Quote:
Originally Posted by rover_ed
Hi my zt 1.8t is blowing warm air through the heaters when stationary. If i rev it just to 1k rpm it comes through nice and hot, slightly cooler on pass side. I have changed PRT (to) 82 degrees - - - -.
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Hello Ed. Getting into the realm of the PRT these days is like studying the Black Arts. You don't mention your car's year, but I guess like mine your 1.8Turbo was fitted with the original buff coloured PRT? If that's the case, then it was certainly rated as 88°C by MGR. However, like many aspects of car mechanics, things aren't always what they seem. I have here an OEM buff PRT from a 2004 1.8T (not mine) that failed in service due to oil contamination. One way or another, a detached bit of rubber got trapped in the main vave, so preventing closure.
Anyway, as part of a larger investigation, this stat was dismantled to examine the innards.
Surprisingly, the relief valve is stamped 82°C.
So, is it an 88°C or an 82°C? The odd thing is this detail is not visible unless the stat's cut apart, so you might say it means nothing useful. This PRT's actual 88° rating was defined by MGR through the colour of the plastic body, in this case buff=88°C. My OEM buff one ran the engine at 93-96°C.
Unfortunately, that was then and this is now. The case colour is still supposed to tell you its temperature rating, but it really depends on where you go for your PRT.
If you want an 82°C one - and I did, so I can understand the logic - you should look for the grey one. That's what they reckon to fit in the 1.8T engine for the Lotus Elise. I bought one, but after measuring the refief spring tension, decided not to fit it. As an extended trial, I'm currently sporting the black version (82°C, purportedly low pressure). While this runs about six degrees cooler than the 93-96°C from the OEM buff, I see no pressure relief operation at all.
Did you get your replacement from DMGRS? Hmm, more confusion then.
The DMGRS (Buff) PRT listing for 1.8T says:
Originally PEM100990 referred to the 88 degree item - since these are 82 degrees, I've also added the 82 degree part number (PEL500110) as this is cross-compatible." Errm - -
There's an even lower one at 78°C (grey -?) though I can't imagine why.
As to your heater problem, I think you probably have an air lock. I sounds like the matrix is starting to silt up, so a backflush with a hosepipe might fix the passenger side heating.
Good luck.
TC