G'day.

First I'll say I have an 1800 Type4 motor in my van.

I was just doing some cleaning up and stuff on my van today. Among other things I pulled off the rocker gear so I could check out the pushrods, clean the tubes etc.

It was all pretty uneventful until I went to put the rockers back on. One of the nuts wouldn't torque

I have a vague memory of something not feeling right a couple of years back when I was putting the motor back together. However at the time it was freezing, I was absolutely knackered with the flu, and I only had a week to do everything, so some details may have slipped by me.

I just thought 'stuff it', and put everything back on. Partially because I wanted to test the exhaust repairs.

It did start up, and the oscillation on the inlet manifold vacuum was far, far more pronounced than it was previously. This made me realise where some of my issues are coming from. Even though I have the valve clearances set correctly, the pressure from the pushrods may have been causing the shaft to flex out a little, causing the valves to open less and for shorter. Well that's my theory.

The important thing here is how do I fix it? Helicoil, a stud with an oversized anchor end, or replace the head?

I'd gladly swap that head out if I knew I could do it without pulling the engine out. Not my favourite job.

I cleaned up the head in the garage that was possibly still good. Haven't done it completely but I think I was wrong about it having a crack.

What should I do?

Are the studs similar to the type1,2,3 1500/1600 heads? Have you got access to taps for re-tapping the head to a larger size for a modified stud? The alternative method is to have an isert and screw an M8 capscrew in to hold the rocker shaft rather than a stud. Similar to pic below from a Type 3.

DH

yes,
Hopefully studs with one large end may be available...

if not, get one made...

best of luck

LEE

1500S: Yeah, I have tapping stuff. Barely gets used but I'd be lost without it. It's one of those kits that the cheap shops sell. They work quite well when treated with care.

I'm trying to figure out what I'm looking at there. Does it have a hollow tapped centre? If it does, I'd have to countersink it, but it is possible.

One thing I am lucky about is that the stripped thread is on the left hand side, closest to the back. There is nothing behind it. If I felt like it I could drill straight through and the bit would pop out next to a support fin thing on the other side. It is the least critically positioned stud of them all. So if absolutely necessary I could bore in a bit deeper and put in a longer stud. Not my favourite idea though.

68AutoBug:

I was thinking it may be necessary to get one made. Probably work out cheaper than getting a helicoil kit. To be honest I could buy new head shims and swap out the head cheaper than a helicoil kit.

This was the bottom of a broken one someone else had. The 9/19" UNF thread was the size of the locally produced replacement studs of the 60s when it became a problem with the 40 HP and early 1500 engines. It could have been drilled and tapped M8 and a capscrew used to hold shaft. What diameter is the stripped thread in the head? Send me the dimensions of the stud and I'll make you a couple if you like.

DH

Hmmm

Didnt VWs have issues with expansion rates on the rocker bolts back in the late 50s / early 60s requiring a tappet clearance of .8 (from memory).

Would this fix create such an issue? (just a passing thought).

Newt

I had a look recently and they were at least $100. However the off-brand ones available in the US can be had quite a bit cheaper.

Haven't had anything to do with Type 4s so I'm not sure on what the rocker post looks like. Is the stud recessed into the post that bit as the Type 1,2,3 heads are? I made a couple of inserts some time back for someone in QLD from 16mm hex stock. That way you can get them nice and tight with a socket if you use the insert with M8 hex head capscrews (no, I don't mean socket head capscrews!).

The old original replacement studs for the 1200, 1500 engines had the oversize 9/16" UNF thread and also a short length of 5/15" UNF thread where a nut was locked to prevent it coming loose. That was deleted on later versions and they were changed to metric. You didn't really want to know that old junk from the 60s!!!!!

Can you measure the size of the standard stud and let me know. I'll make you some oversize ones and you owe me a few sherberts if we catch up some time. Make it quick as I'm out of the country from 19th July to the first week in September.

DH

https://www.bolt.com.au/product_info.php?cPath=296_348_350&products_id=2980 

or for 10mm:

https://www.bolt.com.au/product_info.php?cPath=296_348_349&products_id=2963 

Also HAFCO have some cheaper versions of the same type of thread repair kit.
Thay have stores in most major cities.

Got your PM Tristan. Will have a look tomorrow for you. Better PM your postal address for me so I can send the oversize one(s) to you. Better make you 2 in case you stuff another one!

DH

After calling in to a nearby "mechanical reparer"/wrecker at Riverstone to check on the features of a Type 4 head, we have to use Graham Kenedy's famous television exclamation of faaaaaaaaaaaaaaaaaaaaark!! Never have I seen a workshop with so much filth and I do not know how this fellow can put a working engine together which would last.

