by outbackyarder » Sun Nov 29, 2015 9:36 pm
I bought a 1997 outback a few months` ago and had overheating problems pretty much from the first day.
It overheated sporadically ,the temp guage went from normal to extreme in the blink of an eye while i was looking at it, it spat and sprayed coolant out of the radiator and the heater inside the car got really ,really rediculously hot and then went cold. Radiator was cold and sometimes hot,the lower radiator hose was cold and sometimes hot , if the thermostat opened. The coolant went out of the radiator in to the expansion tank ,but never returned. EVER.
The alarm bells in my head said HEAD GASKET . I tried for about 3 months` to discount the bigger problem of a head gasket by eliminating all the other possibilities. I had to drive my other car to work and try to remedy the outback`s problems on weekends, so this was a long ,drawn out process . The first thing i found was the waterpump belt was missing and the thermostat had the centre taken out ,so i put brand new OEM items in straight away.
I flushed the system several times and kept putting new coolant in because it kept overheating. A couple of times i flushed and replaced the coolant/water with the car on ramps to release air bubbles and other times the car was flat on the ground. I had the radiator cleaned out and checked by a radiator shop and tried driving in different conditions to see why the overheating was occuring . I drove with the heater on and heater off, uphill ,downhill ,highway ,backroads,slow speed ,faster speed and drove varying distances to assess what the problem was. I could smell coolant when i reached 40 kmh or more ,but couldn`t pinpoint the smell in the engine bay.
The fans only worked with the aircon on ,but the main fan wouldn`t work on it`s own.
I checked all the relays for the fans in the engine bay to see if they were working and what ohms they were running at . Everything worked and the ohms were within tolerances. I couldn`t get to the fan relay in the footwell because it is in a very tight spot and the thermo solenoid ontop of the back of the motor is concealed by everything else and too many things would have to be taken off the get to it.
I worked out that the thermostat wasn`t working in the car because water wasn`t getting to it and the thermo solenoid wasn`t activating the fan for the same reason . The thermostat was tested side by side with a non - original subaru item using boiling water in a saucepan. The OEM opened up 20 seconds or so quicker than the non - original part ,it opened wider & closed 40 seconds after the non - original had closed . The OEM part was MUCH better and worked perfectly , it just didn`t work in the car.
I tried to get any airblocks out of the system by feeding water through the top radiator hose when filling the radiator and motor . My radiator is the bigger aftermarket version and doesn`t have a bleeder valve. With the car on ramps to get the radiator higher than the heater core ,there weren`t any air leaks.
Still it overheated .
I tried the trick of joining up the two heater pipes with a t-piece to by-pass the heater core ,but still have heat . It works ,but still it overheated.
I tested the waterpump and it was working fine. I changed the hose in the expansion tank, incase it had a leak that effected the vacuum pulling the water back into the radiator. I changed the radiator cap to an OEM very early in the piece ,so i knew that was right. The car has a new battery and the alternator checked out ok ,so the electrolisis effect wasn`t part of the problem.
I did two block tests for carbon dioxide in the coolant because the coolant was a sort of green /white color. The block tests came up negative for a blown head gasket.
I got my snake camera out and put it under the driver`s side head area where i found a small drop of coolant in an obscure place ,but couldn`t work out where it came from .
At one point in the investigation process , i put in a mix of 7.5 litres coolant and water and the next time i drained it ,only one litre came out.
No smoke coming out the exhaust ,but alot of water missing and the car is overheating.
A common problem with this model is a head gasket failure where it fails on the inside and water goes into the cylinders .
I think the motor overheats sporadically with this sort of head gasket failure because the pressure builds up in the water jackets at different pressures depending on how much water is in the engine ,how hot the enine is ,what rpm the engine is doing at any given time , the ambiant temperature outside and where the notorious hotspot is inside the engine.. All factors in when or how much water you lose into the cylinders and how quick that happens. That is my assessment ,anyway.
This is what happened to my car and it has been in the repair shop for nearly 3 months` getting fixed because i don`t have the time to do it myself , at the moment.
The new improved head gaskets are a better design and are said to last alot longer than the original factory item.
Sorry to say Soul ,but this could be you ,too. I hope it isn`t because the parts are not cheap. I had to get the heads crack tested and all the seals , pulleys and bits and pieces that go with it ,as well as the shop labour.
Good luck and a i hope it is not this serious for you.