Camshaft thrust bearings

[mthielk]

My son bought a 85 vanagon, 1.9, 110000 miles for $800, the engine had problems. The first thing was this:

It had bad gas in it for a long time. The previous owner probably added gas to get it running probably several times over the 10 years it sat. The valves were actually glued into the guides. One of the guides was actually pressed farther into the head by cranking or running. Took the heads off, didn't see any signs of bent valves any interference with the pistons (hard to imagine). Pushed the guide back in place, replaced the 2 lifters in question. Many other fixes not relevant I will not mention. Measured .006 inches of end play in the crank, just at wear limits, but I think it is actually good. The rods felt good, but I didn't measure, and I didn't initially dissemble beyond the heads.

Probably in too much of a hurry, should have checked further. Pistons and cylinders looked good and measured good. My sense was it had a recent, in terms of miles, rebuild. Previous owner said 10000 miles. But #1 piston is different than the rest.

#1 piston:

Other pistons:

Put it back together got it running nice, passed smog (required a little retarded spark to pass NO) but there was this nasty knock, sounded a lot like lifters but it wasn't. Checked oil pressure, it was good under heavy load fully warm.

The knock was loud at idle but went away at running speeds. But not runnable in that state. Did a lot of test to isolate the sound before pulling the engine again. The final one was turning the engine over using a big hill on my street, engine was not running but I had spark and used a timing light to determine the noise was synchronized closely to #1 piston TDC firing (synced to the camshaft not crank). Got back down the hill, removed #1 cylinder lifters (were on with removable push rod tubes), reached a screw driver into the can and checked endplay. Visually it was about 1/8 inch. Well my first thought was the rebuild didn't have the thrust bearing in place.

Took the engine out again, split the crank:

Found the thrust part of the bearings in the bottom of the crank case:

This engine only has the half thrust bearing and I would replace it with the full (both sides version) but the case only supports tabs for 1 side. Should I cut a little notch in the block or remove the tab on the bearing or just stick with a 1/2 thrust bearing? Everything I have looked at so far looks good. The cam has a little nick on # 1 intake lobe but I think I will just polish that out.

Another concern is since I located the knock synced to #1 I think I have some imbalance in the engine that is causing this. I think I am going to weigh the pistons. What do you think?

My theory is the failure of the cam thrust bearings happened very quickly related to the seized up valves and extreme camshaft loads.[/img]

[jberger]

So.. number one I would check the runout on the camshaft journals. It may be trashed.

You can feel free to add another thrust bearing shell.. just hit the tab with a grinder so you can install that half.

From the pictures it looks like you have the Brazilian pistons in at least one jug and an OE Mahle in at least one other. The Brazilian castings have an incorrect pin location (at least in the 2.1 version) that equals 1mm extra deck height. The stock pistons flush out with the top of the cylinder and the head gasket\sealing ring provides the deck clearance. If it were me I would want a nicely balanced, tight deck engine if I were going through all this work.

[mthielk]

The cam shaft runout is less than .001. That is the best I can measure. But the cam lobe height has a range of about .010. I was surprised at that and don't think it is just wear. I measured another cam I had around and found the same variation but the cam bearing surfaces were good just like the original cam.

Will check pistons later.

[jberger]

Check the cam on v blocks, not on your lathe with live center. Check each journal. It may surprise you.

I also like to use my spring loaded brown and sharp indicator for this task.

[mthielk]

This is an improvised vblock measurement of camshaft runout for the person with out a lot of tools. It measured .0003, even if that was caused by the valve problem I am not going to worry about it.

[mthielk]

I measured .003 inches total main bearing clearance on the one piece bearing #1. I didn't see a spec on that in Bentley. Probably would be tighter with new bearings but it ok with me, 20W50 oil. Taking off the gears on the crank is difficult and I won't do it if I don't need to.

[mthielk]

Thanks jberger for the heads up on those pistons. The three newer aftermarket pistons are 1.5 mm lower than the Mahle piston. I am going to replace them even though they are new. I am going back to all OE Mahle pistons. I happen to have some used ones that are in great shape.

I measured the bearing clearances again and found that both the crank main bearings and the rod bearings have .002 in of clearance rather than .003. I was stressing my calipers a little between inside and outside measurements and getting about .001 error. At .002 I am not going to change the main and crank bearings. I did find out a previous owner ha the connecting ro journals ground down by .020.

