Who can guess what this is out of?

[quattrorunner]

I saw these and thought they looked a little odd. Not OE if you ask me. But I don't know. This is from my 79sc. I updated the tensioners so all is OK now. Don't they look rigged? My guess if they are reused older types is that the mechanic tried to recoup some losses on the estimate? Hopfully it has a top end I didn't know about as well
The 101 projects shows a part number starting with 930. Mine starts with 901 so I thought these might be early?
Thanks

[quattrorunner]

By the way, both sides are the same deal.

[Early_S_Man]

Probably the original tensioners in your engine ... which, after one or both failed, were fitted with the adjustable, threaded inserts you have now! Sometimes, these are called 'mechanical' tensioners, and have been used for years in racing engines.

[quattrorunner]

Thanks, I just found a thread in which you responded to as well. Indeed this is what they are. I guess they are good tensioners too. Well, goodish anyway. I now have hydrolic installed.

[quattrorunner]

OK so here are more photos to look at. I got worried about my chain and gears from reading other threads on the subject. I have put about 15000 miles on this car with these solid tensioners and I don't know how long it ran them before me!
Please look and let me know if you see anything like too much wear. Thanks again.

[Walt Fricke]

Quattro

A guy can worry himself to death over these things. It is hard to tell by pictures, but I don't see signs of imminent doom here - but see below for what looks like a problem you don't suspect.

Mechanical tensioners are reputedly a bit harder on chains. If set for hot running they are too tight when the engine is cold, and vice versa (maybe it is the other way around - doesn't matter). You now have a nice set of spares in case one of your pressure fed tensioners fails (or someone else's does at the track). Some racer types swear by mechanical tensioners.

Motorcycle guys tell me you check for excessive chain stretch (which is really due to internal wear on the individual internal pins and housings, so you can't see it) by trying to pick up a link where it is half way around the chain wheel. There should be little if any movement.

You can replace the chain with little more effort than you put into swapping tensioners, using a removeable link chain. But engineer types say you should always replace all the gears when replacing a chain, and that calls for complete engine disassembly.

I'd be inclined not to worry about any of this.

WHOA - I think I see one serious problem in your pictures. Did you replace the idler arms that hold the idler wheels? They are on the same shaft as the tensioner, and the tensioner pushes against one part of this gizmo to give it tension.

Your old tensioners were made for the old thinner idler arm bushed area. Your new tensioners are for a wider arm, so where they attach is thinner. You can see that in the photos. There is a big gap between the tensioner and the idler on the shaft. With the old tensioner there would have been only a little gap.

If you want to use your tensioners with your old arms you need to add a spacer to each one. The idler wheel will sort of self center things, but best not to give it too much room for mischief. Carrera tensioner kits used to all come with a pair of these spacers. But most of us bought new idler arms. Why? Because it was widely suspected that inadequate idler arm bearing surface was the root cause of tensioner failures, and that the pressure fed tensioners were another solution after the problem had already been solved.

Fix that. And try not to worry about the other stuff.

Maybe some kind hearted person, with left over spacers from a kit installed long ago with new arms, will donate them to you.

Walt Fricke

[RickM]

Walt: Nice write-up. Does the red bracket define the area where the gap exists? Just curious.

[Grady Clay]

Walt is right on and may have saved your engine!

The space (yellow arrow) shouldn’t be there. You need the later
idler arms for use with these tensioners.





Save your “mechanical tensioners. You can modify them to work
with the later idler arms by thinning the boss (use your new
pressure-fed tensioners to transfer the measurements. The
mechanicals are useful when setting the cam timing and of
course as emergency spares, (you need to deal with the oil
plumbing so the cams don’t get starved for oil).

Best,
Grady

[89turbocabmike]

Nice catch Walt!

