Valve Problem

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Marc W

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My 2180 VW started misfiring shortly after take off. It was right at 32 F. and it was about 80% relative humidity so I naturally suspected carb ice. I put the carb heat on and no help. I have an A/F monitor and it had gone way lean so I richened the mixture and that helped but it still was misfiring badly. I wasn't far from the airport so I just headed back and landed and put it away. I started it up when the temps were warmed up and it still misfired so I don't think it was carb ice.

I did a compression check and #4 was down a little. I next did a leakdown and #4 exhaust valve was leaking. So I pulled the head and took it apart. I only have about 50 hours on a valve job. I don't think the valves look right. I am not sure the valve grinder did a very good job. The intake valves are both hitting on the inside of the seat. The exhaust valves seem to be hitting evenly across the seat but the leaky valve is not seating all the way around.

First picture is cylinder #3 where the valves were sealing. You can see the shiny ring on the inside of the seat on the intake seat.
upload_2020-2-21_17-24-42.png

This is #4 with the leaking exhaust valve. Again, you can see shiny ring on the inner edge of the intake seat and the carbon toward the outside of the seat. You can't see it but the exhaust seat toward the top is all carbon.
upload_2020-2-21_17-29-45.png

I am not an auto machinist so I am not sure about this. It is my understanding that the valve should contact the seat on the outer edge of the seat first. Am I wrong?

Do these seats look like they were ground correctly?
 

Dana

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I think the need for regular valve jobs is just the nature of the beast for VW engines... though mine manifested in difficulty starting and poor idle; it always ran fine at higher rpms. When I had misfiring problems with a warm engine it turned out to be a bad magneto coil. But Pops is the VW expert here and no doubt will chime in.
 

proppastie

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Need to use the suction cup thingie and valve lapping compound. When done should hold gas in the upturned head.
 

Hot Wings

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Do these seats look like they were ground correctly?
NO. But it is hard to tell from the photos - even enlarged. It looks like a single angle valve job and the exhaust seats are too wide. Yes, thy can be too wide.

Find someone with a Neway cutter, that knows how to use it, and get them to touch things up. Done properly, cut not ground*, lapping is not required.

What does the surface on the matching valve face look like?


*This can get into a discussion that rivals politics, best whisky and nose gears in intensity. I won't partake any further. ;)
 

Pops

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Anytime I have a valve problem, I install new SS exhaust valves and stock intake valves. They are very cheap. I don't have the valve seat cutting tools, so if I have a seat that needs work, I take it to a local VW engine machine shop that I have been using for 50 years. I hand lap using the suction cup tool and if I'm lazy, I use a battery powered drill on the other end of the valve to spin it. Doesn't take long and I want a width of .065 wide, checked with blue machine dye. For a aero VW engine, I like to have a spare set of heads and at 500 hrs switch to the new rebuilt heads with new valve guides and valves, keepers, springs and studs. I check the valve lash at the 25 hr oil change and record the lash of each cylinder to catch a trend before something happens. Also 500 hrs is when the Slick mag needs to be checked by Slick. I check the mag drive puck at each conditional inspection. On the compression check a good broken-in cylinder and well seating valves, it will be about 77/78 over 80 .

I have a set of 1965, 1200 cc , 40 hp heads I need to rebuild. Finally got the crank end play set correct. When setting the end play, I miked some shims I had and picked out the shims for the .006 end play that I always use. Something was wrong. Finally found the problem, the 1200 cc, 40 hp crank end play shims have a slightly larger ID than the 1966 and up cranks. Some of the shims got mixed up. So the three shims I used was one with the smaller ID.

What ever Hot Wings tells you about VW's, it will be right.
 
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Mike Stewart

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I'd agree with everything Pops said regarding using new springs, keepers, and some Manley valves. Check to make sure they are true. Even the best ones (including Continental and Lycoming) come out of the box slightly crooked sometimes. True them on a lathe or valve grinder. I'd buy the Neway cutters and do a three angle job yourself. Lapping not recommended if you use the Neway cutters. Use Dykum. It's fun.
 

Marc W

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It looks like a single angle valve job and the exhaust seats are too wide.
That too! I think I got half of what i paid for. I paid high dollar and got half-**ssed work.

I may just buy the cutters and do it myself. It seems to be nearly impossible to get consistently good work out of an automotive machine shop.
 

