Type IV Engine Build/Repair Thread: Broken Camshaft

[vwwestyman]

What other photos would be more helpful? (Besides the mentioned cylinders and pistons photos.)

I have certainly implied that I want to "slap it together" and probably said as much.

That said, I also feel like it would be a waste of money if "slapping it together" would result in a motor that wouldn't run well for for very long.

The title says "rebuild/repair" for a reason:

If everything else checks out as usable and this seems to have been some kind of freako thing, then a "repair" would be reasonable. "Repair" defined as replacing the cam, the bearings, and seals, and maybe any other parts that clearly need replacing.

If everything is on the edges of wear tolerances, or indicates the need for major refurbishment, well, then we're in the realm of "rebuild and I'll really have to rethink what I do. At this moment, I don't have the cash for a total rebuild and may have to go a different direction for getting the bus on the road.

I've said a few times here and there that I would like to look at some kind of engine conversion (and for the record, with this one I would only do it if I can make it totally reversible). That said, if the engine goes together decently I can certainly envision enjoying driving an aircooled motor.

Hopefully that clears up my aims with this project a bit. Maybe not, I dunno.

So, to get/keep this thread on track, I need to determine if the motor needs a "repair" or a "rebuild."
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[CraigTee]

[chazz79]

Do the quickie bechtop leak down check of your valves. You might be able to avoid a trip to the machine shop there.

Buy a cam

Pull your lifters apart and clean them. It's tedious but a spec of metal might keep one from pumping back up.

Mic the rods and crank journals.

Machine if necessary*

Buy appropriate bearings

Buy gaskets.

If you can avoid machine work you can do this much for @500.00.
_________________
One day as a lion, or a lifetime as lamb

The green monster in bits and peices: http://www.thesamba.com/vw/forum/viewtopic.php?t=332556&highlight=green+monster

[CraigTee]

[vwwestyman]

Replies, comments, and questions bolded throughout.

[CraigTee]

When I CC'd and then shimmed the heads for valve combustion chamber clearance/compression ratio... I shimmed for the LOWEST compression ratio recommended. I didn't want pinging and didn't mind sacrificing a little power. That also would allow for the MOST piston/valve clearance.

If you don't see marks on the tops of any pistons (and I didn't see any on the valve pictures), I think you're good to go... unless somebody with more experience on these engines knows of another way to bend a valve without contacting the piston.

Some people will replace everything all new every time they pull an engine. I'm not going to say they're wrong because it's the safest way to build. I've done a lot of engines and my buddies have often teased me about over replacing also.

Nowadays, I use a mike and dial mic. a whole bunch....

I think it's a clean up and replace the affected parts if that's your desire. At least plastigauge the rod bearings tho... ok?
(Grin!)

[CraigTee]

[Tcash]

Cannot remember on the type4's but sometimes they machine the roll pin holes in both cases. Look under the bearings on the other side and see if the roll pins are located there.

CraigTee bummer sorry for your loss.
Do you remember setting up the backlash on the cam gear? The reason I ask is the wear on the leading edge of the cam gear leads me to believe it was tight. Did you hear any gear wind?

vwwestyman
I would replace the crank gear as well as.
Cam and lifters, cam bearings by the looks of it.
Oil Pump
Oil Cooler
Check that none of the valves are bent
Have the case oil plugs removed and case cleaned.

Good Luck

[vwwestyman]

[Wildthings]

What is the part number on the cam timing gear?

[raygreenwood]

Oh.....one defect I totally forgot about that you can look for that comes from the factory (when it happens....and it is rare)......and I say this because you noted that in the last build that you replaced the crank gear.....but did not mention why.....

