Another overheating question.

[kidwon]

Okay, it's a 97 legacy GT with the dreaded 2.5. Problem is I can't justify pulling the heads until I have some proof. It only overheats after at least 30 minutes on the highway then a slowdown or stop. I can drive around town with no problem. Funny thing is, right before it overheats the heater starts blowing cold on me. I've taken it to a mechanic and he says he can't find any evidence of exhaust in the coolant, compression problems, or coolant in the exhaust. He's also pressurized both the radiator and the cylinders with no problems. I've replaced the thermostat, and radiator and tried to burp it many times. The only other symptom I've noticed is the running temp seems a little higher since this all started. The gauge reads just below 9:00 instead of about 8:00 where it's ran for the last two years.

[cookie]

The sniffer test won't work until it gets really bad. It wil slowly get worse, but if you nurse it you may make it until you can afford to do your gasket job.

If it were mine I would od it now to avoid the chance of furthur engine damage.

[Commuter]

Ditto what cookie said.

 

One other thing you can do. When it overheats, pull over and immediately look in the coolant expansion bottle. If you have bubbles... bingo. See any sludge building up in there now?

 

Commuter

[bearbalu]

Some cars have a feature where a heater valve cuts off coolant flow to heater core if car overheats (either for safety or to force more coolant through radiator)- that would explain cold air blowing just before overheat.

 

Exhaust bubbles could also push excessive coolant out to expansion tank and eventually lead to overheat. Note your coolant level before you start a drive (hopefully between min and max, but it might already be high from previous drives - it it is pour it back into cool radiator) and monitor it. If it keeps rising, another sign of head gasket terror. Normal cars have some coolant (qty no more than between min and max) pushed into expansion tank since it expands with heat. Ask mechanic if he did the sniffer test. Sniffing with your own nose and smelling gas/exhaust in expansion tank is another sign.

 

 

I found this article very informative though it is long!

 

http://www.troubleshooters.com/tpromag/200204/200204.htm

 

[kidwon]

Well 89 views and no one seems to doubt it's the head gasket except my mechanic. I'll give the guy credit he doesn't want me to spend the money if I don't have to. He doesn't understand how it could be the head gasket without affecting the compression or evidence of exhaust in the radiator. Any suggestions how i can convince him?

[bearbalu]

I certainly hope it is something else, and one has to give credit to mechanic who won't just do head gasket - stick with him!

 

I am not convinced of it either, but fewer options remain once you replace thermostat and radiator! Does the car still run at 9pm after you changed the thermo/radiator? Waterpump, erratic fan which doesn't turn on for some reason when you slow down after highway driving...Any coolant loss ?

 

Did you look for symptoms of bubbles/coolant pushing into exhaust? Did you ask the mechanic what he did to validate no exhaust in coolant? I hope he did sniffer test is more accurate than block test. If negative sniffer test was done and you don't see bubbles, there is good reason to look somewhere else.

 

Read the link I sent and you can gather more info to trouble shoot the problem.

[kidwon]

I did read the link you sent, most was review. He took the timing belt cover off and checked the water pump and said it looked alright. He said he checked for exhaust in the radiator by using some kind of infrared detector. I assume thats the sniffer you're talking about. i personally checked all the fan relays and they seem to be ok. I haven't changed the thermosensor yet, but it really doesn't seem like that's the problem. The gauge still works and apperantly in this car there is only one sensor. The only trouble code I got out of it was after I pulled the original radiator and flushed it-p1502 radiator fan function problem. The code never repeated after it was cleared, I think there may have been a little water in the fan motor or something, just a fluke. The primary fan seems to come on when the gauge is almost to halfway. I'm not really sure when it's supposed to activate but like I said before the car is definitely running warmer than it was before. I can hardly believe it's the head gasket myself because the car runs so good. I even seem to be getting about the same mileage as before. I plan on taking the car back to him on monday and insisting he does the head gaskets. I hate to have to spend the money but I work about 50 miles from home and I need the vehicle. I just hope it cures the problem.

[Nug]

Make sure the latest OEM head gaskets are used for the repair, or you will be inviting trouble.

