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Mon Jan 19, 2015 9:23 am

No. 4 exhaust valve barely opens causing extreme intake backfire.

Inspected pushrods. They look fine. Cant get lifters out without pulling jugs?

Anyone ever seen a cam wear like this? Making sure im not overlooking something. And any suggestions on which cam to buy and where? Thanks!

Mon Jan 19, 2015 9:39 am

You can't get the lifters out without splitting the entire case in half. (edit- type 1 cases)

But I would start with pulling the heads off and see what the valves/seats look like.

Mon Jan 19, 2015 9:44 am

what type motor? Type 1 motors require splitting the case while type 4 motors can remove lifters without splitting the case.

Yes, lobes can go flat.

How about putting your bus year and engine type in either your sig line or your avatar so we don't have to guess what you are driving.

Mon Jan 19, 2015 9:46 am

I have 120 psi on all cylinders which leaves me to believe the valves, rings, seats etc are all fine. Just wanted to know if it was semi common for cam lobes to wear on these motors.. about to pull the motor just wanted a second opinion. Thanks

Mon Jan 19, 2015 9:47 am

Sorry 77 westfalia was fi but just went to carb. I believe these are type 4 motors

Mon Jan 19, 2015 10:18 am

You can pull the lifters on a Type 4 motor quite easily with in the engine in place. Buy a set of pushrod tube o-rings and a pair of valve cover gaskets and go at it.

http://www.thesamba.com/vw/forum/viewtopic.php?t=420944

Also easy enough to see how much lift you are getting by pulling the valve cover and watching the rockers as someone else turns the engine.

I am guessing that you may have a valve seat that has regressed badly into the head. Pull the rockers and check the valve stem heights with a straight edge.

Mon Jan 19, 2015 10:58 am

I did spin it over with valve cover removed. Thats what led me to believe the cam was worn. I will pull pushrod tubes next. Hopefully its just a worn lifter and a new set will fix it. Thanks

Mon Jan 19, 2015 11:12 am

The only way it would be a lifter is if it is a hydraulic lifter and it is collapsed. When you run it does it run on all 4 cylinders? It is normal for an open lifter to bleed down while the engine sits. It should pump up as soon as oil pressure builds.

Mon Jan 19, 2015 11:15 am

Its a worn cam then. Lifters are solid. It will run just bacfires thru intake because exhaust valve won't open

Mon Jan 19, 2015 12:05 pm

If you have one cam lope that is flat it should affect two opposing cylinders.

Mon Jan 19, 2015 12:38 pm

If its popping back in the intake....unless you are really sure that the exhaust is not opening at all...It sounds like a bent intake valve or one that is stuck open allowing combustion flame back into the intake tract. Ray

Mon Jan 19, 2015 4:35 pm

I thought the same thing. But I have great compression on all cylinders. And yes i think its not opening on both sides. I guess the exhaust lobe for no. 4 and 2 is flat. Any suggestions on where to find a cam? Thanks

Tue Jan 20, 2015 8:33 am

ApexMoto wrote: I thought the same thing. But I have great compression on all cylinders. And yes i think its not opening on both sides. I guess the exhaust lobe for no. 4 and 2 is flat. Any suggestions on where to find a cam? Thanks

http://www.webcamshafts.com
Get the #142 w/matching lifters as its the replacement for a oem stock cam.

Tue Jan 20, 2015 8:40 am

the 142 is as close to a stock bus cam as one can get. The profile is from a 2.0 GA 914 engine so it is a little higher reving than the bus cam. You will need new lifters too. The new cams are bolt on so you need to have the existing gear ground off and spot faced. If the existing gear is a B gear then it is magnesium, in which case you might look for a C gear which is aluminum. You will also need the same clearance gear, somewhere between a -5 to +5.

Tue Jan 20, 2015 11:18 am

I had a lifter mushroom on my t4 1700. Solid lifters. Had to split case. Be sure new cam clears the oil pump.

Tue Jan 20, 2015 2:01 pm

Lifters Hydraulic or Solid ?

Boston Bob's history of Hydraulic Lifters