Sudden Overheating - Mechanic says it's blown head gaskets but I don't believe it

[BlueBaja]

Good morning,

I have a 2006 Baja with the EJ255 turbo engine. The car has 155,000 miles on it, and I've owned it for about a year.

About six months ago I replaced the radiator because it was leaking. I also replaced the upper and lower hoses and filled it with the special Subaru 'Long Life' coolant and conditioner. Everything seemed fine for awhile, but I kept noticing a burning antifreeze smell from time to time. Several weeks ago I came home from work, parked the car in the driveway and when I came out a little while later I saw coolant on the ground, if I had to guess I'd say about a pint's worth or so. I couldn't find where it was coming from, and when I checked the reservoir it still had coolant in it but was low so I topped it up. It didn't do this again for about two weeks- the second time around I put it up on ramps and got underneath so I could see where the dripping was coming from- it looked to be coming from the water pump, but it's very hard to see with the timing case being in front of it. Again, I topped up the reservoir and didn't see this happen again.

On Memorial Day weekend I got in the car and was heading out when I noticed the temp gauge was pegged at hot. This happened from a cold start in less than two minutes, I never even made it out of my neighborhood. I brought the car back and had it towed to an independent Subaru shop the next day (very reputable people, I did my homework on that first).

They verified that the water pump was leaking, but told me that is not what is causing the overheating. They are telling me now that the head gaskets are blown, and that's what is causing it- which doesn't make sense to me. They tested the coolant for hydrocarbons but found none. I asked them to go through and check the thermostat and make sure the radiator wasn't clogged (I bought a cheap one on Amazon, and didn't have a way to flush it when I installed it, so that seemed like it might be the cause). They say no, it's blown head gaskets.

The reason I'm having trouble believing this is that I don't see how blown head gaskets in and of themselves would cause overheating this quickly from a cold start, or why they would be blown in the first place when the car had not been overheated. Plus, they say there are no hydrocarbons in the coolant. If they were blown I would have expected to see bubbles in the coolant reservoir or for the cap to have blown off from pressure. Since the car did get hot the last time I drove it maybe they are blown now, but someone please explain to me how that could have been the problem in the first place and the ongoing cause of overheating.

The car has 155,000 miles on it as I mentioned. Not long after I bought it I realized it was consuming about a quart of oil every few hundred miles, though I never see any smoke except sometimes at night in my rearview mirror under hard acceleration with the headlights of other cars behind me and it's not that much. I actually found this out when on a long trip about 3 months after I bought the car- I had been lazy about checking the oil and didn't know it was consuming so much. The low oil pressure light came on and though I should have just stopped and gotten oil I had my two young children with me and decided I needed to get home so kept driving for another 40 miles or so. I drained the oil the next day and there wasn't much more than two quarts, if even that much, in the crankcase. I filled it with new oil and haven't had any problems with the engine since- in fact the oil consumption seems to have tapered off and I check it constantly. I was suspecting ring lands on the pistons, or possibly the PCV valve, but once it abated I quit worrying about it and just keep up on the level.

The reason I mention the oil consumption issue is twofold- if the head gaskets are really blown and I'm having them replaced, would it be economical to have the pistons replaced with forged at that time? I was a mechanic in another life and still work on my own cars, but I don't know this engine well. Can the pistons be replaced with the engine in the car, or does it have to come out and the crankcases split? Looking at pictures of the block, I think it does as it doesn't seem to have bolt-on cylinders like an air-cooled engine would. But if it can be done in the car, should I do that and assume that the bearings will be fine having relatively high mileage on the engine and being deprived of oil like they were at least once? I'm also wondering how long the turbo might hold out with all those miles on it.

I have about $10K into this car including the purchase and what I've put in to new wheels and tires. I haven't done much else to it. I was actually considering trading up to a 1 ton truck as I have a need for better capacity. I haven't gotten the estimate from the shop yet but I believe they're going to tell me something like $3500-$4500 for replacing the water pump, timing belt and head gaskets. If I do put out the money to fix the car, I want to fix it right and if things are already apart I want to make sure I replace anything that could be a problem moving forward. Then I will keep the car for a long time. Cosmetically and otherwise it's in very good condition.