Pops

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Memories.
I bought a new VW Bug in summer of 1969, ( $1868). In 18 months it had 76 thousand miles on it. Traveling on my job. I didn't know anything about it having solid lifters and needing a valve adjustment from time to time. At about 50K, it burned a valve, yep, you are right, #3. At that time most garages would not work on import cars because they were metric and they didn't have any metric tools. That is when I started learning about VW's.
I have drove VW's over a million miles and have had 2 burned valves. The second was in 66 beater with the 1300 cc, 50 hp. At the time I was buying and selling VW only and building engines as a side business. Bought the 66 for very little and decided to see how long I could run it without adjusting the valves. Can't remember for sure, but I think it was about 35/40K when I was on the interstate running about 75/80mph. On the interstate, I ran it wide open all the time if possible. The head of a valve broke off and went thru a piston and left engine parts on the interstate. Rear wheels locked up at that speed. It was about to swap ends when I got the clutch in.
I found out that by driving the car correctly and checking the valve lash at each oil change, new plugs and points and condensers and timed correctly ( 50 deg dwell) at 12K miles. I usually got 150/175k out of a engine and getting 32/33 mph with a 1600 cc engine. For toys, I also built several Baja's and a couple good running street cars and a pipe mud buggie that I ran on the highway.
I have a very good VW only machine shop about 50 miles away. They have been doing my engine machining from 1970. Never had any machining that I was not pleased with at good prices. When building engines in the evening, I usually built one engine a week. Drop engine parts off and pick up parts at Kieths Auto Parts on Saturday each week. Keith's son Vick, is still running the business. Great people. They used to have the worlds record holding VW dragster. They know VW's.

Had a 1966 split window VW camper bus with a 1700 cc engine I built for it. Wife and I and 3 kids in the bus , pulling a little fold out camper behind it, would go to OSH each year and also spend about 2 weeks on the road traveling having a great time. Great memories.

To much demand, I quit building engines and selling cars after about 7 years. Sold hundreds of VW's. Usually had 6/8 for sale at a time.
Wasn't enough hours in the day.
 

Hot Wings

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I may just buy the cutters and do it myself.
Keep in mind that they are kind of expensive and there IS a learning curve associated with the Neway cutters. Done by hand, the power drive is even more expense, it requires some 'feel' to get a consistent lap free surface. A permanent marker is fast and works for the first round of cuts but the ink is thicker than Dykem. It tends to ball up on the final cut.

That is when I started learning about VW's.
Your VW history is even more similar to mine. My first VW was a 57. At that time my state still required a safety inspection to get plates. I thought "Who better to do the inspection than the dealer? I don't know what to look for."

They called several hours later telling me to "Come get your car! We can't get it out of the service bay." They managed to get the crash box transmission stuck in 2 gears at the same time. After some fiddling with the stick I managed to get the trans unstuck and drove home. Fortunately I did have a mixed set of metric hand tools. 3 days later I had a syncro trans installed and was back on the road.

Yes, you really can do all that with little more than a set of hand tools and the stock VW jack in your driveway.

Thus began my VW repair adventure..............A few years later the dealer was bringing their Tp III engine work to me. Their mechanic just couldn't work with the analog FI. If we had a competent VW dealer in my town back then my life would have probably been spent in a chemistry lab somewhere.
 

delta

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Make sure your guides aren't worn first, then lap the valves to determine width and condition of seat.
 

wsimpso1

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I am accustomed to having three angles on the seat, with the middle angle close to matching the valve. This gives high unit load on the contact stripe, which is good for sealing and preventing contamination of the sealing surfaces. Single angle valve seats = don't do business with that shop again.

Small valve leaks will grow into big valve problems, so you had to fix it. Nonetheless, small exhaust valve leaks will rarely cause much in the way of running problems. Intake valve leaks will...

I would go looking for other issues if you were having a misfire that responded to mixture changes...

Billski
 

bmcj

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One of the nice things about living in Southern California as a kid (a long time ago) driving VW bugs is that dune buggies and Baja bugs were popular and there seemed to be a skilled VW engine shop or parts shop on every corner. The old Volkswagen engines were simple to work on and I did a lot of my own maintenance on the ones I owned. However, I am not an engine guy, so for the two full rebuilds I did for my long term ‘keepers’ I enlisted the aid of a couple of longtime family friends. Joe Vitone helped on one of the rebuilds and Joe Horvath helped on the other. (Vitone founded EMPI and Horvath founded Revmaster). Though each had made a name for themselves in VW racing, I only asked them to rebuild for street use (we even shimmed the cylinders on the 1600 to reduce compression, eliminate dieseling on shutdown, and make starts easier, all without sacrificing much power... it also changed the sound of the engines so there was less pop-pop-pop).

Oops, I’m rambling. I guess the takeaway on this is that “I’m not an engine guy” so I can’t offer much help, but others here like Pops can.
 

jeff naul

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If you havent go to N56ML.com
Read up on his experience with VW heads... scares me now knowing whats out there. I need to send mine off for new guides but dont know who to trust. Will anyone say who not to use publically?
 

