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Wed Oct 21, 2009 7:40 am

A few months ago I rebuilt my 1600dp due to excessive end play. Since then I've put about 1500 miles on it and have it running pretty nicely. I don't remember when I first heard it, but at idle there is an intermittent knocking. I initially chalked it up to being the fan hitting the housing, but after disconnecting it and starting it up, the knocking persisted.

You can only hear it at a very specific RPM range, somewhere around 850-950. I disconnected the spark plugs one at a time while running, and the knocking sound didn't change. I crawled underneath the engine and I could hear it loudest right in the middle of the case, just in front of the oil plate.

I did some searching and found a number of people that had something similar, but it wound up just being the flywheel, so I dropped the engine and checked that out yesterday, but it was fine.

During the rebuild I put in all new crank/rod bearings, a new Engle 100 cam, new cam bearings, and new lifters. Broke it in with Brad Penn 30W break-in oil, and have been running Brad Penn 10W30 ever since. Any ideas as to what's clunking around in there? The only things I can think of are a lifter smacking into a lobe, or a loose cam (not sure how that's possible). I've accepted the fact that I'm going to have to crack it open and figure it out, but just seeing if you guys had any ideas first. :)

Wed Oct 21, 2009 8:33 am

The first time you started the engine did you run it in the way Engle and Wilson say to do it? Initial break-in is most important for the cam and lifters. A lot of people have real early performance cam failure.

Wed Oct 21, 2009 8:38 am

Yup. Brought it up to 1800-2000 rpm immediately on its first start, then held it there for a good 20 minutes. Shut 'er down and changed the oil.

If I wiped out a lobe would it cause a knock or just run like crap?

Wed Oct 21, 2009 9:17 am

You could always check the valve lift to see if a lobe was shot. But if it was that far gone it probably wouldn't run good. That's just some guessing, I don't know.
A friend bought a new (new) cheapie stock engine but it did have a new case and supposidly new lifters and cam. By the time it got to 12,000 miles it was making a real disturbing noise. So long ago I couldn't describe the noise accurately. It still ran good. But needed more frequent valve adjustments. Anyway, the cam and some lifters were gone and it wiped out some of the lifter bores in the case. We don't know what caused the failures maybe just cheap parts and poor assembly.
Are there any other concerns you might have about the engine assembly? Assuming you were doing a top notch job and maybe closely following Wilsons instructions. With the Engle you would have a bolt on cam. Probably aluminum. Was the gear mesh good? I think I've heard of some gear or bolt failures. And I didn't understand about "in front of the oil plate". But, did you have good tang engagement of the pump into the cam and also clearance between the pump and cam gear bolts? That's also been a problem some have had.
Finally, did you drain the oil when still warm and very closely check the oil for metalic particles? Glistening in the sunlight?

Wed Oct 21, 2009 9:32 am

I was turning the engine over by hand yesterday and watching the rocker arms to see if every valve was being opened all the way, and they all looked good. And I've adjusted the valve lash a few times in its first 1500 miles and they've been almost spot on every time.

I followed Wilson's book to a T, and all of the clearances/tolerances were well within spec. Had a bolt-on cam gear and the teeth meshed nicely -- no slop. Got the proper 26mm oil pump for the flat cam gear as well, so that sits in there nicely.

I have a magnetic oil sump bolt, so the last time I changed the oil (had about 1000 miles on the oil) I had quite the collection of metal flakes down there. I've never broken in an engine before so I'm not sure how many there are supposed to be, or how many are created from breaking in cylinders and pistons, but I'd say there was about a teaspoon of this metal flake and oil sludge mixture.

Wed Oct 21, 2009 9:58 am

That's alot, not alarming yet but should be monitored. I saw a GEX that ate a cam once, it made a constant horrible snapping clatter when it was running, like rocks in a blender.

I wonder if the cam has some endplay or a lifter bore is sloppy?

