Overheating (car, not plane)

[Marty_d]

One for the mechanical whizzes, you know who you are!

 

Our 2005 Subaru Forester has had an intermittent overheating problem since Christmas. Took it to the mechanic then, they couldn't find the cause. It's been mostly fine since, but just recently has been playing up - after a trip of 20km or so the needle starts creeping up towards the red. Also, intermittent power loss, especially uphill when engine is cold.

 

Took it back to the mechanic a couple weeks ago, he thought it may be the water pump cavitating, so replaced that, timing belt, thermostat and radiator. (He thought the radiator was a bit heavy but getting it checked would be $250; getting a new one = $299.) It overheated again on the way home.

 

The other day I took him for a drive in the morning and we stopped when the needle went to 3/4. He checked that the fans were working but found they air coming from the radiator was cold, even though the engine was hot.

 

So now he thinks it's a leak in one of the head gaskets, which is sucking in air until there's an air lock in the cooling system which prevents circulation. He said it's not your normal head gasket problem, because usually they're more sudden and serious. It's going back in Monday to get the the heads planed and new gaskets.

 

Just putting it out there - anyone had similar experience or have any ideas? I trust my mechanic but he doesn't seem entirely sure about this, and it's a $2,500 job.

 

Thanks, Marty

 

 

[old man emu]

Marty_d,

 

Just out of interest I googled "2005 Subaru Forester overheating" and got a lot of hits. I looked at this link: ('03-'05) 2005 overheating on the highway - Subaru Forester Owners Forum

 

OME

 

 

[Yenn]

Your mechanic is doing OK.

 

No knowledge of a Forester as I havn't worked as a mechanic since the sixties, but I would be looking for someone who could do a diagnosis, rather than keep replacing pieces at your cost.

 

 

[Paul davenport]

Speaking as a practicing mechanic diagnoses boils down to basics Has the radiator been removed dismantled and checked ,proceed no further till it has, from the symptoms described a gradual heat increase indicates that heat is not being lost fast enough and from past experience blocked radiators cause this ,only dismantle of the

 

Radiator can eliminate this

 

 

[Marty_d]

Speaking as a practicing mechanic diagnoses boils down to basics Has the radiator been removed dismantled and checked ,proceed no further till it has, from the symptoms described a gradual heat increase indicates that heat is not being lost fast enough and from past experience blocked radiators cause this ,only dismantle of theRadiator can eliminate this

They replaced the radiator. It was $50 more to bung a new one in rather than disassemble the old one.

 

I've got the car back now, seems to be behaving. The final diagnosis was that the head wasn't warped, but the bolts had stretched enough to let air into the cooling system. This led to an air lock which prevented the circulation of coolant and hence the overheating.

 

 

[Paul davenport]

That in my opinion is an extension of your leg . I would be more confident in saying it was blocked all the time and on most modern radiators this can only be eliminated by dismantle and inspect . From my experience and your description of the problem this is where I would have started BASICS before you look for expensive problems . Glad to hear it's ok

 

 

[Paul davenport]

By the way on dismantle was the radiator blocked ?? And by how much ??

 

 

[SDQDI]

By the way on dismantle was the radiator blocked ?? And by how much ??

Marty said earlier that the radiator was replaced early in the saga so if there was a blockage it wouldn't have been in the radiator if the problem persisted.

 

That's not to say they aren't pulling his leg and didn't find something else simple wrong but it does rule out the radiator.

 

 

[Paul davenport]

My point diagnoses basics

 

 

[Marty_d]

Hey everybody, thanks for your input.

 

In the end it turns out that the mechanic was correct. Analysis of the coolant found traces of exhaust gases which had escaped from the head gasket. The head itself was not warped, but the bolts had stretched. The escaping gases had caused an air block in the cooling system.

 

Had the car back for about a week and it hasn't overheated again, so I'm hoping he got it right.

 

 

[nomadpete]

Hi Marty

 

Glad to hear that the problem is solved.

 

Just curious though. How was the coolant analysed?

