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| GT4 Cooling System Help http://www.gt4dc.co.uk/forum/viewtopic.php?f=2&t=6776 |
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| Author: | jgtcracer [ Fri Oct 04, 2013 4:00 pm ] |
| Post subject: | GT4 Cooling System Help |
Recently the car has started showing a strange symptom when driving under certain conditions, the radiator cap lifts when applying heavy load to the engine. My coolant setup incorporates an external header tank and aftermarket digital temp gauge and has been like this for approximately 8 months with no issues. When cruising and even applying moderate throttle the cap relief remains closed however when applying full throttle above 4500rpm the oem needle goes to max before returning to normal once throttle is removed. I can only assume this is as a result of rapid system de-pressurization when cap lifts. The needle returns to half way position once the relief re-seats. Initially I thought the cap may be faulty however I replaced it today with no change to symptoms. Other concerns were possible head gasket fault though I have no other symptoms to suggest this is the case. The water pump is working and the thermostat controls temp well when cruising. I can find no leaks within the system itself I tried removing the thermostat and the symptoms are still there with it removed, I had it on the cooker and seems to be opening fine Sorry for the in depth post however a little advice wouldn't go amiss at the moment thanks Marcus |
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| Author: | Sirius [ Fri Oct 04, 2013 4:07 pm ] |
| Post subject: | Re: GT4 Cooling System Help |
Hi Marcus, How easy would it be to revert the system to stock temporarily, would give you a fault finding base. I wonder if a cracked block could give symptoms like this. |
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| Author: | jgtcracer [ Fri Oct 04, 2013 4:24 pm ] |
| Post subject: | Re: GT4 Cooling System Help |
You trying to scare me mike?? I suppose I could try and revert to normal,don't think I'm using any water mind you |
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| Author: | wolfiehere [ Fri Oct 04, 2013 6:26 pm ] |
| Post subject: | Re: GT4 Cooling System Help |
Could be cracked liner or a head lift issue under boost Sent from my GT-P5110 using Tapatalk 2 |
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| Author: | Sirius [ Fri Oct 04, 2013 6:47 pm ] |
| Post subject: | Re: GT4 Cooling System Help |
Not deliberately! Promise! |
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| Author: | TrackToyFour [ Fri Oct 04, 2013 9:57 pm ] |
| Post subject: | Re: GT4 Cooling System Help |
Is it just the OEM temperature gauge which is displaying this behaviour? Where is the aftermarket temp sensor located and does it display the same behaviour as the OEM sensor? If they are both showing the same then then it probably eliminates the possibility of a faulty sensor/gauge. You don't mention if its the pressure cap on the header tank or the rad which is lifting. When you rev the engine you always get a slight rise in the level of the coolant anyway due to the pump swirl. It might be worth doing a hydrocarbon test on the coolant for peace of mind. |
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| Author: | jgtcracer [ Sat Oct 05, 2013 8:05 am ] |
| Post subject: | Re: GT4 Cooling System Help |
With the header tank fitted the radiator cap doesn't have relief fitted, its just a cap. Its the header tank cap that's lifting. Aftermarket meter is in top rad hose as its the hottest and shows none of the same signs as the OEM temp meter. I don't think its the meter, the symptoms are predictable and the cap is definitely lifting as the meter goes off scale. It then settles again within seconds. Does coolant system pressure rise with engine revs or is there something other than the cap that maintains pressure within the system |
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| Author: | Nibbles [ Sat Oct 05, 2013 12:34 pm ] |
| Post subject: | Re: GT4 Cooling System Help |
The normal scenario for sudden temperature increases & drops is a big bubble of hot gas accumulating at the highest point - water elbow where the sensors sit. The standard temperature gauge is normally very slow & insensitive so by the time that moves above the 'normal' position you have a serious problem. Normally it's a fast aftermarket gauge that shows the issue while the standard gauge stays where it is. If your aftermarket gauge is in the hose, it is likely to be immersed in the coolant with just bubbles passing by, so will probably not show the problem. It is possible that it's a gauge fault, but if it co-incides with gas blowing out of the cooling system it is very likely it's head gasket or cracked block (latter more common on 205). Header tank setups are very efficient at removing gas from the system quickly without coolant loss wheras the standard setup blows it's coolant out the first time you boot it then stays overheating. You can confirm a gauge fault by connecting a multimeter on volts across the ECU sensor (splice into wires) as this will show the same overheat if it's happening. Read the voltage once up to temperature then give it some welly and see what the voltage drops to during the overheat. I can translate voltage to temperature for you. I currently have this happening in my 205. The standard gauge doesn't move but my aftermarket gauge (connected to ECU sensor) goes up to 120 odd degrees every time I put my boot down then drops straight back down again. In my case it's also losing coolant without having any leaks. |
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| Author: | jgtcracer [ Sat Oct 05, 2013 1:00 pm ] |
| Post subject: | Re: GT4 Cooling System Help |
I think Im just going to have to monitor this over the next few weeks and see what happens. If I do have a cracked block then obviously its not a a quick fix anyway so it looks like Im stuck between a rock and a hard place. At least the car seems ok unless I really hammer it, just means I have to take it easy for the foreseeable future |
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| Author: | Nibbles [ Sat Oct 05, 2013 2:32 pm ] |
| Post subject: | Re: GT4 Cooling System Help |
On a 205 with a metal headgasket it shouldn't get worse at any great rate. The header tank setup will hide the symptoms - I drove a 185 round for a few months with a headgasket gone until I got round to sorting it. |
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| Author: | martinking6 [ Thu Oct 10, 2013 7:28 pm ] |
| Post subject: | Re: GT4 Cooling System Help |
Hiya Why not just carry out hydrocarbon test its an instant answer Martin |
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| Author: | jgtcracer [ Sat Oct 12, 2013 8:49 am ] |
| Post subject: | Re: GT4 Cooling System Help |
Will the hydrocarbon test differentiate between a hg fault and cracked block though? |
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| Author: | Nibbles [ Sat Oct 12, 2013 9:14 am ] |
| Post subject: | Re: GT4 Cooling System Help |
No. It will just confirm combustion by-products in the coolant. |
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| Author: | Sirius [ Sat Oct 12, 2013 3:31 pm ] |
| Post subject: | Re: GT4 Cooling System Help |
But either way you'll be doing some work on the engine so it will be useful to do. |
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