Bizarre overheating coolant loss issue. - Page 2 - Forums
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post #21 of 23 (permalink) Old 13-02-2017, 18:26
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Originally Posted by TipperMG View Post
Are you sure there isn't a standard stat in the engine too? (May have missed that bit if you've already said it is removed)
That's a good point. I can't see why a PRT would run to too hot unless it's the wrong one or stuffed. Mine is fine. You say say you got the car for a song, fair enough but who knows what may have been done to it in the past. They are cheap for a reason.
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post #22 of 23 (permalink) Old 13-02-2017, 18:54 Thread Starter
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Originally Posted by TipperMG View Post
Can you explain what you mean? I modded my Steppy with a PRT mounted up front and had far better temperature control as seen on my Scangauge. Not high at all and I wouldn't expect a standard PRT down the front of the engine to run high temperature either. Are you sure there isn't a standard stat in the engine too? (May have missed that bit if you've already said it is removed)
The car currently runs 92-94C average.

I would like that to be around 82-88 with it closer to 82 so there is a 10C ceiling increase to give the system time to accommodate extra heat.

Currently either someone has fitted the wrong PRT or it just is a bad setup (clogged/busted PRT)

I want to remove the PRT and fit a modified 82C Stat near the radiator with a small bypass so I can run the car harder without fear of temperature spikes.

A 82degree PRT is 40+ whereas an 82 degree stat with bypass (for me) is just in the 20 mark or so.

I already have the non PRT piping so I want to make use of that.

You're right of course, you can fit a PRT up front instead but I do not have an 82C PRT, only a 92C V6 one which I want to use for other reasons.

My last 3 ZS's ran in the ~84 range, my current ZS has a stuck-open stat so runs at 74-78C almost constant, which I can live with as I know it will never overheat on long distance, which I use it for a lot in the summer.

TL;DR PRT is probably the wrong one, I want to fit a radiator stat to make the temperatures even more stable for harder driving, before I sell the car on knowing it's going to be reliable for whoever else uses it.

They are cheap for a reason.
I am perfectly happy with working on the car for what I purchased it for. It isn't costing me anything but experience points and time. Both of which I am happy to invest.

I don't want to buy a perfect car because i'd be complicit in it's reliability until it died completely because I never took it apart to see what was wrong with it.

So far none of the issues have been mind benders. They've just been a long series of troubleshooting stages that left me stumped because I didn't think to check :P

Me being less stupid in future means me wasting less time.

Last edited by Stargatemunky; 13-02-2017 at 19:03.
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post #23 of 23 (permalink) Old 15-02-2017, 20:28
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Son brought a 04 tf with head gasket failure, got so hot that the plastic timing cover which bolts to the head had melted. anyway new head gasket and big coolant flush, new prt and all was good...... The heater would go cold, the coolant fan would start running but the rad was cold but the coolant was boiling in the expansion tank?
No leak of coolant anywhere, new cap. Cooling system was bleed at all 3 points, pressure tester fitted with obd live data showing coolant temperature. would be fine for a couple of days then back to cold heater, temp gauge showing over heating but rad cold.....
I have an 82c prt thermostat fitted which works perfectly, live data shows about 92-94c when thermostat opens(sensor at top of engine and t'stat at bottom....heat rises).
Checking the bleed hose that runs across the engine bay to the expansion bottle this wasnt getting hot and there was no flow into the bottle! i removed the complete hose from the 4 way connector to the inlet manifold to the bottle. This pipe was blocked with sediment in a couple of places.Cleared and refitted the pipe was hot but poor flow to the bottle. the short pipe from the inlet manifold was cold!!!
This pipe was removed and a short narrow rod fed down the brass pipe to the bleed valve and given a "smack" this caused constant coolant flow and when the coolant pipe was reconnected i had flow into the expansion bottle. From cold start up i have flow half way across the expansion bottle and when warm at about 1500- 2000 rpm the flow can be seen hitting the opposite side of the bottle.
If the coolant cant circulate then the engine is like a kettle and only good for boiling water. thats my theory....
Anyway check for flow into the expansion bottle, check the cross pipe for blockage,all of them 3 part hose section. Check the valve hasnt stuck in the inlet manifold use a piece of stiff wire to bleed off the air. this car has now been trouble free for about a month as well as a track day at goodwood.
Sorry about the long reply but hope the info is useful.
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