Automotive Help - old Subaru is overheating

[gnome]

Would like to ask the mechanically inclined for a little help with my '97 Subaru outback.

A few months back it overheated, I cooked it pretty good. Took it to two mechanics, both said head gasket, with a price tag around $2,000. Car has a few other problems and not really worth it to me, so I just let it sit for a bit. Then a friend says take it to his friend who is a backyard mechanic, so I did.

Cool guy, replaces the thermostat and fiddles with the radiator. Flushes it out, refills, carefully bleeding all the air out of the radiator using the bleed valve. Seems that the passenger side fan doesn't come on if there is air/steam in the radiator, only when it is full of fluid.

$180, I'm out the door, car is cooling itself just fine. :banana:

Car runs fine for a week, then overheats. :bear_noexpression:

I copy what the mechanic did: bleed a bunch of steam out and fill with water. It sucks down 3/4 of a gallon, easy. Cools itself fine after that.
:bear_thumb:

This sequence has been repeating itself for 2-3 weeks now. Car is fine for a few days, then starts overheating. I add water or coolant, bleed the steam and it is fine for a while.

Seems to overheat more when I'm running the AC. Happens around town, seems highway driving is mostly OK, because wind is cooling the radiator, rather than relying on the fans. I keep trying to find a leak but I can't. Radiator does not seem to be drawing from the reservoir very much.

The new mechanic is out of town on a cross-country motorcycle trip. :bike:

Help please. Any ideas? :idea:

[Haole]

I wonder if you have coolant in your motor oil or vice versa?

If you really overheated it well you might have warped your heads slightly and sounds like your slowly losing coolant at any rate. I'd be willing to bet you need head gaskets and possibly the heads machined. I'm fairly sure you have a horizontally opposed boxer in that thing in which case you will need two head gaskets, etc. - 2 heads. Good luck.

[gnome]

The motor oil is clean. Coolant...a few floaties, I guess.

[TnAndy]

Having to keep add water means only two things:

You have an external leak, and it should show somewhere on the ground under the car at some point,

Or

You have a blown head gasket, and the water is seeping into one or more cylinders, and leaving via the exhaust pipe. Water may show in the oil, or oil may show in the water, but also neither case is possible and the failure of the gasket is simply allowing a small amount of water over the course of a week of driving to enter the combustion chamber and blow on out the exhaust.

[138]

Sure sounds like a blown head gasket. As long as is there is no coolant in the oil which would indicate a very bad gasket/cracked head, you may want to try a pour in head gasket sealer. I've used it in the past and it kept a Lincoln with a blown head gasket going for another two years.

[shades]

Park the car up on a clean surface (concrete). Let it run/rev it a bit, then let run for 20 minutes or so. Move car, look for coolant leaks on concrete, also check plastic pan for leaks under engine... If you're lucky, it's just a hose or similar.

Andy has indicated what the problem likely is. If it is a head gasket/slightly warped head, a head gasket sealer is a quick, cheap and nasty solution, you can add it to the coolant, let it repair the gasket break/gap by idling the engine for 30 minutes or so (hot operating temp), and hopefully seal the gap between the gasket and the cylinder head. Dump the coolant and fill with fresh coolant once resolved. Typically this stuff is sodium silicate mixed with some other stuff, and turns to glass if it is able to dry out (leaks into hot head/gasket area) around 100-105C and will not re-melt at temps below 810C.

This sort of repair can hold for 2 years or so (can also go at any time), it is a temporary measure until you remove the engine and replace the gasket / machine the cylinder head, and re-assemble. I ran about 3 years on a straight-6 Ford 3.9L. (Cast iron block / aluminium alloy head).

If you are going to eventually do that work on a '97 Outback, you probably want to get ready to do the valve timing belt, idler/tension pulleys, plugs, oil pump and water pump if they haven't been done also, CV joints, and check/replace the crankshaft bearings, and any valve work that may be required. Might as well do that all at the same time.

Do not let it run out of coolant, if it is left to do so, it will warp the head/break the gasket completely, and coolant will just pour out of there. If the engine is continued to be operated in that state, it will overheat, stall and potentially damage the engine further (scored cylinders, etc. all possible).

Use the correct Subaru coolant, they contain silicates, phosphorus and borates apparently, and protect the aluminium head interior from corrosion.

[Scorpio]

great answers above for you,

might add, you need to make sure both fans are operating normally, so the coolant isn't 'boiling' out so to speak

you can run a pressure test on the system to see where it is going if a external leak, as Tn said though, if it is going in the exhaust from the cylinder, this test won't show that.

yep on the 'quick fixes', it does work on some of them.

head gasket can fail and show up as, leak coolant into oil, you said no to that, or leak oil into coolant, check your coolant for oil deposits, as it will be floating on top of coolant in the reservoir, especially since you put in new coolant.

is there a check engine light on?

S

[southfork]

I wonder if you have coolant in your motor oil or vice versa?

If you really overheated it well you might have warped your heads slightly and sounds like your slowly losing coolant at any rate. I'd be willing to bet you need head gaskets and possibly the heads machined. I'm fairly sure you have a horizontally opposed boxer in that thing in which case you will need two head gaskets, etc. - 2 heads. Good luck.

Thats what happened to an old car I had, if you watch the tail pipe you will see an abnormal amount of steam coming from it, I had to use two gaskets with old indian head.

