Monky

Hi,

Wonder if someone can help. The heaters in our Sti Wagon Ver3 96 most of the time work, quite often when the car is in traffic or idling for a while they go cold and stay cold until you put your foot down. At this point I would say it was a sticking thermostat.

But, a few days ago as I was waiting for a car wash and sitting for a while and the temperature gauge showed it was hotter than normal and slowly climbing, it didn't reach the red but went up about 3/4 the way so it definitely overheated a little. The heaters at this point were blowing cold, I put them on full to try and cool it down as couldn't really stop the queue and luckily after a while they blew roasting hot and the car came back to temp.

Does anyone have and ideas?

On a side note when we bought the car the seller said a new rad was fitted and coolant, something about having to borrow the original for another Scooby. Maybe they noticed an issue and tried to resolove it with a new rad or maybe just a coincedence!

Thanks for anyones time

dazdavies

iTrader: (22)

I would try swapping the thermostat first, dead easy to do and the symptoms you describe point to just that.

Shaun

Airlock!

Monky

I was thinking thermostat but most of the time it would stick one way or the other meaning it could either run too cold or too hot, not both as in my case?

Shaun simple case of bleeding the rad and replacing coolant? This was done before we bought the car, well rad and coolant were replaced.

Thanks.

AndrewC

Thermostat or Water Pump.

Monky

I'll replace the thermostat on the weekend, could this be sticking both open and closed?

Thanks

sy.

iTrader: (8)

this sounds like the pump to me but try changing the thermostat and also flush the coolant first either way get it sorted as this type of fault will lead to head gasket fail dont trust what you were told replacing the coolant is not the same as flushing it through and could save you £££

Monky

Thanks for the advice

Bought a thermostat, going to fit that first and re-bleed the coolant system to make sure their are no air locks. If it still happens then will flush the coolant system, replace coolant and fit a new pump.

I don't have any oil/water emulsification but will do a compression test just to make sure.

Thanks again.

AndyP's_P1

iTrader: (1)

Dont think it will be the thermostat as they wont fail in both positions. Firstly check coolan level and top up if needed. Hopefully it will just be an airlock in the system.

Monky

Thanks Andy that's what I thought, for the £7.00 it cost I'll replace anyway. Hopefully after a good bleed it will reslove the problem, if not will do as mentioned. Now I just need to sort out the bogging down issue!

chocolate_o_brian

iTrader: (22)

Bogging down when setting off? Had this myself on my old Scoob. Changed the Idle control valve, M.A.F. sensor, and the Lambda sensor. Was a mixture of M.A.F. and Lambda though

PeeVee

iTrader: (1)

This is almost definately not a thermostat problem, but seeing as it's only £7 then it's worth a go.

Because of the inconsistency of the fault, it sounds very much like you are suffering from air locks which are probably being caused by either, the fittment of the rad by the previous owner who hasn't bled it properly, or you have a head gasket failyer causing gasses to seep into the cooling system.

I would fit your new thermostat & properly bleed the system to start with.

If the symptoms re occur, then the next logical step would be to take it to a garage and have a "sniffer test" carried out on the cooling system to see if CO2 is present.

Phil

joz8968

iTrader: (13)

Hi again Phil, lol

What's the procedure to bleed the coolant system to eliminate air locks?

Shaun

It can be a pain.

a) top up the header tank
b) start the engine with top off tank
c) watch the water swirl inside the header tank
d) continue to fill header tank to level when level goes down
e) put top back on header tank

Make sure stat opens and heaters come on and stay on. Look at temp gauge.

Top up header tank if required.

Monky

Thanks Phil appreciate the advice ten fold.

I actually had to get the car recovered last night as the temp needle went up to 3/4 but wouldn't go down again so thought best to be safe than sorry. I tried reducing the temp with the heaters which were blowing cold air, sometimes the heaters go hot again which reduces the temp but they stayed cold and the water temp stayed high. I also had coolant being pushed out of the expansion bottle, not much but noticeable on the floor.

