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!!!

[bd1308]

the hydro lifters need to be pumped off...

turn the adjusters in until you FEEL ANY RESISTANCE, and then instantly turn *ONE* TURN IN.

****VERY**** IMPORTANT****

final adjustment is contact plus TWO turns.

[Jake Raby]

What rocker arms are you using? what valve adjusters? what rocker spacers?

Most importantly, what oil are you using and what oil pump?

The issue you are experiencing is common with hydros and a huge reason why I won't use them in any of my engines..

did you block off the pressure relief piston at the back of the 1-2 cam oil galley or did you leave it stock with the spring in place??

If you left it stock thats the issue as it is dropping the oil pressure in the lifter galleys and not supplying enough pressure to get the oil up to the rockers with tighter clearances.

When i built hydro engines I would cut off a welding rod and jamb the pressure relief tightly shut to boost oil pressure in the lifter galleys, thus pressurinzing the lifters, pushrods and entire arrangement more...

Hydros are a step backward with these engines-

[bd1308]

yet it works fine as long as the hyro lifters stay pumped up

[Jake Raby]

yet it works fine as long as the hyro lifters stay pumped up

Thats all acoording to ones definition of "Fine"...

[bd1308]

for stock trim, I dont understand why one wouldnt want to use hydros.

For RAT, they seem to take stock and push it beyond the envelope.

I would never recommend a hydro cam to anything other than stock, but for a daily driver running a stocker, whats the harm?

Plus for stock stuff, the engine'll only last 90k anyway.

actually im just cuirious to see why you dont like hydros

[Jake Raby]

I could literally write a book on hydro deficiencies within the realm of the TIV engine.. Do searches as I have posted many of them...

The main ones are the undue wear the rest of the valvetrain sees and the lubrication issues that hurt valve guides fast...

And its not just with engines pushing the enveloppe, stockers see the negaitve aspects just as badly, especially when the owner neglects valve adjustments and kills his own engine. Hydros cover up issues that would normally let you know they are present before things scatter...

[bd1308]

I GOTTA find a easier way to do valve adjustments.

[Jake Raby]

Its not hard- and it only has to be done every 6K....

I have not had to adjust a single one of mine since 2003 in the 912E, every time I have checked them in the past 80K miles they have been spot on.

[bd1308]

Well I would expect them to be perfect Jake

How can you set an example for a reliable engine if you have to mess with it all the time (IMG:style_emoticons/default/tongue.gif)

[Mueller]

for stock trim, I dont understand why one wouldnt want to use hydros.

For RAT, they seem to take stock and push it beyond the envelope.

I would never recommend a hydro cam to anything other than stock, but for a daily driver running a stocker, whats the harm?

Plus for stock stuff, the engine'll only last 90k anyway.

actually im just cuirious to see why you dont like hydros

correct me if I'm wrong, but the motor as is never came factory with Hydros until the wasserboxer motor correct??? there is a good chance the wasserboxer motor was designed for hydros and it just happens to be that they fit the air-cooled motor so people throw them in there and hope that they work...of course they have been proven to work, but then again, not as well as one would want them to (IMG:style_emoticons/default/smile.gif)

it's like a fat man wearing a Thong, just cause it fits it does not mean it's right (IMG:style_emoticons/default/blink.gif)

[jk76.914]

What rocker arms are you using? what valve adjusters? what rocker spacers?

Most importantly, what oil are you using and what oil pump?

The issue you are experiencing is common with hydros and a huge reason why I won't use them in any of my engines..

did you block off the pressure relief piston at the back of the 1-2 cam oil galley or did you leave it stock with the spring in place??

If you left it stock thats the issue as it is dropping the oil pressure in the lifter galleys and not supplying enough pressure to get the oil up to the rockers with tighter clearances.

When i built hydro engines I would cut off a welding rod and jamb the pressure relief tightly shut to boost oil pressure in the lifter galleys, thus pressurinzing the lifters, pushrods and entire arrangement more...

Hydros are a step backward with these engines-

stock.stock.none.10W40.stock.no, it's stock.

Thanks for the advice. But the cam is in now, so I need to make it work.

The articles seem to substantiate the theory that the problems arise from inadequate lubrication to the head, and it sounds like you're agreeing with that. It's all anecdotal for me at this point, however, as I only have a sample of 1. The known fact is- my personal engine has inadequate oiling to the valve train. I wouldn't have noticed it myself if I hadn't tried setting the valves the way I did, with the cutoff valve cover. Anyway, I'm treating this like a time bomb, and so I will fix it. The oiling that is. If everything goes to s--t later, well then I can revisit the cam decision...

I question whether I could make the pushrod-to-rocker joint "leak" (my term) by boosting the pressure in the galley, regardless of how high I boost it. The rocker would have to lift off the pushrod by oil pressure acting on a very small surface, but it has to counteract the same (or probably higher) oil pressure acting on a much larger surface- the diameter of the plunger in the lifter- that's fighting to hold the gap closed, which is the job of the hydraulic lifter after all. No matter what I boost the pressure to, the force trying to maintain zero lash will always be greater than the force trying to crack open the pushrod-to-rocker joint to release oil. And even if it were successful, the delivery would be far from controlled or predictable.

I think the Corvair solution is more certain and more elegant- it has a guaranteed, known (and low) resistance path for the oil to get to the valve gear, just like the legacy solid lifter design has, but it also maintains zero lash. In addition, the Corvair solution releases oil continuously, not just when the valve is closed, unlike the legacy design. Also, because the rotation of the lifter in its bore imparts a rotation to the pushrod, the side hole sprays the oil around the rocker box like a lawn sprinkler, which I think may be another improvement over the legacy design in oiling. And I see no downside to it. And, over 1.7 million Corvairs were shipped, each one with 12 hydraulic lifters, which is not anecdotal.

One reason for my verbose postings, which I didn't state, is that I think this is a real problem. And I know for a fact that there are a lot of folks out there with hydraulic cams in their 914s, either by choice or inherited from POs, who may want to know about it and think about it and maybe look into it on their own engine.

[bd1308]

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.

[Bleyseng]

Yeah, but Jake you are running the Porsche swivel feet which helps sooo much to keep the valvetrain nice.

buses had hydro's starting in 78 withthe GE cases which had the blocked off cam oil gallery.

[bd1308]

Geoff, your bus has a hydro engine, right?

[jk76.914]

for stock trim, I dont understand why one wouldnt want to use hydros.

For RAT, they seem to take stock and push it beyond the envelope.

I would never recommend a hydro cam to anything other than stock, but for a daily driver running a stocker, whats the harm?

Plus for stock stuff, the engine'll only last 90k anyway.

actually im just cuirious to see why you dont like hydros

correct me if I'm wrong, but the motor as is never came factory with Hydros until the wasserboxer motor correct??? there is a good chance the wasserboxer motor was designed for hydros and it just happens to be that they fit the air-cooled motor so people throw them in there and hope that they work...of course they have been proven to work, but then again, not as well as one would want them to (IMG:style_emoticons/default/smile.gif)

it's like a fat man wearing a Thong, just cause it fits it does not mean it's right (IMG:style_emoticons/default/blink.gif)

'78-'79 aircooled Type 2's had hydraulic lifters.

[Bleyseng]

NO!!

seen way too many problems over the years with hydros....in a VW.

[bd1308]

well slap me silly.

Huh.

Well I'm still in newbie status right?

Yeah, i'm still a newb

[Jake Raby]

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..

[bd1308]

Alright i'll take the bullet on that one.

Solids it is...

Lets start the sodium valve vs. the SS valve war now lol