Hi,


jumped in my car this morning and after 15 mins driving,I gave it a little blast up onto the Motorway and I smelt something but pressumed it was another car ahead,thenthe temperature gauge climed the 3/4's,I immediately pulled over and shut the car off.

pulled the bonnet and no signs of coolant anywhere,gave it a few mins to cool down and took the cap of the header tank,it wasn't pressurized,it had lot a little coolant but only 200ml or so,I topped it up and drove to work,heaters still blowing red hot and the temp gauge didn't budge all the way to work (10 miles)

put the car in the car park and left it running for 10 mins,again temp didn't budge,heaters still hott


been and had the car sniff tested and no exhaust gas in the header tank,so gave it a good blast back to base and again no over heating issues


let the car cool a little then went for another steady 20 mins drive to the gas station,and then a good blast back home and again no problems,when i got back the car had 3/4's filled the expansion bottle and was slowly bubbling as I stopped,no creamy stuff on either dipstick,filler cap,or either rad caps




now I did do the coolant bypass mod a week or so ago,and I never bled the coolant system?


airlock maybe? it was a week ago tho when I did the mod,or is it the head gasket?

any help appreciated,and cross your fingers for me please!

 

hopefully only air lock, but the start of headgasket issues are overheating when on boost,idle etc wont cause overheating.

 

strange how it was only a little blast from 3rd to 4th and then temp guage went up,I can't get it to run hot now tho

 

im not sure but i think its the boost that pressurises the system.
hopefully you just had an airlock,bleed the system and hopefully it has fixed it.
which engine is it you have 2.0 or 2.5?

 

it's a UK car so the 2.5,i'm stumped as to what to do now?

after the 30 min blast it had as I say put some coolant into the expansion bottle,but will surely suck that back in once it cools right down,if it was a gasket it should have burnt it off right?

surely that 4 seconds of boost can't overheat the whole coolant and get it to run warm?

i'm really hoping it was just the air lock but these 2.5's don't have me holding my breath

another point it,I always put my car in the garage over night,but last night I left it on the drive which is quite steep,mayube thats caused the air to move around

 

Its just the heat of the water that pressurises the coolant system(I think), I wouldn`t have thought doing the bypass mod would have caused it as it is only a very small pipe but you never know, How have you connected the pipes back together(Jubilee clips?), Is it possible you could have lost coolant from where the pipes join now they are no longer going through the throttle body, This would explain the loss of coolant and the smell as it wont be easily spotted behind the throttle body under the intercooler, Just a thought,

Gaz.

 

Hey,


i'v connected the 2 pipes together with hose clamps you know the common springy ones. I did lose a little coolant when I did the mod but no more than 100ml if that?

when it ran hot this morning the header tank only took 250ml to make it full again,but I cant remember how much was in the expansion bottle.

 

another thing I noticed when I first bought the car,it warms up very quickly,even in single figures above freezing,3 miles and it's upto
temperature,

is that normal on the UK STi's?

 

That sounds normal to me.

 

My head gasket went on my Hawkeye STi just over a year ago.

What does your water temp get to with the car idling once you have been for a blast?

 

check both top and bottom hoses , we have changed quite a few sticky thermostats on 2.5's ... Just a suggestion .

 

If overheating started when the coolant bypass was done the it was an airlock.
The subsequent "good blasts" while in this state may well have made the problem a lot more than just a simple air lock.

 

Fitted a new thermostat today, re bled a couple of times, drove the car off boost for 25 mins, the car had put a little more water into expansion botlle and was bubbling.

Would cometic gaskets solve it, or are bigger head bolts required to stop it going again?

 

Did temp gauge rise

 

No temp guage stayed at a constant 1/4 where it usually is, just got back from being out for dinner which is 15 mins each way, again temp stayed the same, i will check coolant level in the morning

My guess is a leaking head gasket but only problematic when under boost

Starting to miss my M3 at this point

 

If the temp gauge is reading normal it's fine just keep an eye on the expansion tank near radiator. Might need topping up or it might b over filled. Check in morning should read max or just under.

 

Um i wonder if the rad cap is failing ??? ....

 

would the coolant leak out if the rad cap fails?

 

Just thinking perhaps the seal is weaking and bleeding off to soon ..... um

 

been out for a short blast and it's overheated again,temp went to 3/4's, pulled over,it didnt seem hott,top rad hose wasnt hott I could hold it easily. expansion bottle was full again,but it was cold water

I checked the expansion tank this morning before setting off and it was half inch before maximum.


I'll start looking for another M3

 

1. GET THE SNIFF TEST DONE!

2. How did you fill it with coolant? Did you search on here and follow the instruction, plus do it VERY S L O W L Y?

 

Re bled the system,and fitted 2 new rad cap,s and seem's to have solved it!

a quick blast to meadowhall and back and coolant level is about the same,just over the max mark!

a little gutted now as I saw it as an excuse to go FORGED!!!! haha

 

Keep a eye out for little bits of paint flaking off your headgaskets and ending up in your expansion bottle.Thats one sign of your headgaskets going hope it is sorted now though.

 

Have you advertised this for sale Motion Mx? Selling already.Did you manage to trace the head gasket issue? GLWTS.

 

As has been said get the coolant sniff test done, went through proper bleed procedure, new water pump and thermostat before finally getting the test done...turned out it was a slight head gasket leak under pressure/on boost.

If it is gasket failure get the heads machined properly and fit slightly oversize Cosworth or Cometic gaskets (along with a new water pump, thermostat and all new seals/gaskets while you are there), that will sort the problem.

And while the engine is out it's a good time to check/replace the clutch, change the timing belts and do a major service. If you have the budget (I didn't) it's also a prime time to replace the pistons and rods with forged ones (and get the block honed) and fit ACL bearings and ARP head studs.

The standard head gaskets look cheap and poorly made compared to the Cosworth & Cometic ones, no wonder they fail so often on the 2.5