Stripped bolt to oil screen

[kirk knighton]

Is anyone here familiar with the bolt that is right between cylinders #3 and 4 that goes into the engine casing and connects to the housing for the oil screen? Mine was leaking there and I pulled the bolt out to find it was stripped. I got a new bolt but it won't thread into the housing thing. I think the housing thing must be stripped. I was wondering what purpose this bolt-into-housing serves, and if I can install a self-threading larger bolt in its place, or do I have to take out the engine and take the engine to pieces just to get to this thing. In other words, is this a MAJOR problem or can I fix it with a new plug? Right now my car ( a 412 ) sits dead because of this problem.

[glutamodo]

That sucks. The type IV engine is a rock solid bottom end, a much better and stronger engine block than the type 1 ever was. With one exception... that damn oil strainer stud setup, VW was just asking for trouble when they put something so weak and easily accessible from below with a torque range of 7-9 foot pounds (and, according to the 1971 411 Workshop Manual I have here, maximum torque was only 9.4 foot pounds.) Way too easy for unknowing/unsuspecting mechanics to overtighten. And if overtightened too much, the boss that the support bolt you're talking about screws into - it can crack.

(It also can put undue stress on the center cam bearing saddle)

You have stripped threads... the big question is, were they just messed up or were there actaully pieces of the case threads stuck to the bolt? If so, you may have gotten lucky and the boss is still solid. Still, trying to force an oversize bolt into it may not the be best thing to do. Taking it apart and inspecting is probably what is needed here. If it is not cracked, then Time-serting or Helicoiling it using proper tools could work. If not, well you'll need to find another engine case.

In other words, your problem likely falls in the 'major' category

More pictures and discussion here, in the late Bus forum:

http://www.thesamba.com/vw/forum/viewtopic.php?t=504194&

-Andy

[kirk knighton]

So the threads are in the engine casing itself and not in something beyond? When the filter screen is out and you pull this bolt out the screen unit thing drops down half an inch or so. To put the bolt back in I've had to use a small jack to push the unit back up so the bolt will go back into place. But it just won't thread! I didn't see any metal shavings on the old bolt, and the case doesn't appear to be cracked by the hole; can I try to install a larger self-threading bolt? Otherwise - damn! - an engine rebuild?

[glutamodo]

I only quoted one photo from that other thread... head over there for more.

The cracking I'm talking about is inside the case, you won't be able to see it from outside.

The reason I recommend against simply trying to force in a larger bolt is that the case isnt' exactly very strong there to begin with. Also, I'd want to avoid as many shavings inside the case I could. Usually when someone has problems with that bolt, it means the engine case is bad. Unless something unsusual happened that will allow you salvage it, but to know exactly what's up in there, you'll have to go inside.

[kirk knighton]

Yikes! Do you know just what the hell the purpose of this bolt is? I mean, if I just wedged a glob of something there to block off the hole so the oil wouldn't run out what would happen? What does this bolt actually do?
BTW, thanks for these replies and pictures!

[glutamodo]

The purpose of the bolt is two-fold, one it's one of the bolts holding the crankcase together. Second, the whole oil pickup tube assembly bolts through it. This thing... another Samba Gallery photo:

It's needed so that the oil strainer cover has something to pull against to be able to be tightened.

It's been many years since I've worked on any type IV engines myself. You might try posting about your issue in the Bus forum, with all the 72-82 USA Transporters using the type 4 style engine there's a lot more people, experience and opinions there.

-Andy

[kirk knighton]

Thanks - I see that now. So are the threads in the engine casing beyond the oil pickup tube and not on the outside of the case?

[raygreenwood]

The bolt does what all of the other bolts do that flank either the cam or crank. It keeps solid contact/crush on the bearing and constant force together for the case halves.

Taking that bolt out will not compromise the integrity of the case...but it does release clamping force from one side of the cam bearing it supports. It will lead to oval wear of teh cam bearing...which may be a long running thing...but evntually will cause problems. It also can/will allow the case halves to back apart just a hair..releasing some oil pressure at that joint. Of course it leaks into the case...but it reduces the oil pressure at that cam bearing.

That bolt alone was a bit of an issue...but its a double issue because it goes through the steel loop that supports the oil pickup tube and keeps it in place. Without that bolt going through the steel support loop...vibration can very quickly cause the oil pickup tube to pop out of its bore...loosing all oil feed to the pump....and making it the catestrophic end of the line for the engine.

The options are these...and they are not great.

(1) if splitting the case is out of the question....then you could thread the outer portion of the hole at the outside edge of the case tothe next size up...10mm I believe.....and get a long 8mm bolt that bottoms just inside of the stripped hole where the original bolt was. Put an 8mm id/10mm OD threaded insert arount the top area of the bolt so it threads into the 10mm threads you put in the case...and locks there and seals there.

This will do two things only for you: (a) it seals the case from leaking. (b) it keeps the oil pickup tube centered and supported.
What it will not do is put clamping pressure on teh bearing saddle for the cam or keep oil from leaking as the case seam internally. If your oil pressure is good and case wear is low...you will most probably get 10's of thousands of good miles with no trouble. On tearing down the case you may find the cam bearing saddle is worn out there...mayb not.

(2) If you disassemble the engine and you find the case is not cracked....this can be fixed if you work carefully. Useing the case for a drill guide...with a depth stop on the drill...and a fast twist drill bit or a three flute mill reamer....you can carefully open the hole up for a thin wall, coarse thread (not fine thread) steel insert. the EZ-thread version with a slot att he top to be driven in with a flat blade screwdriver is ideal...because after lock tighting this in....you peed aluminum into the screwdriver slots to keep it from backing out. Next.....measure carefully to make SURE that the new 8mm bolt cannot bottom out in the bore jacking the thread insert out.
I have successfully fixed several cases this way.