TFF

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Part of the diagnosis is the valves. Were they new or used? Multiple issues can come up. Face of valve wrong angle. Seat wrong angle. Seat cut too much. Valve cut too much with no margin. Were the seats cut too many times. Most shops now have 5 angle cutters that are awesome. You can botch the setup.

No VW expert but I worked in a predominantly head only machine shop for a while. Mostly for my FYI; I’m definitely not a machinist. Lap the valves in now and verify the contact. It will also show if valve is warped. Just enough to get a pattern. A lot of times I do that once back from The machine shop for piece of mind. If you are trying to get warrantee, just take them to the shop and talk to them.

There is a lot of talent out there but like all jobs, off day, being pushed for productivity, or you just happen to be the training part for the new guy. All the stuff behind the scenes. When I had my crank ground, I watched. The guy was good, son of the guy I worked for, and even though I could not run that machine, I can tell when all is not given. I have been in that shop enough to know some stuff is brilliant and some stuff was not.
 

Mike Stewart

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I'll second the thought about having guides that aren't worn. Straight, non-worn guides are critical, as is using valves that are true. As I learned from an old A&P who taught me to use his Sioux valve grinder machine, valves are not always true out of the box. He had found many over the years that weren't. In my batch of eight new Manley's, two of them needed touching up. Really . . . this is an important thing to know. Many unhappy owners of big Continentals and Lycomings that are either new or newly overhauled end up having valve problems 100 hours in . . . never realizing their guides were not installed straight from the factory or shop - and that one or more of their new valves were slightly bent right out of the box. Extremely important considerations, straight guides and true valves.

One way to keep guides from being worn is to use swivel feet (elephant feet sometimes called) on the rocker tappets. This keeps the rocker arm tappet from side loading the valve stem. Side loading over time causes worn guides. Thanks to having swivel feet, my guides were absolutely perfect at 483 hours when I top-overhauled my 2180 in 2009.

Re the Neway cutters - they aren't expensive nor are they tricky to use.
Neway company video:


I'll echo reference to Mark Langford's Corvair engine build. It's a world class effort and extremely informative and helpful. His info is as applicable to the VW as to the Corvair. One needn't perform absolutely everything he does in this extremely comprehensive tutorial . . . take what's usable and leave the rest. Measuring and equalizing valve spring tension for instance, or measuring and equalizing combustion chamber volume. The word thorough barely covers this website.

http://www.n56ml.com/corvair/valvejob.html

Looking at the Neway site just now the prices are scary but don't let them fool you. Cutters and pilots for a VW were only $200-$300 when I bought my set in 2009. Give the company a call and talk to the rep & tell him what you're doing. He'll fit you out and it won't cost all that much. Plus, once you're finished with your work surely you can put the Neway equipment on eBay or a site such as this one and get most of your money back.

Avoid dune buggy crap like Monnet stuff. I recommend Manley valves and genuine German VW springs. Don't ever take anything to Rimco. They once had a good reputation but are now just a dune buggy shop. My 2 cents.

Stock VW seats are so soft that even though I did a careful job of creating 3-angle seats, the SS valves will eventually beat them down into 1-angle seats . . . which is fine. As long as the valve/seat seals all is well. An option is to replace the stock seats with something with nickle - something necessary if and when there's no longer sufficient seat material to cut new ones. Check valve clearances every 25 hours. That interval corresponds with my oil changes.

Mike
 

Marc W

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I am familiar with Langford's site. A lot of good info there.

I have been working on house projects. Have to keep the chief cook and bottle washer happy! I am going to look at the valves again tomorrow. I don't know how old the heads are. I thought they were new when I bought the plane but that turned out to be a mistaken belief.

Billski's right. The valve isn't leaking enough to cause the severe misfire so I still have to diagnose that problem. I will check the carb first. I have dual ignition so something would have to be wrong with both ignition systems to cause the miss.
 

Hot Wings

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Re the Neway cutters - they aren't expensive nor are they tricky to use.
Expensive is a subjective variable.

Tricky? No. But they do require a minimal learning curve that the video doesn't cover - especially with engines like the VW with small valve stem diameters.
Side load on the pilot can make getting a concentric seat hard until you learn how to spin the tool. The tapered guides are stiffer than the expandable ones. Even then with the 60 and 75 degree cutters if the seat is off center it takes patience to not force the cutter to cut off center. This is especially true with the VW if someone has just jammed in a new set of oversized intake guides. They tend to curve away from the port wall. When reamed to straighten they point to a new center.

Soft seats on a VW? Compared to some of the new valve seat materials they are soft. But if the seats cut as easily as the flat head seats in the video, with rolled chips coming off the cutter.......you have junk heads and need to find a better source.
 

Pops

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Went on their site and check the price. For a complete kit #1608, for VW's, its $1035.50 . Looks like I will keep having the local VW machine shop do the work.
I would like to have the set and do the work myself.
 
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