Troubleshooting Help: 1986 Subaru GL Coolant Explosion

[TheRustyWolf]

History with car: I've had this 1986 Subaru GL wagon for a little over a year. It has 211k miles. I purchased it from an old guy who had records dating back to the early 90's. Well maintained, but rarely driven (45k in the 17 years before I bought it). There has been a gargling after a drive for as long as I can remember. Sounds like it is coming from the coolant reservoir. 

Recent changes: I put 20w-50 in it a couple weeks back to cut down on how much oil i've been leaking. I've driven enough on this to run through a tank of gas. Longest recent trip was about 60 miles with this oil type.

Why I'm Needing Assistance: Three days ago I had some issues with my brakes and figured out it must be my rear shoes being worn/snapped. After further inspection this was the case, and today after work I got the new shoes and drums put on. During my "I hope this spoob works" lap around the block I was speeding up rapidly to brake and make sure the car was stopping as it should. On the last straight away before I turned onto my street I hit my max of about 40mph, I quickly braked and turned onto my street which has a decent hill that descends about 30 yards before I turned into my driveway. As I turned into my driveway I noticed my steering was super stiff like my power steering wasn't working. I pulled into my driveway, which is level, and turned the steering wheel left and right. The wheel turned just fine on level ground indicating the power steering was working.

I turned the car off, and popped the hood. There was a ton of steam coming from the radiator/front of the engine. There was also a pool of coolant on the engine bays lower sheet metal and the radiator fins were soaked. The coolant reservoir was dry.

My Thoughts on Where to Start Trouble Shooting: I did a quick search and found some threads about similar issues. Most of the suspects were Head Gaskets, Thermostats, and Radiators. My initial thought is get the radiator back up to level if possible by briefly starting the engine with the radiator cap off to burp it, and see if I can find a leak anywhere. Since this was an abrupt/acute issue with the power steering going out and then a lot of steam with a coolant explosion being the source I would think this process would allow me to spot the leak.

Advice and thoughts would be greatly appreciated! Please let me know if there is an obvious source to this issue, if I should go about trouble shooting a different way, or if any clarifying information is needed.

Sincerely,

CarNeededBySkiSeason

[DaveT]

Need troubleshooting to be sure of the cause.  The gurgling is not a good sign of a well functioning cooling system. 

Verify all 7 cooling system hoses are in good condition,  not made in 1986.  

Verify the radiator is in good condition,  all of the fine fins still soldered to the horizontal tubes.  Including looking where the fan duct traps stuff to accelerate corrosion. 

Make sure the radiator flows coolant freely. 

Fill with water.  Start engine.  Idle only, no driving.  Keep adding water for a few minutes,  as the pump should stir up air.  Tapping the throttle to momentarily rev helps work the air out.  

One of those no spill coolant funnels that attach to the radiator cap are worth having.

If you see a never ending steady stream of bubbles, that is likely failed headgaskets.  The stream can be anywhere from one small one per second,  to a good air flow pushing coolant all over the place.

Subaru engines of this era do not like running low on coolant,  it is rare that the headgaskets survive running over normal temperature while low on coolant.  

[TheRustyWolf]

I filled up the coolant level, and ran the engine at idle with the radiator cap off for a bit. The coolant level slowly rose until it overflowed a bit and I shut the engine off. There was no bubbling that I could see. Just a slow rise of the coolant. I put the radiator cap back on, and then filled up the reservoir until it was in between the low and full lines.

I then then drove around the block driving as normal. Temps and pressure were gauges were reading as usual. When I pulled into my driveway and popped the hood, there was definitely a lot of steam coming from the radiator, but I couldn't spot the source of the leak. I popped the radiator cap off, and the level was a bit lower, but only by about 3 ounces. I filled the coolant level back up, put the radiator cap back on, and then had the car at idle for a good 5 minutes. The fan came on, and the heat still blew hot. I had the engine running for a bit longer, revving it up to 3000, letting it drop back to idle, and then revving it again, holding it at 3000RPM for about 10 seconds, and then letting it drop again trying to get the radiator to steam again. It didn't happen.

I then drove around the block again, and pulled into the drive way. With the car running I popped the hood to see if there was steam coming from the radiator again, but there was none. The fan was off, but quickly came back on after the car was stopped for about 10 seconds. I turned the car off, and decided to pop the radiator cap off to see if it was hot enough to boil out, and it definitely was. 

So I take a half hour break or so, and realize I'm hungry as codswallop and need to get some food. I pop the hood, and the coolant level has remained consistent, so I figure what the hell, I'll drive a mile away to where the restaurants in town are. I drive about 2 miles total finding a parking spot and a place to eat. This is about 6 times longer than driving around the block. When I park I pop the hood and I don't see anything abnormal. I have a couple slices of pizza and a beer while looking at newer cars on craigslist, and then head home. I purposefully accelerate fast after stop signs to build up heat and pressure. I pull into my driveway and pop the hood. Everything is fine. I did not pop the radiator cap as I didn't want it to boil out again. I'll check the level tomorrow morning.

I would assume that if the coolant came boiling out, that the system is retaining pressure. This makes no sense to me since it was steaming out of the radiator, or the radiator was steaming from getting coolant spewed on it. The car idles smoothly, it maintains oil pressure, and I have no white smoke coming from the tail pipe. Would it be safe to assume the head gaskets are fine? The fan comes on and off as it should, and I'm guessing the thermostat is fine if the heater is working, and my temp gauge is reading accurately as normal. I'm at a total loss here, but I'm also very inexperienced with cooling systems. 

[DaveT]

It's best not to open the cap when hot, as you discovered.