 

Peter

 

 

[Marty_d]

Hi MartyGlad to hear that the problem is solved.

 

Just curious though. How was the coolant analysed?

 

Peter

Thanks Peter.

 

I have no idea how he analysed the coolant - someone with mechanical experience may know. Sorry!

 

 

[Yenn]

I hadn't realised that Subaru and Jabiru used the same design team.

 

 

[nomadpete]

I had an older Suby, and when it overheated once, it got a soft head ( Jabstyle). Thereafter it developed cylinder head leakage into coolant. And again after cylinder head machining and refitting. In this case it was easy to identify - open the radiator cap and watch for bubbles. Yours, Marty must have been harder to identify. Interesting. I'll store that one away for future reference.

 

 

[Yenn]

The old flat head Fords were known for the ame thing.

 

 

[spacesailor]

And all the Ford v4s/6s & 8s, had problems, if stopped (switched off to early) when hot they cooked the heads,

 

Modern cars use coolant not water to stop this heating problem.

 

spacesailor

 

 

[allowera]

The EJ25's Thermostat is located in the Water Pump housing next to the Heater hose inlet. Combustion gasses (particularly #4 Cylinder) tend to rise into the Heater outlet. On arrival at the Water Pump the gasses form bubbles around the Thermostat pellet, insulating it, and causing it to close. Cylinder Head hardness testing is considered vital.

 

 

[facthunter]

What happened to your car is the normal "fate" of older engines. The head gasket deteriorates and the coolant gets contaminated with "corrosives " from the escaping combustion materials. Your system will become pressurised long before the motor gets hot. It's likely also there will be hot spots formed where the coolant is displaced which doesn't help matters. Often the head and block get fairly corroded. On some makes the face of the head has some quite thin walled areas. The removed heads should be pressure tested. You can apply pressure to the static system and leave it on overnight and often one cylinder will misfire indicating coolant in that cylinder. It's hard to know whether it's worth while repairing this stuff when it's fairly old especially of there's much corrosion there. Todays cars are relatively cheap, but looking after them is an art form, if you want them to last forever. Repairs are labour intensive. You have to know when to put it down. Nev

 

 

[pmccarthy]

My 1992 Brumby is still running happily on its original engine at 250,000 km touch wood.

 

 

[old man emu]

My 1992 Brumby is still running happily .

Wow! a 25 year-old wild bred horse still on the go! That's hybred vigour for you.

 

 

[nomadpete]

Again I ask of those 'in the know', how does one test for combustion residue in engine coolant?

 

 

[allowera]

It's called a 'Tee Kay' test.

 

This is a syringe like device with a diffuser in the lower end (think fish tank bubbler).

 

A special liquid that reacts to combustion gasses is added to it. A sample is drawn through it from the Cooling System. If the liquid changes colour it is a clear indication of trouble.

 

 

[allowera]

My 1992 Brumby is still running happily on its original engine at 250,000 km touch wood.

Keep the Cooling System serviced and you will get a lot more than that.

 

My 1985 Bumby is still used every day with an estimated (odometers were a problem with the earlier ones) 500,000km. Original Engine, Transmission, Diff. and Front Struts. I bought it in 1992 with an odometer stopped at 180,000km.

 

First thing I did was to fit brass Welch Plugs and re-tension the Cylinder Heads. Changing the Coolant every 2 years and regular servicing since then seems to have paid off.

 

 

[facthunter]

Cars and engines don't get rebuilt these days. 250K isn't high mileage if it's looked after properly but often they aren't looked at at all unless there's smoke coming out of it or it's knocking. My son was just relating a story of a lady who purchased a Subaru in a country town of VIC and never came back to the dealer until about 5 years later on a tilt tray with about 100K Kms on it. Had never even had oil added or changed, and had completely run out of oil and stopped. The dealer just lifted the engine and put a new one in it. Parts and labour are too dear. I get crazy high miles out of stuff, and run most to over 400,000Kms. It pays to know what the problems are with certain models and know when to quit them.. Nev

 

 

[nomadpete]

Thanks Allo. Interesting.