If it were yours, what would you do?

[BlueBaja]

So I talked to the shop this afternoon. They are standing behind their diagnosis and quoted me $3400 to replace the timing belt, send the heads out for reconditioning, put them back on and replace the water pump. I hate to do this with the mileage on the car and the fact that the engine was starved for oil as I explained above. I have no explanation for why it would have been using oil the way it was, nor do I have any idea what sort of condition that lower end is in. So I inquired as to the cost of a new short block, reconditioning of the heads, replacement of necessary parts like the water pump, and a new turbo since I don't want to put the original one with 155,000 miles on it back in the car and have it blow up on me. That would cost me $8000. I can't justify spending this much money on a car that would be worth maybe $12K afterward.

Again, I'm looking for advice from you experts on the forum based on the details I've described here. Need to go pick the car up tomorrow if I'm not moving forward with some kind of repair- so hope to get some answers soon! Thanks to you all in advance.

[TastyHuman]

You might check to see if there is an independent shop in town that works on Subaru's and get a second opinion.

If they agree with the dealer their estimate would probably be 20-30% less. Maybe worth a try.

Example. My 2003 Baja's automatic was shot (no question about that). Dealer wanted $3900 to replace with a rebuilt. I checked Angies list and found a highly rated independent transmission shop that rebuilt the original transmission to current specs for $2900. It just may be the smoothest automatic I've ever driven now.

[BlueBaja]

I took it straight to an independent shop that specializes in Subarus, never even considered taking it to the dealer. The shop is very highly rated, and I have no reason to think they wouldn't be honest or fair with me. I am just having a hard time figuring how blown head gaskets would cause overheating with no other symptoms- I've had blown head gaskets before on other cars and it's always resulted in coolant in the engine oil or some other obvious sign, not overheating within 2-3 minutes of startup.

[BlueBaja]

After some careful thought I decided I couldn't justify $3400 to replace head gaskets when they didn't really convince me that was the problem- so I had the car towed home this afternoon with plans to buy a short block, send the heads out for cleaning/inspection/machining if needed, install a new timing set, oil pump, water pump and the refurbished heads along with a new compressor and intercooler- then I got to thinking, and decided to take the car for a ride to see what it was doing. No harm in it really if I'm pulling the engine anyway...

By the way, the shop installed a new thermostat and at least the cap on the radiator, but it doesn't look like they replaced the cap on the expansion tank. They charged me $148 for coolant and the thermostat R&R. Then they told me the only thing to do is pull the engine and replace the head gaskets.

I drove the car about 1/4 mile and the temp gage showed normal. Then suddenly, in about 5 seconds it was pegged at the top. I pulled in to a parking lot and popped the hood- there was a little bit of vapor coming off the engine, presumably from the ever-present water pump leak. But I know what an overheated engine acts like- there was no 'diesel' sound of detonation, and the engine did not feel hot at all. I happened to pull in to a Harbor Freight parking lot, and decided to go in and buy a hoist and stand since I might be pulling this engine.

I spent 20 minutes in the store- and when I came out and started the car, the temp gage showed normal. That's weird, because if the coolant had gotten to near boiling there's no way it could have cooled that fast. I drove home and it got back up to hot again in less than a minute.

I popped the hood again at home, and felt the top radiator hose. It was hot, but not overly so. I felt the bottom hose- quite a lot cooler. I had turned on the heater on my way home to see if that brought the temp down but it didn't- and the defroster caused my interior windows to fog over. So I felt the heater hoses- one was hot, the other not. The hot one is right by the exhaust manifold. I removed them both from the heater core- no coolant present. I started the car to see if anything came out- no. Popped off the radiator cap and expansion tank cap- looks like nothing is flowing. By now, after ten minutes, the temp gage shows normal again.

I expect this is nothing but a water pump, and/or an obstruction in the cooling system. But I don't know for sure.

What do you think? Is there any good way to test the water pump?

[Scrappy-Doo]

Compression tests will prove if (or which) head gaskets are (is) blown.