Their is no emulsification of oil and water as far as I can see, no mayo on the cap but I'll bleed the rad today and see if I can get rid of any air locks that might be in there. If it doesn't reslove the issues will get a sniffer test done. What about the water pump Phil could that not be a possibility, maybe the fins are corroded hampering flow?

I would have thought last night with the cold air temps and open roads that the temps would have been fine but it shows that the coolant isn't flowing around the engine which could be either an air lock or maybe the pump?

Let me know when you can and thanks once again

joz8968

iTrader: (13)

Cheers.

And presumably, if bubbles, er... bubble in the header tank, then new H.G.s time?!

PeeVee

iTrader: (1)

Monkey,

I could never say that your water pump is not knackered, but they are generally very good & if they do fail (which is very rare) they tend to leak and not suffer from corrosion.

Generally, if the pump had corroded to a point where it did not flow enough water to cool the engine, you would have a permanent flow problem to the heater & it would not inconsistantly blow hot & cold, you should also have consistent overheating & the temps would go through the roof & not intermitantly recover to a more normal level.

Air in the system at this point is still my best guess.

As for having no emulsification or mayo, this only happens if there is oil mixed with the water & if you are suffering air locks then it could be contamination from the combustion chamber which would be more normal on a Scoob than having oil contamination.

You say that there is water being pushed out of the expansion bottle. This could be caused by either the engine over heating or by a leaking h/gasket so it's not conclusive either way yet.

If you wan't to be 100% certain that the system is air free then carry out the following procedure:

Fill the cooling system through the header tank, turn the heater fan on to no:1 & the controls to hot, start the engine & twist the throttle linkage under the bonnet to run the engine at about 2000 rpm (you may want to use a cloth, as it can get a bit hot in that area)..

You now need to keep the header tank topped up so it doesn't run dry (don't fill it to the brim, about half way will do) & the rpm at 2000 whilst you wait for the engine to warm up and for the thermostat to open (steam will start comming out of the header tank when the thermostat opens & you will see coolant starts to circulate through it) At the point the stat has opened you will find that the water in the tank starts to rise and may overflow (this will be excentuated if you let the revs drop).

Run the engine for about another 30 secs, then raise the rpm to aprox 3000 and you should find that the water level drops slightly, at this point, top up the header tank to the brim & put the cap back on. Let go of the throttle linkage & allow the engine to idle.

You now need to go the the expansion bottle (which is located in front of the battery and has a yellow lid) and top this up to the point midway between low and high.

Job Done!
Best of Luck
Phil

PeeVee

iTrader: (1)

I would not go to the expense of fitting head gaskets just because you can see bubbles in the header tank.

Due to the way the return pipe joins the header tank, it is possible you will see bubbles that are created when returning water hits the water already present in the tank.

If you suspect head gasket failyer, I would sugest you have a sniffer test carried out on the cooling system.

Phil

joz8968

iTrader: (13)

No I don't see bubbles. Just asking for future reference...

...BUT...

...One night, the car misfired badly on the limiter, as I was seriously hooning off a roundabout (I need two new coilpacks - other two are new). This immediately coincided with the temp. gauge having risen to the top and the Commander displaying 137deg. I immediately limped it to a stop, opened the bonnet and quite a lot of coolant had obviously been forced past the rad cap and into, and out of, the expansion bottle by the battery. It probably took about 1 to 2 litres (didn't pay attention, really) to re-top up.

At the time, I assumed this to be head gasket.

However, I've since re-instated the lost anti-freeze and made sure everything's topped up... and now do not suffer coolant loss whatsoever. However, it must be said that - although I do accelerate upto 6000+ rpm - I so far have not ventured to the 7,020rpm rev-cut (as set by JGM when mapped), since this happened.

Any ideas why I lost quite a lot of coolant that one time?

Monky

Top advice mate star

I went to see a guy I know today who specialises in Subaru's, he said their was no need to do a sniffer test as he was 100% the head gasket was on the way out. What I didn't notice was that the top rad hose was completely swollen when I got there (car didn't play up on the journey, heaters went a little cold once I got there and stopped though), around twice the size of normal as we compared it with another Subaru that was there. Couldn't an air lock also cause this?

