I just removed the timing (cam) gear from my son's '71 142. Three teeth are chipped and there is a lot of wear on the rear part of the steel portion of the gear. Let's see if I can explain the wear. If you look at the engine-side of the cam gear, there is a ridge immediately outside the hole where there has been no wear. Extending outward, the steel part is worn all the way to its periphery so it is level with the fiber material. The ridge is about 1/8" x 1/8". The gear is still intact and looks fairly new.

There was nothing between the gear and the cam retaining flange. The flange shows no unusual wear - it's not grooved and it ought to be if it caused the wear on this gear.

Ity's been a few years since I changed these gears, so I'm not certain what should be here. The Haynes manual isn't as clear as I'd like. Should ther be something between the cam gear and the retaining flange? and should there be something between the flange and the block?

This is the same 142 I've asked for - and gotten - help before. I wasted time by the same looking at the same possible problems several times before getting to the timing gear. Our executive assistant has a sign on her wall: "If you always do what you've always done, you'll always get what you've always got (sic)". I needed to remember that.

Thanks for any help,

JIm Hampton

My son-in-law, a former tool-maker, came around when I was fooling around with the gear and cam. When he looked at the timing gear he told me that it wasn't worn, but someone had machined it that way intentionally. The marks were from a cutting tool, poorly finished , quickly done by someone who didn't care a lot about the finish.

So the question now becomes "why would someone machine the back of the gear so it fits inside the thrust flange?" The only reason I can think of is that the spacer on the end of the cam didn't ewxtend forward enough for the timing gear to contact it, so the guy machined the gear to extend inward. I couldn't move the cam by hand until I had removed the the push rods and tappets. The last three seemed to be stuck - they were harder to get out (if that means anything). After they were removed I was able to move the cam easily and I could slide it forward enough to be properly flush with the front of the block, which wasn't the case before. Before the stuff was removed the cam wouldn't move in any direction at all by hand.

I guess I may get some answer when I take out the cam Friday. Work seems to get in the way of the really important stuff. I guess when you work on a car someone else has played with you have to expect these types of things. A friend calls it compensatory problem solving. For some people, if there's a problem they can't solve properly, they compensate by doing something that might work for a while. Sometimes they get lucky.

Any ideas?

Jim Hampton

Phil said "there should be a spacer ring on the nose of the cam between the woodruff key and the frontmost lobe".
Shoulda said: there should be a spacer ring on the nose of the cam between the woodruff key and the frontmost cam bearing journal. The lobes start behind the
bearing journal. The ring should be a couple thou thicker than the brass
plate. Don't EVER want to squeeze that plate!
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George Downs, Bartlesville, Oklahoma, Central US

I just looked at the flange and the spacer in the 142 (B20)and compared with the same in a B18 in my garage. I assumed they are the same, since configuations in the two engines are the same for most things. In the B18, the spacer is firmly positioned and extends outward so the front end of it is just past being flush with the flange. In the 142, the spacer has a lot of play - it sort of flops around on the cam and is not firmly against the key. It only extends outward partly through the flange. As I think of it now, it's probably the same as the depth of the wear on the back of the timing gear.

The front-most journal in the engine in my garage is approximately flush with the front of the block. In the 142, it is substantially short of that. It appears that the spacer is of the wrong thickness to position the gear away from the cam-retaining flange and that's causing the wear. The flange has some irreularities in it that I missed at first, but no circular grooves. 'nuther coupla questions. I assume the cam is the right length - is that valid assumption? If it is I need to get a spacer of the correct thickness, right?

In other words, what do you suggest that I do?

We have the previous owner's service, repair records and know who perpetrated this and a score of other "creative" solutions, some of which are unconscionable, especially for someone who represents himslelf as a foreign car specialist of some renown.


Any help is appreciated.

Thanks,

Jim Hampton

The spacer ring only needs to be thicker than the retaining plate. The only thing keeping the cam in place (fore and aft) is the sandwich of cam (bearing surface) retaining plate/spacer, Cam gear and nut (sometimes a tab-washer too). The cam, without gear firmly attached, is free to bang back and forth. Therefore, seeing that it is not flush with the front of the block is not alarming, you should be able to grasp the cam and pull it out (don't or your day will get very complicated regarding the lifters!!!!).

New gear and retaining plate (and perhaps spacer) should make it all better.

Mike!

