Cooling/ Heater Mod fix

I have a 97 mgf MPI with the later alloy vvc manifold and PRT fitted.
when I bought the car I was losing a little water and changed the pipework and manifold and she is now water tight and runs well.
But.... (there is always a but .....)
The heater is a bit meh, fine in the summer but...
this part of the 25 interest factiods posted on .Org caught my eye

"17 Have you got a late 2003-built TF with an ineffective heater that is not cured with a higher than RD 622951, then the car may be missing a flow restrictor within the four way hose connection. That VIN was he effective Pressure Relief Thermostat (PRT) was introduced during production (June 2003) and the coolant hoses were reconfigured. If the restrictor is missing, then not until the engine is revved will coolant flow through the heater deliver effective heat."

This describes my problem exactly. Sooo, do I ?
1 locate the correct pipe/restrictor and fit it.
2. fit a restrictor near the rad and restrict the flow there, as it is much easier to work in the front.
I am presuming the restrictor reduces flow to the rad and diverts it to the heater in a controlled way, but I am often wrong.
any thoughts or advice gratefully received

Carl,
The 4 way connector wasn't introduced until the TF. The F has a more complicated pipe setup that already includes a restrictor to push water to the heater circuit so unless you(or a previous owner) have changed the pipework this shouldn't be your problem.
You need to look at the pipe/hose configuration where the coolant outlets the engine and the hoses connect to the metal engine coolant pipes to tell.

The F 4-way hose setup is in the orange circle.
In the TF this is simplified into a 4- way plastic connector.


This shows where the restrictor is positioned on the F hoses. It was this restrictor that dropped down out of position and blocked the hose below causing the split you can see.

First thing to do is check that the valve is opening fully. Take of the trianguler kick panel and follow the red bowden cable. Rotate the control knob and watch the travel. Clive has a how to on adjusting it.
With the engine up to temp, lift out the ashtray and you can feel the heater pipes against the side of the tunnel. If all is good they should both be red hot(careful!)
Check there's no air in the heater matrix.

David Aiketgate wrote: First thing to do is check that the valve is opening fully. Take of the trianguler kick panel and follow the red bowden cable. Rotate the control knob and watch the travel. Clive has a how to on adjusting it.
With the engine up to temp, lift out the ashtray and you can feel the heater pipes against the side of the tunnel. If all is good they should both be red hot(careful!)
Check there's no air in the heater matrix.

Thanks for the pics and explanation. My pipes are similar (but no rusty damp bits )
I have previously checked the heater valve and it is working well, but a re-bleed cant hurt the heater.
The heater pipes have always been warm/hot but not red hot.
When I fitted the PRT I used the old stat with the centre removed as per the instructions I was following. I cant help thinking the water just needs encouraging around the heater citcuit.

The heater pipes should be too hot to keep your fingers on for long.
Do you know if the heater worked well before the PRRT was fitted? Is it the correct PRRT? What colour is it?
Does the engine get up to temp quickly?

I do remember the heater working well when I first had the car,prior to hunting down the manifold and other small leaks. The engine was rebuilt about 40K ago the paperwork suggests the garage made a costly mistake and paid to rebuild it at a specialist. I generally bleed and bleed again a day later to be sure. The car doesn't warm up that quick,it gets up to quarter temp after about 5-6 miles of 40mph driving, just as I hit the motorway usually.
The PRRT is a cream one S/H from one of the Main resellers.
I have ordered a new cream PRRT from Rimmers and I will replace the PRRT and see if that makes any difference.
I had the chance to look at it all last night cover off and everything seems bright and tight but there is a marked difference in temp between the two sides of the system; cooling is as you describe but heating is only warm. The fluid is a steady clear blue no signs of previous contaminants.

Carl...

If your coolant is BLUE then you need to swap to PINK as its the wrong kind if coolant in your car. As far as In know all MGFs and TFs use Pink OAT coolant

I am sorry but I believe the correct coolant for early F models is ethylene glycol. I am not sure that this would affect my heater problems though.
Thanks for the reply though.

What about the temperature sensor? Could that be a contributor factor in this? I'm no expert on these things, just picking up knowledge one fault at a time. Good luck in curing it. I had a cold heater in my old TF, turned out the cable was a bit higher than usual and a clip had come off the dash vent.

I have replaced both sensors this year, and the knob on the dash.
I joked with the scrap man recently that he could have nearly built another F out of my throw-a-ways this year.

Would the heater be affected if the flow was reversed in that part of the circuit only? I seem to remember when fitting the PRRT that there was the potential to put the hoses on either way.

I am inclined to believe that either the heater circuit is partially blocked or the cooling circuit isn't restricted enough to encourage flow through to the heater

Do make sure the heater control knob hasn't split the sleeve the grips the shaft,
if it has it will slip on the shaft and you may not be opening the heater control valve enough to get sufficient flow.
It's an easy thing to check and as easier to fix. So it's wise to pull the knob off and have a look before you go to a lot of effort chasing other causes.