After spending a week traveling around Devon and Cornwall the bus never missed a beat. We just noticed it to be a little slow and drank loads of fuel. About a mile from home it became to run rough but we made it home. Spent then days looking around the engine and replacing the odd component here and there. It wasn't till i removed the distributor that I noticed the crack in the manifold. A credit to VW reliability that it kept going for so long in this state. No wonder it drank so much. Anyway with the help of this site we managed to sort it. http://www.vw-resource.com/intake_manifold.html I could remove the alternator so decided to grind the old intake pipe off to be able to feed it out. The new one a performance one from CB Performance in the states (Be careful of import duties if you go down this route. But I picked this because of the 10 week wait otherwise). It has the intake pipes individual so it is easier to get back into the space.
Now thats what I would call serious fatigue damage!! Was the steel badly corroded from the inside of the preheater pipe, check the faces of the crack and mabe you can see what started the crack. Check to see if the cylinders on that side of the engine are not loose. Tony
One of the heat riser pipes was slightly choked up. This could of caused the imbalance and hence the crack. Also I've recently noticed a small hole in the left hand manifold end. I guess this could of caused the choked heat riser pipe and have a cascade effect. Or another thought could be a topic from the same site I found out how to repair it from. http://www.vw-resource.com/heat_risers.html#flange Yes it does take some determination to get it off
I was looking at those cb performance manifolds a while ago apparently they flow better than the stock manifold which was interesting Ive seen a few stock manifold castings crack like that but not as severe and non of them have caused an air leak Im pretty certain that the pipework is all welded/brazed together and the alloy jacket is just to aid heat transfer I highly doubt a partially blocked heat riser caused the cracking either but may have contributed to a degree of carb icing Can i ask what stopped you removing the alternator?
Plan to finish the job this weekend. Removing the alternator was advised but it means removing screws to the fan behind it. Seemed like a lot of work that a grinder would sort out instead. The engine was not running too hot or overworked. It's been rebuilt and we've been breaking it in for a thousand miles before. The inlet manifold must of just been cracked previously. The performance inlet manifold is supposed to provide a better flow. Watch this space I'll let you know if we see a big difference. I suspect just not having air leaks will make it perform better so it's going to be difficult to see what difference it has made. I like the fact that the replacement one is lighter and aluminium and it's looks to be made well.
If you need to remove the alternator in future its only the electrical connections the alternator strap and the four bolts on the back plate and the alternator and fan assembly all lifts out as one unit Have you checked your points gap? Often slow dgredation of performance over many miles is the points gap closing up
So was the crack in the manifold causing an air leak? If it was, a new one should as you say solve it. Any air leaks cause the engine to run lean and therefore hot.
Thanks for that. I managed without removing the alternator. I have electronic ignition so don't need to worry about points. Although I'm having trouble getting it started again. Having removed the distributor the problem with the lack of points is doing the static timing because with electronic ignition the usual light method doesn't work because the light is always on.
Yes I think the crack was always there and been getting steadily worse. It makes sense that the air leaks have been affecting the performance, fuel consumption and idling was always fluctuating.
