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1972 Beetle running hot

Hi, everyone. I've just rebuilt my 1972 Beetle engine (again), and I've run into a problem I've not encountered before. I found that the side with the number 3 and 4 cylinders was running really, really HOT. So I checked the intake on that side, and put in some sealant on it to make absolutely sure it was not sucking additional air. It helped, marginally. So then I did a compression test, found #3 to be at 120 lbs, but #4 at only 60 lbs. OK, I know that's not good. So then I checked the valve clearances and found that #4 intake is pressing against the rocker arm, even when the screw is backed out all the way. The other 7 valves are adjusted to spec.

Can anyone offer some suggestions? Am I looking at a broken valve? Or something more sinister?

-Mike

Reply to
Michael Ashley
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On Sun, 03 Aug 2003 21:45:33 GMT, Michael Ashley ran around screaming and yelling:

remove your rocker shaft on that side..use a straight edge across the valve stems...they should all be the same length with no *major* differences...if this test checks out okay, then chances are you need a bit of shim under the rockershaft mounting blocks...did you put

*new* pushrods in the engine? if so where they "cut to length"? if they are the cut to length it is possible that this one p-rod is a bit long... good luck J
Reply to
Joey Tribiani

Check that the pushrod is seated properly on the lifter. To do so, untighten the rocker shaft assembly and wiggle the puhrod arround, and rotate it.

Bill, '67 bug.

Reply to
Bill Spiliotopoulos

................That's what I was thinking.

......................BTW Bill, where've you been?

Reply to
Tim Rogers

I had problems contacting a newsgroup server from work. Anyway, I saw it as a "detoxication" period... it's been allmost a year.

Bill, '67 bug.

Reply to
Bill Spiliotopoulos

Thanks very much for the suggestions, here's what I've found:

The rocker arms are all exactly the same length, and I removed the rocker arms and verified that they were seated correctly. Just to make sure, I swapped #4 intake and exhaust rods. Same situation. So I then measured the length of each valve end to see what I could see. The straightedge test showed that there is a significant difference between #4 intake and exhaust. The micrometer confirmed it. Measurements follow:

#3 intake: 41.72mm #3 exhaust: 40.72mm #4 intake 42.75mm #4 exhaust 39.55mm

So it would appear that #4 intake is possibly stretched, warped, or seated too far? In any event, it seems I'll need to take the head off to look at it much closer, yes? (which means pulling the engine again. Damn.)

-Mike

Jim Adney wrote:

Reply to
Michael Ashley

On Wed, 06 Aug 2003 04:33:05 GMT, Michael Ashley ran around screaming and yelling:

Yes...if the seat isn't sunken into the head, then i would consider a valve job....or new head...

Yes...easy job...gotta pull mine soon too.... J

Reply to
Joey Tribiani

Most people don't realize it, but intake valves ARE longer than exhausts. Your numbers appear to reflect this, although I don't quite know what they mean since you didn't tell us what you were measuring (from the top of the valve stem to where?)

You probably measured from the end of the valve stem to the face of the head casting, but the surface you measured to is just a cast surface and isn't a reliable reference surface. With everything together like you you're really pretty limited to just observing how the 4 ends meet up with a straightedge.

Most manuals show the overall lengths of the valves, but you can't measure this until you have the head off and the valve out.

-

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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Reply to
Jim Adney

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