(3) If its cracked....I do not know what to tell you.

Ray

[glutamodo]

Ray, thanks for chiming in. While you were doing that, I was I looking all through my Dealer 411 Workshop manual hoping for some decent illustration I could scan, but nada. The chart along with the illustration is particularly (and surprisingly for VW) bad - it lists hardly any torques, none for this bolt - and the other cover plate (the "taco plate") it erroneously calls it the strainer cover.

So all it says, is that it's a 8mm bolt, 113mm long, (about 4 7/16") and you have to replace the sealing washer under it.

[kirk knighton]

One thing I should add here is that I have shoved a chopstick into the hole and found there is some kind of spring-loaded thing way down in the hole that opens and closes as I turn the squarish chopstick. I can't be any more technical about it, and I'm doing it all by feel since the engine is still in the car and the heater box is in the way.

[kirk knighton]

If I have to end up pulling the engine and splitting the engine apart I'm considering instead doing an engine transplant. I have a 411 wagon with d-tronic fuel injection, automatic transmission. This engine is actually 2-litre with hydraulic lifters with about 25,000 well-cared-for miles on it. My 412 with the stripped bolt is a fastback, 4-speed tranny and dual carbs. I think I would stick with the carbs with the transplant. This 411 engine just purrs like a kitten and is powerful - a great piece of machinery. The body of the 411 is okay - exterior very good, interior fair at best. My 412 is real sweet, excellent condition ( except for this engine issue!) I'd love to have the 2-litre motor in it. Would it be that complicated to do this switch?

[glutamodo]

The only thing I can think of that might explain a "spring-loaded thing" is a helicoil insert.

Engine swaps - you should be able to make it work. Sound like it was already a transplant, 2L hydraulic is from a later Bus. I think there are a couple of things with the shrouding and dipstick setup that have to be addressed when going to the Fastback body. And you'd have to swap the flywheel/clutch over.

[kirk knighton]

Yes! That must be it, because the bolt that came out was not the original 8mm but a standard ( non-metric ) one slightly larger. Damn it! The guy I bought the car from had had the engine rebuilt in his restoration process, and probably the rebuilder over-torqued this bolt and so did the heli-coil fixit thing. And now the heli-coil has failed. No wonder the bolt won't go in!
Looks like this means a definite engine rebuild. Or switch. I don't have the tools or the skills to do this myself, but there's a great VW shop here in Seattle that could do it ( I hope!). I've had my other 412 worked on there. They had to R&R the engine and transmission to replace the torque converter and they did a great job.
Thanks so much for your extremely helpful information and wisdom here. Now I know what I'm dealing with, at least!

[Mike Fisher]

Nate M. in Anacortes is doing an amazing job on his ProVolks shop car. Nate could swap in 2 liter/AT and you'd have a sweet street machine! He could also fix/swap the bad engine into the 411, so you don't have to part it out.

http://www.thesamba.com/vw/forum/viewtopic.php?p=5989585&highlight=#5989585
_________________
https://imgur.com/user/FisherSquareback/posts
69 FI/AT square Daily Driver
66 sunroof,67,70,71,71,71AT,72,72AT,73 Parts
two 57 oval ragtops sold
'68 Karmann Ghia sold

Society is like stew. If you don't keep it stirred up you end up with a lot of scum on the top! - Russ_Wolfe/Edward Abbey

[raygreenwood]

[raygreenwood]

[raygreenwood]

[kirk knighton]

The 2-litre "bus" engine in my 411 has the stock D-Jet and the automatic transmission. The 411 itself looks good on the outside but the inside is pretty beat up, so I wouldn't mind sacrificing it for its great engine.

The 412 ( not Sparkie - she's doing great and is not part of this discussion ) with the stripped bolt is a 4-speed with dual carbs. I would put the 411 engine in this car and use the dual carbs rather than keep the D-Jet. This seems simpler. The 412 has a great body and is worth putting a great engine in it.

That "springy-thing" in the hole looks like it's shaped like the letter "c" and then it opens as I twist the chopstick, and then closes again when I take it out. THAT thing is in the way of a bolt going all the way in. Confusing!

[kirk knighton]

BTW, the 411 with the 2-litre and automatic is MUCH faster than the 412 with the 4-speed. It's even faster/more powerful than Sparkie, which is 1.8 litre with stock L-Jet. It's really a great motor.

[kirk knighton]

About that helicoil, if it IS a helicoil: Can I just reach in with a pair of needlenose pliers and pull it out? And then try to thread-in a slightly larger bolt?

The bolt I pulled out was NOT the standard 8mm but a standard size, not metric, probably indicating the builder of the engine stripped the original and tried to fix it with a helicoil and larger bolt.

I've had the car ten years and it has always leaked a little from that bolt. It would never tighten completely. Then I recently changed the oil, gave the bolt a couple of nudges ( maybe half a turn ) and went for a drive. I filled up the tank at a gas station, drove home and parked the car in the garage, satisfied. Next morning I discover a large puddle of oil where that bolt leaks, so I pulled the thing out and saw that it was stripped, and I never could get a new one back in. I tried and 8mm as well as the same size as was in there. That's when I used the chopstick and discovered the spring thing. Then I gave up and turned on the computer to seek expert advice - and boy have I learned a thing or two! A leaky bolt turned into an engine transplant!