10uptobase Posted July 5, 2010 Share Posted July 5, 2010 Sorry if there is a thread I should have used - but coulnt see this exact fault... Driving back from Wales yesterday in the rain I had the hood up. No problem except evytime a drove in a "spirited" fashion, IE accelerating past a row of traffic uphill, I am getting vey hot air out of the heater vents. Aftyer a while it cools down to just slightly warm. It bloomin hot in the meantime! 😳 I checked and the valve is shutting correctly when the heater control is pushed in. Was wondering could the valve be faulty, but then why just when the engine is loaded? Could I be getting hot air into the vents from the engine bay? (The rubber is correctly fitted on top of the blower which seals on the inner surface of the bonnet.) thanks! Link to comment Share on other sites More sharing options...
Dan Marsh Posted July 5, 2010 Share Posted July 5, 2010 I noticed this when I drove my 7 for the first time this weekend. Opening the vents with knob in and out produced the same amount of hot air. Turning the fan switch on merely produced hot air at a greater rate. Does this just mean the heater need only actually be used in winter with the hood down? DM My Sigma 125 SV build photos Link to comment Share on other sites More sharing options...
fred_gustafsson Posted July 5, 2010 Share Posted July 5, 2010 I noticed a little bit of it too but closing the vents themselves takes care of it. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 5, 2010 Share Posted July 5, 2010 Closing the 'eyeball' vents doesn't stop the air passing through the triangular vents towards the front of the footwell though. Unless the heater valve isn't closing fully, the fan should only move air drawn through the bonnet louvres ..... this won't be the coolest of air at this time of year, but shouldn't feel 'hot' ? Link to comment Share on other sites More sharing options...
fred_gustafsson Posted July 5, 2010 Share Posted July 5, 2010 "triangular vents towards the front of the footwell"??? I can't recall seeing any of these on my RS175 SV. Are they connected to the heater? Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted July 5, 2010 Share Posted July 5, 2010 They are on my 2002 SV Link to comment Share on other sites More sharing options...
charlie_pank Posted July 5, 2010 Share Posted July 5, 2010 When you get these symptoms, do the pipes on the heater side of the valve get hot? back here because I want to be. Link to comment Share on other sites More sharing options...
10uptobase Posted July 5, 2010 Author Share Posted July 5, 2010 Was going to my next check ( Honest!!! Will check the pipes from the valve to see if they are hot with the valve shut - but why the change in air temp with engine load / speed ???? Link to comment Share on other sites More sharing options...
charlie_pank Posted July 5, 2010 Share Posted July 5, 2010 Air comes through the heater matrix that is full of coolant from the engine, the harder you drive the engine the more heat it produces. The faster it turns, the faster the water pump turns. If your heater valve doesn't shut off the water to the heater matrix, you'll get the symptoms described. back here because I want to be. Link to comment Share on other sites More sharing options...
john milner Posted July 5, 2010 Share Posted July 5, 2010 Check that the heater valve is actually shut when the knob is pushed in. Mine wasn't and I think it's a fairly common fault. If it is this then it is easy to put right by adjusting the cable where it connects to the valve. Link to comment Share on other sites More sharing options...
Gingerbread Man Posted July 5, 2010 Share Posted July 5, 2010 On the way back from Le Mans in the hot hot heat, I noticed that the heater was giving out hot air even though the heater was meant to be shut off. While stopped at a service station, I popped off the bonnet to find that the valve wasn't shut 100%. After making it fully shut by hand, hot air didn't come out of the heater. So is it 100% closed? Link to comment Share on other sites More sharing options...
bstark Posted July 6, 2010 Share Posted July 6, 2010 Other thing to check is if there are any unsealed gaps through the bulkhead - for example where the steering column passes through, pedal box if uncovered etc. Does your passenger experience exactly the same? Bob Stark Supersprinter Link to comment Share on other sites More sharing options...
10uptobase Posted July 6, 2010 Author Share Posted July 6, 2010 Its definatly coming out both of the vents - she was moaning too! Plan to check the pipes / manually adjust tonight. Thanks all! Link to comment Share on other sites More sharing options...
