How reliable are the Coolant Bottle Pressure Caps.

Abott10 · 10th June 2016, 10:26

My 1.8t ZT left a patch of coolant underneath the Expansion Bottle Area. Has been very warm the past few days. That wet patch following an 80 mile round trip. After a good few hours, I removed the the cap and topped up the coolant loss. For good measure, I used another Expansion Bottle Cap which looked identical but, instead of the original show "200" on the underside of the Cap, the replacement showed 140. No idea if that means anything. Otherwise the two looked identical.

In yesterday's heat ~ the temperature showing 26 C on the Instruments took the car for a quick five mile run up onto the Cotswolds. Parked up and lifted the bonnet. A very hot engine but no sign of any coolant escaping.

Carried on driving including some brisk sessions of acceleration using full boost. Car went very well. Did about another twenty miles in the continuing heat of the day. It was very warm.

This morning, I could not see any tell tale wet patch, even a drip or two. Nothing. 50-50 OAT Antifreeze does not dry up and disappear quickly as plain water would do. So looks like no coolant past the replacement cap. I removed the cap and checked the level. The top of the Bottle where the MAX index and tubes are was very wet, but not under water.

So, all things considered it may simply have been a worn Pressure Cap.

Even so, may have been a premature first indication that all is not well. At no time did I hear the Fan being activated but being on the move.

Do these Caps need to be replaced at regular intervals on a nothing lasts forever basis?

Any advice or suggestions here will be most appreciated.

T-Cut · 10th June 2016, 10:39

The 200 cap is non-standard for the 75/ZT system, but of little consequence for a healthy system. It's a 30psi relief type whereas the standard 140 is rated at 22psi or so. The details here: https://www.the75andztclub.co.uk/for...45#post2293745

A primary cause of cap leaks is a damaged/crushed rubber washer.

TC

10th June 2016, 10:26	#1
Abott10 * Join Date: Apr 2014 Posts: 227 Thanks: 1,275 Thanked 1,917 Times in 1,328 Posts	How reliable are the Coolant Bottle Pressure Caps. My 1.8t ZT left a patch of coolant underneath the Expansion Bottle Area. Has been very warm the past few days. That wet patch following an 80 mile round trip. After a good few hours, I removed the the cap and topped up the coolant loss. For good measure, I used another Expansion Bottle Cap which looked identical but, instead of the original show "200" on the underside of the Cap, the replacement showed 140. No idea if that means anything. Otherwise the two looked identical. In yesterday's heat ~ the temperature showing 26 C on the Instruments took the car for a quick five mile run up onto the Cotswolds. Parked up and lifted the bonnet. A very hot engine but no sign of any coolant escaping. Carried on driving including some brisk sessions of acceleration using full boost. Car went very well. Did about another twenty miles in the continuing heat of the day. It was very warm. This morning, I could not see any tell tale wet patch, even a drip or two. Nothing. 50-50 OAT Antifreeze does not dry up and disappear quickly as plain water would do. So looks like no coolant past the replacement cap. I removed the cap and checked the level. The top of the Bottle where the MAX index and tubes are was very wet, but not under water. So, all things considered it may simply have been a worn Pressure Cap. Even so, may have been a premature first indication that all is not well. At no time did I hear the Fan being activated but being on the move. Do these Caps need to be replaced at regular intervals on a nothing lasts forever basis? Any advice or suggestions here will be most appreciated. Last edited by Abott10; 10th June 2016 at 10:30.. Reason: @ 11:30 ..Typos...quick double taps key strokes = single letter.

10th June 2016, 10:39	#2
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	The 200 cap is non-standard for the 75/ZT system, but of little consequence for a healthy system. It's a 30psi relief type whereas the standard 140 is rated at 22psi or so. The details here: https://www.the75andztclub.co.uk/for...45#post2293745 A primary cause of cap leaks is a damaged/crushed rubber washer. TC