Is....that on some cranks, the boss that the timing gear is pressed onto is machined out of concentric with the centerline of the crank. When I found this on a totally pristine standard/standard 1.7 crank....I thought I was losing my mind. I spoke to Jake Raby about in passing when I was picking up a crank from him........and he noted that while its not everyday common.....when you work with a lot of cranks like he does.....you see a few this way. He noted that since undersize gears are not available, unless you want to weld, grind annd then nitride or re- case harden there is nothing you can do really.
It causes not adverse running but it does cause an oscillation that at really high milage will show up as a lopsided wear pattern on the softer cam gear.
Because we cant get anything other than a "0" gear anymore....if your lash is excessive and you have a heavily sprung valve train it can cause problems.......that is not your problem here....
But.....if you have any other lash issues or say....a cam gear out of plane for any reason... . It can cause a failure.
I found this problem on the engine that I wrecked that had not enough clearance and was knocking the oil pump bolts. I only found it because.....oddly.....the crank gear no longer fit. It had either vibrated or been wrung hard enough by shock to be .015" oversized.
I measured the boss anx it was perfect. .....which was when I noticed the boss was out of center. I have found one more crank like it since. From the side you can literally see that it was machined out of center.
I still have the crank. I will see if I can unpack it and get a pic for you. Its worth checking. Ray

[vwwestyman]

[SGKent]

it is a magnesium gear (B). They fail at a higher rate than the aluminum(C) ones.

The lifters cannot be reused without resurfacing. When using a new cam it is best to get new lifters from the same source.

The gear came loose and impacted the oil pump. When the pump is opened up it is likely to have scoring in it from the debris, making reusing it unwise.

If there is no smack mark on the pistons they did not hit the valves. However it would be foolish to not send them to someone like Adrian or Len to look over and check for flaws before the engine is rebuilt.

The rods should be checked for both small and big end sizing. You may be able to polish the crank but it should be put on a run out gauge to be sure it runs true. It only takes a small microscopic bend to put wobble into the cam gear.

The brass and small gear that drives the cam should be replaced.

Clean up the cam gear with solvent and look for a number on the outside ring. Try to find a good used aluminum (C) gear that has that same number. Start checking lash there and go up or down based on that.

Take your time and do it once.

[vwwestyman]

The cam Craig included has an aluminum gear, marked C at the end of the otherwise same part number.

I had a few minutes to spend with the parts and camera tonight. Here's what I found.

Marks from the gear inside the block. Are any of these a problem with using the block?

There is some roughness on the drive gear. Guess that means for sure it needs to be replaced.

Pics of the valves. I remembered seeing a couple places here where it was recommended to place a straight edge across the valve stems to see the difference. Most of mine were all slightly shy of the top of the springs. Here is a couple pics of the differences. This is the 1/2 side.

Pitting on the stem of the 1 exhaust valve. Set too loose?

Similar (though worse) pitting on the stem of the 3 exhaust valve.

Pistons. No indications of valves contacting them whatsoever.

Cylinders. You can see the line where the bottom of the bottom ring bottomed out. I can feel the difference in texture, but cannot catch my fingernail or anything here. In the area where the carbon has come off at the top, there is a bit of a catch, sort of. Barely perceptible. This is consistent between 3 of the 4.

This one has a few spots of pitting or something going on.

Where does this info put me on what I might need to do/spend to get it going?
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[SGKent]

I think the case marks you can just clean up with a small flat file if there are any burrs.

You do need all new bearings. Look at the saddles and back of the bearings closely. If they show signs of being really shiny in spots, they will have been working. If the backs are just blackened, matte in finish then they have been sitting solid in the saddles and the main bores are probably Ok. You can also feel for a ridge where the edge of the bearing was to see if the saddle is showing signs of sinking.

If someone gave you a used cam, the lifters have to go back on the same lobe or be reground first. The are not flat but have a slight crown to them so be careful if you have them resurfaced. Many of us here have been burned by reground camshafts and lifters. It isn't like that 454 where you can pull a timing gear cover off, the gears, the intake, rockers and pull out the cam to swap it. The whole VW engine has to come back apart so think carefully about the cam. I use a Webcam 142 grind new, and pass smog easily - and the engine will pull to 5K+. The 142 profile is from the 2.0L 914 T4 95 HP engine used in some Porsche motors. More than a bus needs.