Team Escargot Posted July 6, 2010 Share Posted July 6, 2010 As Ginger suggested I would check the heater shut off valve they can seize up and not close properly (or the push-pull operating cable can get out of adjustment) Nick Link to comment Share on other sites More sharing options...
10uptobase Posted July 6, 2010 Author Share Posted July 6, 2010 Thanks. I did check the valve quickly when I got home, it was open a tiny fraction (about 0.5mm) is this enough to cause the heater to get so hot??? Will check again after a run tonight and manually close again / check if the heater pipes are getting hot. Thanks! Link to comment Share on other sites More sharing options...
10uptobase Posted July 6, 2010 Author Share Posted July 6, 2010 Hmmmmm. Been for a run, and same thing, tootle along - fairly cool, faster and air through the vents gets hotter. Checked and the valve still seems to be fully shut (but just to be on the safe side, have moved the cable in the clamp about 5mm, so the heater knob sticks out a bit now, even when pushed in all the way. Valve moves freely enough, but interestingly the top pipe from the valve to the heater is as hot as the rest on the engine, whilst the bottom is pretty cool (till the valve is opened then they are both hot.) Question is, is this normal? IE: Should the valve completely isolate the heater, or just shutting off the return? thanks! Link to comment Share on other sites More sharing options...
Team Escargot Posted July 6, 2010 Share Posted July 6, 2010 The heater valve only controls the flow rate not the temp so even if it is only a little open the heater will eventually be at the temp of the engine. Nick Link to comment Share on other sites More sharing options...
DaveMorris Posted July 6, 2010 Share Posted July 6, 2010 I find that mine does the same thing. To be honest I think that the valve is a diverter valve - either lets the fluid flow thru the matrix OR circulates the fluid through the "flow and "return" lines. Having looked inside one I can see why they woiuld easily pass slightly - and that is all that you would need. Link to comment Share on other sites More sharing options...
Jason Plato Posted July 7, 2010 Share Posted July 7, 2010 Check that there is not a gap around the area of the wiring through the transmission tunnel - this allows a huge ammount of heat to come into the cockpit. Other options include using a decent valve in the hot water circuit to the heater that you can completly shut off manually under the bonnet for summer months - I've used a simple domestic plumbing valve to do this in the past . The Caterham lever and valve appears to allow a % of water flow through on some. here is my Duratec R .... C7 TOP Taffia AO Link to comment Share on other sites More sharing options...
Area Representative Richard Price Posted July 7, 2010 Area Representative Share Posted July 7, 2010 Valve moves freely enough, but interestingly the top pipe from the valve to the heater is as hot as the rest on the engine, whilst the bottom is pretty cool (till the valve is opened then they are both hot.) Question is, is this normal? IE: Should the valve completely isolate the heater, or just shutting off the return? Yes, that's normal. The important indication is if the heater matix is hot or not. I'd guess that your cable adjustment should make a difference. Link to comment Share on other sites More sharing options...
Jaseb Posted July 7, 2010 Share Posted July 7, 2010 I had this problem last year predominantly caused by the 'draught excluder' stuff between the top of the air intake for the heater and the bonnet being shot causing air from the engine bay to sneak round the edges and on to my tootsies Link to comment Share on other sites More sharing options...
Tony Whitley Posted July 7, 2010 Share Posted July 7, 2010 Other options include undoing the heater feed and looping it round to the water rail, taking the heater out the circuit entirely. To clarify Dave J's suggestion: I'm pretty certain (on a K) you shouldn't block the heater feed on the engine side of the bypass, it's part of the main flow. Link to comment Share on other sites More sharing options...
10uptobase Posted July 7, 2010 Author Share Posted July 7, 2010 I suspect I have some "bleed" through the valve from the comments above. Will test run again now I have adjusted the cable. May live with it for the rest of the year as next "big" run is off to IOW in Sept - so hopefully not too warm. If touring Scotland as planned 2011, may have to consider an extra isolation... Thanks guys! Dave Link to comment Share on other sites More sharing options...
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