After arguing my case on not using a helicoil for the repair as it relied too much on loctite rather than the thread fit he still offered me a helicoil to do the job as it would only take 10 minutes for the fix and off you go again........................ untill it works loose again! He also looked puzzled when I declined the offer and reminded him that I have far more stock of helicoils, both metric and imperial than he seemed to have!

On the technical side, if we use the oversize stud method, the fixed portion of the stud has the thread slightly bigger so that it is a neater fit and either locks mechanically in the hole by binding on the LAST thread or as in the Type 4 head situation, it looks like it relies on thread locker compound as the stud can only sort of bind on the last thread.

With that gripe over about SOME of the motor mechanics who advertise as "expert VW mechanics", I'll get on with making the stud for Tristan.

DH

Edit to add pic for Tristan. Use the stud driver to screw it into position.

DH

That is a beautiful sight!

I'm still surprised that every rocker stud on every head here is loose enough to be hand turned. I never heard of such an issue.

Thank you so much 1500S. I had severe doubts about the veracity of helicoils in this circumstance.

I think when it comes time to refit, there will be some loctite added just for that little bit extra. However I can't help but wonder if that would be a bad idea. It seems pretty plain that the effects of uneven thermal expansion have loosened these up. Would loctite even work Especially given the severe heat that the heads are when running.

The fact it was sort of stripped without my heavyhandedness bothers me a lot. Has this ever happened to anyone else?

Use stud locker (can't remember the number) or even 648 high temp retaining compound as well as screwing it in tight against the last part formed thread. Just make sure that the shoulder is below the boss by a few thou so that the block is pulled down tight on the boss. Better loctite any other loose ones just to be sure. You should get them in the post tomorrow as I put them in one of those overnight bags.

Don't forget that if you are through this way I'm quite partial to a Toohey's Old or Guinness

DH

Quote:

Originally posted by 1500S Use stud locker (can't remember the number) or even 648 high temp retaining compound as well as screwing it in tight against the last part formed thread. Just make sure that the shoulder is below the boss by a few thou so that the block is pulled down tight on the boss. Better loctite any other loose ones just to be sure. You should get them in the post tomorrow as I put them in one of those overnight bags. Don't forget that if you are through this way I'm quite partial to a Toohey's Old or Guinness DH

Those studs are fantastic!
Tomorrow morning I'm planning on boring, tapping. and installing. After that, besides needing to add some heater stuff, the rest for inspection is pretty easy.

Happy to help Tristan. I was waiting for other material to cut for another job and had 10 minutes spare. Sould be strong enough as they are from 4140 steel!

DH

What thread did you put on the large end 1500s?

ahhhh tooheys old mmmmm

I had to run a drill through. There seemed to be some sort of a relief cavity at the bottom of the stud hole.

Anyhow, once a few equipment related issues were sorted, it went well.

The end result is my van seems to be running better now. Personally I think all the rocker studs should have been made with that thread. It just seems so much more solid.

Oh, I want some Tooheys Old now. And not my homebrew using the Tooheys old kit. It's hard to get real beers in Victoria. Well, real to my tastes anyway. I'm sorry, but Victorian beers have never really done it for me.

Even the old Cane Toad Juice isn't all that bad these days. Good luck finding a XXXX in Vic though.

What was I saying?

The stud is good! And when tapping don't skimp on the quality of the tap. If it doesn't have a nice taper at the top, throw it away.

When purchasing tap sets, be careful with some brands. There are some being sold at H & F as well as other outlets such as Toolbox which are "serial" taps and you don't get the full form untill you run the plug (bottoming) tap in. What this means is you have to buy the whole set of 3 rather than the usual getting away with the intermediate one. If you don't follow the whole procedure the thread will bind on the crest of the bolt thread.

DH

I forgot about that. The stupid tp in my set was almost a normal bolt with three grooves machined out of it for cutting the thread. The lack of taper messed everything up.
Anyhow the stud screwed in almost without issue. The only real problem is that I'm hopeless with aligning things. The tap went in just fine, but the alignment of the stud ended up a little bit off, so it meant I drilled out the hole a little bit off. Only by about .5 f a mm though. enough for a percussive insertion of the rocker bar to proceed with minimal effort. Ie. I hit it with the spanner a few times and it went on.

I wasted hours trying to tap the hole with the useless tap before I went to home hardware and bought a good tap, which tapped instantly.

In a van-length it can get going enough now that hitting the brakes causes enough front end dip to nearly hit the stops. Not great on its own but it shows acceleration is a bit better.

There is a dirt track running along behind some housing near here that I'm going to take it for the final test. Before now I have been lucky to get 40km/h out of the motor (but still enough torque to spin the wheels). It seems much more tuned now, so another try is in order.
I'm still mystified at the insane amount of drift in the rocker clearance though. Still hoping it will settle down.