Mike the ring for both OD and thickness and post the results here.
I'll czech one tomorrow and we'll compare notes.
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George Downs, Bartlesville, Oklahoma, Central US

I did some measuring. OD is 1.457", thickness is 0.160". There are a couple of other aspects that have come up. I think I mentioned that the front-most journal isn't flush with the front of the block and I think it's supposed to be. It is recessed into the block 0.89"", which is the height of the ridge left on the cam gear when the rest of the steel has been ground away. The width of the ridge coincides with the opening through the flange. The gear has been pressed or pulled against the flange and ground down. Second, I can't move the cam with my hands and I should be able to. There's absolutely no play at all - front-to-back, side-to-side, etc.

I see a couple of possibilities I don't like, and I hope I don't have to explore them. First, the cam may have been pushed back in the block. However, the car was driven without oil being tossed all over, andI hope that suggests that one's not right. Second, the guy who rebuilt the engine for the previous owner put the wrong cam in it and it's short by 0.89". Either would cause a bunch of problems.

If you have a better, more simple possibility, let me know. If it comes to removing the cam to determine if it's the wrong length, is it better to remove the engine to get the cam out, or remove the head, pull out the push-rods, etc. and pull the cam out the front?

It just dawned on me - I can check the oiler to see if it's stopped up. Would that cause the cam to shift to the rear? Probably not.

Thanks for the help, advice, etc.,

Jim Hampton

The cam is moved back because of the wear on the timing gear. It's not installed wrong -- the location and endplay are determined by the spacer ring, and only the spacer ring.

I have no clue what caused the wear on the gear, though. Odd one...

Yeah, it is strange. I took the gear, spacer, retaining flange to a guy who works a lot on old Volvos and he said he's never seen anything like this. The gear isn't worn as if it has been rubbing softly or intermittently against something. It has been ground down as well as is it had been pressed against a grinding wheel. It looks as if it has been pressed hard against the flange, which in this instance is steel.

Thanks.

There's no need to pull the engine to replace the cam. Just take off the radiator and grill and take it out the front (after removing the head and lifters first!).

I recently had to replace the cam in my engine due to the cam nut coming loose and allowing the cam to slip backwards into the engine. The lifters were operating half off the lobes, and the #1 lifter had the big bearing sliding along it (that's what stopped the cam from going back any further) which wore it out rather quickly. If it slides back too far it can knock out a metal plug on the far end of the block behind the flywheel, which would necessitate removeal of the engine to replace. I did that once replacing a cam on my 1800E. I didn't have a puller, so I chocked the gear outward and tapped on the nose of the cam. Tap tap tap, and when it broke loose it slid back and I heard a metallic clatter inside the bellhousing. *GROAN* My project got a lot bigger in that half second.

You could loosen the adjusters on the rockers all the way to take the pressur off the cam and see if that loosens it up. It should move quite freely when the lifters aren't pressing on it with a great deal of force. Also, the mechanical fuel pump lever might hold it in place too - you'll have to take that off too (if you have one).

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I'm JohnMc, and I approved this message.

Thar's what I thought and what I hoped for. Is it possible for the plug to be moved without being completely "punched" out of the block? There's no indication of oil being trhown around, so I suppose the pluga is still there.

Thanks.

I'd imagine that there would be a pretty noticeable amount of oil coming out of the bellhousing if that plug was knocked out or ajar. No oil - no problem.
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I'm JohnMc, and I approved this message.

I haven't measured a ring spacer yet.
The cam DOES move endwise but if the rocker shaft is still on, the pressure
of the lifters against the cam will make it hard to move. Could also be
gummed in place.
I guess you've read the other guys' posts....
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George Downs, Bartlesville, Oklahoma, Central US

Someone might have substituted a 'found' item for the correct spacer at some point in the past.

The back inner portion of the timing gear and the front edge of the cam bearing are bearing surfaces which rub against that thrust plate/flange. But they don't always look like it - in particular I've seen new gears with fairly rough looking surfaces there. You can get steel thrust plates now which probably won't wear as quickly as brass, although if everything is OK in there the brass should be perfectly adequate.

Some steel gears will make slightly more noise but should last longer. Although with a stock valve train a replacement fiber gear is perfectly capable of lasting as long as the rest of the engine is everything is OK. Make sure that the oil sprayer is working correctly. Once the new gear is on but before putting the cover back on you can crank it around a few times to check it. If it isn't spraying, the gear won't last long.
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I'm JohnMc, and I approved this message.

Should ther be something between the cam gear and the retaining flange? and should there be something between the flange and the block?

No to both, but there should be a spacer ring on the nose of the cam between the woodruff key and the frontmost lobe.