[steved]

97 outback - 118000 miles 2.5L engine.

I'm having almost identical problems to kidwon - car overheats - sudden spike in temp. to H (or maxes out), coolant boil over into the reservoir. Mechanic tried to "burp" it today - said a big air pocket in coolant system - but still overheats. Thermostat checked; water pump was replaced.

 

I did have a problem w/ a timing belt repair (at 106k miles). The tensioner pully (not replaced) broke, belt nearly sheared through the cover. Mechanic replaced belt and said vehicle "did not go out of time". But perhaps this caused valve damage?

 

The car runs ok local for short trips,but any highway driving and its overheat city.

 

Do I try to sell it at an auction and cut my losses, or try to fix this problem?

[bearbalu]

Steve D, do the sniffer test.

 

Kidwon, I would wait to do head gasket...

 

I think infrared is sniffer test, but you might want to double check with mechanic. What about bubbles in expansion tank? You might want to do the test one more time with a really warm engine before you embark on head gasket.

 

Radiator fan is supposed to come on when coolant is close to operating temp. On highways it would usually be off since relative speed with air provides cooling. When you are at stop or driving at low speeds, it should come on. Since you mention the symptom being slowing down after highway driving, I suspected that fan is not coming on. You might want to hotwire the fan or change the fan relay, given you have seen the p1520 error.

 

Your car might be running at 9pm because the new thermostat might have different properties (if it isn't OEM). Or radiator might be slightly different since you replaced it.

[kidwon]

Actually the car is running at the same warmer temperature with the old thermostat/radiator or the new. In fact I put the original thermostat back in after I changed it because the non-OEM one I got didn't have a weep hole. I tested in my kitchen and it seemed to work okay so I put it back in trying to get the temp back down to normal. It didn't make any difference. As far as the bubbles in the overflow the only time I've seen any is after I've tuned the motor off. I really think the fan used to come on at a lower temp but I didn't really pay that much attention or document it. I also thought the overheating could have been caused by the fan not comming on properly but I'm not sure how to tell, maybe I'll rig up a light to it so I can tell when it comes on. the relays seem fine I pulled all of them out and bench tested them. Is there any way to adjust the activation threshold for the fans within the Onboard computer?

[Clutchbob]

As far as the bubbles in the overflow the only time I've seen any is after I've tuned the motor off.

I've been through this. Two weeks after buying (98 O/B), I saw the symptoms. My head gaskets were replaced (dealer warranty) at 90,000 mls. I had bubbles whether the engine was running or not, but always after a lengthy drive. It wouldn't always overheat either.

It may have been this way for a long time, as it ran great, but a thick black goo had formed inside the expansion tank.

I believe the sniffer is similar to the CO2 tester they use for emmissions.

Steved, if you didn't go out of time, you did no valve damage, but it certainly sounds like you got "headgasketitis". With new gaskets, your car will be good for another 100,000+, is that worth $1200?

Check earlier posts, you'll find good info.

[kidwon]

I discovered today that it is bubbling in the overflow while it's running. It's going in tomarrow for new head gaskets. I sure hope it's "good for another 100,000+". Maybe I'll actually have the car paid off by then. HA HA.

I'll post when I get it back, hopefully my troubles will be over (for a while).

[Cougar]

Good luck with the new gaskets. Make sure you get the latest versions and keep us posted on the results.

[bearbalu]

If you recently added some coolant and didn't burp it fully, you could still get bubbles with air just working it's way out of the system. However, if you have bubbles all the time due to head gasket problem, the coolant level in expansion tank would keep rising.

 

Another thing to worry about is whether head gasket is the chicken or the egg - what lead to overheating the first time and whether blown head gasket was a result of repeated overheating. You don't want it to happen again! In my case, I suspect it was a clogged radiator that lead to overheating climbing a steep grade (grapevine to LA) which lead to blown head gasket. Since you have replaced thermostat and radiator, you might want to still double check the fan, radiator cap and waterpump.

 

 

While you are at head gasket, consider doing the following based on condition: waterpump, timing belt, resealing oil pump, new cam/crank seals, valve clearances. None of these should require engine removal, unless you include do clutch-if you have one. See the following for additional info and links.

