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Post by osomayor on Jun 15, 2019 9:44:07 GMT
Good morning all.
I am lost. Working presently on a 1962 Daf 30 750. The exhaust is rotten and will be replaced but on the left side of the engine there is a 1/2 inch pipe originating from the inlet manifold and ending in a rectangular box, now heavily corroded, tucked behind the left exhaust pipe.
Amazingly our wonderful parts suppliers in Holland do not know what it is or have a replacement. However Danny did say that it was not fitted on the later models. Can I conclude from that that it could just be blanked off? The only use we can imagine is that it provides warm air to the manifold that stops the carb from icing up such as the one fitted to early VWs?
Any advice would be gratefully received.
David
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andrew
Likes DAFs
Posts: 1,097
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Post by andrew on Jun 15, 2019 10:38:39 GMT
This pipe is one of two pipes which connect to the inlet manifold and their purpose is to allow hot exhaust gases to pass under the manifold, thereby warming it and thus increasing the vaporisation of the petrol vapour. Putting it delicately, this was not one of Daf's "finest hour" as regards design.... This is how it should work:
Hot exhaust gases travel along the heat exchanger, thereby heating air forced through is by the fan, thereby providing warm air for the car's heater. The exhaust gas then passes into the transverse silencer, but just before doing so, there's a small pipe on the top of the near-side heat exchanger, allowing hot gases to flow under the manifold. A similar pipe carries returns the hot gasses from the manifold down to the transverse silencer. On the early Dafs like the 31s a box surrounding the pipe allowed warm air to be passed up into the air filter box, although later air cooled cars used a different design, where the air intake came off the back of the cylinder housing. So much for the theory.....
What frequently happened was the pipes under the manifold broke away, leading to the exhaust gases escaping. The usual (and cheaper!) solution was to either cut off or blank off the 2 pipes at the points where they diverged from the exhaust system (the heat exchanger and the transverse pipe). Most drivers didn't notice the difference and were happy with the dealer's solution. The effect would be slightly reduced economy and perhaps lesser performance, particularly in the winter months.
My 33, a model 3303 car, meaning it's a 12 volt one with an "environmental" carburettor, suffered in this way and I bought a new manifold from Dafhobby, the fitting of which was not an easy job, but doable by a decent D.I.Y. mechanic. As a result it was quite and smoother. I can't say it's any more economical, since a number of other adjustments, in the way of timing, valve settings and carburettion were done at that time.
Happy to offer more advice or assistance, if needed!
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Post by osomayor on Jun 15, 2019 17:32:44 GMT
Andrew, thank you very much. That back's up our conclusion.
Will you be at Princethorpe next weekend? The 750 won't be ready but I thought to bring the 66.
David.
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andrew
Likes DAFs
Posts: 1,097
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Post by andrew on Jun 15, 2019 18:46:30 GMT
Yes, we'll be there! I think (think....) that somewhere in my lock-up I've some of the pipes that run from the front of the transverse silencer to the hot spot on the carburettor. You're welcome to it if you're looking for one.
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Post by osomayor on Jun 20, 2019 8:22:41 GMT
That would be a great help Andy.
See you Sunday.
David
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Post by starider on Jun 30, 2019 23:56:18 GMT
Hi, Just picked this up.During my years working on 30s/31s/32s and 33s,this manifold heating system was the bane of our lives and although not too difficult to fit, the price was expensive and customers were reluctant to have a new manifold fitted. I spoke to the UK Daf Concessionaires chief service engineer on this matter and was told that blanking off both ends of the "heating pipe" would have little effect on performance, as long as the Summer/Winter lever on the air filter intake ,was religiously set on Winter during cold weather......................starider
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Post by osomayor on Jul 4, 2019 16:21:47 GMT
Thank you Starider. That confirms our thinking here so that's what we will do!
Thanks and regards David
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Post by dafman50 on Jul 4, 2019 18:30:55 GMT
Have these modified in stock .was told same by daf service engineer from factory years ago.
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