OK i,m pretty sure my head gasket/gaskets is letting go

Whilst driving last weekend noticed temp gauge was right at the top!!! pulled over, coolant coming out of expansion & small pipe under inter cooler. Called AA, done coolant pressure test.......fine,did a sniff test which stayed blue so apparently not head gasket.

recovered back to Kent & got a mechanic to check it out, said rad bypass pipe to header was blocked causing over heating, cleared blockage & drove fine according to him with no over heating. Drove the car myself once got it back & within 10 mins was over heating again accompanied by strange chirping noise & check engine light! once cooled down checked bypass pipe for blockage but was clear, removed header cap.........no coolant visible!, filled with 2 ltrs of water to the top of tank, temp stayed in the middle when driving home but engine light came back on once home.

Checked it next day,coolant still there did bleed system to check was correct and was fine but once started up with header cap removed it pressurized & over flowed, once up to temp engine light came on & also noticed like slight steam coming from exhaust which i'm sure its never done before. No creamy stuff in oil filler cap or on dip stick though.

Read ecu codes by connecting black leads under steering column

codes

21-coolant temp sensor
22-knock sensor
31-throttle position sensor

So i'm guessing its head gasket and wanted to know if anyone's used m n m engineering in kent for there classic impreza. There pretty local to me & have a recovery service as i'm not keen on driving car in case of more damage being caused, I've used slow boy racing before but are a bit further for me to get car to but was satisfied with there service, any recommendations on who to use in kent?

 

Not heard of MnM, maybe others have? If it was me i'd be taking it straight to Slowboy, they have a very good rep.

Have you have had a compression test? If it is/was the HG then i would have thought the sniff test would of picked it up? I guess it depends where on the HG is gone

 

Yeah i was originally gonna take it to slow boy but just wanted to know if anyone had experience of mnm as there closer.

No not had a compression test done yet, once i get it to someone i'm hoping they'll take a more in depth look at it and point me in the right direction of whats gone on with it and get it sorted....hoping its not head gasket but looks that way to me.......more expense!!

 

What year is it and whats the mileage? It would be advised to refresh the engine internals at the same time, bearings, crank, pistons etc as the engine is already out. I would say go with Slowboy as they are Impreza specialists with a great rep. Neil knows his stuff and will be able to diagnose and advise of your options based on budget.

 

Its a 98 2000 on r plate, had a rebuild at 85k just before i got it & has covered 14k since so everything should be good.

im gonna call Neil tomorrow and see when he can look at it & see how much £ i'm looking at roughly if head gasket

 

Is the thermostat opening when it should? Have you checked to see if the bottom hose gets hot? It should get hot as the stat opens when the coolant reaches a certain temp.

Just an idea/thought. There is a test you can do with boiling water IIRC - something like putting it in boiling water to see if it opens

 

The mechanic that 1st looked at it checked the stat & said it was fine, i've checked to see if bottom rad pipe gets hot when reaches temp and that seems to be fine so think the stat is working as it should>

have thought about doing a ecu reset to see if this clears engine light & faults???

Car drives ok but haven't put my foot down hard case it brings on more damage if gaskets on way out

 

Are your heaters blowing hot air still? Maybe you have an airlock? I would also try draining the coolant and re filling via the turbo hose, so it back fills. Run car up to temp with heaters on max temp and cap off, squeeze hoses to try and dispell any air.

 

The heaters still blowing hot air nicely, would a air lock cause this to be cold then?

Never back filled the system before through turbo coolant pipe?.....

With the cap of it pressurizes straight away & over flows the coolant this is one of the reasons why i'm assuming its the head gasket

 

Heaters not blowing hot air is also a sign of HG failure. It does sound like an airlock tbh, but obviously only a mechanic will be able to confirm. An airlock will/can cause overheating.

Take cap off on Header tank
Undo bottom hose on rad, let coolant drain out (takes a good 10 mins), re fit bottom hose on rad, then remove the rear most hose on the Header tank (one on top that goes to turbo).
Use a funnel and VERY SLOWLY re fill cooant via this hose, trying to avoid 'glugging'.
Re fill until you see coolant filling up the Header tank. Re fit turbo hose, and then start car with Header tank cap still off, and heaters set to hot. Squeeze hoses to try and get out any air, mop up and top up where necessary. Once up to temp, re fit header tank cap, go for a gentle drive. Allow to cool and check level.

 

Ok thanks i'll go give this a go and see if this helps

 

no worries - if you get a load of steam when starting the car back up after filling, it will most likely be coolant that has dripped/spillled onto the exhaust headers from draining. This happened to me and i **** myself at first then realised it was this lol

 

Ok just went to back fill coolant through turbo pipe, checked bypass pipe that was originally blocked also checked the expansion pipe that leads from header tank to expansion bottle along top of rad, turns out the pipe that travels along top of rad is blocked with rusty crap, did have a rad fail cpl months ago 7 the guy who replaced it cant of flushed cooling system through good enough. Left the pipe from header tank to top of rad disconnected so no pressure can build up where it cant pass through, to expansion tank, back filled system & bled of air. Started car left running up to temp for a good 20 mins engine fan cut in & out 4-5 times which it never got chance to before, before engine light came on, left expansion pipe disconnected & took it for a short drive & all seems ok. Guess expansion pipe being blocked was causing engine light to come on.

Still going to get Neil at slow boy to have a look over the car to double check things & somehow unblock expansion pipe

Got me bo**ox crossed i've gotten away without head gasket damage

 

Sounds like it needs a good proper flush out . I would still get Neil to look over it as you say

 

yeah i'm hoping i can get it checked out this week & get back to driving it as been stuck in a toyota aygo rental all this week lol mind its only cost £40 in fuel for the week!!!!

thanks for the advise on back filling

 

have had a similar problem on a 2003 wrx, mine you could drive of boost and it would be fine, but found to be head gasket leaking when on boost , i could drive car off boost and it would be fine , doing the head gaskets this week and going to change main and big end bearings at same time

 

Did you get a sniff test done?

 

Me or the op?
I did and mine failed sniff test

 

sorry mate yer meant you. Was curious because the OP had a sniff test done and it passed. Was just wandering in what circumstances could a sniff test be passed and HG still be 'gone'

Out of interest, what symtpoms did you get to suspect HG?

 

A sniff test will only show if there combustion gases in the cooling system. i.e. Gasket has gone from a water way to a cylinder.

It wont show if gasket has gone from an oil way to water way or from an oil way to cylinder or from either an oil/water way to the edge of head where the fliud just leaks out.
Or if its gone across two cylinders.

And probably more ive forgotton

 

ah right i see. So i'm guessing a compression test will be able to pick this up?

 

Just one day it overheated and blew the water out the expansion tank , first though it was just a air lock , but done the sniff test and liquid changed colour, so was leaking combustion gases into cooling system , showed no other symptoms