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Strange tintop overheating prob....
NigeEss - 27/6/15 at 07:44 PM

Sisters car has a strange overheating issue I'm at a total loss as to why.

1997 Subaru Legacy 2.5 quad cam.

No problem at all whilst stationary, it'll stay rock steady at 90 deg heater works fine and fans cut in and out as they
should, radiator working fine. Can even hold it at 3000rpm for 20 mins and again, no increase in temp and fans in
and out.
However, take it for a drive and within five mins it'll boil over and dump the coolant. It will do this with or without a
thermostat fitted.

So far it's had a new water pump, new radiator, system flushed, new thermostat (currently removed) hoses seem fine.
Now oil in water and vice versa. I haven't done a compression test but my thought are if it were head gasket then surely
it make no difference if driving, as said, held at 3k it's fine. I've even pulled the new pump out to see if the impeller was
faulty but seems fine.

Suggestions ??

PAUL FISHER - 27/6/15 at 08:09 PM

Very often headgasket problems only show when driving the engine under load they over heat, have you done a combustion test and see if the exhaust gas is in the coolant.

sonic - 27/6/15 at 08:11 PM

I would say head gasket or cracked head, i had a Freelander and a Celica GT4 which did the same thing. no oil in the water or vise versa only time the problem can was when you drove them.

You could try a sniffer guage in the header tank

ian locostzx9rc2 - 27/6/15 at 08:17 PM

Agree with the above poss head gasket or crack or porous head or block test for exhaust gas in coolant if it's the case maybe worth putting a bottle of k seal in the coolant may fix the problem !

JoelP - 27/6/15 at 08:30 PM

My Jeep did the same when it had a cracked head. A bottle of sealer sorted it for 2 years.

BigFaceDave - 27/6/15 at 09:05 PM

I had a s reg 2.5 4cam legacy estate which pretty much was the same symptoms and it would be fine but as soon as you tried to drive fast enough to get anyway (it was a auto) it would boil over and turned out to be head gasket. Sorry probably not what you wanted to hear but google k-seal ive had pretty good experience with cheapy old cars, not a permanent fix but I used it on a old supra and did about 6000 miles with no problems.

rusty nuts - 27/6/15 at 09:49 PM

If you can get it to a garage that will allow their exhaust gas any loser probe to be Putin the top of the header tank it will show up a leaking head gasket by giving a hydrocarbon reading

NigeEss - 28/6/15 at 07:00 PM

quote:
Originally posted by rusty nuts
If you can get it to a garage that will allow their exhaust gas any loser probe to be Putin the top of the header tank it will show up a leaking head gasket by giving a hydrocarbon reading


One of the garages I deal closely with has a sniffer tester but been waiting two months for them to get some new fluid

I had dismissed head gasket due to the fact it'll rev all day off load, but I will bow to the experience of others.
I'll try some of that Steel Seal stuff as I haven't got time to do two gaskets at the mo. Especially as I know my sister will expect it
done for free.

rusty nuts - 29/6/15 at 07:14 AM

Sorry ,auto correct changed the spelling , I meant an exhaust gas (emissions) tester rather than the fluid test . It's much quicker and more accurate ,any H/G failure shows up as a Hydrocarbon reading