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Old 23rd October 2019, 10:48   #11
SD1too
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Thanks for your helpful post Pete. Since both you and Ben are experiencing the same low running temperature, I'm wondering whether the housings are fitted with a thermostat rated at a lower temperature. When you and Ben remove the suspect units, could you note whether the thermostat is fully closed as it should be? It would be even more interesting to know at what temperature they begin to open when heated in a pan of water.

It's unusual that your straight pipe developed a hole Pete. Do you have a photograph? Where's the damage exactly?

Simon
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Last edited by SD1too; 23rd October 2019 at 13:08.. Reason: Grammar
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Old 23rd October 2019, 11:12   #12
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Quote:
Originally Posted by Dubya View Post
The expansion tank cap has 140 on the top, is this the temperature at which it opens?
It's the relief pressure rating in kiloPascals (kPa). The '140' translates into 1.4Bar or 20psi in English. To vent off at that pressure the coolant will be at around 118 -120C (if 50% antifreeze mix is used). The temperature will vary if a different coolant mix is used.

If you want the detail see: https://www.the75andztclub.co.uk/for...d.php?t=245253

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If so would it be wise to replace this too, seeing as it is opening at 107 degrees, or could the pressure at this temperature have been sufficient to open it?
The usual cause of cap leakage is the rubber seals. If you replace them the problem is usually fixed at lower cost. You can get these from forum traders, ebay, ring suppliers, etc. Obviously you can replace the cap if necessary.

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Old 23rd October 2019, 14:20   #13
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A stuck thermostat sounds probable. Nothing wrong with a running temperature of about 85 degrees however. In cold weather using the heater you can easily see that.
I would however be cautious with Chinese parts. The money saved on purchase is not worth it in most cases. Taking chances with this item is a bit silly.
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Old 23rd October 2019, 15:10   #14
Steve42
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last night fitted new thermostat and sender unit from dmgrs .
the thermostat was rated at 82c. have just taken it for a drive round.
in free air at 50 mph temp was 88c.
around town at 20 to 30 mph , been stuck behind buses went up to 93c
temp did move about depending on rpm due to the water pump pushing slower or faster.
the drive round involed twisting road with lots of bends, taken up to 80 mph, then the last test was around the town.
now befour we changed the items my v6 petrol 2.5 allways ran at 93 only hitting the 100c when standing still.
only problem i have had is the coolant filler cap. again brand new from dmgrs when i went to open it up today to check all was well. the top of the cap broke off in my hand and left the valve part in the filler part of the tank.

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Old 23rd October 2019, 16:19   #15
kaiser
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Quote:
Originally Posted by Steve42 View Post
last night fitted new thermostat and sender unit from dmgrs .
the thermostat was rated at 82c. have just taken it for a drive round.
in free air at 50 mph temp was 88c.
around town at 20 to 30 mph , been stuck behind buses went up to 93c
temp did move about depending on rpm due to the water pump pushing slower or faster.
the drive round involed twisting road with lots of bends, taken up to 80 mph, then the last test was around the town.
now befour we changed the items my v6 petrol 2.5 allways ran at 93 only hitting the 100c when standing still.
only problem i have had is the coolant filler cap. again brand new from dmgrs when i went to open it up today to check all was well. the top of the cap broke off in my hand and left the valve part in the filler part of the tank.

steve
Chinese parts. Altogether not a brilliant idea. The Chinese make decent stuff, but many importers think they are clever and press prices, this is the result.
Buy decent tools and decent spares. They are never the cheapest, how can they be?
Some people learn very, very slowly, if at all..
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Old 23rd October 2019, 16:51   #16
SD1too
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Quote:
Originally Posted by Steve42 View Post
... fitted new thermostat and sender unit from dmgrs . the thermostat was rated at 82c.
Steve; 82 degrees C is moulded into the upper thermostat casing of a genuine MGR part but it should be ignored. The thermostat inside will definitely not open until 88 degrees. I have tested it.

Quote:
Originally Posted by Steve42 View Post
... temp did move about depending on rpm due to the water pump pushing slower or faster.
By how much did the temperature vary, can you give us some figures please? When the car is moving the temperature should be reasonably stable in the low nineties. However, if you are saying that temperature variation is directly linked to engine speed, rather than road speed, then you still have a problem. In that case I would suspect that your cooling system isn't pressurising due to a minor leak somewhere.
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... now before we changed the items my v6 petrol 2.5 allways ran at 93 only hitting the 100c when standing still.
That's normal.
Quote:
Originally Posted by Steve42 View Post
... only problem i have had is the coolant filler cap. again brand new from dmgrs ... the top of the cap broke off in my hand and left the valve part in the filler part of the tank.
Please see my earlier reply:
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I'd suggest that you change your supplier to a recognised X-Part dealer.
Simon
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