He said with this and the heaters being sporadic it was a classic sign. Now I'm back I''ll follow your procedure, I need to flush the rad next week is it okay to bleed and top up using water for now as it's not that cold yet? I've preliminarily booked it in for next tuesday for a head g replacement (both) maybe I'll get him to do a sniffer test before he starts any work just to make sure but I think he's trustworthy and impressed with his work before.

I am getting bogged down performance and the occasional mis, not all the time, some times it feels quick as an Sti should but other times more like a WRX (I have both so can compare! ) but I put that down to either a faulty lambda/maf or the fact it's not mapped for UK fuel yet.

What do you think bud?

PeeVee

iTrader: (1)

You lost coolant because the engine overheated,..... whats not apparent is why it overheated in the first place, and it's strange that it has not done it since.

If it never does it again then you will never know

Lets hope for the latter
Phil

joz8968

iTrader: (13)

Ha. Totally what I thought!

Could it have been that violent misfire on the rev-limiter that momentarily caused the 'one-off' overheating/pressure rise then?

PeeVee

iTrader: (1)

Monkey,

I'm gutted for you, it would appear now that you have said that the hoses are swollen, it's pretty much a foregone conclusion that your h/gasket has gone (an air lock would not cause this).

Obviously, sat at a computer terminal, it is impossible to confim this.. There is no substitute to having the car in front of you, but all indervidual pieces of info, on their own, point to a failed gasket... When you have all the symptoms that you have pointing in that direction, well..........

If the garage has the ability to carry out a sniffer test, then for piece of mind I / we as a business always would, as it's easy to do & very cheap. It's all very well having lots of experience and diagnosing faults based on this, but having the head gaskets renewed is not cheap & cars can catch you out sometimes....

I would be happy to bet my money on it..... but NOT yours

Phil

Monky

Fair play thanks Phil, looks like it is to be honest especially as power is a little sporadic at the moment. Before I go relpacing any other parts I'll get the gaskets done to see what it rectifies to avoid wasting money.

I've had a quote of £600.00 (supply and fit) and £250.00 (fit), not a job I'm prepared to tackle myself. The more expensive quote is local to me, the cheaper one around 2 hours drive so I need to way up petrol costs, both are compitent mechanics experienced with Scoobies just one is a close friend!

I'll let you know how it goes though cheers for all the tips made life a lot easier. Need to get a few other things done while I'm there like ball joints/track rods/ARB links so fingers crossed it will be a pleasure afterwards!

Thanks

oadamo

iTrader: (1)

fill the header tank and squeeze the bottom right hose a few times on the rad looking at the front of the car. you will here the water suck in. then top up and keep squeezing the hose you should here it sucking again it takes a couple of mins then start the car and top up again.
adam

Monky

Hey mate

Where you referring to bleeding the system before getting any work done? From the above I didn't think an air lock could cause such swelling in the top rad hose? Although maybe a blockage? If there was an air lock or blockage it would surely overheat constantly?

Thanks

PeeVee

iTrader: (1)

Monky,

Both quotes seem reasonable, considering that to have the job done properly, by the book, at a dealer, is going to cost you around 1K.

Just make sure that whoever carries out the work, carfully checks to make sure that both the heads & the block are not distorted in any way & that you use metal shim head gaskets, not the cheap UK version during the re build... Otherwise you could end up having to go through the whole process again!

All the best
Phil

PeeVee

iTrader: (1)

Bleeding the system costs nothing, but in reality I honestly don't think it's going to make a blind bit of difference.

I'm also very consious of the fact that I have not seen your car in the flesh & am not about to tell you to go and spend this sort of money without taking you through the basic procedures to try & prove the point.

Monky

Yeah that's completely fair always hard to diagnose faults on a forum but appreciate all the tips. Little update the top rad hose literally exploded yesterday leaving me in a cloud of white smoke so I've trailered the car to my Scooby man in Worcs.

The sporadic bogging down could be related to the compression being lost in one or more cylinders due to the HG but I'll update you once the engine is apart

Cheers