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BASSPLUCKER View Drop Down
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    Posted: 18 Oct 08 at 19:49
Hi all, does anyone know what the fan on the side of a 2.4 petrol engine is for? It has a tube about 40mm in diameter which stops just before the carb and the other end vents down to the ground. I think it is either to pull petrol vapour away from the carb or its there to cool the carb. It cuts in on its own when the engine is stopped. Any ideas?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SyncroSpares UK Quote  Post ReplyReply Direct Link To This Post Posted: 18 Oct 08 at 20:40
carb cooler,surprised it still works,cj.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BASSPLUCKER Quote  Post ReplyReply Direct Link To This Post Posted: 18 Oct 08 at 20:53
so it is a cooler, it seems to come on way after the engine has been stopped. where is the sender?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote grahamthemaker Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 08 at 20:29
is a warm air inlet? not sure about the fan??
1984 LT 31 2.4 petrol.bit slow but sounds great!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote team french Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 08 at 20:46
my guess is that its cold air to prevent heat soak in to the carb from the residual heat from the engine. got to remember that engines heat up slightly once turned off(no air flow and the cooling system stops circulating) with the engine position on the LT it will contain the heat and the remaining petrol in the carb bowl will vaporise quickly. thus ingnition dangers and it could even be because of emmitions control. just my theory mind
1978 2litre LT28 abbomination!!!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Swidda Quote  Post ReplyReply Direct Link To This Post Posted: 24 Oct 08 at 09:38
Originally posted by team french team french wrote:

my guess is that its cold air to prevent heat soak in to the carb from the residual heat from the engine. got to remember that engines heat up slightly once turned off(no air flow and the cooling system stops circulating) with the engine position on the LT it will contain the heat and the remaining petrol in the carb bowl will vaporise quickly. thus ingnition dangers and it could even be because of emmitions control. just my theory mind
That makes sense, my petrol 2,0 Lt is a pig to start when it is stopped for more than 5 minutes after it has been running, when it starts again it is smokey for 2 or 3 seconds but it's not burning any oil or losing water, and the smell is just like concentrated regular exhaust fumes, If you theory is correct then the evaporated petrol may be condensing in the manifold or the carb venturi again causing an over rich mixture making it smoke and show reluctancy to start? anyone else's van suffer from this? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote team french Quote  Post ReplyReply Direct Link To This Post Posted: 24 Oct 08 at 12:34
if its the same as mine it needs a non return valve fitted in the fuel line as the fuel flows back to the tank when the ignition is off, if you can see the fuel filter thru the inspection flap see if it fills up when you turn on the ignition(first click)dont know if they all do this or if my pump is on its last leggs. when i bought it they told me theres a special knack to start it(turn it over once with no throttle wait for a second then touch the trottle,turn it over again, do three rolly pollys, rub tour head and pat your tummy, count to 5 in arabic then it will start. or at it was something along those lines ) but i realised that it was the fuel filling up the carb you had to wait for. turn the key to the first click wait a few seconds then crank and it fires first time. dont know about the smoke tho, could be an over rich mix like you say.
1978 2litre LT28 abbomination!!!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Swidda Quote  Post ReplyReply Direct Link To This Post Posted: 26 Oct 08 at 20:57
Cool! I'll check that out! My knack to starting it is foot to the floor and hold the key in the start position and count backwards from 100.

Edited by Swidda - 26 Oct 08 at 21:40
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Post Options Post Options   Thanks (0) Thanks(0)   Quote grahamthemaker Quote  Post ReplyReply Direct Link To This Post Posted: 27 Oct 08 at 09:33
i just pump the throttle two time, turn the key it starts. But it's harder to start when it's hot.
1984 LT 31 2.4 petrol.bit slow but sounds great!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MerlinusTheWizard Quote  Post ReplyReply Direct Link To This Post Posted: 08 Nov 08 at 11:01
Glad to find this post - a while back, I bought a 1988 LT35E 2.4 6-cylinder petrol which has this fan, and I have had a great deal of trouble finding anybody who knows anything about it (or indeed how to get the engine working properly!). It doesn't get any mention at all in my trusty Haynes Manual (which only purports to go up to 1987).