 

 

 

http://www.ultimatesubaru.org/forum/showthread.php?t=27848

[Clutchbob]

Good luck and have fun.

 

I was lucky enough to not have to pay for the work. I regret that anyone would lose money on this. That said, I really like my OB and feel more confident about the engine, having been inspected and overhauled to a point.

[kidwon]

Bad news, it doesn't look like the new head gaskets fixed the problem. I picked up the car today and the temp is still running high. It hasn't overheated yet but I haven't taken it for a long drive on the highway. Just to recap I've replaced the Radiator, cap, thermostat, head gaskets, and I had him do the waterpump while he had it apart. The temperature gauge is sitting at about halfway and I can actually see it go up slightly when I accellerate from a stoplight it then drops back to about halfway within a minute or so. The fans both seem to be functioning ok, at least they're running at the operating temp. My mechanic is stumped, he thinks I should find a used engine and swap it. Seems a bit extreme and besides, I don't really have the money to do that. Any suggestions?

[mtsmiths]

Unless the shop really REALLY knows Subarus they may not have burped it correctly and you may be airlocks (which may have been the problem all along).

 

Unfortunately, even some dealer techs don't get it right.

[cookie]

It is a worry but a headgasket is not always done right either.

[kidwon]

Well I made it to work (50 miles on the highway) with no overheat. The weird thing is, when I was cruising along at 75mph the temperature dropped back to about where it used to run. About 1/4 of the gauge. When I got off the highway it went back up to halfway. This tells me the fan is not moving enough air between 1/4 on the gauge and just below halfway where it wants to run when I'm not on the highway. I suspected fan problems before when it would overheat when I'd get off the highway. The mechanic mentioned to me that there are two fan speeds. A lower speed when it first warms up and a higher speed when it passes a certain threshold. it seems like it's never coming on for the lower speed but it does come on for the higher speed (about halfway on the gauge). Does anyone know how I could diagnose this or find more detailed information on the cooling fan?

[bearbalu]

Subaru Service Manual with radiator fan diagnostics - it is exhaustive with 15 pages in it. You can subscribe for 3 days for 20 bucks and it would be worth it for future repairs. Alternately, send me a private message with your e-mail and I will e-mail you this particular diagnostics.

 

I think it might be other way round - your low speed fan works, not the high speed. At highway speed, no fan - radiator is cooling of external wind. When you stop, only low speed comes on, bumping up your temp.

[svxpert]

<<The mechanic mentioned to me that there are two fan speeds. A lower speed when it first warms up and a higher speed when it passes a certain threshold. it seems like it's never coming on for the lower speed but it does come on for the higher speed (about halfway on the gauge). Does anyone know how I could diagnose this or find more detailed information on the cooling fan?>>

 

if this is what he told you, your in need of a new mechanic. Have you blead the coolant system of air at all? or has your mechanic always done it?

[kidwon]

I've bled it he's bled it, I'm reasonably sure there is no air in the cooling system. The question is, I think the fan should be coming on when the gauge is 1/4 but it doesn't come on until it's 1/2 why?

[svxpert]

<<I think the fan should be coming on when the gauge is 1/4 but it doesn't come on until it's 1/2 why?>>

 

the simple answer is because its only a gauge. it could be wrong. any decent mechanic, i mean what i do is stick a thermometer into the rad as the car warms up and as i blead the air out. the thermometer should open around 195* and the fans come on around the same time. thats when you can tell the fans are operating properly i use a select monitor to get an exact temp from the ECU.

[outbackbaby97]

SteveD, and Kidwon, i feel your problem, i'm having the same problem! someone please tell me its not the head gasket- i've had two different mechanics look at my car, one of them has "burped" the system three times, eveyrtime telling me it ran for two hours great for him. But then i drive it to work and it starts to overheat. I've replaced the thermostat and the waterpump was replaced not too long ago, there is nothing leaking from the car, and all my mechanics are cooless as to what it could be. I'd rather trade it in than replace the head gasket- and i am just not conviced that it is b/c of the inconistancy of the overheating. Anyone have insite?