Personally I find it easier to buy new Mahle cylinders and pistons than rering them. Sometimes it can be really hard to find rings that will fit the ring lands right. You can bottle brush it and re-ring it if you want to save that money.

I would send those heads to Adrian in San Diego County to be rebuilt. The valve stems are worn. From the depth, it may be that the keepers are pulling through - or they may have been tipped a few times already and are shorter. If you want to save on that get some lash caps and run those until you can afford to have the heads done.

Just my 2 cents worth

[Wildthings]

[raygreenwood]

Don't be too quick to get rid of the main crank gear. That damage is out on the edge. The crank gear is steel and the cam it it drives is aluminum. As long as the steel gear has no high spots and basically full tooth contact and no missing teeth....it should cause no wear to the cam gear.

Put the crank in a makeshift V-block set up...like two pieces of wood with a "V" cut in each and covered with a simple sheet of plastic bag in each V with some oil. Set up a dial indicator.....and check that the crank gear is round.

Take a needle file and/or dremel and carefully remove the burrs from the edge of the gear. They need to be lower than the surrounding gear surfaces that touch the cam gear. You will note that the crank gear is wider than the cam gear. You dont need all of the gear area.

Your gear could be just fine. I say this...because unless somebody knows something newer than I do....they do not make type 4 crank gears any more so all you will find is good used ones....of which you should acquire a spare anyway before they disappear.

Its also odd....but not really...that the damage is on the backside of the gear. Usually in a cam gear damage scenario involving striking the oil pump and grenade-ing....the damage is on the pump side of the crank gear...not on the crank side.

Question: is it only a couple of teeth on the crank gear that are bad or is it all the way around? If its just a couple of teeth....most probably it was a rivet head or piece of debris that caused this just in teh last couple seconds...either way it had to be steel and not aluminum to do that damage.

Another note....or possibility.....that may have caused this whole thing. If a nut or piece of debris somehow fell into the case through the oil fill chimney....and jammed the cam gear between gear and pump....it could have caused this.

I say this because of the type of damage I saw on the engine I cratered.

Yes...the root cause was because of inadequate pump to cam gear bolt clearance.....but the final damage was caused by one of the oil pump nuts coming loose from 89,000 miles of knocking.....and landing in a tight spot between cam gear crank gear and case. It stripped most of the teeth from the cam gear...and did crank gear damage to all teeth just like in your picture....but on the cam gear side.
Just some thoughts. Ray

[CraigTee]

(This is way too long but had lots to say and explain)

David... you have the reason for the camshaft gear failure is in that picture of the CRANK gear.

When the shop removed that gear, it wasn't done per the manual which calls for a mild application of heat (heated oil comes to mind... but I can't swear to it) and gentle persuasion. Instead, he simply hooked up a gear puller and blasted it off the 1.7L and back on to the 2.0L crank. I was NOT happy.

Like I mentioned earlier... it was not a time that I should have had my fingers into a rebuild. My mind was not on my project. It was one of those things where I started fixing the damage, got distracted, went back and did some more polishing, got distracted... and, at the end of the job, I was scratching my head, asking myself... "Did you ever finish cleaning up that gear?"

Obviously I hadn't. Your picture of the backside of those crank gear teeth show what I've pictured in my nightmares ever since that engine failed. Oh well... it got you a cheap Wild Westerner and me out of yet another project at a time I'm trying to downsize.

However, it's like I told you in the beginning... I truly believed that (if I HAD neglected to finish polishing that crank gear) the damage was going to be limited to a stripped cam gear.... and of course the associated clean up. I had no idea that the pounding on the cam would result in thrust bearing wear, causing the rivets to impact the oil pump like that. What a mess.... but certainly not catastrophic.

You're getting lots of good advice on the build... to me, some of it kinda goes beyond and above what may be necessary, but you are the one with the engine in front of you... so ultimately it's how far YOU want to take it. If it were me, I'd just be really diligent on the clean up side and inspecting everything under magnification... TWICE!

