Hot ait intake

DanW · Post by **DanW** » Sun Mar 07, 2004 12:34 am

quick question... WHY do I need it?

SpikeyG40 · Post by **SpikeyG40** » Sun Mar 07, 2004 12:26 pm

basically, when the car has only just started, u need warmer air so that the car has time to warm up, once the car has warmed up, a valve moves closing the hot air feed n opening the normal air feed.

thats why, when u put an induction kit onto some cars it doesn't run too well when its cold! thats bout it really!

hardhitter · Post by **hardhitter** » Sun Mar 07, 2004 1:39 pm

You don't need it.
It's put there from factory to help warm up quicker, if you take it off it might take slightly longer to warm up, thats all.
It wont make it run bad in the cold. Only cars with carbs suffer from this.

SpikeyG40 · Post by **SpikeyG40** » Sun Mar 07, 2004 2:20 pm

thats true, although i was told that only multi point injection cars don't need em! my dad reckons that u do need it on the single point injection cars n he's delt with these for a long time, we'll have to see when i get my induction kit on! gotta change the breather pipe to get it to fit!

DanW · Post by **DanW** » Sun Mar 07, 2004 6:07 pm

"thats true, although i was told that only multi point injection cars don't need em"

if thats right then i dont need one then?

amstrange1 · Post by **amstrange1** » Mon Mar 08, 2004 9:27 am

Dan's right - it'll take longer to warm up but that's all.

My mum's Mk4 had been running without the warm air feed connected, and a fair bit of mayo had collected in the filler cap. The journeys the car was doing weren't long enough to let it warm up properly, but now the warm air feed's back on it does and the mayo's gone. Worth thinking about if you don't drive your car a fair distance very often.

DanW · Post by **DanW** » Mon Mar 08, 2004 9:33 am

Yeah I don't always drive that far,15min walk cos im lazey, to college and back. Or if im feeling like driving fast, back roads trying to squeeze the car to 70 down a well known back road. But even then it doesn't warm up above the 70 mark. Time for a new temp sensor?

amstrange1 · Post by **amstrange1** » Mon Mar 08, 2004 11:35 am

If it doesn't get above the 70 mark on a run it's either the black temp sender for the temp gauge, or the thermostat that needs changing. Judging by the amount of discussion amoungst Mk3 owners on this topic recently, many of them are finding they need new thermostats which cure the problem. They're less than a tenner new from VAG - not sure on the price of a black temp sender, but I'm guessing around Â£15 for a genuine one.

optima21 · Post by **optima21** » Mon Mar 08, 2004 1:33 pm

I think I've got a 70C thermostat in my GT, but its worth a note that if you have a modified engine its worth running at a cooler temprehature as it could prevent the engine knocking when you hit the loud pedal as the intake charge will be slightly cooler.

DanW · Post by **DanW** » Mon Mar 08, 2004 3:28 pm

I'll try and get some running stats this evening with my bro.

amstrange1 · Post by **amstrange1** » Mon Mar 08, 2004 3:37 pm

optima21 wrote:I think I've got a 70C thermostat in my GT, but its worth a note that if you have a modified engine its worth running at a cooler temprehature as it could prevent the engine knocking when you hit the loud pedal as the intake charge will be slightly cooler.

I thought there was only one thermostat available for the Mk3? Or is yours a non-VAG part?

Some guys on the G40 group were discussing the merits of having a stuck thermostat and the temp not getting over 70C. I think in the end people decided it was better to having it working properly, as the engine's designed to run at a certain temperature and then ran better etc. I forget all the reasons - there's a post on the Pitstop forum about it. As a result a whole load of people went out and bought new thermostats!

amstrange1 · Post by **amstrange1** » Mon Mar 08, 2004 3:41 pm

DanW wrote:Yeah I don't always drive that far,15min walk cos im lazey, to college and back. Or if im feeling like driving fast, back roads trying to squeeze the car to 70 down a well known back road. But even then it doesn't warm up above the 70 mark. Time for a new temp sensor?

Does the gauge move if you leave the car idling for a while after a hard thrash? Even with a dead thermostat it should climb up the gauge a bit then. With the temporary GT engine I've got to tide me over til the G40's rebuilt I'm fitting a new thermostat as a matter of course, along with a new blue temp sender. Might not bother with a new black one seeing as I've got a couple of working spares.

DanW · Post by **DanW** » Mon Mar 08, 2004 4:24 pm

I've never left it idling on my drive before, but in the bad traffic coming back rom swansea, i saw the steam evaporating the water from the engine bay. The temp at then was around the 95 mark. But it quickly disapated going along the motorway, then it went back down to it's normal 65/70 deg

*eidt, just ragged it all the way home (ok not that long but i was trying to rev it all the way home lol) and it only got to about 65deg. edit*

optima21 · Post by **optima21** » Mon Mar 08, 2004 6:04 pm

amstrange1 wrote:
Some guys on the G40 group were discussing the merits of having a stuck thermostat and the temp not getting over 70C. I think in the end people decided it was better to having it working properly, as the engine's designed to run at a certain temperature and then ran better etc. I forget all the reasons - there's a post on the Pitstop forum about it. As a result a whole load of people went out and bought new thermostats!

well if an engine is showing that its warming up then it shows the thermostat is working. I've got the thermosta that came with the car, but I know that 70C ones for triumph herald 13/60's will also fit.

The main reason I believe fitting higher temperature thermostats is that it reduces emissions from the engine. If you look historically engines in general used to run much lower temperhatures than they do today. Another reason could be that the aluminium conducts more heat away from the combustion chamber, so at smaller throttle openings a warmer engine will give slightly more power than a cooler one. I think I once read somewhere that an engine with a cast iron cylinder head will produce 3% more power than one with an aluminium cylinder head just because of the difference in thermal conductivity.

hardhitter · Post by **hardhitter** » Mon Mar 08, 2004 6:52 pm

Ok, a few things on the cooling system.

The green gt I've just got on the road has had amongst other things a new thermostat & housing. It warms up really quick (without a warm air feed) and stays at a fairly constant temperature (around 90 on the gauge).

If your polo takes a while to warm up (or seems to) it could be a few things. Your thermostat needs renewing or the black temp sensor is giving false readings to the gauge.

If you renew the thermostat, get a genuine one which is about Â£10 plus the seal. The thermostat housings are very fragile and break quite easily, again they are about Â£20 from vw.