Car overcooling?

Post by **pettaw** » 19 Jun 2005 10:16 pm

Nope, its not the fan clutch. Change your thermostat. In the 1.4s and 2.0 its in the top hose for the radiator, where it exits the engine block. On the 1.7s its behind the cylinder head, below the dizzy cap.

Cost: about 10 quid from the dealer for a proper Volvo one. I find they last about 3 years before they start going soft and need changing because of over cooling. The cheapy ones don't keep a steady temp and don't last more than a year.

Just a quick tip, as I'm sure there are quite a few 300s out there that are not warming up properly and therefore slowly getting damaged.

Post by **foggyjames** » 20 Jun 2005 10:41 pm

My car's temperature has been getting increasingly less stable over the last few months...time for a new thermostat for sure! That and the electric fan conversion should see my cooling system be more than up to the job of coping with the extra heat from the increased power!

cheers

James

Post by **Vario Si** » 20 Jun 2005 11:09 pm

Where exactly should the temperature dial be pointing to when the engine is nice and warm? I don't love the small gauges the cars have... with not many markings on them!

Cheers

Simon

Post by **lentinj** » 20 Jun 2005 11:21 pm

When perfect the needle should be vertical, pointing exactly at the LED.

Least, that's what mine always used to do. Since replacing the radiator several years ago it points at the left edge of the LED when warm.

Maybe I should also change mine, but I normally change my mind when I look at what I have to do to get to it on the 1.7....

The gauges could be alot worse. A micra just has a light for too cold, a light for too hot, and a new Yaris' fuel gauge is 4 LED segments. Our renault 5 has a better fuel gauge than that, and that jams constantly.....

Post by **5lab** » 20 Jun 2005 11:52 pm

one of the things thats nice about early 340s.. they warm up QUICK (under 5 mins of idling) cos of the small rad.. the temp can rise a bit if its hot, but then it drops back down again when the fan comes in, which sorts it

Post by **Vart** » 23 Jul 2005 02:40 pm

are 1.4 thermo's the same as 1.7 thermo's?

Post by **pettaw** » 23 Jul 2005 03:01 pm

Post by **pettaw** » 23 Jul 2005 03:06 pm

James, when your car's running, that mechanical fan can pull in far more air than any electric conversion so really, buying a new fan clutch and new thermostat will be more than adequate to deal with the increased power you have then once the engine is cooled down, the clutch will pull in and will hardly use any power.

I can hear the difference particularly with the A/C on, when pulling off at the lights, after about 20 seconds of the fan roaring away, it quietens right down as the clutch disengages.

Post by **foggyjames** » 23 Jul 2005 03:53 pm

I haven't posted this yet, but my undercooling was due to a totally shot radiator. If anything, I'm now running cold! The trouble is, for the cost of a new fan clutch, I can have an e-fan which doesn't prolong my warm-up, and doesn't drag at high rpm. Ravennexus said the difference at high rpm was amazing when he fitted one to his 240. I think it's one of two (or maybe three) things making my peak power figure appear at 5500 rpm rather than over 6000.

Of course it wouldn't make 'the' older Volvo sound without the VC fan...

cheers

James

Post by **pettaw** » 23 Jul 2005 04:43 pm

Once you get a new thermostat in, warmup won't be prolonged if there's a force 10 gale blowing through the radiator because its shut off solid by the thermostat.

Interesting to hear the Ravennexus experience. Trouble is that if its on a dyno, then you're not going to get that windmill effect and also on a dyno run, the fan clutch won't have cooled enough to disengage so probably on test it would make a difference, but I still would say in reality it makes very little difference.

Post by **foggyjames** » 23 Jul 2005 09:29 pm

Mike's experience was based on on-road use - We've tried getting him to do a dyno run...

He said it was quite noticable...I'll ask him again when I speak to him next.

I've read a number of 'keep the VC' type articles, and they generally seem to be written by uber-cautious old-timer mechanics (or based on the opinion thereof)...the kind who said my engine was worn, and the old carb was just fine (looking back, there was obviously something wrong with it)... There are very good reasons to keep the VC ("if it ain't broke, don't fix it" being the main one stopping me jumping in with both feet)....but the tone of these articles doesn't help!

We boiled up my thermostat, and it worked just fine. I know this sounds daft given that the radiator shouldn't be in the circuit, but e-fan cars always seem to warm up faster - notably in 940s, where you get both VC and e-fan versions. I don't have many suggestions regarding why this is, but one is that only one end of the pipework is sealed off by the 'stat.

You'd struggle to buy a modern car without an e-fan, so I think I'll follow - in the pursuit of efficiency!

cheers

James

Post by **jtbo** » 23 Jul 2005 09:42 pm

I can monitor my engine temp quite well and what I have noticed is that when stopped at traffic light engine temp is few degress(C) less than driving 100kph. This is case when temp is +23C, but after rain temp goes to +15C and then there is no difference.

Intake air temp is very much different then, at slow speed cruising in town it gets to around +50C while on highway it is same as ambient temp. This seems not to affect to engine temp in any way, only power is clearly cut down when temp goes high.

Engineroom temp is changing as intake air temp, there seems to be enough air flow to keep things cool, maybe also bit too cool in cold weather, it could be that thermostat is closed but still it is hard to get proper heat to engine when there is so much wind that cools engine block.
This was case in one car at work, there was not enough heat to defrost windscreen at -20C....

Post by **pettaw** » 24 Jul 2005 08:32 am

I've noticed that even the worn ones open and close when boiled up. Unfortunately they don't seal against the pressure of the cooling system. If you take the stat out and try and push open the flappy thing, you'll probably find you can move it slightly with your fingers.

As regards the fan thing, after being stuck on the A2 when it was closed in unbearably high heat. I found the viscous fan AND the auxiliary fan too weak to cool the engine, even with the A/C off, and found myself winding the window down and putting the heater on max. Especially with the rebuilt, didn't want to overheat that with less than 500 miles on the clock.

So I am interested in an electric conversion, if I can find one that can mimic an OE setup and run on low speed all the time the A/C is on, switching to high when pressure or temperatures rise.

Just trying to see both sides of the argument. For example BMWs are designed as performance cars and most of them still use mechanical fans.

Post by **jtbo** » 24 Jul 2005 09:19 am

Like this?

http://www.turbobricks.com/mods.php?content=art0008

Post by **pettaw** » 24 Jul 2005 10:12 am

Similar, but he has no low speed option.