Author |
Messages |
dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
|
Posted Friday, October 11, 2013 @ 02:18 PM
At 10 hours I started doing a valve adjustment and noticed that a couple of valves (one in particular) has developed a very large valve/rocker gap. It is well beyond what can be fixed with the adjustment screw and I would need to take out the shims under the rocker arms to fix it. And there would be a large variation between the valves.
Is this part of the engine break-in or an indication of something else going on in the lifters, pushrods, cam, etc.? An inspection shows no obvious signs of loose heads, or studs coming out or anything.
-------------------- Dann Parks RF4D #4051 N2188 now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
|
dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
|
Posted Friday, October 11, 2013 @ 02:47 PM
Well this is weird... I took out the pushrods are was startled to see that many of the engine-side ends were distorted and a few even cracked.
The cheap metal on the ends seems to be forming itself into the oil channel holes in the lifters (just on the engine side). These are the stock (aftermarket) pushrods that came in the kit, and it seems to me that they are utter crap. Has anyone seen anything like this before?
-------------------- Dann Parks RF4D #4051 N2188 now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
|
dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
|
Posted Friday, October 11, 2013 @ 10:19 PM
A few more details...
I did a valve adjustment at 30 minutes, one hour, and 3 hours with only slight or no adjustments needed. In the last flight, I noticed the EGT on one cyl was down a bit, and it didn't seem to be getting the power it was earlier. Obviously something was amiss. It seems like something either wore down (or something) to enlarge the valve gap and as the gap grew larger it really started to pound on the pushrod(s). It still seems to me that something is off. Were the rods not hardened? Has the cam worn down? The rod with the pointed bit on it was the one that had the huge gap, and is noticeable shorter than the others, but almost all are showing signs of deformation.
This is very bizarre.
-------------------- Dann Parks RF4D #4051 N2188 now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
|
Jorgen
Captain
Gender: Male
Location: Lund, Sweden
Registered: Apr 2007
Status: Offline
Posts: 835
|
Posted Saturday, October 12, 2013 @ 05:45 AM
Hi Dann,
sorry to hear about your trouble but I am impressed as always with your meticulous way of going about your building, testflying and breaking in the of the engine. Good thing you caught the trouble early! I talked with my local VW contacts and as you probably have already deduced the wear could be anywhere along the cam-lifter- pushrod- rocker arm- valve seat and it does sound a bit bizarre. It's probably a good idea to remove the heads and check the valve seats if you haven't done that already. Do you have seats made compatible with non leaded gas?
From what you say it could be that the alloys on the pushrods and the lifter faces don't match and that could be why it's been worn down so fast. I'll check with the local VW guru next week if he's heard about different alloys used in different engines/ pushrod configurations. I seem to remember your engine is a Great plains 1600, correct? Were the pushrods sold together with the engine or are they spares? I seem to rember that at least studs can be had from Brasil, Germany and elsewhere, and quality control is said to differ. Maybe you need to track down the pushrod origin: made in Brasil, Germany or elsewhere?
May the 4's be with you/ Jφrgen
|
JamesB
First Sergeant
Gender: Male
Location: Near Seattle, WA; USA
Registered: Oct 2006
Status: Offline
Posts: 257
|
Posted Saturday, October 12, 2013 @ 10:36 AM
Others, like Collin, have a lot more experience than I. But having been involved with Type 1 VW engines since 1968, I've never seen anything like that. Especially since these sound as if they were part of a kit, you'd think they were matched to the springs, etc. Sounds like they changed suppliers and didn't test them. However, push rods are not exactly extreme science and just getting a good set from another source, the most expedient solution.
Absolutely weird....and stupidly unnecessary.
|
Collin
General
Gender: Male
Location: McMinnville. Oregon
Registered: Oct 2006
Status: Offline
Posts: 711
|
Posted Saturday, October 12, 2013 @ 01:25 PM
Hello,
It looks like the hardness of the push rods. Run a file on the end of the push rod you may find it to be soft. I like aluminum push rods over steel push rods for low RPM engines. I will send you some German push rods and rockers.
James I still need to send you a Fiat starter. Has anyone herd from Eugenio. My last few emails to him has been kicked back.
Collin
|
dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
|
Posted Sunday, October 13, 2013 @ 09:32 PM
Thanks Collin.
A neighbor had a theory that the nipples are not caused by metal deforming into the lifter hole (as I postulated), but from the pushrod wearing down and leaving the nipple sticking out. The fact the ends of the nipples are all about the stock pushrod length adds credence to the idea. If that is the case, I wonder if there could be something wrong with the lifter surface that is wearing them. It could also be that there is a hardness issue as the wear would cause the nipples to appear. I'm going to try to better inspect the lifter surfaces.
I ran a file on an end and it made a groove easier that I expected it would. Softer that the tube itself, but difficult for me to tell anything specific.