Wed Oct 21, 2009 10:05 am

When I did the 20 minute run-in on both of mine I drained the oil immediatly while the little stuff was in suspension then looked at the oil in sunlight. The oil had glistening streaks running through it. They had a lot of microscopic glistening particles in suspension. And just a very few little things in bottom. Plus a little bit of goop which evidently was the white assembly lube I used. I don't remember anything on the plug magnets. Both had external filters and only on the second one cut the filter open to wash and inspect it. It did have a few little particles. Very few. That would have only gotten stuff floating in the oil. Solids would hav been in the sump bottom. Then the next oil changes at around 100 miles were nice and clean. Nothing else was sitting on the sump plate.

Before you get to the point of tearing into it, it might be worthwhile to pull the pump and do a looksee. Signs of any wrong contact or looseness.

Polly also had a beautifully built engine that made some funny noises, not big noise but enough to make her uneasy. The builder finally tore it down and it had an upside down piston in it. I triple checked my pistons and then when it was finished was still uneasy so ran a light into the plug holes to check the 4th time.

Do you know if your metal flakes were magnetic steel?

Wed Oct 21, 2009 11:25 am

Hmmm... I was just going over the engine build in my head over lunch and I came up with two things that might be contributing to this:

1) When I was lubing up the lifters and installing them right before I sealed up the case, I noticed that some of them got stuck in the bore. They slid up and down in there fine without slop, but when I pushed them down in there the last few millimeters, some of them kinda got wedged in there and I had to push them back out from behind. Is it possible that this is happening while the motor is running, causing the lifters to more-or-less smack into the cam lobe on its way down instead of sliding? If this is the case, I kinda figured it would have remedied itself in 1500 miles, but maybe not.

2) I didn't replace the valve springs. The heads were replaced at some point with dual port heads, so I'd image they got new springs at that point, but I have no idea the strength of them or how worn out they are. Though I've read that you don't necessarily need HD springs for a 100 cam.

Perhaps I'm dreaming optimistically, but those are the only things I can think of during the build that may cause issues. Everything else went together smoothly.

Wed Oct 21, 2009 11:30 am

busdaddy wrote: That's alot, not alarming yet but should be monitored. I saw a GEX that ate a cam once, it made a constant horrible snapping clatter when it was running, like rocks in a blender.

I wonder if the cam has some endplay or a lifter bore is sloppy?
I have re-overhauled many of there engine's and trany's.

Mon Oct 26, 2009 7:58 am

Dropped the engine and disassembled it again -- getting pretty fast at it these days. Pulled off the 1 and 2 cylinders so I could watch inside the case as I rotated the crank to see if I could notice anything funky going on with the valve train. All of the lobes and lifters looked perfect, but I did notice a bit of a gap that would come and go between the thrust bearing and the cam's thrust plate. The gap looked to be about the thickness of the thrust bearing itself -- obviously well outside the tolerable range of .001-.005.

I have an Engle 100 in there with a brand new set of Mahle STD bearings. How in the world did it end up with such a gap? I'll be honest, I didn't check the thrust clearance when I was building it (don't remember reading about that in Wilson's book), but if anything I think it would have been too tight, not this loose. :?

Mon Oct 26, 2009 11:01 am

having too large a cam thrust will cause a knock. When you build an engine be sure to test the cam thrust end play and the crank thrust end play. Both are critical to the longevity of the engine. If you don't have a dial indicator with a magnetic base, get one. I use the magnetic base when setting the crank endplay and then use a bolt and washer with the tower part of the base when setting cam thrust.

Mon Oct 26, 2009 11:04 am

Right, but if that was a brand new cam and brand new bearings and there's too much end play, what do I do to get it within specs? I've read that if there's too little you can sand the bearing to get the proper clearance, but if there's too much?

Are there different bearings I can get with a thicker thrust bearing? Different brand?

Mon Oct 26, 2009 2:39 pm

Was it a single thrust or a double thrust bearing? I have been using double thrust bearings and then file a little notch in the case for the bearing tang. But if you had a single thrust is there anyway it could be in backwards? Sound like you're going to be carefully looking for damage when you tear it down. Hope it's ver little.