[gnome]

Thanks for the many responses. :bowdown:


No steam coming out the tail pipe.

What would the oil in the coolant look like? Oil floating in water? Or something else?

Plugs were just replaced. They were overdue....some big gaps, but otherwise not too messed up. I believe it is horizontal boxer type - 2 plugs on each side, way down where they are a PITA to get to.

Belts were done at 125,000 miles, now at 165,000.

Whenever it overheats, the passenger side fan is not coming on...this only seems to happen after the radiator has leaked a fair amount of fluid. If the radiator is full, the fan comes on.

[southfork]

Thanks for the many responses. :bowdown:


No steam coming out the tail pipe.

What would the oil in the coolant look like? Oil floating in water? Or something else?

Plugs were just replaced. They were overdue....some big gaps, but otherwise not too messed up. I believe it is horizontal boxer type - 2 plugs on each side, way down where they are a PITA to get to.

Belts were done at 125,000 miles, now at 165,000.

How long does it take to overheat after you fill the engine again, I doubt your leaking it into the oil, it would be brown and foaming, could still be cracked block or head, head gasket issue but that the fissure is small so it takes time to leak the water in which case you wouldnt see the steam emiiting from the tail pipe.

[gnome]

How long does it take to overheat after you fill the engine again

If I'm just doing a few small trips around town, I can add a little bit it every 2 or 3 days without ever overheating. A 45 mile trip down I-95, on a hot florida day blowing AC the whole time was OK until I got off the interstate (again, the fan).

[Professur]

I miss my old Sube, but what I don't miss is the cost of repair. If 2 mechanics told you head gasket ... I'm gonna go out on a limb and agree with them. $2k on the other hand seem excessive in the extreme. On a regular inline 4, $600 would be normal. But given the nature of the boxer style engine, it could be, but it all depends on what they're including in that bill. Gaskets and planing the heads ...very high. Gaskets, leak testing and possibly replacing the heads, new timing belts and tensioners, possibly even replacing the water pump (all common when doing the heads) could put you into that ball park.
One question, do you have a real temp gauge, or an analog idiot light?

[southfork]

If I'm just doing a few small trips around town, I can add a little bit it every 2 or 3 days without ever overheating. A 45 mile trip down I-95, on a hot florida day blowing AC the whole time was OK until I got off the interstate (again, the fan).

Gota go with a crack then in the block, head or gasket, I would try a head gasket sealer first as some will work for years. The only other thing I have found some times and has not been mentioned is the radiator cap, could very well be the seal and spring shot on it, that's been the occasional fix also.

[gnome]

One question, do you have a real temp gauge, or an analog idiot light?

um...a needle...stays at normal temp, just below halfway, except when it overheats, then it starts creeping up slowly.

No check engine lights are on.

[gnome]

The only other thing I have found some times and has not been mentioned is the radiator cap, could very well be the seal and spring shot on it, that's been the occasional fix also.

How could I tell? The spring has some spring in it, but doesn't seem real strong. I have seen a lot of fluid around the cap area, but I thought that was from spills, after refilling so many times.

[Scorpio]

it does not make sense to me that 1 of the fans is only coming on when the rad is full,

I didn't think those had level sensors on them? Heat sensors only.

Is there an issue with the sensor turning the fans on and off? That is where I would start as that just isn't passing the smell test from what you are saying,

rad caps are cheap, just throw a new one on it, as they should be replaced now and again anyway. Some say when you flush the fluid, change the cap also as a maintenance item.

S

[shades]

Keep the coolant filled. Keep the bonnet open after you've been for a drive and the engine is hot. Do not open any radiator caps. Look for any steam being dissipated off the engine (leaks) look for evaporated coolant colour. You can smell coolant evaporating off. Check the overflow bottle, overheated coolant could be being expelled into there, and boiling off slowly, that side of things is not pressurised.

Replacing the caps is cheap as Scorp has indicated. Check the condition of all radiator cap seals when cold.

When idling, rad fan should come on and off when required automatically.

I should have also mentioned, replace the thermostat earlier. It's a cheap part that can fail over time.

[Goldhedge]

Replace the cap. It's cheap.

I had a sube that leaked oil all over the air cooler once!

Pulled into a parking spot and oil drained out (there's a small
hole in the air filter can). I KNOW! Sounds weird eh?

The fix? I had the oil changed at a Jiffy Lube prior to and they
didn't TIGHTEN down the oil filler cap. This caused air to
enter which sucked oil into the air filter from the recycle tube
(if i remember correctly? It's been years ago). There's a lot
of vacuum at the carb.

Not your problem, but watch for "loose" anything.

Steam is very bad for an engine. It's high pressure and
will blow gaskets and hoses and all kind's of 'things'.

[southfork]

How could I tell? The spring has some spring in it, but doesn't seem real strong. I have seen a lot of fluid around the cap area, but I thought that was from spills, after refilling so many times.

As mentioned caps are cheap and should be replaced as a time change, Ive also found after an over heat the thermostat sometimes sticks, those also are cheap and worth the change out. As Scorpio mentioned check the fan sensors , you should be able to to that by simply taking the plug off and shorting the end out that attaches to to sensor, that will tell you the fan is ok, then monitor the fan and see if it comes on, you can increase the temp load standing still by putting ac on and car in drive (ONLY IF YOU HAVE GOOD EMERGENCY BRAKE OR CHOCK WHELLS VERY GOOD)