-------------------- Dann Parks RF4D #4051 N2188 now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
|
dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
|
Posted Monday, October 14, 2013 @ 06:57 PM
Another update. Draining the oil and removing the sump cover revealed a large amount of "metallic" sludge in the plate that would be attracted to a magnet. So there has been a lot of metal moving through the engine. Still no answer as to what is happening, but it does look like I will be removing and disassembling the engine, cleaning it all out, checking everything and reassembling with some new parts since that is really the only way I am going to trust it.
...After the reason for the wear is determined.
-------------------- Dann Parks RF4D #4051 N2188 now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
|
dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
|
Posted Tuesday, October 15, 2013 @ 01:48 AM
OK, I finally found some pictures and discussion of the same pushrod damage in a VW engine forum, so it is not an unheard of issue.
http://www.thesamba.com/vw/forum/viewtopic.php?t=304108
Although there wasn't a definitive answer, the discussion pointed to poor material hardness, poor mating surface machining, plugged oil ports, and excessive rocker/valve clearance (or a combination of all). The recommendation was basically not to use cheap parts, but there was a mention of valve clearance for aluminum vs. steel pushrods. The expansion of steel and aluminum seems to be different and the clearances will change as the engine gets hot.
The Great Plains manual shows a clearance of .008 for the stock steel lifters, but I have seen discussion of using zero lash for steel and .008 for aluminum. What are you all using for the different materials? Could I have set the lash too wide and inadvertently helped create the damage?
I will also be able to check the oil ports in the lifters when I take them out.
-------------------- Dann Parks RF4D #4051 N2188 now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
|
Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2029
|
Posted Wednesday, October 16, 2013 @ 04:36 AM
Hiya Dann,
I am really sorry to hear about all the trouble you're having.
As regards valve clearances, I have been told another reason for not having them too big. Apparently over time, because of the cam followers hitting the quietening ramps, it wears the camshaft lobes, which means a complete engine teardown to replace the camshaft. Because the case halves become distorted over time, that requires line-boring before reassembly, so it all becomes very expensive, all for the sake of some tiny gaps.
Just to confuse things, all the VW books seem to give different figures, and we know that an aero engine, without the cooling fan, will run hotter than an auto installation.
All my engines have aluminium pushrods.
I have experimented over the years, and now I use very small gaps with no loss of performance, and very little if any need for adjustment, even after 100 hours or more.
I set mine to about 6 thou for the inlets, and 10 thou for the exhausts, but mostly between 100-hourly inspections, I simply check that there is a slight clearance gap (by rattling it with my fingers) on each valve when its neighbour is fully open.
I would be very interested to hear what Collin and other experts have to say.
Yours, Bob
|
eugenio
First Sergeant
Gender: Male
Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
Registered: Oct 2006
Status: Offline
Posts: 294
|
Posted Thursday, October 17, 2013 @ 02:19 PM
For sure the problem is due to the pushrods caps too soft. In any case keep the figures given by the engine manufacturer, don't invent the hot water. If you keep too small gap you risk to burn the valve because it does not close, if you have just a little bigger gap your only problem is the valve/rocker noise, plus keep in mind that the 1200 uses 0.20 for the intake and 0.30 for the exhaust, while all the others uses 0.20 for both. Also take into account that rocker arms for the 1200 have a 1:1 ratio, while the others have 1:1.1, so the lift is different.
Only hidraulic lifters are set to 0 + 1.5 to 2 turns because compensates automatically the gap.
Most of nowadays aftermarket parts come from China ........
Eugenio
|
Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2029
|
Posted Thursday, October 17, 2013 @ 02:24 PM
Hi Eugenio,
Presumably those numbers are metric? .02mm for inlet and .03mm for exhaust?
Yours, Bob
|
eugenio
First Sergeant
Gender: Male
Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
Registered: Oct 2006
Status: Offline
Posts: 294
|
Posted Thursday, October 17, 2013 @ 02:36 PM
Absolutely yes, sorry but we're used to the metric figures in Europe.
Eugenio
|
eugenio
First Sergeant
Gender: Male
Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
Registered: Oct 2006
Status: Offline
Posts: 294
|
Posted Thursday, October 17, 2013 @ 02:39 PM
Plus metric is 0.20 mm not .020 that is thousands.
Eugenio
|
Donald
Command Sergeant Major
Gender: Male
Location: Scotland
Registered: Jan 2007
Status: Offline
Posts: 489
|
Posted Friday, October 18, 2013 @ 02:24 AM
My RF3 manual, same Rectimo engine, gives the gaps as 0.20 & 0.30-0.35. Metric of course.
