Serious lubrication problem in my top end..., possibly the cause of hydraulic cam failure? Options

[jk76.914]

I was lashing my valves on my '76 2.0, after 1000 miles since the rebuild. When I took the valve cover off, I was mildly surprised at the lack of oil in it. Everything was coated with a film, but there was virtually NO liquid oil in the top end.

I didn't think TOO much of it until I started my adjustment process. I had installed an hydraulic cam when I did the rebuild. This was based on 100% reliability experience in 3 Corvairs over about 450,000 miles. Anyway, I really wanted to lash them like a Corvair- with the engine running, back off to clatter, allow to stabilize, turn in 1/4 turn, allow to stabilize, turn in 1/4 turn, etc until I reach the desired lash of 1 turn. I can't do that on the Type IV of course, because the adjuster screw is moving when the engine is running. So I decided to approximate the process. I'd set the valves to .006" clearance on all 4 valves (I did one side at a time), and let it run for about 10 minutes. Then I'd shut it off, turn each adjuster in 1/4 turn, start it up, run for 5 minutes, shut it down, etc until I turned each adjuster in 1 turn from .006" clearance.

To facilitate the process, I cut an extra cover in half lengthwise, put a half gasket in, and held it on with the bail. That way, I reasoned, I could shut it down and do the 1/4 turn and restart without having to remove and replace the cover everytime.

So. After adjusting the valves to .006", I started 'er up. And what do you know? COPIOUS amounts of oil were splashing around in there. A puddle formed on the heat exchanger, causing white smoke, not to mention what it did to my driveway. And this was with the half cover collecting oil from below.

So, after 10 minutes, I shut it down and turned them in 1/4 turn, put some plastic down on the driveway, and started 'er up again. And guess what? The oil stopped! What was happening? The push rods have a hole in the end to deliver oil up from the lifter to the rocker box. At .006" or .008" clearance, there is plenty of space for the oil to come splashing out. At 5000 RPM, I suspect it GUSHES out because of the higher oil pressure. At zero lash, the domed top of that pushrod mates into the hardened cup of the rocker and is held there by the oil pressure acting through the lifter- and it gets turned off like a faucet.

Then I thought about my Corvairs again. In that design, there were two holes at one end of the pushrod. One in the tip, and one on the side of the pushrod. The manual states that this goes at the rocker end, and the side hole delivers oil to the rocker mechanisms and valve stems and springs, and the end hole just lubes the tip at the rocker. Eureka! I was starving my top end of oil!

To confirm whether you need a LOT of oil up there anyway, I started searching on the internet. I discovered that Lycoming and Continental aircraft engines both migrated to hydraulic lifters in the late 70's. Both are horizontally opposed, air cooled, pushrod, overhead valve engines. Continental was very successful, with minimal problems, while Lycoming had problems with lifter spalling, cam lobes going flat, valve guides failing, pushrods bending, and (picture this) valves disintegrating in flight! Sounds like the 914 experience a lot of people have had. Anyway, the Lycoming problem (never directly admitted to by Lycoming, by the way) was due to inadequate oiling of the top end! In their case, it was due to using a lifter design that was originally intended for a flat head engine, not OHV. It was never intended to deliver oil up a pushrod. The Continental engine used a barrel lifter, almost exactly like the automotive lifters used today with OHV engines.

The failure mechanism was inadequate lubrication of valve guides, causing coking and valve sticking, initially. The sticking required inordinate forces to open the valve, which overstressed the lifters, and caused galling and damaged lobes.... Eventually the valve could stick fast, and break something....

Here's one article I found on the topic. There are many more, lots of pictures, other descriptions, etc., but this one covered most bases the best I think....

http://www.prime-mover.org/Engines/Marvel/tbo3.html

It's a long article, but very interesting reading. To quote their summary paragragh-
"What you need to remember is simply that we have found an inverse correlation between oil flow to the rocker boxes and valve and guide distress. Valve/guide distress in turn places huge loads on the lobes of the camshaft during the valve opening sequence and we believe this is most likely the cause of Lycoming's camshaft problems, which also have never been formally solved. You also need to know that even if you do everything involving engine operation and maintenance perfectly, you may still encounter upper end problems if the mission of your aircraft involves extended flights with cruise power and cruise mixture set, regardless of CHT levels . This is the fault of the design, not of the pilot or of the mechanic who maintains the aircraft. In short, if you have this problem, there is nothing you can now do to prevent its continuation other than to fly at greatly reduced power levels and/or enriched mixture settings."

Other points. Maybe these aren't relevant to us, but they're certainly food for thought-

1. better oiling of the top end will increase oil temperatures, as the oil now is carrying away more engine heat. Later versions of Lycoming engine were the same in HP and displacement, but needed bigger oil coolers.
2. sodium-cooled exhaust valves will make the problem worse because the stem will run hotter. If there is good oiling to the rocker box, however, sodium-cooled exhaust valves will help.


Things I still need to find out-
- Was it just my kit, or do other manufacturers hydraulic 914 kits address top end lubrication? I suspect not, because I really am thinking this is the root cause of the "hydraulic cams are evil" movement...
- what did VW do to make up for lack of lubrication at zero lash when they went to hydraulics in '78? Different pushrods a-la Corvair? Or special rockers with oil passages instead of a blind cup?
- what do I do now? I've "grounded" my 914 until this is resolved. I'll probably order a set of custom length Corvair pushrods to use, but I'm still investigating.

Sorry this was so long. I hope somebody actually reads it!!!

[Bleyseng]

Yeah Britt, go to a junkyard where they are breaking apart VW Buses motors. You know the ones that are completely fried and look at the cams.....and lifters.

