Strange overheating issues

[MALCHICK]

The background info:

91 Legacy NA
New waterpump about a year ago
New thermostat and coolant change today
New Radiator cap today


After having overheating issues on my way to work today (in 20 degree weather no less), I decided to change the thermostat and coolant after I got off work.

Everything went okay, flushed, changed the termostat (spring side towards water pump), filled, bleeded air out with heat full blast. It idled fine in the driveway for a good 20 minutes, no overheating at all, even revved the engine for 30 seconds at a time to about 3k and still no overheating.

Started the drive home and about 15 minutes in to the drive, suddenly out of nowhere, the temp guage goes up and the heater core starts blowing cold. I stopped and checked the overflow bottle and the system had expanded and overflowed the overflow bottle and shot coolant all over the ground. So I let it cool down and babied it home.

Rode my bike to the part store and got a new radiator cap. Filled the system again and bleeded it. Again, drove about 15 minutes and suddenly the heater core goes cold and it starts to overheat.

I keep testing it on and off trying to burp the system some more but I have a feeling I am getting nowhere. On a semi-cold start (before the t-stat opens), the heater core blows warm air. I see small amounts of white smoke (I think! but not sure, its cold outside, could just be steam) coming from the exhaust.

I am unfortunately suspecting a clogged radiator considering that is really the only link in the chain that I haven't replaced recently. When it overheated, I felt the core of the radiator in different places and it was cool near the bottom of the rad and hot near the top.

If its not the rad, I am fearing a small head gasket failure... but I am hoping to the almighty it isnt that because I don't have the time or money to fix something like that right now.

Anyone had similars issues? Any help would be greatly appreciated. Thanks!

[waldo320]

Yah read my thread a few post down called do I have a blown head gasket, this sounds like the same problem I had which resulted in a blown head gasket. Try this drive around the block no boosting at all does the car over heat? If yes then you probley have a radiator problem, but if it does not over heat till you boost you have blown head gasket. Next any oil in the run off tank if so blown head gasket just a oil line around the top, if that white smoke comming out of your exhasut smeels sweet blown head gasket, check oil is it brown and foamy like a milkshake blown head gasket, check cy#3 igntion wire boot is it dirty more than the others blown head gasket, compresion check is one cylinder less then others blown head gasket. But go to your local auto parts store and rent a cooling sys pressure tester just to make sure you have no leaks. The the short version of what I have reciently learned about head gaskets and the such. If your in need of a set of head gaskets call hybrid conection in new york I just got the stock metal oem head gaskets for 60$ a set they are the cheapest around that I found after searching for a long time, get your heads checked for cracks etc 50$ at the most, plus intake manifold and exahust manifold gasket 20$, so you can do a head gasket job for around 150$ doing everything yourself.

[MALCHICK]

The background info:

91 Legacy NA <---

[waldo320]

Fine take away the boost part but no matter how much you rev the engine at park you still do not get the same load on the engine as driving it. How did the other five tests I gave you turn out???

[MALCHICK]

Well I havn't done all the tests because I havn't had a day off for over a week.

But, there is no oil in the coolant. There is no coolant in the oil either. Havn't done the coolant system pressure test.

The only evidence I had that suggested blown head gasket was the "white smoke" but I was just mistaking the hot exhaust in cold weather (like seeing your own breath) for smoke.

[douglas vincent]

Try running without the thermostat and see what happens. This should allow ALL the water through, and if you have a clogged radiator, you will definately be able to tell, since all the water should be flowing through.

[subytech]

Sounds like a clogged radiator to me if it was overheating and the bottom of the radiator was cool.

[Legacy777]

Are you using a subaru OEM thermostat. If not DO THAT. Any and pretty much all aftermarket parts store thermostats will give you problems.

In addition, you must open the bleeder screw on the passenger side of the radiator to properly bleed the cooling system of air.

Do both of these things if you have not done them.

[vtxrider]

My son's 93 na has the same symptoms. I have replaced water pump thermostat (subaru) and radiator cap. Without thermostat water circulate through radiator with thermostat coolant is not flowing and coolant is being pushed into the overflow tank. I am suspecting head gasket but shouldn't it still circulate through radiator. Not getting coolant in oil or not losing any in the exhaust.

[subytech]

Are you using a subaru OEM thermostat. If not DO THAT. Any and pretty much all aftermarket parts store thermostats will give you problems.

In addition, you must open the bleeder screw on the passenger side of the radiator to properly bleed the cooling system of air.

Do both of these things if you have not done them.

Yes and Yes we get people in all the time at work that have aftermarkes T-stats the are "brand new" but stuck closed/open, pritty much any aftermarket T-stat has a good chance to give you headaches no mater what you drive. Boy i wish my ss had that bleeder screw it makes things much easier oh and having the Radiator cap ON THE RADIATOR!

[entirelyturbo]

Are your fans working?

[subytech]

My son's 93 na has the same symptoms. I have replaced water pump thermostat (subaru) and radiator cap. Without thermostat water circulate through radiator with thermostat coolant is not flowing and coolant is being pushed into the overflow tank. I am suspecting head gasket but shouldn't it still circulate through radiator. Not getting coolant in oil or not losing any in the exhaust.

Some overflow is normal due to expansion of the coolant as it gets warmer, and this will happen before the t-stat opens in alot of cases, I know in my 92 SS it takes FOREVER for the t-stat to open if the car is just sitting still, even if the temp gauge is reading normal the lower hose is cool/cold for a long time before it starts to warm up.

[vtxrider]

I understand that some coolant going into the overflow tank is normal, but not until it is overflowing out of it. Also after this happens the engine then overheats and the heater starts blowing cold. The radiator is cold when this happens. I really don't want to do head gaskets especially if that is not the problem. I had a 90 legacy that would over flow out the expansion tank and I babied it for a lot of miles (20000) before replacing head gaskets and solving the problem. That car now has 280000 miles and going strong. But when it was doing this it was a least circulating coolant through the radiator. that is the part that really has me stumped on this one.

[subytech]

well one difinative way to find out if these problems or any prospective headgasket failures are truly head gasket failurs is a combustion gas dye test. I've never heard of anyone doing this test on this forum, I guess because of the cost of a kit and the fact that not many people have heard of it. What it is is a glass tube that looks like a turky baster, in the tube is a liquid that is dyed blue with a chemical, you place the tube over where the radiator cap would go and once the car is warmed up you suck air out of the top of the radiator though the tube(before the test you suck out a small amout of coolant from the radiator), if there are any combustion gasses present the chemical dye will turn yellow indicating a combustion leak into the coolant system.

[shtbxr22]

I have used the gas tester, several times at work, and it works the balls. Also I noted someone said "are your fans working?" I had the problem today, that my fans would not turn on, unless the a/c, or def was turned on, causing a bypass in the loop. I watched the engine coolant temp reading with the select monitor, and the temp sensor would intermittently work, but the reading would miraculously drop 50-60 degrees F. Bad coolant temp sensor. so when I can scrounge $18 I will get a new one from work. Otherwise, I wish you the best of luck, and try to go to some parts store, with a OBD scanner, and see if they will show you your readings when it overheats, or not.

[HobbyWrench]

My guess and (unfortunate) experience would also indicate this probably is a blown headgasket.

My '90 Legacy LS Wagon, NA, 166K miles, started overheating infrequently, and then everytime within 10 minutes of heading down the road. It NEVER overheated just idling in the driveway.

A compression check indicated a drop in cylinder #3 for me, as well.

Pulling the heads confirmed the headgasket deterioration on cylinder #3.

Mike

__________
'90 Legacy LS Wagon, EJ22, NA, 4EAT w/194K+ miles