Heater
 

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 chaned prt 82 degree new coolant flushed the system twice once with rad flush the digital temp reads correct fans come in as normal but still have the warm air problem till reved.

Hello Ed,

An 88 degrees thermostat is the correct specification for the UK.
Using the car's own instrument pack diagnostics, what running temperature are you getting?
After working on the cooling system did you follow the MG Rover procedure for refilling and bleeding? It sounds as if you have trapped air.

Simon

Did you bleed the system? It reads like an airlock if all.else checks out.(and a still slightly blocked matrix, if left and right temps are set equally via the atc or knobs - but I would solve the fluctuating temp first)

Sent from my SM-A600FN using Tapatalk

Heaat
 

I refilled the coolant system with bleed screw out till i had a flow of coolant topped to max set heaters and run the car with cap off then replaced waited for fan then switch off let cool then checked coolant i dont no the rover way so could be doing this totally wrong. On the dig temp it reads 80-85 the thing i noticed is if i put the heaters on it drops the temp quick. It is the manual heater controlls

Hello Ed,

You did refill and bleed more or less correctly as far as I can tell. Here's the official method for your 1.8T.

To find a 88 degree PRT and fit that would be my next move.

Simon

Thanks for your help. The return to the header tank is clear and the ball move freely but i always thought there should be a return flow through there or am i wrong

With a partially blocked matrix you will have less heat available to enter the car.

When you rev the engine the flow will speed up. Hence the incoming air feels warmer.

Your problem is the matrix.

Yes, I see your reasoning Jon and I don't disagree with it but Ed's coolant temperature is 10° too cool to start with ....
This is why I'm recommending that he begins by fitting the correct PRT then assesses the heater's performance again.
There's no return flow through the expansion tank Ed.

Simon

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.


https://www.mediafire.com/convkey/da...r457bxgf6g.jpg

Surprisingly, the relief valve is stamped 82°C.

https://www.mediafire.com/convkey/09...vvepcw4z6g.jpg

https://www.mediafire.com/convkey/0f...0po1y1jt6g.jpg


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