Advantages of the short nosed bonnet?

toddao · Post by **toddao** » Sun May 17, 2009 5:23 pm

Today when I was driving along the autobahn at average 130 kms with 25 degrees outside I was watching the recently installed temp gauge hovering around 90 degrees and I started thinking that the short nosed bonnet offers better opportunities for air-flow through to the top of the radiator. Perhaps this is why they changed it and it wasn't just a styling excercise? ( plus the plastic grille thing that sits there is designed like a air duct)

I've got the original long nose steel version which probably not only provides less airflow ( as the nose sits almost on the bumper) but also dissapates heat more slowly. It got me thinking that I should switch to the short nose plastic version - also it must be 5 KG lighter I reckon.

Any thoughts?

Post by **mat_fenwick** » Sun May 17, 2009 6:30 pm

toddao wrote:25 degrees outside

Lucky sod!

I reckon it was mainly for the extra cooling, wasn't it just fitted on the turbo diesels and valvers?

toddao · Post by **toddao** » Sun May 17, 2009 6:49 pm

Have you got a long nose bonnet then on your car Mat? My yellow one has the short version.

Yes it was pleasant enough today for shorts and the father-in-law helped me make new fixings for the rear louvre which, of course is Stylin but also provides shade for the little one in the back when the sun has got his hat on!

Post by **mat_fenwick** » Sun May 17, 2009 8:29 pm

No, mine's the short nose. I wonder if there was any logic to the cars Citroen fitted them to? Hey, you could always swap it from the yellow one while it's 'resting' and have a 2 tone silver and yellow BX!

Post by **Tim Leech** » Sun May 17, 2009 9:44 pm

As fair as I know it was to aid cooling, from memory ALL automatic and turbo diesels have them as standard, I prefer them with the short nose and small grille.

DLM · Post by **DLM** » Sun May 17, 2009 11:02 pm

Sounds more like thermostat and/or radflow problems to me than airflow if it's a steady 90 degrees - even in higher temps. Try the swap and see if it makes any difference. I suspect your temperature gauge is telling you something you don't want to know. A long-nose TGD I owned with temp gauge fitted was fine after radiator flush until the silting-up of the rad started again, and it moved from the low 80s to the upper 80s.

Late normally-aspirated diesels have short-nose metal bonnets (19TXD).

The short-nose on turbodiesels helps allow extra airflow to the intercooler, as much as anything else.

kiwi · Post by **kiwi** » Mon May 18, 2009 1:32 am

I respect what DLM has posted that the problem is not the bonnet but your new gauge telling you something about a problem you didnt know about before, most of the time DLM is right.

Probably is something in the cooling benefits of a short nose and saying that my 19TZS is short nosed where as the 19TRS is long nosed. Gets more interesting when I tell you a 19TZS I had the interior off had a long nosed steel bonnet.

Only thing I have noticed is that the BXs start better once they are warm or the surrounding air temp is up. Doubt anything to do with the air intake from the grill.

You say it was 25 C and you were doing 130kph! You lucky thing atempting 130kph around here either results in a speeding ticket or more likely running out of road

As for temperature wanna trade!!! Winter has come early 15c is as warm as its got and as for the rain....aghhhhhhh!!!!

So if the grill has an effect then during the colder months the reverse effect of over cooling could be present?

interesting

DLM · Post by **DLM** » Mon May 18, 2009 2:00 am

Thank you for your kind words, Kiwi. I'm certainly fallible - and didn't notice the speed mentioned.... a case of "Wir Fahren Fahren Fahren auf der Autobahn" speeded up just a bit.

I did once end up with a BX where the previous owner gave it up because it overheated mildly at a steady 90 mph in warm weather. It needed a new thermostat and a good flush of the cooling system and then drove like a dream - I was stupid to let it go in favour of a rather bigger red BX rustbucket some time later.

Winter has come early 15c is as warm as its got and as for the rain....aghhhhhhh!!!!

That's a pretty good description of the late spring here at the moment.

toddao · Post by **toddao** » Mon May 18, 2009 8:41 am

Thanks for replies. I did give the cooling system an overhaul a month or so back : flushed the whole system with some Wynns cleaner, then removed the rad and back flushed it. I took the thermstat out and tested it in the pan of hot water and it responded accordingly. I have since acquired a new one which I suppose I should fit one anyway, perhaps when I do the cambelt and water pump.

Regarding speed - 130 kmph here is moderate compared to the other German tin whizzing by at heaven knows what speed. The BX travels quite smoothly up to 150 Kmph and is remarkably quiet with the radio still clearly audible.

