I wouldn't worry too much about measuring the clearance exactly opposite the nose. In theory it doesn't matter where on the base circle the adjustment is made but unfortunately cam grinds are not always accurate these days and maximum clearance could be anywhere. If you think you have an over noisy tappet stick a feeler gauge in it with the engine running – it will be oily and the feeler will be knackered but you'll hear the tappet go quite. I have a set of feelers just for this purpose. Incidentally, almost all Type 4 cam grinds have the same inlet and exhaust profiles. There are exceptions, for instance a Web cam 73-86 (good choice for a bus engine if you can find one).
Combustion at the cylinders highest compression? You don't want to be burning valves that aren't quite shut? Happy to be corrected. I'm thinking that if the one that measured 0.3 was set to 0.15 at that point, then at TDC cold it would measure zero.
But you want the valve to be shut all around the base circle. Maybe you should check the clearance as soon as the follower comes off the flank and before it goes back on the flank and set the clearance at the tightest point? I'm not going to bother doing that.
My first bus had a T25 hydraulic follower engine, apart from a couple of times a lifter bled itself it was super quiet.
@andyv , @77 Westy ,@Zed - thank you for your thoughts once again - so very helpful and appreciated. That was fun! Just come back in rather oiler that I was having stuck a sacrificial 0.13mm feeler gauge behind each valve tip - none of them made any difference! The engine was cold, but the noise still there. As much as I'd like to play with the Wilson alternative/Engine Co valve setting method I think I'll stick with the TDC way as I really don't think it's going to solve my diesel knock, and I'm with @Zed - closing up a 0.30mm gap will have the inlets on 1 & 3 only just closed at TDC which won't be good. Quickly running out of things to fiddle with now before I start the increasingly-inevitable strip down, at least as far as the oil pump to see the cam drive bolts.... but I will have a last play with the ignition to make sure all is as it should be.
Maybe you're just having new engine freak out. lol You should hear mine these days but do I care? Nope.
This too has crossed my mind - and that of everyone around me! I could just drive it and see what happens. Oh, I know what I was going to do next — make a smoke bomb leak tester…
Well I'm glad you did it so I don't have to. Last week I pulled off a valve cover and ran it just to see if it was getting enough oil. I thought I'd squirt some extra onto the tappets from an oil can. Bad idea, but that's one avenue I'll not need to try again.
I told you it would be oily. At least you know oil is reaching the rockers and the noise has nothing to do with tappet clearance. I'd pull all the followers and check that none of them has broken up or gone concave and look at the cam lobes, if nothing is wrong I'd just run it. Are you sure you've torqued all the big end bearing cap nuts?
Thanks Geoff… sage advice. In the same way as you asked whether I torqued down the big ends, I’m also wondering whether I locked the back door. Yes - I’m sure I did. I think. I’ll have another fiddle early next week.
'Afternoon all. I've had all the rockers, push rods and lifters out and give them a jolly good looking at, as @77 Westy suggested. There are no unusual wear patterns on the lifters and nor the cam lobes as far as I can see (which isn't that far given the heads are still on but my little dentist's mirror is very handy). Annoyingly there is a very small amount of pitting on No 4 exhaust lifter (but as I say I couldn't see anything untoward on its cam lobe) and also on the ball of the adjuster - not really what you want after only 300 miles of use; The thing I did notice whilst lying on my back is a crack on the flange of No 2 HEx manifold pipe (it deffo wasn't there when I cleaned and sprayed them up). Can anyone confirm what the construction is of this, please? I think the cast iron flange (that the studs to the head pass through) acts as a joiner between the bent pipe coming out of the Hex box and a stubby short oval section that mates with the copper gasket on the head. So if the brazing has failed, then there is a potential for an exhaust gas leak? Next, I covered the cracked area in soapy water and started her up; I'm pretty sure I saw some bubbles from the fracture in the few seconds before the water boiled off. Annoyingly though, I can't hear a tell-tale phut-phut sound from the area with my listening pipe in my ear, just the whoosh of the cooling air being blown through. Surely it would be obvious if the is was the source of the mechanical knocking I've been searching for?? One last rather annoying thing - when I started her up and ran her for a number of minutes on the drive, the knocking noise itself seems to abated considerably to the point where I'm not sure it's significant. Perhaps the Hex needs time to get properly warm for he crack to open up? But on previous cold starts the noise has been there form the first cranking. I've read on the Samba that JB Weld is as good as anything (and a whole load easier) than trying to re-braze the crack. Any thoughts on that? Cheers
The entire cast end piece is one part, a press fit onto the pipe with a couple of welds to stop it moving. Normally if there's movement the weld(s) would be cracked which yours don't obviously appear to be but it's hard to tell. It most certainly does look loose though.
Old heat exchangers like yours often need dressing flat with a huge file so you can file both stub ends at the same time.
Ah, right, thanks - so not an obvious place to leak from itself but will stop the HEx from snugging up to the head. But I did see this on The Samba which suggests gas can leak through the flange, which I don’t understand, unless it’s cracked all the way through; https://www.thesamba.com/vw/forum/viewtopic.php?p=9258258 Don’t worry, I dressed the mouths of the pipes together with my biggest file…
I would go and get some exhaust jointing paste, squidge it into the potential crack and see what happens. I think I can see traces of soot in your picture over to the right by the nut on the stud where it looks like theres some metal or paint and a cracked section .. I have used a finger in the past - hold it near the potential crack in the exhaust and you can feel the pulses and eventual burning sensation. The crack may well clear up as it warms up - I went round for a while with a nut missing on my T1 exhaust on one of the ports facing forwards, and as I drove down hill towards St Austell for the next days visit to the Eden Project, it would crackle and backfire like mad, but a few miles down the road, silence.
No, it's definitely a place it could leak from and snugging it to the heads can exacerbate it if the surfaces aren't level, but you did attend to that. I'd run a weld right round it or get a replacement HX. Cast will weld good enough to seal with a mig. You might guess I've been here myself.
Thanks @mikedjames - that’s what I was expecting to observe - some distinct pulses. @Zed thanks for the straight advice, nothing like hearing it from someone who’s been there. MIG it is.
You wonder if there's a reason VW didn't weld all round but I can't think of one apart from... you may have to get that file out again afterwards. exhaust fitting paste? I don't think so if you want it to last more than one warm up. The software engineer strikes again.
