How to... Type 4 engine, cooling guide

Discussion in 'How To' started by Joker, Jan 6, 2012.

  1. I'll be building a new engine soon so will improve this with a complete photo guide of what goes where. But for now, see below for a guide to how it all goes together and what it does.

    :)


    Here is the fan casing front.

    [​IMG]

    Here is how the air to the rear of the engine is channeled down around the cylinder heads on the left hand side (you're looking at the rear of the engine which sits towards the front of the van.

    [​IMG]

    The lower 'under pushrod tubes spanned between heat exchangers and engine which are like rocking horse poo' tins attach to the rear part of this tin. This ensures that the air is directed to the rear of the vehicle

    Here is how it looks on the right hand side of the engine

    [​IMG]

    You can also see the 'heat riser' tube. This takes some of the warm and feeds into here

    [​IMG]

    This connects to the air filter intake box and behaves as a warm air intake which prevents the carbs from icing and helps the engine warm up quicker

    So now, if you look here this is the upper over cylinder tinware as it is fitted to the engine on the left hand side as you face the front of the fan casing.

    [​IMG]

    Directly beneath this side is your oil cooler, look here for how the engine looks without all of its tinware

    [​IMG]

    So now, what you can see on the left of the engine is the oil cooler, on top of this you can see a piece of tinware. There is also a piece which fits to the opposite side on the other cylinder bank. As you can see, whilst it has a gaping hole in it which channels the air onto the cooler, it is also shrink wrapped around the cylinders, as it also channels air onto them. This is what the one on the other side does.

    As you can see in the picture below, this is how the over oil cooler tin interfaces with the upper over cylinder tinware

    [​IMG]

    and this is how the aforementioned piece sits on the other side

    [​IMG]

    and this is how they look when they are together - so imagine these sat either side with cylinders beneath them and the engine block sat between them.

    [​IMG]

    Now, imagine them with the front fan casing on them all bolted up on the engine, you can start to get the picture of how, when the fan is spinning, its sucking air in through the fan, into this casing, and its getting blasted out of the back of the fan casing, out of these rectangular holes left and right

    [​IMG]

    which are attached to these tins

    [​IMG]

    which are shrink wrapped around and interfacing with all of the other tins on the engine.

    So now, when you look here under the engine you see push rod tubes

    [​IMG]

    above these pushrod tubes and screwed to the bottom of the cylinders you can see a piece of tin. This stops the air from just getting blasted straight out of the bottom, and makes sure it gets blown through the fins on the cylinders and the heads. Without this you will have a cooler top side of the cylinder and a hot bottom side. This will lead to the cylinders warping and the heads will overheat

    Here is how they look when they're not fitted. See they are a different shape for either side

    [​IMG]

    [​IMG]

    So now, on the right side of the engine is where the thermostat is mounted.

    [​IMG]

    the thermostat is the thing which looks like bellow. This is closed. Can you see the cable coming off it, going around the wheel and then upwards? Well, this cable goes up, guided through the tinware and comes out here

    [​IMG]

    this is on the right hand side of the engine.

    Now, compare these 2 pictures (i've just learnt that either my thermostat or cable have failed!!)

    This picture shows the thermostat open position. This is the position the thermostat opens the flaps too when it heats up. This is also the failed position, so should the thermostat or cable fail the flaps behave as if the thermostat has heated up

    [​IMG]

    this picture shows that same piece, but I have depressed it with my finger. This is the thermostat closed
    position - therefore, this is the position its in when the engine is cold. Notice how it is spring loaded. I'm pushing against this piece, therefore against the spring.

    [​IMG]

    So now the voodoo fun bit.

