Cooling system problems re-visited

[FUJI-HEAVY]

O.K. So I had a previous thread dealing with a possible blown head gasket and the feedback was limited but generaly said it probably was a head gasket.

 

Here's the situation.

 

I did some work on my 85 GL-1O turbo wagen a few days before christmas and at the end of the work decided to throw in a new thermostat. Well, a 5 min job became a half day job when one of the bolts was siezed in and broke off. After trying to easy-out it I was forced to tap it out and clean the thread and yada, yada, yada. I just had to vent that.

 

Well a few days later I was set to head to the ski hill and checked all my fluids and noticed the coolant was low. I topped it off but opted to not take her to the hill. When I got back I drove around always checking for leaks and checking the engine when I arrived anywhere. I got home and could hear bubbling in the coolant reservoir. On a suggestion from my dad, I waited untill she was cool and removed the radiator cap to see what happens on start up and look for movement indicating the water pump was working once the thermostat opens.

 

Well, the first thing to happen was a bubbling of air for about 5 seconds and then coolant pushing out of the radiator. Now the thing is that everytime I drive her, she pushes coolant into the reservoir and when cool, draws it back but seems to loose a bit everytime. Like i said before, when I stop from a short cross town trip there is bubbling noise from the reservoir.

 

Here are some diagnosis:

- No water or "foam in the oil".

- No white smoke from the exhaust.

- No oil in the coolant.

- Very little heat inside the car now since problem started.

- The engine temprature gauge reads the engine is cooling better than before.

 

I just wonder if anything could cause this pressure excluding the cylinder gases. Could a stuck, faulty thermostat combined with the water pump do this? what about the turbo? Could the turbo be pressurizing the system through some kind of leak?

 

I plan to remove the thermostat all together today to see what happens. It appears that the system is gaining pressure some how but the engine is cooling allright. I'm confused.

 

Thanks for taking the time to read this long winded account but I wanted to lay down as many details as possible to assure correct assistance.

 

Steve M.

[Subarian]

A head gasket leak doesn't have to display any of the other symptoms you mentioned, although any of them can be symptoms. If the leak is only between the cylinder and the water jacket, it can pressurize the system without any other symptoms being present. Normally, the engine will run hotter, not cooler, but it could be that your sending unit doesn't have enough coolant running past it to get a good reading.

 

If you want to be sure, you can get a combustion gas leak detector. They look like this and cost about $30. You can have a shop do the same thing for you, but they'll probably charge you at least as much.

[robaru]

Did you replace the head gasket? If not, do a compression check on the cylinders. You could try parking with the nose of your car up a pretty good hill and making sure you have all the air out of the system. Pockets of air will do some weird stuff. If you do take your thermostat out, put it in a bowl of water and put it on the stove and bring it to a boil. The Thermostat should open just as the water starts to boil. It kind of sounds like you still have air in the system.

[FUJI-HEAVY]

well I pulled the thermostat and started it up and the bubbling is hardcore now. It runs like sh*t and I've further noticed that my muffler seems to have large amounts of rust holes, out of the top! The rusty muffler and drips of water coming out of the exhaust seem to me to be more than usual condinsation. I'm pissed. This thing is turning out to be a lemon and my wife... .

 

Looks like a head gasket is undeniable at this point.

 

So whats the best way to do a head gasket. Drop the motor or do it in car.

I'm going to do a compresion check next just to confirm and the old man is coming to inspect and administer his 2 cents.

[Syonyk]

So whats the best way to do a head gasket. Drop the motor or do it in car.

 

You can do it in the car, but it'll be easier (and probably just as fast) to pull it out. While it's out, you may want to replace most of the seals on it. There's a kit from somewhere (not exactly sure, 1stsubaruparts.com maybe?) that has all the gaskets for the engine in it (including the head gaskets). Replace the front & rear main seals, cam cover o-rings, and other stuff while you've got the engine out.

 

-=Russ=-

[Caboobaroo]

isn't sounding like a headgasket to me. Sounds more like the car isn't cooling very well ie plugged radiator or a plugged heater core. I would recommend a coolant flush to help determine if it in fact a headgasket or just a plugged radiator.

[TomRhere]

As stated earlier, the 1st thing you want to do is a compression test. This will either eliminate possible HG problem, or atleast show you which side/cylinder is the culprit. You'll be looking for one cylinder to be much lower than the rest.

 

Next step, is to bring that low reading cylinder to TDC on it's compression stroke and apply some comressed air to it thru the spark plug hole. Look for bubbling in the radiator. If it's there, yep, popped the HG. Or,, and I hate when this happens, you cracked a head.

 

Now, if all cylinders read about the same, chances are the HG's and heads are good and you have a cooling problem.

 

If,, when you removed the T-stat and started the engine, (with the engine cold), and got bubbles imediately.... Then yes, I would suspect that you have a bad HG or head. But,,,, it still could just be trapped air in the cooling system.

 

Do the compression test before doing anything else.

[BoostedBalls]

I would pull the spark plugs and pressurize the coolant system through the reservoir. You might be able to hook up a compressor to the small hose and regulate your air pressure at 15psi or less. If you have gurgling noise from one of the spark plug holes it could be a head gasket!

 

It could also be a crack in the exhaust port of one of the heads. <--- my $5 goes on the cracked head.

You might drop the header pipe during the test to see if water drips out of one of the exhaust ports.

 

I hope it goes well!

[NorthWet]

I'm throwing in with Caboobaroo (radiator) on this one, though doing a compression check won't hurt... but also may not tell you much.

 

Tale of two cars: First, XT with rapid overheating 2-3 minutes of running, worked better with rad cap off and no thermostat. Compression test looked OK. Turned out both heads had long-term gas leakage to water jacket without actually "blowing" the HG. Compression gasses were pressurizing the cooling system and basically air-locking it. Running without t-stat or rad cap allowed it to vent enough to allow coolant flow.

 

Second, SPFI overheating after several miles, cool heater output, cool radiator hoses. Compression also looked OK. Replaced t-stat, no change. Backflushed radiator, cooling improved for a while, but came back after a few weeks; backflushing didn't help. Turned out brand new t-stat started sticking and wasn't opening; lubed its spindle, worked great afterwards.

 

Moral? Not sure that there is one except that cooling system problems on older Subarus can be hard to diagnose, as there are many things that can cause you problems, and one might appear about the time you fix one.

 

Along with the compression test, I would loosen the radiator cap (so that it can vent), and then feel the radiator surface top to bottom feeling for hot/cold areas. I have had a lot more problems caused by plugged radiators than by HGs.