My first theory on the fan was that it was to keep the carburettor cool (given the very cramped and enclosed installation of this large engine), to stop the fuel vaporising too early. However, I spoke to the garage that maintained the vehicle for many years for a previous owner (Autohaus), and they said that it was precisely the opposite - apparently the carburettor is prone to icing-up (perhaps because of the jet design), and the fan is there to duct warm air from near the exhaust to stop it from freezing! Does this make sense to anybody? I have never followed the ducting to the bottom end, so I don't know whether it starts near the exhaust.

The problem I have with my fan is that it takes *forever* to finally shut down after the ignition is turned off - it switches in and out erratically (sometimes you can hear the relay buzzing even) for an hour or more. When I am sitting in the van, having arrived on site, I have often felt like  tearing out the fuse to stop it!

The engine also exhibits the following issues:
- very poor running when cold
- poor fuel consumption (18mpg on the motorway, 14mpg on lumpy roads)
- low power (20mph on steep hills) - I would expect much better from a large engine like this; I had another LT 10 years ago, and I swear it went much better than this one, but I can't remember whether it had this engine or the Audi 5-cylinder (is that likely?)
- difficult to start when hot

So, it may be that my expectations for this engine are too high (and from looking around this forum, that may well be the case!) - and some people have said to me that this was not one of Volkswagen's better engines - or it may be that all these issues (cold running, performance, fan running on) could all be down to one malfunctioning temperature sensor somewhere.... anybody got any ideas?

Of course, the final drastic action if I can't find somebody who can sort out the engine woes might be to swap the engine altogether, perhaps for a better petrol engine or a diesel engine (although it would be a shame to lose that lovely six-cylinder sound!!). Does anybody have any experience of doing this, or any suggestions?
LT35E 1988 2.4 Petrol Cutty Sark
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Post Options Post Options   Thanks (0) Thanks(0)   Quote team french Quote  Post ReplyReply Direct Link To This Post Posted: 08 Nov 08 at 12:39
hi merlinus. its possible that its to stop icing but id be supprised as the the oven like conditions that it sits in. my previous posts are only my theorys any way and as i have a 4cyl 2 litre i dont have the said fan as a sugestion on your running problems tho, as a starting point id renew(unless you know they are newish) your plugs,leads,rotor arm, dizzy cap and fuel filter, these will posibly have no effect but it rules them out. checking your timing is an idea. and ive heard that its a good idea to fit a manual choke as the autochokes can be a bit dodgy.

Edited by team french - 08 Nov 08 at 12:41
1978 2litre LT28 abbomination!!!!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MerlinusTheWizard Quote  Post ReplyReply Direct Link To This Post Posted: 09 Nov 08 at 20:35
Thanks for your advice team french. All the items you mentioned have recently been replaced, in fact, to no avail, unfortunately. You could well be right about the automatic choke though - if that malfunctioned, it could make all sorts of mad things happen (except make the carburettor fan run on for so long!). I'm tempted to just disconnect the carburettor fan altogether, and see if it makes any difference....

Anybody have any thoughts on that engine swap? I should probably start a new thread for that one...
LT35E 1988 2.4 Petrol Cutty Sark
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Post Options Post Options   Thanks (0) Thanks(0)   Quote grahamthemaker Quote  Post ReplyReply Direct Link To This Post Posted: 10 Nov 08 at 08:41

sounds like choke problems to me. Although your mpg is about right it could be improved but not by much. I'd get a service kit for your carb and take it to a rolling road. they will put all together and give it a tune for around £80 to £120. should sort it out, worth a go before doing and enging swap.

1984 LT 31 2.4 petrol.bit slow but sounds great!
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