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Big Trouble ? Camshaft gone ?

David Stroud IM Roadster DDavid Stroud IM Roadster DOttawa Canada '83 IM Soob
Lads, I may have a serious problem with my camshaft after only about 10,000 miles. The engine got a bit noisy after about 1,000 miles on latest valve adjustment. A quick check under the right cover showed the no.1 cyl valve lash was about 3/16" instead of .006" and there was no where near enough adjustment to correct that. It was as if the exhaust pushrod had shrunk in length. I pulled the rocker arm and checked all pushrods and they were all the same. With the rocker arm off, I got a neighbour to turn the engine over with the pushrods down against their lifters. In particular I checked the distance of movement of the number two cyl. exhaust pushrod against the number one counterpart and found that the number one pushrod is just not moving nearly as much. Best I can figure is that the lifter shrunk, (not bloody likely) or the cam lobe became a lot smaller. Any and all ideas appreciated.

David Stroud

 '92 IM Roadster D 2.3 L Air Cooled

Ottawa, Canada

 

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David Stroud IM Roadster DDavid Stroud IM Roadster DOttawa Canada '83 IM Soob
Lads, I may have a serious problem with my camshaft after only about 10,000 miles. The engine got a bit noisy after about 1,000 miles on latest valve adjustment. A quick check under the right cover showed the no.1 cyl valve lash was about 3/16" instead of .006" and there was no where near enough adjustment to correct that. It was as if the exhaust pushrod had shrunk in length. I pulled the rocker arm and checked all pushrods and they were all the same. With the rocker arm off, I got a neighbour to turn the engine over with the pushrods down against their lifters. In particular I checked the distance of movement of the number two cyl. exhaust pushrod against the number one counterpart and found that the number one pushrod is just not moving nearly as much. Best I can figure is that the lifter shrunk, (not bloody likely) or the cam lobe became a lot smaller. Any and all ideas appreciated.
hillhill
Are the head bolts still tight?
You wouldn't need to retorque the bolts -just lightly turn them clockwise as if to tighten them. If they're loose or if you can turn them at all with relatively light pressure I'd suspect a set of casesavers might be neded or worse.

1000 non-racing miles seems like unusually fast cam lobe wear to this extent, unless you've lost oil pressure or adjusted a valve too tight.

If that cylinder was not at TDC when the valve adjustment was done it could result in incorrect clearance or no clearance. No clearance might wear a cam lobe this quickly, I'd guess.
hillhill
Does CB grind their own cams and if so, don't they harden them?

I've got a hard time imagining how a cam could be so worn after so few miles, especially without the gradual loss of power and eventual dead cylinder that I've known from both a Chevy and a BMW camshaft, and apparently I have a CB engine in my IM car.

Makes me think I'd better shop for a spare engine.
David Stroud IM Roadster DDavid Stroud IM Roadster DOttawa Canada '83 IM Soob
Just got back and had a chance to look at the other side of the engine. I got no. 3 cyl. up to TDC and checked the valve lash on the exhaust valve and it's the same as no. 1. I'd say the cam lobe is definitly trashed. The head bolts are tight. I'm seeing about 45 psi pressure on startup. Anyone have any ideas what might cause such a failure...what to look for on teardown ? Blocked oil gallery..? Could be just a bad camshaft when made ?
David Stroud IM Roadster DDavid Stroud IM Roadster DOttawa Canada '83 IM Soob
Thanks for the comments. The cam is a SCAT C35 and the lifters are new Lube a Lobe which I believe are compatible. I won't be able to get into the engine for a few weeks or so. Getting busy at work into the Fall season. Yes Jack, we'll be at Carlisle...Francine is booked to fly into Florida and I'll drive down to pick her up, hit the Keys then back up to Carlisle. We'll likely hook up with you in Christiansbug but Russ and Brenda invited us to their digs so we'll have to see what develops.
Gordon NicholsGordon NicholsMassachusetts 1993 CMC Supporting Member
Dave:

Yes, it definitely sounds like a dead cam lobe. The reason is poor heat treating, followed by less-then-optimum modern oils for our solid lifters. Yes, one cam lobe can be soft while all the rest can be hardened better.

When you replace it, I would also replace the oil pump (might be a good time to full-flow the case if it hasn't already been done) all the lifters and pushrods (they're cheap enough) and have your engine builder thoroughly clean the case halves, including blowing out the oil passages. If it were mine, I would probably replace the oil cooler tower, too, or at least have someone solvent-clean it under 20psi forced solvent for 15-20 minutes. All of that is cheap insurance against getting wear-causing debris back into the oil system once rebuilt.

gn
David Stroud IM Roadster DDavid Stroud IM Roadster DOttawa Canada '83 IM Soob
All good ideas, Gordon. I'm getting very curious to find the cause of this. I'll rebuild the engine myself as I've done Soobs, Corvairs and Lycomings before...not often though. Can anyone recommend the best layman's rebuild manual for a Type 1? I'm looking more for the tips and tricks type of book that might help best to keep the engine oil tight and dead reliable. I do have Muir's book. I will upgrade from generator to alt and will consider a more open exhaust and dual carbs...twofootitis I called it in my sailing days.
SS Scott S.
David-try this guy's YouTube series for amusememt. Start with this part 3; parts 1 and 2 are useless. It will instruct you to play best at "240p". Under video screen, lower right, there is a little "360p". Click this and select "240p" and you should be good to go. (I just tried this and it is cumbersome, but it will work. The first time I reviewed this series of videos, it was NOT as cumbersome as it seems now.)

http://www.youtube.com/user/6d4vdub#p/u/2/NZsQzp1hBBA
hillhill
Maybe it doesn't still apply, but way back when I did some VW engines it was important to match the crank, cam, and cases. VW had a number, +/- 7 in steps from -7 to +7, stamped onto the parts and if you didn't match them up the engine would never be right.