The head gaskets are not blown badly, if they are.  When they are bad, exhaust gasses are pumped into the cooling system, and push the coolant out fast enough that you wouldn't have made the trip to the restaurant.

Lack of white smoke doesn't mean a lot, as that is not the most common failure mode.  Usually the white smoke is a failed intake gasket.

Here is what I do to determine cooling system & head gasket condition -

During this, never open the cap.

Before every start from cold, check the coolant level in the recovery tank.  If it's moved off the full mark, add some to get it on the full mark.

Sharply squeeze the upper radiator hose, and listen for gurgles and the giggle pin.  Remember how it sounds, so you can compare to the next drive.  You can hear the difference between air and no air in the system.  A little bit of air doesn't worry me.

The real thing is to note any changes.  More air or less air?  Does the level in the tank change?  Which direction, disappearing coolant, or additional coolant?

Run this monitoring for at least a week of trip or 2 per day driving.

Intake gaskets, or the seal under the carb or throttle body can make coolant slowly disappear.  Also, they let air back in as the engine cools down.

I have seen small leaks to the outside, from slightly loose cooling system, hoses, pinholes in the radiator, seeping from a head gasket.  They keep or grow the amount of air in the hoses that you check with the squeeze test, and also cause coolant to slowly disappear.  If one of these leaks is onto the block or other part that runs at 190 degrees plus, there is little evidence left to find it visually.

About cooling system hoses - I use plumber's silicon grease when installing them - just a little - it makes removal a LOT easier.  And seems to help with sealing - after the first drive with any re clamped hose, once it cools back down, re check the clamp tightness.  Sometimes things settle in and they are loose.

The tricky head gasket failure mode is when a tiny pinhole develops at one of the fire rings, that allows exhaust gasses to leak into the cooling system.  These will slowly get worse over time.  It can take 6 days, 6 weeks to 6 months before they get bad enough to make the car undrivable without risk of serious engine damage.  The best way to catch this before serious engine damage is to check the level and air before every drive, until you determine that things are stable.   Once this starts, any over normal temp while low on coolant accelerates the failure.

At the beginning of this kind of slow leak failure, there is no other way I have seen discussed to detect it.  Lots of ways once it's pretty bad, but the above will tell you before it gets bad, so you have more time to plan, and if you are checking, and refilling, you get away with it longer than diagnosing by the temperature gauge.

I have nursed them along for months using this procedure, while I resealed a spare engine.  Also ran one with a cracked head for months the same way.  If you are near seal level, you can also modify a radiator cap and run zero pressure in the cooling system, which makes the coolant loss slower, which is also part of how I got away with that.    This is probably not a good idea at significant elevation.

 

 

[Steptoe]

So many words mister !

But you've some pretty good detail

My recent EA82 coolant losses have been water pump Seal so leaks out weep holes top and bottom of water pump housing.

The other, seemed to come and go. Having ethylene glycol  in there helps engage the smell and taste senses for diagnosis.

Noticed each time I smelled, tasted coolant, was moments after spirited driving requirements. Turned out to be a 5.5 mm inside dia rubber hose from the middle of the top of engine block to the thermostat housing next to temp gauge sender unit.

This hose had a cats bum * look about it with no extra spirited driving pump pressure surge behind it. These cats bum * like cracks opened up spraying fine spray all over the place making it tricky to spot source

New hose. Job done

[TheRustyWolf]

Thanks for the replys.

DaveT - I will continue troubleshooting as you recommend. 

Steptoe - I will go inspect that hose and others. I didn't notice anything off about the hoses, but I was looking for obvious defects. I'll see what I can find with a closer inspection.

Based on both of your recommendations I will probably go through and replace all the upper hoses to start since that is relatively cheap. Then I will run Dave's troubleshooting test next week after I get back from deer hunting. I'll decide next steps depending on the outcome from that.

[TheRustyWolf]

Whelp I feel like an idiot. I'm pretty sure I found the source of my issues, but I'll keep tabs on it. 

Today after work (I took a rideshare) I checked the coolant level in the radiator, and noticed it looked to be about the same. I then checked all the connection points for coolant and the only one I noticed that was wet was from the pump to the upper radiator hose. Just some seepage that I could see dripped onto the belt cover. I was overly concerned about the huge amount of steam that I over looked some obvious check points. Also the amount of moisture that accumulated on the front of the engine and radiator made it hard to pin point the source. 

I'm guessing this was the scenario: Radiator hose has real slow drip, and I never checked my levels so I didn't notice how far down it was getting. I repair my brakes and with the car lifted up on jack stands for a couple days causes this to leak more than usual. I fix my rear brakes, and on my lap around the block, accelerating and stopping repeatedly, the little coolant I have left gets pretty heated and hits the point of least resistance, my upper hose connection. It sprays all over the belts, causing me to lose my power steering for a second, and also reflects off the belt case/engine onto the radiator creating a massive amount of steam from the fins, and a huge wet spot on them. 

The hose looked fine, but I'll replace it and get some new clamps. For my most recent test run, I changed the position of the clamp, and tightened up as much as I could with a socket wrench. After a few miles with rapid acceleration when I could, I didn't notice any new moisture from the connection. 

Thanks for the help you guys. Lesson learned, keep an eye on  your coolant levels.  First time in 13 years of owning a car that I've had any issues cooling related, but this was great learning a bit more about how the system works out of necessity. I feel a bit more confident that I could diagnose the common issues now after trouble shooting. 

[DaveT]

Keep a close eye on the levels, as previously suggested.   That kind of overheat is exactly the kind I have experienced that started the slow headgasket failure.   Btdt.  

[TheRustyWolf]

Drove on the highway for 20 minutes or so for a beer run test drive. The connection still has a very slow leak so I'll replace the hose and clamps, and keep an eye on it.