[edited to correct the exhaust gap 0.30 - 0.35, not 0.32]
[Edit by Donald on Friday, October 18, 2013 @ 12:53 PM]
|
Jorgen
Captain
Gender: Male
Location: Lund, Sweden
Registered: Apr 2007
Status: Offline
Posts: 835
|
Posted Friday, October 18, 2013 @ 04:35 AM
Thanks for good info Guys,
I also heard from my local VW guru that it's unfortunately not all that uncommon that pushrods are ground down, most often on the rocker end though. I'm not sure weather it's predominantly a quality issue, compatibility or perhaps lubrication issue.
On "SE-XST" one of the previous owners has put a lable on the front side of the firewall with the valve gaps (intake 0.20, outlet 0.25-0.30), pretty practical and makes annuals easier. Don't worry Dann, this cloud too will pass. Keep us updated, will you?
May the 4's be with you/ Jφrgen
|
Collin
General
Gender: Male
Location: McMinnville. Oregon
Registered: Oct 2006
Status: Offline
Posts: 711
|
Posted Saturday, October 19, 2013 @ 00:42 AM
Hi Dann,
If not to foggy I will visit with the Cessna around 10am Saturday.
Collin
|
dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
|
Posted Saturday, October 19, 2013 @ 02:46 AM
Fog is supposed to clear by 9-10-ish. If you have a case-splitting tool, that might be helpful. Thanks.
-------------------- Dann Parks RF4D #4051 N2188 now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
|
eugenio
First Sergeant
Gender: Male
Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
Registered: Oct 2006
Status: Offline
Posts: 294
|
Posted Monday, October 21, 2013 @ 02:23 PM
There's also another possible problem, the valve springs, if someone switched to the stiffer racing springs, the pressure to lift the valve is higher, so the pushrods may be affected from that.
Just a thought
Eugenio
|
Collin
General
Gender: Male
Location: McMinnville. Oregon
Registered: Oct 2006
Status: Offline
Posts: 711
|
Posted Monday, October 21, 2013 @ 06:27 PM
Hi,
Visited Dann on Saturday. It looks like poor quality push rods and lifters.
Good Mahle lifters are about $10ea.
Collin
|
dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
|
Posted Monday, October 21, 2013 @ 09:19 PM
Collin sent a photo of one of his lifters and I noticed how polished the contact surface was. Looking at mine, I was surprised to see how rough they were. Collin had noticed something odd with them as well. Some look like maybe the cutting tool was chattering in there and left a jagged surface (first photo). Maybe this was what contributed to grinding away some of the pushrods since some lifters were rougher than others. Curiouser and curiouser...
-------------------- Dann Parks RF4D #4051 N2188 now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
|
dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
|
Posted Wednesday, November 13, 2013 @ 03:37 AM
Well, the engine is back together with new bearings, lifters, and original VW pushrods and rockers from Collin. Flew it a couple of hours on Sunday and it ran well. I'm keeping a close eye on valve lash and so far it's stable. Flying weather is becoming marginal now, but hopefully I will be able to continue break-in and testing. Steve at Great Plains has asked me to send the parts back and he will have the manufacturer test them.
-------------------- Dann Parks RF4D #4051 N2188 now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
|
Jorgen
Captain
Gender: Male
Location: Lund, Sweden
Registered: Apr 2007
Status: Offline
Posts: 835
|
Posted Wednesday, November 13, 2013 @ 04:04 PM
Thanks for the updates Dann,
it would be interesting to hear what the manufacturer has to say about those lifters. Good luck with the break in; "Break a leg" as they say in showbiz...
May the 4's (all 4 cylinders that is) be with you/ Jφrgen
|
Roger.Camp
Sergeant
Gender: Male
Location: Ireland
Registered: Nov 2013
Status: Offline
Posts: 35
|
Posted Thursday, November 21, 2013 @ 07:53 AM
Hi all
Although I have built 7 aero converted Vee Dubs, I have never seen the damage to the pushrods as Dann has shown. I have seen this on road going engines. Normally caused by a culmination of occurances and mainly through aftermarket pushrods, wrongly set tappet clearance, stronger valve springs and most important of all the rocker or tappet offset.
I build all my engines using standard components and have never had a problem. The present engine to be installed in the sytky is a 1600 cc using all standard components with some tried and tested mods from my VW racing days but nothing wild or power increasing.
Regards
Roger
-------------------- It takes 1.460 bolts to build an aircraft and 1 nut to spread it over the landscape
|
dannparks
Sergeant Major
Gender: Male
Location: Parkside Airpark, Battle Ground, WA
Registered: Oct 2006
Status: Offline
Posts: 391
|
Posted Friday, November 22, 2013 @ 03:39 AM
Welcome to the group, Rodger. It's nice to have someone with your VW aero experience on board. Please start a new thread and tell us about your "tried and tested mods."
-------------------- Dann Parks RF4D #4051 N2188 now flying!
Pictures at: https://picasaweb.google.com/111628310900713778468/RF4D_N2188?noredirect=1
|