Just double checking but you wouldn't have used straight cut gears, would you?

Mon Oct 26, 2009 3:08 pm

Single thrust bearing. Not straight-cut gears. I guess it'll all make sense once I tear it down. I went looking in the Bentley and Wilson's for anything special about installing the bearings and cam, and there's nothing aside from lining up the dot correctly with the crank gear.

On a positive note, I didn't notice any damage while I had it apart, and it's been running fine. The cam and crank gears didn't look beat up or anything, so hopefully they're fine, too. I guess worst case scenario is I can put the original stock cam back in there -- still have it, it's in great shape, and the bearings that it was using have perfect thrust (I'd get new bearings).

And not that I'm going to do it, but I have read a few threads where people claim to have driven 15k+ miles or so knowingly with excessive cam end play and it was fine. Makes me feel better about the 1500 I've already put on mine. ;)

Sun Nov 08, 2009 3:46 pm

Tore 'er down this weekend and confirmed that it was indeed an excessive amount of end play in the camshaft. After pulling the cam and bearings, I measured it with a feeler gauge and it wound up being a little over .010in. Ouch. Upon further inspection of the bearings, I found them to be torn up pretty badly. These were a brand new set of single thrust Mahle bearings; I'm new to this whole engine building thing, but I'm pretty sure they're not supposed to do this:

Picture of all of them. The metal pieces below the thrust bearing actually came off the back of the thrust surface, leaving a beveled edge.

Little fuzzy (don't have my macro lense right now) but as close as I could get. You can kind of see how the right thrust surface got beveled.

Probably the worst wear out of the six of them. One of the middle bearing halves.

I'm not exactly sure what caused this, but I'm pretty sure this is where all the metal flakes in my oil has been coming from. Any ideas?

And I used KS bearings when I put it back together. About .001in of end play. Perfect.

Sun Nov 08, 2009 4:03 pm

Wow!, when you split the case and the bearings were still in place did you happen to notice if there was more wear on say the front and rear LH ones and the center RH one? I'm just wondering if your case is warped. How was the oil pressure before you dismantled it?

Sun Nov 08, 2009 4:16 pm

Oooh, hrm... not sure which locations had the most wear. I was just chalking it up to either something caused by the excessive amount of end play or perhaps a bad set of bearings or something. A warped case would make sense, though.

Oil pressure has been pretty good, I think. Have a VDO pressure gauge hooked up with the dual pressure sender. Been getting around 50-60 psi on a cold start-up, and 25-30 cruising down the highway at 55 when the engine is fully warmed up. Using Brad Penn 10W-30 with oil temp readings at 180-190 from the pressure relief valve.

Hope I don't rip through this set of bearings, too... :(

Sun Nov 08, 2009 4:52 pm

Hmm, was just thinking about this a little more. I have the old camshaft and its bearings still, and they look fine... not torn up like these ones were, at least -- just well-used. I guess something could have happened in the align boring of the case, or with it just sitting around for a couple months during the rebuild, or the new cam could possibly be warped? I don't know. Just thinking out loud. :)

Sun Nov 08, 2009 5:08 pm

did you beef up the valve springs?

Did you put the camshaft on v-blocks (you can make a set with a couple of pieces of 2x4 and your pocket knife) and measure the cam for runout with a dial indicator?

Are the lifters still sticking or did they free up?

also: Quote: but I'd say there was about a teaspoon of this metal flake and oil sludge mixture

That is not normal on a new engine if you cleaned the case. Steel parts in an engine do not wear that fast. I would take the camshaft, case and bearing back to your machinst and have them look at it. I am equally concerned about your cam developing end play and hammering itself to death.

Sun Nov 08, 2009 5:12 pm

thinking some more on the photos, it almost looks like the cam has been running a little dry. You want to pull your #2 rod bearing and see if it looks good. Also check the oil pickup tube to see if it is loose. You may be sucking in a little air with the oil and that can play havoc with bearings at the bearings where it escapes as the air will make them run a little dry.