On normal local trundling duties the temperature stays around 80 but always when sat at lights goes up to around 90 til the fan cuts in at 91 degrees. I wanted to fit the fan switch that comes in earlier that Jon specified in BXDIY as FAE3780 - but I can't source it here, the number doesn't match any search at auto factors. So if anyone knows where I could find it or for what vehicle it was originally specified.

As for the weather Kiwi - we all go green here when your temps start to climb up as we slip into Winter. The perfect scenario would be a migratory lifestyle following the seasons

DLM · Post by **DLM** » Mon May 18, 2009 3:22 pm

Thanks for replies. I did give the cooling system an overhaul a month or so back : flushed the whole system with some Wynns cleaner, then removed the rad and back flushed it.

Apologies Todd - forgot you'd been through that cycle and I switched to autopilot posting mode. At least you can now see what 's happening and cross-reference temp and fan cut-in, though it'll always be a few degrees higher at the head/thermostat end than the other end of the rad. Poor thinking on PSA's part. You can keep an eye on what's happening now without guesswork and so long as the temperature doesn't suddenly soar on leaving the 'bahn you shouldn't have need to worry.

Jaba · Post by **Jaba** » Mon May 18, 2009 5:50 pm

Todd, yes its getting a bit hotter than it should. The fans should never have to come on when you are at these sort of speeds.
Do you have a rad cold spot anywhere, usually at the bottom ?
If the cooling system is marginal then the temperature will rise with speed and keep rising.

The fan switch temperatures are stamped on the switch body. From memory I think there are two colours, black and blue. will check my stock and let you know which is which and the cut in and out temps.

toddao · Post by **toddao** » Tue May 19, 2009 11:52 am

Jaba asked

Do you have a rad cold spot anywhere, usually at the bottom ?

No, it gets uniformly warm since it was flushed. The fan switch that I've got ( I looked today) is 88/92 but if anyone does know where I can get the lower temperature 82/88 version that would be appreciated. We're expecting very high temps at the weekend and I'm doing a long journey so I'll keep an eye on it.
Before I had that gauge I drove in blissful ignorance and now I'm fixated on it. It doesn't help that it's digital and more precise than the traditional needle style!
As DLM observes - there is quite a journey for the water between the thermostat and sensor til the fan switch by which time the temp will have gone down I suppose.

prm · Post by **prm** » Thu May 21, 2009 12:37 am

Todd

The lower temp rad switch
Fan/s slow speed, – on @84°C, off @ 79°C.
Fan/s fast speed - on @ 88°C, off @ 83°C

Utilising a 82°C thermostat, (which is fully open at 90°). with the lower temp rad switch. The slow speed fan will start to operate at 91-92°C, as there’s 8° temp difference between the positions of the stat and thermal switch. Presuming yours is sited at the lower base of the inlet side of the rad.
With this set-up, fans should only come on at low road speed, heavy load or stationary.

Might save you some fuel??

For a factor part No. - try Intermotor, 50101, 84-79 / 88-83°C
Or numbers below

Alfa Romeo 60533503
Citroën 1264.16
Citroën 95630939
Lucas SNB715
Lucas SNB796
Peugeot 1264.06
Peugeot 1264.16
Valeo 819772

Vehicles Using Part 50101

ALFA ROMEO 33 1.8
CITROEN BX 1.8
CITROEN BX 1.9
CITROEN C15 1.8
CITROEN C15 Champ 1.8
PEUGEOT 205 1.0
PEUGEOT 205 1.1
PEUGEOT 205 1.2
PEUGEOT 205 1.3
PEUGEOT 205 1.4
PEUGEOT 205 1.6
PEUGEOT 205 1.8
PEUGEOT 205 1.9
PEUGEOT 205 Cabrio 1.1
PEUGEOT 205 Cabrio 1.4
PEUGEOT 205 Cabrio 1.6
PEUGEOT 205 Cabrio 1.9
PEUGEOT 305 1.5
PEUGEOT 305 1.9
PEUGEOT 504

Regards

toddao · Post by **toddao** » Thu May 21, 2009 1:31 pm

Thankyou for the reply prm. That's very interesting and makes me feel better about my journey tomorrow.

I will try to get the lower temp switch next week. All those switches on that extensive list would presumably fit the thread on the BX rad and offer the three pin plug option?

Where did you find such infomation prm? I scanned the net without luck.

toddao · Post by **toddao** » Thu May 21, 2009 6:02 pm

I've now tracked one of these down and bought it - made by Quinton Hazell - it was €7 cheaper than the Valeo version. Thanks again prm, I'd wasted quite a lot of time going round auto spares places here without result.

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Advantages of the short nosed bonnet?

Advantages of the short nosed bonnet?

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