Newbie with probable bad head gasket

[brianl]

Just bought a 1997 Legacy Outback in incredibly pristine shape, with 107K miles. Body phenomenal, interior excellent, suspension tight, trans fine, runs fantastic, clean as a two year old car underneath. Appears to have been garaged since new AND dealer maintained since day 1. Only one owner before me. Was able to get timing belt replacement info from dealer...had just been replaced in June.

BUT....

I have cooling system issues and fear I just bought a car with the infamous DOHC head gasket problem.

Radiator was replaced immediately before purchase, allegedly due to a leak in the old one.

Drove locally for 3 days fine, then it overheated. I now believe radiator had gotten critically low, but I had previously only glanced at the overflow tank instead of pulling the radiator cap; lesson learned. Refilled, took to local shop, they tested with chemical kit for combustion byproducts in radiator and overflow tank, said all is well. They attributed to a leaky connection at hose from bypass to radiator, at radiator; clamp applied. They claim they drove quite a number of miles with no issue.

Still, CONSISTENTLY, coolant is forced from my radiator into my overflow tank. In my 15 mile one-way commute, maybe 2/3 to 3/4 of the overflow tank.

Tried new radiator cap (NOT Suby OEM part, dealer was out of stock.) Little or no difference.

Noticed today after it cooled for about 4 hours, that radiator, though cold, was still mildly pressurized; as I started to turn cap, SIGNIFICANT gasses flowed into overflow tank. Radiator was again low, overflow tank again high.

(Been carrying a baster around to move fluid from 1 to the other!! :-( )

No external leaks except when fluid is forced out the top of the cooling overflow tank. No coolant in oil or vice versa. No white smoke.

My fear/guess is, I DO have combustion gasses pressurizing the cooling system from a bad HG. (NO idea why it passed the chemical test.) With all that air in the radiator, it NEVER goes down in pressure far enough to draw fluid back from the overflow tank.

Yes, I've bled...repeatedly. But the volume of gas I keep finding is inconsistent with bleeding issues; they would get smaller and go away with repeated bleeding. This recurs every time driven.

Any thoughts/concerns?

This car is in WAY too good a shape to throw out, and I love it. I guarantee you will not find a 1997 in nicer shape. I do NOT want to throw it away. If it is HG, what do I do - have replacements done and the blocks machined? Have an engine swap done? What??

Should I specify or avoid a particular replacement HG?

Thanks,
Brian L

[chuckthefuk]

Who replaced the radiator? You? Your mechanic? Previous owner?

I would check the upper and lower radiator hose for temperature. They should be both hot however if one or both are cold then the coolant isn't flowing. This could be because of a bad thermostat / heater core / bad coolant lines or hoses.

It is recommended to use a OEM radiator cap or a performance cap that is a quality product.

Many people see after market or OE equivalent parts as a deal but in the long run they are iffy and cause problems. (rad cap/ t-stat are 2 dealer items that are a must)

When a H/G goes there are so many different ways the gasket can fail.. In your case it sounds like the exhaust gases are leaking through the H/G and forcing the coolant out.

Any current head gasket which are (MLS) multi-layer-steel revision will work.

Expect to send the heads out to get machined (decked or flush) in order for the head gasket to sit flat on reassembly.

You're looking at $1000.

-Chuck

[Dead91silvia]

A common reason for popping HG's is people not knowing how to 'burp' the system and they think it's just like an old V8 Chevy. They take time and some odd ways to get all the air out. Any DIY Subaru nut learns this fast. Never go off of the expansion tank to RAD level, it can lie.

I would definitely fix that motor! Thats super low miles for blown HG's, but it does happen. My 98 GT has had 3 sets, but I also beat the crap out of my car.

This is what I do for my customers and have not had a comeback yet.
-surface heads (no need to do block)
-new valve cover gaskets
-new front and rear crank seals
-new seals cam
-Air/oil separator plate at the back of motor w/bolts. (Known for making massive oil leaks over time, originals are plastic, new is metal)
-New Head Gaskets from Subaru (Only OEM parts I use). Price is pretty reasonable.
-New NGK plugs
-New T-belt kit, includes belt, bearings and tensioner. (I use Gates kits, same bearings Subaru uses and good belts)
-New water pump. NEVER get a re-man pump! Thats just asking for trouble!

I dont give a warranty without doing a new timing belt, unless I had already done it and this has only happened once. I recommended doing the HG's at the time and they opted out and 10K miles later they popped. This customer oted to play it safe and got just a new belt, not the whole kit. However, if it's not that old, you should be fine. A good belt is only like $50 though.

If you are doing the work yourself, it will cost about $300-400, if it's a shop, it's going to be $1000+. Last time I did a HG job for a customer it came out to about $1300, but thats with towing and tax.

[harrymaneuvers]

-Air/oil separator plate at the back of motor w/bolts. (Known for making massive oil leaks over time, originals are plastic, new is metal)




Note that there are two versions of the METAL oil separator plate. The older style is thick metal with recessed holes for the bolts.

The new style is much thinner and the bolts holes are not recessed, they are flat as are the new bolts.

[phi11]

yup, one is steel the other is aluminum.