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frankieh

Strange overheating issue

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Firstly, I already posted this to fordmods but they don't seem to have the traffic they used to anymore so figured I'd come to a site more specialized to xr6T.  This post has much more info too.

 


I've got a strange situation with my XR6T getting hot. The temp gauge now gets to half way.. that doesn't sound hot but this car has always sat at 1/4 and it is not because if you stop driving suddenly you can hear it bubbling coolant out the overflow. If I let the car idle for a while after stopping the temperature drops a bit, but not all the way back to where it used to sit. considering the huge radiator and stuff in this car I'm puzzled as to why it would be running hot at all. There is a gauge in the lid of the overflow and that shows that the coolant is somewhere around the 100C point.. and it's never been anywhere near that point before.  The AFR output shows nothing out of the ordinary either.  For a long time it sat at 1/4 mark no mater how thrashed or how hot it was.    The only thing that happened that might be related is that in an effort  to improve my idling issues, I took the top half off the intake manifold and pulled off the plastic press fitting under it with a tapped brass  part that can't leak.  I used hylomar and tested for leaks and "start you barstid" has no effect on revs when sprayed around the intake.    I've checked the codes and there isn't anything unusual in there either.

Car is a very late 04 BA, 6spd manual, tuned for around 16psi on JTG liquid gas injection.  except for dropping revs too much when clutching in to stop it was running pretty well except a bit rich till recently.    Heat is there on either fuel though.

The car has:
* newly replaced thermo fans. (did that trying to solve this problem.) cost was 20 bucks so WTH.
* 4 core radiator, only about 6 months old.. it's twice the thickness of the standard V8/turbo radiator. (which is twice the thickness of the standard radiator) so it only just fits in front of the engine with the fans on the front.
* Silicon hoses all round.. they came with the radiator. Seem pretty good as they don't get soft with heat the way the rubber ones do. There are no springs in them to hold them open and it doesn't' seem all that hard to collapse them so I"m wondering if I should source a spring for the bottom hose.
* New thermostat... did it yesterday. the old one looks fine but figured what they hell.
* No leaks and coolant is clean and green.

The water pump isn't leaking and doesn't' seem to have any slop or movement. If I put the heater on full when the car is hot it's so hot it burns your feet so there is definitely a problem of some sort.

Thoughts, I am concerned that the temp sensor on the block might be naffed and causing issues by not regulating the fans properly... at around the same time my external oil temp guage started reading 120 all the time which means either the sender has died or gotten disconnected or I have serious engine issues.

what else can I look at here that I have not already checked out? It's pushing two litres of coolant out the overflow every time I go for a decent length drive so it's driving me nuts.


I'd appreciate any suggestions.

cheers

Frank

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Is all this concern purely from the dash temp gauge ?

Or have you put an OBDii reader on the car and got an accurate number ?

Have you changed the coolant recently? If you put to much concentrate in it can make temps increase slightly

95 - 100degrees coolant temp is quite normal

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15 minutes ago, frankieh said:

It's pushing two litres of coolant out the overflow every time I go for a decent length drive

That's an unusually high amount of coolant to lose out of the overflow... is there heaps of evidence around the exhaust where the coolant has spilt? is there any evidence of where it's going if it comes out of the overflow?

 

For the "bubbling" thing, that's totally normal, as the xr6t's have a thing called "thermosyphon" so that the coolant gets bubbled around to the turbo after the engine has been turned off to prevent oil coking inside the turbo.

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Mine reads 96.6c cruising and 101c when flogged on hptuners. The gauge shows 1/3rd regardless.

 

FYI thermosyphon is an effect that takes place in nearly all cars. It is not xr6 specific. That is the reason that coolant takes the route it does.

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Indeed. It's much more noticeable in my stock BA XR6T than my mates stock N/A XR6, though.

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17 minutes ago, k31th said:

That's an unusually high amount of coolant to lose out of the overflow... is there heaps of evidence around the exhaust where the coolant has spilt? is there any evidence of where it's going if it comes out of the overflow?

 

For the "bubbling" thing, that's totally normal, as the xr6t's have a thing called "thermosyphon" so that the coolant gets bubbled around to the turbo after the engine has been turned off to prevent oil coking inside the turbo.

I guess I'm mostly wondering why the recent change..  other than replacing the plastic pipe I've changed nothing.     It's definately coming from the overflow as the puddle is directly under the outlet and all "car" between the overflow and the ground is coated in green coolant.   There doesn't appear to be any other leakage.  I made a point of checking at work where I park it and sure enough the only place with a puddle of coolant is the front drivers corner right under the overflow hose.  

 

I suppose it's possible that the radiator cap has lost pressure or seal and it's allowing it out under lower pressure, I have a spare here so I can try it.

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Only two things that I know of would cause that sort of leaking if the coolant level is not too high in the overflow tank to begin with...

 

1. like you suggested, the radiator overflow cap isn't sealing correctly and regular coolant system pressure is pushing out of the opening.

2. the coolant system pressure is too high (due to a blockage or something in the cooling system) and coolant is pushed out of the regular overflow.

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22 hours ago, Puffwagon said:

Swap the cap and see how it goes. 

 

Ok,   it was at least partially the cap.. put the original back on and it's bot p1ssing coolant out the overflow anymore..  gauge is lower too.. sitting between quarter and half now..  but it's still hotter than it was 2 weeks ago and it even smells hotter too after a moderate drive...  I've just ordered a physical digital temp gauge and sender so I'll have a much better idea of temp going forwards.   Engine still has that hot engine smell though...   wish I knew why it suddenly started running hotter.

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On ‎26‎/‎02‎/‎2017 at 6:42 PM, Wilko16 said:

Is all this concern purely from the dash temp gauge ?

Or have you put an OBDii reader on the car and got an accurate number ?

Have you changed the coolant recently? If you put to much concentrate in it can make temps increase slightly

95 - 100degrees coolant temp is quite normal

 Wheres 95-100 sit on the gauge

 half or more??

Cheers Steve

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