Coolant Airlock removal tips ?

[thetyrant]

Hmm ok few more hours on it tonight and a revelation confirming something i mentioned earlier, after much buggering about with bleed screw on rad changing o-rings etc so i could bleed system properly i think ive got the air out system.

Start the car and let it warm up massaging all pipes to help keep coolant moving and all pipes nice and hot  heater blowing hot as well , BUT the one from rad outlet going back to engine/thermostat is still cold, as is half the rad!....bled it some more but nothing much came out!  sick to death of it i buttoned everything up and went for a thrash to see what happens.

Closely watching coolant temp on Laptop it soons upto its usual 90-93c while driving normally but goes no higher until you give it some death, it then goes up a couple of degrees but drops back down while cruising, go to shops and park up letting it idle to heat soak everything for 5minutes or so and again it goes up a couple of degrees but stable around 95c dropping back to 92-93 when driving again, all in all pretty much what its always done from memory so i dig through my data...

Ive always thought it runs a bit hot but its been stable and never overheated on hot days in traffic or trackdays etc so havent worried about it, now looking back more closely at my datalogs right from when car was NA before turbo went on and the coolant temps are the same, sat in low/mid 90's but stable at that.

Seems all along the car has been running without the radiator cooling things since i got it in 2018!, ive done about 8k miles several trackdays and sprints its never had an issue with temp going any higher than middle of gauge, which now looking at Link G4 data is where it sits until it gets over 100 then it goes up, as i noticed the other day when airlocks heater circuit as its the only thing cooling engine it seems.


SO what do i do now!!...im thinkings its probably the thermostat stuck closed not letting water back from rad.... or the water pump not pumping it but my money is on the stat as if water pump wasnt working i wouldnt get heat in car and it would overheat im sure ?


Any ideas welcome ? 

[househead]

I would be astounded if your rad has not been providing any cooling for all that time.

When my rad blew a leak, it was not much normal town driving at 30mph before the temp needle was off the top of the scale and car was into complete limp mode.

Then again I guess having coolant in the system even if not actively cooled and pumped is infinitely better than having none.

What temp is your fan(s) kicking in at?

Could be an issue with the pump? A radiator as far as I understand is a complete passive device. Fans and pump are the moving parts in the puzzle right? And the thermostat is there to make decisions based on temp.

In my limited wisdom I would suspect the pump if your fan is coming on at the right time and with the right gusto.

[thetyrant]

I would be astounded if your rad has not been providing any cooling for all that time.

When my rad blew a leak, it was not much normal town driving at 30mph before the temp needle was off the top of the scale and car was into complete limp mode.

Then again I guess having coolant in the pipes even if not actively cooled and pumped is infinitely better than having none.

What temp is your fan(s) kicking in at?

Could be an issue with the pump? A radiator as far as I understand is a complete passive device. Fans and pump are the moving parts in the puzzle right? And the thermostat is there to make decisions based on temp.

In my limited wisdom I would suspect the pump if your fan is coming on at the right time and with the right gusto.

Im as stunned as you, ive never checked the coolant pipework/rad temps until now but I can say for sure that right now the coolant isn't passing through the rad back to the engine and it never gets much about 95c and generally sits at 93c like its always done....unless its cooling so well the pipes are cold back to engine which I doubt, as mentioned looking back over all the data I have since I started preparing for the turbo install shows ECT has been sat in low/mid 90's all the time once warmed up, even before I fitted Turbo.

Ive got a log from stock Ecu via torque app as well I will check on that.

Fan is set to come on at 92c which was set by previous mapper of the Link ive not touched that part of map, basically the fan is always on once your warmed up which I did notice once I fitted Link just presumed they had it set like this to help cooling on track, don't think it was the same on stock ecu but I never paid lot of attention to be honest until I fitted the Link ecu, what temp does stock ecu fire up the fan ?

I think if it was the pump it would overheat quickly as coolant couldn't circulate at all, its certainly getting through the the heater matrix and input to the rad, its  just not getting back to engine, when I squish the pipework I can move the coolant through the rad so its not blocked, its just not allowing flow back to engine which I can only think is the stat stuck closed stopping or restriction heavily the flow.

[thetyrant]

For reference here are a couple of datalogs which show ECT, ive checked the Link G4 coolant temps compared to ones the stock ecu shows via Torque app and they are within a degree or so, just in case here was a sensor calibration issue but all ok.

First a 25minute run out including warm up back in October last year, just after fitting Link G4 ecu onto otherwise stock car.



Second is a 20minute run out last weekend after a few jobs on turbo, before i airlocked the heater!  as you can see same sort of temps.

[jonbill]

There's no way it's maintaining temp at 95 under significant load without the coolant going through the rad.

It's more likely that your fingers are numb and you have a 95 deg thermostat.

[househead]

According to a thread on Spyderchat which references the BGB, stock fan activation temp is 93C and it will stay on until it drops below 83C. Not sure if Spyder vs Roadster is relevant but can't see that it would be.

95C then seems a fairly stable and reasonable temp to me.

[thetyrant]

There's no way it's maintaining temp at 95 under significant load without the coolant going through the rad.

It's more likely that your fingers are numb and you have a 95 deg thermostat.

I wouldn't believe it either if I couldn't see it right before my eyes, I can promise you rad exit pipe on drivers side going back to engine has no heat in it and that side of rad is cold as well, its hot on other side of rad and all pipework upto to that point, coolant sloshing back and worth ok when squeezing pipes during bleeding so no blockage, at least not total ones as coolant is moving by hand pressure.

I guess only way to be sure would be to plug the pipes in and out of rad and run it again but don't think ive got any bungs that size, the amount of coolant in system and the long pipe run seem to be enough along with the heater matrix to keep it at 95, as soon as heater was locked out the temps soared, it must be a miracle!

Im thinking easiest job is going to be remove/check/fit new thermostat then re-bleed and go from there, I cant honestly think what else would cause it and still be stable under hard use and for so long but open to ideas ?

[thetyrant]

According to a thread on Spyderchat which references the BGB, stock fan activation temp is 93C and it will stay on until it drops below 83C. Not sure if Spyder vs Roadster is relevant but can't see that it would be.

95C then seems a fairly stable and reasonable temp to me.

Makes sense and maybe fan was on a lot before the Ecu change just being a stock car I never paid a lot of attention and temp gauge always sat in middle.

It is pretty stable as it is now, highest I can see on logs is a few points where it creeps upto 98 but soon drops back to 95 area, its weird alright and if I hadn't airlocked heater I would never question it.

[househead]

I can promise you rad exit pipe on drivers side going back to engine has no heat in it and that side of rad is cold as well, its hot on other side of rad and all pipework upto to that point, coolant sloshing back and worth ok when squeezing pipes during bleeding so no blockage, at least not total ones as coolant is moving by hand pressure.

That sounds like a working rad to me! Warm stuff going in, cold stuff coming out?

Could it just be your heater that's playing up?

[thetyrant]

That sounds like a working rad to me! Warm stuff going in, cold stuff coming out?

Could it just be your heater that's playing up?

Rads are not this good though and don't drop temp down to ambient like this, its not even slightly warm on hose heading back to engine,  remember your trying to keep engine temp in the 80's generally.

In my experience both hoses at rad feel about the same once car is warmed up and stat is open so coolant is circulating correctly.

Also when fans come on it doesn't drop coolant temp.

Heater circuit which is seperate return to engine is working fine now, seemingly stopping engine overheating!