You can pull apart 914 1.7 motors with decent cams/lifters and well over 100k on them. Not so with the hydro bus motors....

hell, even the 114k Westy motors cam and lifters were decent and that is with no oil changes (PO just added oil cuz it leaked) and it ran out of oil 3 times and the PO just drove it till he had time to add oil.

[bd1308]

yOuve got a point there.

I got a unknown crap used junk old 1.7L 914 engine....had it going in one day, and put over 4000 on it without a hitch

I put together some dudes bus (I *REALLY* want a bus) and it sounded like crap and it was in same condition, rattled like a MOFO, and sounded like garbage, had no power and burned more oil than a Abrams M-1

[jk76.914]

Hmm

Intresting that VW used hydros in the bus from 7x? to at least 78...

and it was stock like that AND it was aircooled, and still is.

Yep it started in late 78 in the buses.. Went through 83 in the vanagons and on into the wassers.. BUT the bean counters noticed a loss of sales due to idiots that didn't adjust valves and the fact that other vans were available that didn't need valve adjustments.... Those idiots caused the problems at the factory- not the Engineers..


Just because VW did something, doesn't mean a DAMN thing! I threw the Bentley away at least 10 years ago!

what they did do is create an ailment that wears engines out faster than anything, I see 1.7 engines that are 12 years+ older than the late Bus engines and have less wear everywhere, even with more miles on them..

WOW! You've got great connections!!! You probably even know those beancounters names!!!

Seriously, I think there are two questions here-

1. if they can be gotten to work, is the hydraulic route worth it?
2. if so, how do we get them to work?

#1 may be a yes. Even you, Jake, spent a lot of time in the '90s working with hydraulic cams and lifters, so you must have perceived a benefit. And others are posting interest so as to get away from valve adjustments. And then there's the quieter running, as well.

For #2, I think there is enough information out there to lay out a path to a solution. It's not just VW, but the Corvairs, Lycomings, Continentals and other engines that have used hydraulic valve adjustment (since 1929 in fact) that have failed but come up with solutions. If the problem is indeed lubrication to the head, I personally think that's solvable. Tonight is the first time I've seen any discussion about root cause (lubrication) as opposed to just symptoms (lifter galling, lobe flattening, etc), so that's progress.

That's enough for one night. I'm committed now, I have to make it work, because I don't want to pull that engine again and tear it down to the cam!

Good night everyone.
Jim

PS- I stuck with the sodium-cooled valves as well!!!! I guess I'm just a stupid guy!

[jk76.914]

Yeah Britt, go to a junkyard where they are breaking apart VW Buses motors. You know the ones that are completely fried and look at the cams.....and lifters.

You can pull apart 914 1.7 motors with decent cams/lifters and well over 100k on them. Not so with the hydro bus motors....

hell, even the 114k Westy motors cam and lifters were decent and that is with no oil changes (PO just added oil cuz it leaked) and it ran out of oil 3 times and the PO just drove it till he had time to add oil.

I'm not sure VW's implementation was a good one. If all they did was boost the oil pressure.... I can't find anything about differences in pushrods or rocker arms....

To paraphrase Jake- Just VW did something a certain way, doesn't mean a DAMN thing! Look at Lycoming. Took them 20 years of service bulletins to get it right. I keep bringing up Corvairs, because, well I think we should be looking at the guys that made it work as the example.

[bd1308]

Yeah Geoff, I had my fair share of roasted engines


:carnage:

[Joe Bob]

I had a wrench way back that insisted that hydros were the way to go on a Type IV......I said BS.....he insisted and I told him if that it grenades prior to 10K miles it was his dime....engine AND labor. He took the bet and lost. Shortly after that, I built my first six conversion.....

If you want hydros...buy a bus.

[Jake Raby]

The ONLY benefits I saw from hydros was a quieter valve train.
Is that worth comprmising everything from longevity to chamber filling?
Hell no!

about the worst thing in the world is a hydroD jet engine, the delayed opening event of the intake is horrible when coupled to D jet.

Want hydros? Buy a frickin chevy..

[Bleyseng]

Iffen you want quieter valves and less adjustments use the Porsche swivel feet! They are the best thing to come out for the type 4 since sliced bread!

Yes, VW did use special rockers spacers, pushrods for the hydro set up. I use the spacers on my motors to keep the rockers from sloppying around.

pull the hydro cam and don't look back.... (IMG:style_emoticons/default/headbang.gif)

[Mrs. K]

.............one word.....................



"ASTROGLIDE" (IMG:style_emoticons/default/thumb3d.gif)







Lisa
(IMG:style_emoticons/default/mrs.K.gif)

[jk76.914]

Iffen you want quieter valves and less adjustments use the Porsche swivel feet! They are the best thing to come out for the type 4 since sliced bread!

Yes, VW did use special rockers spacers, pushrods for the hydro set up. I use the spacers on my motors to keep the rockers from sloppying around.

pull the hydro cam and don't look back.... (IMG:style_emoticons/default/headbang.gif)

Britt, how are the rockers different? I know about the pushrods.

[Katmanken]

One more thing Britt...

Yer off on the adjustment turns... the manual was WRONG and engine damage can result!!

That's only 2 HALF turns in....

Correct Procedure:

1. Use only synthetic oil

2. Back off the adjusters to say .006 gap and run the engine to heat up the oil and fully pressurize and expand the lifters. Some people run a day or so that way.

3. Re-adjust the adjusters to just touch the valves and tighten in 2 HALF turns. Lock in place..

4. Close up and run the thing.

Don't beleive it? google Vanagon forums, Boston Bob (a guy Jake respects) and on and on..

Kenrunninghydrossuccessfullyfor180000miles

[bd1308]

ah it aint my engine.