat than the radiator. The temperature is the same whether I'm doing 75 down the freeway or puttering around in the city. That's one of the reasons this baffles me so much. The only differences is that it gets way hotter before it cools down if I'm on the freeway. It's probably related to stress on the engine.

 

As for the 1/3 or 1/2 up the gauge, I suspect we're referring to the same thing. I was just guessing around 1/3, but sometimes I guess it does get up to about halfway up the gauge.

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Jay, I was just interpreting what I thought I read. Your wagon is about the same mileage as my '86 when I changed the radiator at 225K so I wouldn't count that out. But, I really think you have a thermostat that is sticking shut until it finally pops open. Good luck with the repair. Sorry I didn't connect the username.

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Flush the cooling system. You don't need to use caustic flushing additives, plain water should plenty to loosen up most problems - especially if you use warm water.

 

And replace the thermostat and radiator cap. If any of the coolant hoses look suspect, replace them. Check the ones that run to the cabin heater.

 

I don't like to re-use any coolant hose once I have had it off. The clamping area gets hard and won't seal well the second time.

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I had the same problem with my 1987 GL-10 turbo. I still haven't figured out the near overheating and temp dropping back down abruptly, but I am going to change the thermostat when the weather is better like everyone has said. As far as smelling and losing coolant, I had an intake manifold gasket leaking allowing coolant into the intake manifold. I went through about 1 gal. per day of coolant driving ~30 miles round trip and my car felt like it was bogging down. My mechanic did a pressure test on the cooling system to find the problem. That might be another good place to start looking for your problem. If there are any leaks in the system a pressure test should find them and it shouldn't cost much to have it done somewhere.

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I had the same problem driving up to Alaska from Detroit..changed the thermostate 3 times .....then drove the car without the thermostate with no over heating...once I installed the correct thermo with the jiggler..no more problems.... the air lock in the cooling system can be next to impossible to remove without the correct thermo.

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All your symptoms sound just like what I chased a few months ago. Ended up being a 'clogged' radiator, got a new one and it runs as good as new.

 

If it's a sluggish radiator, your cooling capacity is lowered -- freeway speeds are a heavy load, so the temp climbs. I suspect the sudden fall in temperature could be when a coolant bubble forms and collapses, which somehow gets more coolant through the radiator for a minute or two. My theory anyway, cuz it did exactly this for a couple months before I narrowed it down to the radiator.

 

Might not be the raditor.... but all the right suggestions are in the responses above. In order of cheapest fix:

1. check coolant level

2. replace rad cap

3. replace thermostat

4. flush radiator (even the caustic ones didn't work for me....)

5. new radiator.

 

216k miles -- is it the original radiator? If so, I might even skip to step #5 directly.

 

-- Mark

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I'm having the same issue with my 86 turbo wagon. It will actually go to the red and hold it for a minute (with me holding my sphinkter tight), and then it will drop to normal op temp. I replaced the thermostat with no effect. Granted, its not OEM. I also had the anti-freeze smell and some leakage, and after some time and alot of looking, I found the source of the leak. It was/is the waterpump. The car has 126K, and I really didnt suspect it. But once I removed it and looked at it, it was really rusted. The car is waiting for warmer temps to install the WP, I removed it when the first storm hit, brrrrrr. Considering the mileage of your car, and the smell of anti-freeze, this could be your problem too. This unfortunatly is not a quick fix:( I have to remove the A/C, Alt, crank pulley and the timing belt covers, and both fans.

Rob

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OK, so it turns out that my thermostat was fine.

 

I bought a new one from Carter Subaru and went to Tex's house to install it. After the install, the car still behaved exactly the same. A new radiator is next on the list.

 

I'd be able to order a new one tonight, but an unexpected expense came up.

 

Take my advice, when doing a thermostat gasket, make sure to avoid getting the silicon stuff on the bolt holes.

 

I was a little too careless about that (I made sure none got on the t-stat, but was unconcerned about the bolt holes). When we went to torque down the bolts, it got really stiff. One of the bolts then broke a head free.

 

Those bolts are very weak. It had a good quarter inch sticking out the top, but we were unable to turn it with a vice grip. We also dremeled a slot on the top of it to turn it with a flat-head screwdriving, but it just broke the bolt more instead of coming out.

 

Since I'm uncomfortable with drilling into the intake manifold myself, and I didn't want to leave my car in Tex's garage (especially since he's on a trip this weekend), I drove it down to Smart Service Subaru and had them drill the bolt out and tap the threads again. The money I would have used to buy a new radiator was instead used to pay them for repairs.

 

Oh well, you live you learn.

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doh! that happened to me... it was cheaper and easier for me to get a new intake manifold put on the XT when the thing striped out on me...

 

if you had contacted me, i might have been able to help you get a new intake... (might have one or know where one is that would work!)

 

anyways, I was gonna vote for a thermostat too, but I am not sure,,....

 

I just fixed my cooling (or lack of heating for that matter) by replacing my genuine subaru 180 deg. thermostat with a used 195deg one... and now it works nice and mid-gauge! (was running waaaaay too cold before..) and btw, I changed my thermostat and a upper heater core hose IN the snow.. (sorta had to, my car had a hose burst!)

 

well, good luck-

if you still need help with it, let me know (PAP run this weekend?)

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I think a faulty radiator is a good suspicion.

 

It has a vicious leak already, so I have to replace it anyway. Too bad I'm recovering from a slow winter-season at work and an unexpected expense for a mechanic, so I cant afford a new radiator for a couple weeks.

 

I guess I'll be putting coolant in nightly until then!

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