A friend of mine neglected this when rebuilding his bus engine and his bus never could get out of it's own way, We'd run up this particular hill frequently and I could pass his new rebuilt '66 with my 40 hp '61 every time. We never figured it out until about three years later.

Just tossing out stuff from the depths of memory and it may not apply at all today. That all dates to years between 1970 and 1975

David Stroud IM Roadster DDavid Stroud IM Roadster DOttawa Canada '83 IM Soob
I hear ya, Amigo and there's a real nice 4 core a couple of miles from me that I looked at a few months ago. The thing is, I know my motor is a perfect cruising setup for me and just let go after about 10,000 miles from this cam thing. Also, a minor item which could have put a big dent in the last trip was the failure of the little
clip that retains the exhaust rocker on number two cyl. Lucky for me
that happend at home a couple of days after returning from Carlise...a 5,000+ trip. I'm getting to know my engine. Right now I'm having big fun for very little bucks and with still flying my homebuilt Christavia and continuing to build my Fairchild 51 there's little extra incentive to change up to a new engine. Tomorrow I order the new engine parts so the reveal of the problem may come in a week or so. CIP1 is the supplier of choice. I tried to buy local but the prices were right out to lunch.
SS Scott S.
David-your cam is a Scat C35 and your lifters are Lube-A-Lobe (Scat) and, by inference, they should be compatible. In the Scat catalog it "suggests" a C25 for 1600-1776 motors. Working with Aero motors, I don't have to tell you the importance of documenting what your tear-down reveals. If you are going to re-cycle the case, I'd mic and document all the critical dimensions and be sure it will still be within limits-and be especially wary of the lifter bores.
(I am NOT saying that your C35 cam is wrong for your 1600; just citing suggested Scat data).
SS
David Stroud IM Roadster DDavid Stroud IM Roadster DOttawa Canada '83 IM Soob
I didn't get the case split like I hoped today but I did get a bit of a look at the cam and lifters after getting no.1 cyl off. The exhaust cam lobe looks ratty, galled and might be a bit concave across it's surface. As comparison, the intake lobe looks flat, smooth and well oiled. The lifters should have about 1/8" "foot depth" and they're down to about nothing and very ratty looking. Tomorrow I'll get it fully apart and over to the local VW expert for evaluation with all related parts. Phuck me! Very interesting but not some fun I had planned on.
David Stroud IM Roadster DDavid Stroud IM Roadster DOttawa Canada '83 IM Soob
I got the engine torn down completely and here's a pic of the cam and lifters. The two exhaust lifters from Cyls. 1 and 3 are shown beside one from number two cyl. Check the left lobe on the camshaft... it's not supposed to look like that. The intake cam lobe for cyls. 1 and three shows a bit of galling at the peak of the lobe and those lifters are starting to feel the effect but no diminishing in physical size. As Johnny Cochran used to say.." If you know," can anyone suggest what might have happened here ? The inside of the case and all else appears to be in nice shape but the bottom of the oil drain plate showed a good amount of grey sludge which I'm thinking is a mix of motor oil and ultra fine grindings from the cam lobe and lifters.

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  • Cam and lifters
David Stroud IM Roadster DDavid Stroud IM Roadster DOttawa Canada '83 IM Soob
That's the lifter foot, Leon. That lifter came from the other (rear) end of the engine. The two other beat up lifters are supposed to look like the one in the middle. The lifters are Lube a Lobe which are known to be compatible with the Scat C35 camshaft. Scat has advised to check the valve train end of things to see if something up there is too tight causing undo friction between the cam and lifter. They also expressed concern that I was running Castrol GTX racing oil...10w40 with low zinc content. I spoke with Jake Raby today and he also expressed concern over my oil selection and recommended Brad Penn.
tmpusfugittmpusfugit
That is not representative of a "wrong oil" problem. That is a defective lifter problem....looks like they were too hard, not properly tempered when manfactured. Having said that, I am not an expert in a commercial sense, nor do I speak for the maker of the lifters. But lifters don't chew themselves up like that if their metallurgy is correct when installed....also, the lifter bores need to be checked for wear...it looks like you need to completely overhaul the engine as there will be metal fragements everywhere, and that will include the mains and rod bearings...and usually the metal of the lifters is much more hard than the crank journals, so there goes the crank...sorry about the bad news. It looks to me like a complete overhaul as a minimum
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