oil relief plunger clearance= headache

[modok]

I'm building a type-4. God have mercy on my soul.

Type-1 stuff, generally the bore is .630"(16mm) and the plunger .629"

So I pick up the oil relief plunger and measure it. ummm, wtf.
Not only is it tapered, it's also NOT round.
The top is .627, middle .629, bottom .631-.633

possibly, somebody jammed something in the bottom of this poor plunger and expanded the bottom outward.

But now what? it's been in there going up and down like that for who knows how long. I tried to measure the bore and I was getting around .633 right before I got the snap guage stuck in there because it's so darn deep the handle is too short to work properly. And I broke the snap gauge getting it back out.

So then I decide..... lets make a extra big plunger. It came out lovely. .6305 is as large as I dared make it, for fear of hanging up on a less worn area of the bore. Still feels awfully loose in the block tho when I tried it. It has at least .003 clearance just be feel.

What should I do?
Should I run it with the .0015" oversize plunger I made?
or do I need to buy a reamer to oversize the bore and make another plunger to fit?

I haven't done enough type-4 engine to know if this is normal or awful

[raymon covey]

This might be a good time to try a ball check valve.

[Dale M.]

[mark tucker]

how about bore the case for the next size up and make one that fits. just run the next size reamer and make a piston, polish it good befopr usage, make it a tad longer for better support, and no sharp edges at all.simple fix.

[raygreenwood]

[mark tucker]

logic thinking says very little clrearance as the case will expand more than the piston.....but it needs to move freely when the motor is cold so...I would shoot for about half a thou to .001". and unless you get realy big I dont think a few thou will change squat in blow off pressure. or.....just add one of those adjustable thingys to the springy thingy so you can have some cake and drip on it too. with that said....Ive never tuched a type 4 so.....I havent a clue what Im talking about......

[modok]

I have a good condition WBX hoarded so I got that out to examine, should be similar design.
the bore is .630 and the plunger is.....627"
nice and wobblyloose. And the plunger has a groove for no reason. I'm pretty sure this thing is 100% OEM, and virtually no wear

SO, I believe, the type-4 wore out it's bore about .002-.003, THEN the hippies turned the plunger into a dunce hat.


My oversize plunger does restore the fit to "almost new"....maybe
I'll wait to see what Ray comes up with.

For MARK:
Why did it need to be so loose? It's odd. I don't agree with it. In the late 70's type-4 they reverted back to the one plunger doing both jobs, with a big hole drilled though the bore so the piston has very little bearing area and can jam easier. I think it's a stupid design, they knew it was, and they didn't care. Poor thing got no love from the beginning.
It's not good enough to me, but if I can say it's "good as new" then it may be good enough for this job.

[raygreenwood]

[mark tucker]

I would go with a max of .001~.0015 clearance ....thats if you have a good filteration system on it. and oh so smooth, possiably even heat treet it so no abrasives can scratch it..
on another note..isant the same size as type1?
on another note I had a motor brought to me after a few hundrad miles that was blowed up...not by the owner but the northwestcoast moron joe that built it. the pistons liikked they were shot with steel ratshot. what a bitch to get out. it was a neer new new case that the "builder" effed over real good,(hammer and chizzell stroker clearancing).

You may e able to get a + size 5/8 or 16 mm to slightly over size the bore, they make a adjustable one with a allen head in the end to expand it a tad too.
or possiabl;y this is just a 20-50 motor.......hmm might be a 50 weight.

[raygreenwood]

[modok]

Thanks Ray, that matches exactly what I found.
the "why does it have a groove?" was directed to the WBX, the WBX has no oil cooler so the groove does nothing, but they used the exact same plunger anyway. I guess......why not.

I have measured OE appearing plungers to vary from .627 to .629
Today I learned...., like a lot of things, they got looser in the 70's

[raygreenwood]

[modok]

The late hippie bus does, in fact, have the loosest plunger orifice of any engine I've ever examined.
You may not be aware of this, because you aren't a specialist in this field.

As long as you feel satisfied in your relationship, it's ok, I don't think it's contagious or transferable.

[raygreenwood]

[Clatter]

It can be a common practice to use a big straight-slot screwdriver to remove the plunger.

I'll admit to doing it..

If the plunger is sticking in place from surface tension, or just wants to stay in place for some reason,
I stick a screwdriver up there that's just the right size to wedge, and grab it, and pull it out.

Surely I'm not he only one..

Now,
That said, I'm careful about it, and would never jam it up in there hard enough to oval it out,
But,
Bet you some ham-fisted types might do just that..

And,
Come on,
Admit you done it al least once...

Add checking for an ovaled-out plunger to my list of inspection measurements!
_________________
Bus Motor Build

What’s That Noise?!?

[modok]

Nope, never done it. I use a valve guide.

Round plug fits in round hole, square plug fits in square hole.
Didn't you have that kids toy?

[raygreenwood]

[Brian Anthony]

You could use an external relief and not the internal one. I plug the small relief hole in the block and eliminate the plunger and spring. I also use a relief cover for the oil pump.

Install it after the remote oil filter and cooler. It ends up just a few inches away from the stock relief. It's much easier than dealing with worn out relief bores. It is easy to adjust the pressure and you don't get the usual drop of pressure with hot oil with the stock system.

You can use a 1/16 NPT plug for plugging off the relief hole.

http://www.jegs.com/i/JEGS+Performance+Products/555/110400/10002/-1

_________________
1965 Double Cab
1967 Bug, Sedan
1967 Bug, Convertible

I’m not old, but I once knew a man who was alive during the Civil War, and he once knew Revolutionary War veterans.

[modok]

If I ever build a type-4 for myself I'll consider that an option!
Plunger is the least of my problems now, now I have to figure out why the oil pump drive isn't inline with the cam.

[raygreenwood]