So I made all the decisions:

Replace all the non Mahle pistons
Replace cam bearings with full thrust bearing type
Keep existing oil pump
Keep existing main and rod bearings
Keep camshaft
Adjust crank end play shims

Anything I am missing?

[atomatom]

the general wisdom i've heard is don't adjust crank endplay unless you are putting in new main bearings. it is a measure of bearing wear, not a repair method. you said it was at the limit. it is a pain to pull the timing gear, but do the main bearings you can inspect look worn?
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84 Vanagon Westy, 1.9L, California raised but defected to Canada.

[jberger]

[mthielk]

Thanks for the comments about thrust bearings and shims. I looked at it a little further, the dowel pin has about .005 inches of slop. It appears to be in both the direction of rotation and also in the thrust direction. It is obvious the crankcase squeeze pressure is not holding this bearing in place and the thrust and bearing rotation forces are being carried by the dowel pin. In the thrust direction on this engine there is about .003 of slop between the thrust part of the bearing and the block surfaces. The block may have some wear but the surfaces aren't supposed to be moving. It is a design problem and I see others have talked about it. I am having a hard time ignoring this. This is the block:

and this is the bearing dowel pin hole:

The first thing I am going to do is put different shims in to knock my .006 endplay down to .003. The reduced distance of travel will reduce overall loads by minimizing the axial momentum gained with thrust forces. Yes, I should probably replace the bearing but it was replaced 10000 miles ago, it is not the problem. What I really want to do is increase the crankcase squeeze force on that bearing and hold it in place that way, the dowel pin is only an alignment pin.

[mthielk]

What do you think about using a piece of .0005 stainless shim stock under the bearing with holes for the pin and oil passage?
http://www.mcmaster.com/#9502k56/=13s5vct

[mthielk]

I looked at some old bearings I found laying around, see photo below. The bearing farthest away is my 10000 mi bearing (manual trans), next I believe is an automatic, and the closest is a manual trans bearing. First observation is the manual transmission clutch thrust is causing the bearing to block surface (way too small) to get pounded down causing lots of effective end play if the bearing is floating in the case, which I think it is. Jberger is right, take it easy on your clutch, and when there is end play the momentum of that heavy crank moving pounds that surface even harder.

Next observation, and this is weird, all the wear I measured on these bearings was on the block to bearing surfaces and not as you would expect on the crank to bearing surfaces. On both the inside bearing diameter and the bearing width all these worn bearings were identical. But the outside diameter and the inside width between the thrust surfaces (surfaces that contact the block) were all over the place. Oh my God, both the pounding action of the clutch (axial thrust) and normal radial forces (connecting rod forces) are beating up the block to bearing surfaces.

[atomatom]

i think your concern is warranted about the bearing slop http://www.thesamba.com/vw/forum/viewtopic.php?t=334696

the correct repair is line bore and oversized main bearing, but this is seldom done on 1.9 cases and you'll have trouble finding anything but a stock main bearing for the 1.9. as you probably read, they changed the design on the 2.1 due to the #1 main bearing failing - and suspected cause being as jberger implies from people cooking it with the clutch.

i don't know if you can fix it with some padding to the outside of the main bearing. it certainly sounds appealingly easy/possible but i've never heard of that, but i don't know all that much. if it was my engine i had no alternatives aside from helpful suggestions like 'find a new case/engine', i would be inclined to try it out.

you might ask in the engine forum. most people in the vanagon forum don't rebuild the bottom ends. they can be pretty snarky over there though.
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84 Vanagon Westy, 1.9L, California raised but defected to Canada.

[PocketRocket]

This is the reason I do not use 1.9 blocks on any of my rebuilds. The thrust brg. is the problem. If the thrust in the block has been pounded stock is .826 if the thrust is below the .826 the brg. will not fit tight, also the block will loose its crush on the brg. as the brg has moved back and forth. With the 2.1 block the thrust is not part of the brg. the 2.1 have thrust shims. I bore gauge every block I do. If you have to find a block get a 2.1. Rocky

[kjono09]

Question about endplay:
On a 1.9L how much is to much?
Is .005-.006 too much?
How do you fix endplay in a 1.9L?
Can you machine in a new different bearing to handle the thrust endplay? I.e a non vw part?

Anyone have a recommended mill/drill for engine machine work?
I am looking at a 1.9 .
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84 Retro-Westy GW 2.2L (Vincent)
67 Bug 2007cc (WBX in progress) (Davey)

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