    Here is the picture lifted off the samba. Sorry its smaller

    [​IMG]

    What can you see is the flaps inside the fan casing. Remember that you are looking at the rear of the fan casing, so the flap you can see on the left of the picture sits in the right hand 'upper over cylinder tinware' and the flap you see to the right sits over the 'top of the oil cooler tinware'

    This is in the 'engine hot' or open
    position. So, see how it works? The flap you see to the left of the picture, see how its attached to the control bar, so attaching it by the bar to the flap on the other side of the engine? No imagine, standing facing the front of the engine and doing what i'm doing in this picture

    [​IMG]

    As i'm pushing down on this bar, I'm replicating what the closed
    thermostat will do, via the cable. I'm effectively pulling this flap (the one you see to the left of the below picture) down. This will close partially close off the big rectangular hole in the fan casing

    [​IMG]

    The opposite action to this, is that the flap you see to your right, is lifted
    off the oil cooler.

    As the engine warms up, the thermostat expands, the cable moves, the flap you see to your left slowly opens, the one to the right slowly lowers, thus ensuring that some of that nice cooling air is channelled onto the oil cooler, the rest to the cylinders

    They were a clever bunch at VW, over engineering to compensate for the [glow=red,2,300]FACT[/glow] that rear engined aircooled is a pretty crap choice for a vehicle.

    Hopefully this will help you understand how these engines are cooled, and that each individual piece of tin, and how it interacts with the piece next to it and other essential items, like the thermostat, is absolutely essential to not only keeping your engine cool, but also ensuring that it operates at its most optimum and efficient state.

    Don't be fooled though, too much cooling is just as bad as not enough - over cooling will prevent the engine from getting up to its correct operating temperature properly, especially in our UK climate, and will massively increase engine wear and massively decrease engine longevity.

    I haven't covered the elusive 'under pushrod tubes spanned between heat exchangers and engine which are like rocking horse poo' tins, I don't have any images to show you. But imagine these channelling the spent air, which is now warm having served its purpose, being spat back out towards the rear of the vehicle. The one to the right of the engine as an essential tin for warm up, not critical, but if you have them you should keep them in good nick. This ensures that the thermostat warms up and opens at the correct time as the engine warms up - it will open marginally quicker with this 'under pushrod tubes spanned between heat exchangers and engine which are like rocking horse poo' tin in place
    :)
     
  2. Just read your guide ,very good and i do think after reading this that all my tinwear is present as ive just had it all rebuilt and the builder was very happy with it .JUST NEED TO DO 100 MILES NOW BEFORE THE TAPPETS NEED RESETING.
    I read with a bit of worry that you said that too much cooling is bad so could you just advise please.
    Its a 1700 type 4 just fully rebuilt and its running a CB mild performance cam ,a complete Empi performance manifold and exhaust and a set of twin 44 HPMX empi webber carbs. The pistons were changed from dished low compresion to domed higher comp pistons .So it does have decent power and runs nice.I am just a bit concerned that it has a large remote oil cooler fitted right under the fresh air intake and also a deep sump added on as well. Is this a bit OTT or do you think it is in your oppinion ok
    thanks for any help
     
  3. Top write up Joker, I'll add that to my bookmarks for later :thumbsup:

    MM
     
  4. Lazy Andy

    Lazy Andy Supporter

    Well done fella!! My garage stripped my engine down and gave it to me in boxes so there are some parts that I do not have a scooby about!!

    The tube on the OS front that goes to the pre heat had me right stumped!!

    When i rebuild, I can add photos of the stock heater ducts to the thread if you like?

    K your way!!
     
  5. Great write up Joker. I had an idea I was missing tins from under my engine and I now know that they are missing and also what they look like. Think I will get them asap and also look into the thermostat mechanism at some point too (also missing) K+ well and truly earned.
     
  6. Thanks for taking the time to do this write-up, I found this really helpful.
     
  7. Cheers Joker, us type 4 owners need all the help we can get, thanks for taking the time.
     
  8. rickyrooo1

    rickyrooo1 Hanging round like a bad smell

    A much missed member on here for how to's and knowledge. Joker if you ever pop on to read stuff, hope all's well mate.
     
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  11. You are missed on here Joker, come back now and then please :)
     

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