I saw a question I'd answered in an earlier post on the original build cam settings, but here it is again.
Quote from a previous post:
-------------
For those wondering about original cam lash setting, here's the answer:
It was a new cam and new bearings, hence new thrust surface. The clearance was within .000 and .002". The play permitted by the thrust bearing was between .002 and .005". The cam didn't lift from it's bearings when the crank was turned backward.

Now... how do I know this? From memory? Nope... it's because there's pencil checkmarks in my Bentley manual which meant "Done! Next?" LOL!

The rebuild was done with a LOT of outside help, the Bentley manual in my right hand and the John Muir's timeless novel in my left (the updated version that included the pancake engine). Yes... I cranked the wrenches with my toes... I'm that good.
-----------
End Quote

Thinking back... that may actually have been partially the reason I got stupid and neglectful on that crank gear clean up... got prematurely involved with cam lash and clearance settings... just a thought. When I see something like that I just can't kick myself in the pants quite enough...

I think it was Ray that suggested you consider finish cleaning up that crank gear (like it should have been cleaned 20 years ago!) and run with it. I think that's a wise suggestion... at least to try it. A file, elbow grease, and investment of time can go a long way there. If you can't get it mirror polish smooth, maybe grab a buddy or shop to finish it off for you. Those ridges need to be gone and I hang my head in shame that I neglected to do it.

Ray also told you how to dial mic that crank. If you use that cam I sent you, do the same thing with that and also check the lobes. Mic out all your journals... and purchase bearing sizes as needed. If you're not comfortable with mics and dial mics, get some help on that.

Bearings are cheap, rings are cheap, I sent you a replacement cam that is probably good, the crank has 20K miles on it (if I remember right, you got the book on that), the jugs were new and as you mentioned, still have the hash marks on the cylinder walls. I'd be willing to bet the heads and valves are fine, requiring a clean up.

You pictured some valve stem pitting. The first set of push rods I got were soft and mushroomed on me. He replaced them for free even though I didn't ask for that. He said he'd been having problems with them. It's possible that pitting that you note came from that period of time. Also possible that some some of the metal fragments floating around in that engine may have helped...

In the specs, there is a specified length and limits for valve length. I'm sure you can polish those and still be within those limits if the valves are otherwise sound. Any "sunken" valve needs to be pulled for seat inspection.

The carbon ring you noted is standard. There's a tool for removing it. I was taught to always remove it to prevent possible ring damage (I guess if the "replacement" pistons have a ring set a little higher on the piston). Anyway, borrow a ridge reamer if you don't own one.

That cylinder pitting? No clue.... I've seen it on water cooled and always attributed it to water damage. Perhaps rust from sitting and then getting "cleaned up" by the rings when you turned the engine over? Just a guess.... Anyway... too deep to hone out from the looks of it. Bottom line? Jugs can be replaced without splitting the case. That would by MY determining factor... but that's ME.

You got a lot of advice on this and a lot of ways to go. People are going to make suggestions based upon their philosophies on builds. No two will probably be alike, and very few, if any, will be absolutely wrong. Appreciate ALL the advice offered, it's given from good hearts... then pick and choose what makes sense to you to develop YOUR OWN philosophy on this build.

Do you own the Bentley Manual? It's invaluable if you want to check specs on anything in that engine.

Thanks for the pics.

[Wasted youth]

What did you finally do about this camshaft problem?

[vwwestyman]

For the time being: Bought a Vanagon engine...

A couple reasons:
First, it popped up and the price was right, and I can sell some of the parts I won't use for the Westerner (sold fan shroud, still want to sell heat exchangers and Vanagon transmission) to make the overall price significantly lower.

Second, I realized that taking the time to build the engine correctly would take a lot of time and money and I'm impatient to get this thing driving again. I had thought about slapping it together with another cam and cleaning up the cam gear, but I don't really want to do that.

Third, honestly, I'm a little intimidated with rebuilding the engine properly. Going this route, I can take my time (maybe over the winter?) and really do it right, while (hopefully) getting to drive the bus around. At that point, I'm confident I can sell the Vanagon motor for what I'll have in it.

So right now, the engine repair project is on pause.
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing