Overheating, passed head gasket test.

Car over heated this weekend after driving 10 mins at around 45 mph.

 

Long saga short.......I needed my car so i could drive to work this week so bit the bullet and had Pepboys charge me a lot of money.....but they did the diagnosis.

 

Results:

 

overheating at idle due to coolant flow issue...possible plugged radiator/ defective water pump. slight drop in coolant pressure during test. possible head gasket leak

 

added the neon green coolant to check for any leaks with a black light but also didn't see anything

 

coolant system held 15 to 20 psi

cylinder leak down test- PASS

Block test- Pass

 

cyl 1 15% leak

cyl 2 10% leak

cyl 3 10% leak

cyl 4 10% leak

 

 

The water pump was replaced 2 months ago but the thermostat wasnt..... after 65 miles of driving at 70 mph today it did not over heat, but the reservoir was over flowing once i pulled into my driveway.

 

so my plan of action to replace the thermostat.... any other ideas?

Head gaskets leak internally. They will almost never fail externally.

 

The only place you will lose coolant, when they fail, is through the overflow reservoir. It overflows out of there into the engine compartment itself.

 

Find a hydrocarbon tester, or someone with one, and test the coolant. That is the only way to tell if they have fail or not, without removing the heads. If they have in fact failed, you will find hydrocarbons in the coolant.

 

If it's not that, your thermostat could be bad or there is a pocket of air somewhere in the system.

Hello;

Are the cooling fans working correctly? Does the heater work? Steven.

it does not sound good for the head gaskets.

 

factory T-stats do not fail very often. i have quit replacing them because i have never had a problem with a subaru factory t-stat.

 

aftermarket t-stats can give you headaches the very first time you drive the car.

 

you need to refill the cooling system properly and then drive it for a while. after a 30 - 45 minute drive at hiway speeds, even if it is not over heating , look for bubbles in the overflow bottle. if yes, then head gaskets are the problem.

 

as far filling the cooling system correctly, advanced search for ''how to fill and burp your cooling system'' or search complete post for ''cooling system siphon vent plug''. searching only my posts will help.

well if the coolant is leaking into the engine, why did it pass the leak test? They compressed it to 50 psi, and it only went down to 45 psi in three and 42.5 psi in on. well need to do more research i guess, made it fine to work today, the coolant was really low when it over heated.....which makes me think its slowly burning coolant. or the system was not burped properly and the t-stat was sticking......well t-stat this friday i think

I've had 3 motors where the head gaskets have failed. Each one passed the compression tests. You won't find anything wrong any time you do it.

 

Okay... When the head gaskets fail, it's because the compressed air/fuel is ignited and leaks out of the combustion chamber into the cooling system. That super heats the coolant. Hence the over heating and need for a hydrocarbon test before you go replacing everything. John is right on with the thermostats. I've only had one fail. But, I notice something particular about it. It was smaller then any other one I've seen and came out of a different OEM water pump.

 

50 psi is not enough pressure to seep through the gases. Only when the expanded gases are compressed do you get enough pressure. That's why you don't see it in a leak down test.

 

Do what John said, and make sure the coolant system is filled properly. Once it is, you can move on from there. Also, get someone to check for hydrocarbons. Save yourself some time and money in the long run. The longer you take, the more time your motor will overheat, and that is not good at all... I have had issues post head gasket repair with every single one of my EJ25D's because of the overheating. The bearings failed on the first one, I sold the second one with my POS before everything got too bad, and my 99 EJ25D with the Phase 2 EJ251 internals needs to be rebuilt because the bearings just started to fail.

 

Also, as Steve suggested, have you made sure that the fans and heater are working?

 

The day I bought my 98 LGT POS I discovered that one of the fans was not working and my car would overheat if it sat idling for a few minutes...

 

Oh, and how many miles are on your car?

145,200 miles 1998 legacy gt purchase in December 1997 ......i will check the fans tomorrow with an voltmeter..... and look into the hydro carbons test.......the over heating went away when the rpms were raised according to the mechanic, who also got it to over heat when they test drove it........ man this is so freakin stressful....im at the point where i just want to keep this going until i can properly afford a 2005 lgt, rather not buy another old car.....but might need to borrow gfs if i have to fix the head gaskets.

Temp lowering at higher RPM's is also something that points towards the head gaskets when they initially start failing. Higher RPM = more coolant flow. Now, if they go quickly, or the worse they get, that will not be the case. The temp won't lower at all really.

 

A head gasket job isn't too bad if you do it yourself. It's really a minor job. At least when compared with the stuff I had to do to my 98... I replaced the whole motor because the oil pump failed and the motor seized. Talk about stress.

 

Let us know what all of your findings are. And remember, don't drive her too much until you get everything taken care of.

the car seems to warm up really quickly as well.....but yeah...one thing at a time....only drive 10 mins to and back from work each day

would love to replace the head gaskets with someone that has already completed it before....is it possible to get it done in a weekend.....any tips and tricks to replace them...and pointers to threads that are helpful.....im in the buffalo area right now

Warming up quicker than normal is another sign. My first Subie did that since the day I bought it in early December, over two years ago. I never realized how quickly it warmed up until I noticed how much longer it took after the head gasket replacement.

 

I'd love to help you out if I was up there. The job isn't too bad if you're mechanically smart and can actually do good mechanic work with you hands. The biggest thing is patience.