[quattrorunner]

Yeah, nice catch. I was hoping for just that. Actually, The whole project stopped saturday night so I could spend some "quality" time with the wife. I didn't do anything other than photos on sunday. I was flipping through the engine rebuilding guide which is in my bathroom and happend across the spacer issue. (why didn't I see it before?) So This mornning I thought about going to Lows to see if they had some spacers with the bore big enough for the shaft as a bandaid till I get some real spacers. But maybe I should put the solids back on till I get what I need? I need to drive the next couple days. But on second thought, maybe I should hope someone would next day a pair of spacers? If someone would, I would wait to put it all back together. Nice save.

[quattrorunner]

Here is the fix. I got a spacer from lowes. It is a 5/8 by 1 inch. I cut it in 1/2 and have .495 inch X.624 inside each. It should work as this is about the mesurements I took from the shaft itself.

[scottb]

Originally posted by quattrorunner
Here is the fix. I got a spacer from lowes.

Assuming you mean the Lowe's home improvement stores, there's something about using a bushing from Lowes that strikes me as being penny-wise and pound-foolish. I wouldn't want to risk my engine's health on a bushing bought at Lowe's, that's for sure.

[quattrorunner]

It's just a spacer dude. And i think it would last till I get a proper spacer.

On a more serious note. After getting everything buttoned up and turning it over for the first time, it makes a bit of a racket. I didn't soak the tensioners in oil, is this possably the reason? I am 95% sure of a tooth not skipping, I would say 100% but I can't. I am as sure as I can be about that, but the cam gear did turn as I moved the idler pully to fit over the tensioner. And I didn't do any of this at TDC. Ir runs in a normal way other than the noise. What have I done?

[Walt Fricke]

Quattro

Are you familiar with the racket this engine made before you made the tensioner change? These engines are noisy.

It is not the cam moving that could cause problems. It is the chain moving a tooth or more at either end that messes up the timing. If you kept idler pressure on things and were watching when this motion happened, chances of the chain moving a tooth are small.

If worried, check the cam timing. If you don't have a dial indicator and a way of using it for the purpose, consider that the thread pitch on the rocker adjusters is 10 threads per mm. Overlap is at a fairly low lift, so I think you could see how far you have to back off until it is loose to make a good estimate of what you have. Being off a tooth at either gear (they are not the same number of teeth, but no matter) ought to show up as a lot more turns to looseness. Just a thought - I've never done this but folks check valve clearance this way often.

I've read (in Wayne's engine book - he doesn't mention this in 101 projects) about priming Carrera tensioners. I've never done it, and think I have gotten away with it. The oil pressure ought to push the air out, I think, especially since the tensioners don't have seals - the thinner air ought to be able to escape? But it sure can't hurt. Brakes need bleeding, maybe tensioners benefit from it too.

Walt

[quattrorunner]

Yeah, they make noise, but I didn't expect noise on startup like I heard. Ihave a loud exhaust and still noticed the differance. I thought the sound might be chain slop before there is oil pressure, but the tension is good on the tensioners. I feel like the chain might be stretched and the solids kept the tension tight enough to keep sound down? Now that I have hydrolic, maybe the chain is just too long?But again, the tension seems good. I'll try to check cam marks tomorrow. I don't know how this could be happening. I don't have the tools to really check cam timing, but I'll rotate the engine slowly to feel for interferance of any kind.

[quattrorunner]

Laast night I read in the engine rebuilding book lots about the sounds I heard and it may be somwhat normal till the tensioners get pressureized. I will check the cam marks with TDC and lower the rear of the engine this time so oil will have a chance to get to the sump. (I still didn't see any oil in the chain area from the quick running it did so I don't believe the cam lines got oil yet) This all seems good to me. I'll keep you posted.

[quattrorunner]

In case any one cares, I had indeed skipped a tooth! I loosened the tension, rolled the chain back over one tooth, and readjusted and buttoned it back up. Before I did any of that, I said a quick prayer(no kidding) and flipped that key. Perfect. HA!

[Walt Fricke]

Good on you, Quattro.

[quattrorunner]

Thanks Walt.