Hey guys,

My Subaru isn't blowing warm air through the heaters, one mechanic thought it was the head gasket but the the car was/is running fine and no water in the oil etc.

The guy who is looking at it currently ran an initial pressure test on the heads and they seem fine. What would be the usual suspects for this problems other than the head going?

Many thanks!

 

Could be an airlock. They are notorious for getting these when the coolant is changed and they can't be bled. Do you hear a gurgling noise from behind the dash when the blower is going as this is a classic tell-tale sign. Also check to see of all of the coolant hoses are getting hot.

If you have an airlock the only thing to do is to drain the system and fill it up again through the rad hose and not into the header tank

A search will show up more hints and tips.

 

Air lock

 

Thanks people I've mentioned it to the mechanic

 

matrix could be blocked.

 

Would agree with the above, would check the matrix is clear, possibly flush out using a hose (had to do this on a few bmws lately), if that dont sort it i would fully bleed the coolant system again.

 

Heater matrix would be the main suspect.

 

Thermostat

 

Thermostat for the entire cooling system or something else like the heater controls?

 

Thermostat for the cooling system. Possibly sticking? I meant to add was his temperature gauge still reaching halfway.

 

Air lock and to bleed it take turbo water hose off at header tank end and small hose that goes to radiator (top left) put hose pipe on turbo pipe and flush through till pure water flows from rad (no air with it) put rad pipe on and then quickly put turbo hose on. Turn fan and heaters on full let it run put cap on job done

 

My blob sti it being strange with the coolant at the mo I've got it off the road the heaters blow hot the temp gauge stays in the middle but the bottom hose does not get hot it's off the road at the mo so I have not driven to see if it gets hot from driving any idea or nothing to worry about ?

 

Temp gauge has always been around half way, cheers

 

As above then, it could be a heater matrix problem. In the engine bay you'll see 2 rubber heater hoses going into the cabin through the bulkhead, check to see how hot the hoses are and if there is a significant difference in temperature between the two.
If there is it is more than likely a blocked heater matrix.

 

+1 heater matrix

 

The heating stopped working on my Spec D when the head gaskets went. I suspect that was due to coolant related problems...

 

hmm so it could still be the head, boo hiss!

 

I really hope it isn't. It is a recognised problem on the 2.0 cars afaik albeit a rare one.

I guess if it is, you'll have an excuse to put some juicer parts in

 

I'm not discounting the headgasket diagnosis but wouldn't there be more symptoms of it?
The temperature gauge is apparently sitting at the normal operating temperature. If it was an airlock I'm sure that his temperature gauge would possibly show signs of it same with a head gasket issue IMO.
Cheers
James

 

Just to add some context; there is no water in the oil, no smoke, the temperature gauge sits around half way.

The only symptoms are no heat from fans and the revs seem slightly up on idling. The first guy I took it to was pretty sure it was the head and also said there was a slight misfire - I'm not mechanically minded so no idea on this one!

 

It was a blocked matrix, got a new one and getting fitted today hopefully

 

Fiddly job but good news that it's not your head gasket

 

 

My heater was blowing cold air the other day in the middle of a long drive..when i was sitting idle waiting for someone.. after about 2 mins of moving again it got hot.. did not think anything of it since it started to blow hot air again.. also get a water swishing noise from behind the passengers side of the dash that you can only hear when sitting idle (2002 bug wrx)

 

That sounds like an airlock from the noise, but if it's blowing hot air I personally would leave it

 

Good news mate