 

Last time I did gaskets it took me 3 days, working for several hours. I didn't take the motor our and took my time. If you don't have a way to pull it, I'm not sure it's necessary. It's easier to work on the engine, but it's more to do.

 

I would get a copy of a FSM and/or buy a repair manual from Advance auto. Plan out your repair attack and make sure you know how everything needs to be taken apart and how it needs to be torqued back down.

 

You're first time through will be a learning process and will probably take you some time. You'll need the proper tools as well. If you don't have an inch pound torque wrench, or a ft-lb torque wrench that doesn't go low enough, you'll need to get one.

 

Easiest first things to do... Remove the intake system, the battery and windshield washer fluid container, the radiator and fans, the crank gear (use a breaker bar placed on the ground and tap crank the motor to break it loose), and the exhaust. Next you'll need to remove all of the timing components (break the cam gear bolts loose BEFORE you remove ANYTHING from the timing setup. You can use a screw driver inserted in the side of the motors rear housing to keep the motor from turning over while do this) and I believe the water pump had to come off as well...

 

Then you can unplug things from the valve covers and undo the intake manifold bolts...

 

Like I said, it's a process... Get a repair manual and make sure you know how everything comes apart and goes back together. If you can get someone who's worked on them before to help, that's perfect.

 

You'll also need to get new gaskets for everything that you pulled one off of. I suggest buying a gasket kit on eBay for $70 to $90. You'll use most everything. If it comes with gaskets, DO NOT use them. Use only OEM MLS gaskets. Make sure you use your VIN when buying them. They are $50 a piece.

It's possible to do in a weekend, but only if you have done it before. Plus when the engine is out it is the best time to check the rear main seal, replace the oil separator plate, reseal the oil pump, check the oil pan for leaks, replace all the cam seals, water pump, idlers & pulleys, and timing belt, as well as plugs and wires.

 

It is also a good idea to drop your heads off at a good machine shop and have them checked out for flatness and see if the valves etc. look good.

 

It sucks if your head gaskets go and a lot of us on here feel your pain as we had to go through it.

 

You'll need a quality torque wrench and see if you can borrow a cherry picker. Download the FSM if you can find a source. There are quite a few threads out there on how to replace the HGs.

Agree with all of the above. If you're running anything but a Subaru OEM radiator cap and thermostat, I'd replace those with OEM. Make sure the system is properly burped - can't emphasize this enough. These are "flat" engines, so it's easy to get an air bubble in the coolant and that will cause hotspots, hotspots can lead to misfires and misfires can lead to compromised HGs. Don't put off doing maintenance on plugs, coil pack, and wires too. You may be getting a persistent misfire that you're not aware of - should CEL-on, but possibly not. PM me with your email addy and I'll send you an FSM for your MY.

thanks, sbt. i have one in my possession already......yeah my car used to not run so well, but i replaced the spark plugs and wires and it runs a lot smoother

Did you replace with OEM plugs, wires? Don't know why, but these just run better/longer than AM ones.

ngk wires and plugs

I'm having this problem, but seems like no help is forthcoming. Some shops don't have capability for hydrocarbon test,( weird, considering the fact that they specialize in Subaru's) and some have just ignored their promise to get back to me with a quote for HG repair. This is getting really frustrating. Changed radiator caps.. seemed to stop the problem for a while. Now reservoir bottle is filling up again. Can anyone recommend a reliable, honest and competent mechanic in MD?

Not from Maryland but just wanted to comment on the motor in your avatar....that is one crazy looking mill, turboed h6?

Not from Maryland but just wanted to comment on the motor in your avatar....that is one crazy looking mill, turboed h6?

 

Yessir!

It seems like you know a mechanic or your pretty good with cars, your previous mechanic burn you? Hg jobs are not bad with these vehicles just a lot of work, not too complicated.

yeah so to make this long story short.....

 

 

i just replaced my radiator cap... was so pissed about spending all that much but passed a hydrocarbon test and with the new rad cap, i have yet to over heat again....

 

now just dealing with my scratched paint and waiting to get a Subaru BRZ once i graduate

drove 10 mins with it over heating and then....pff pfff pfff.... POP..... cloud of grey smoke out back.... pulled over and the radiator fluid had exploded out of reservoir tank.... well I think I either blew up the motor or the head gaskets went...... the car is stuck in Batavia, NY.... mechanic found coolant and oil on the cylinder heads...... tried starting it and it groans..... was quoted at $3000 for new motor and $1300 for new cats..... way over priced....so ....... i am U-hauling it back to RIT tomorrow morning

 

suggestions for fixing this "Dead" motor

Hydro locked and threw a rod is my guess.

 

Used motor go through the heads...

sorry to hear, that really sucks.

 

friend of mine hydro locked her mustang over the weekend as well. sucks. was partly her fault, partly the guys who rescued her from trying to make it through a flooded wash trying to start her motor after it happened.

Find a hydrocarbon tester, or someone with one, and test the coolant. That is the only way to tell if they have fail or not, without removing the heads. If they have in fact failed, you will find hydrocarbons in the coolant.

 

Sometimes you get visible residue in the radiator, and accumulation on the bottom of the cap. I took some inside after finding it, let it dry, and they applied a match. It burned.