1984 3.2 Carrera tensioner collapsed, jumped a sprocket? How to check cam timing?
 

My 1984 Carrera started making loud timing chain dragging noises in the drivers side cam box when I was out for a drive. Noise wasnt there when the engine was cold, but got louder as it warmed up. Figuring I had a collapsing tensioner, I had AAA flatbed it home.

Next day removed the chain box covers, and found the chain holding normal tension, but when I removed the driver side tensioner I found I could press the piston in with my hand! Not good. Passenger side tensioner was super strong when removed so I reinstalled it. Bought and installed a new OE tensioner on the drivers side.

Buttoned it back up and added oil, and the chain noise went away about five seconds after startup. Drove it around until it warmed up, and it felt down on power a little when I ran it to redline. I now heard some quieter rattling on the passengers side of the engine...couldn't tell if it was the chain or valve noise. I took off the chain box covers again and everything looked fine and chain had proper tension. Did a valve clearance check (they were adjusted about 6 months ago) and all was good.

Questions:

1. If one of the chains had jumped a sprocket, my valve clearances would be off when checked, correct? They were perfect as the day I set them six months ago.

2. How can I know for sure the cams are set properly on a 3.2 without the cam end nut marks like the earlier engines had? Supposedly it was rebuilt to stock specs years ago but I don't know what cam it has. Wayne's rebuild book doesn't cover this for 3.2s.

3. Could that passenger side noise be due to me reinstalling the original (possibly weaker?) tensioner that seemed as strong as the new one? I've heard the hydraulic tensioners either they work or they don't, and they are pricey, but I'm tempted to replace it anyway.

Valve clearance isn't affected by cam timing. And since there aren't timing marks like other cars, you'll need to bust out the dial indicator to determine cam timing. Since different builders will sometimes time the cams to their preferred settings and not the factory settings (similarly if it has aftermarket cams), check the known good side first, then compare it to the side that you replaced the tensioner on. Adjust the suspect side to match the known good side.

Hydraulic tensioners usually either work or are collapsed. Once in awhile the air bleed will fall out and bounce around, but that's about it.

Need to get waynes book and set cam timing as detailed. Need the dial gauge and tools

>Need to get waynes book and set cam timing

I have waynes rebuild book and read the chapter on cam timing, but it's describing a freshly rebuilt engine being assembled, not one already together, so the process is a bit confusing to me. Just so I'm clear, there is no way to determine if a cam is at TDC (or very close to TDC accounting for builder preference) without using the dial indicator and Z block?

If so do I only need to get the dial inidcator and Z block and just check the cam timing first?

I'd rather not have to loosen the infamous cam bolts (with the special tools) if the cam timing is still correct.

check timing
 

you do not need to loosen the cam fasteners to check timing.
if you do have to loosen the nut loosen all of the valve adjusters and be very careful releasing tension on the cam.

I could be wrong, but I would imagine the exhaust valves would hit the pistons if the chain jumped a tooth.

Do you need to remove the engine to do this?

engine
 

I did not remove the engine but probably took me twice as long.
but I did not want to remove the axles etc.

No need to remove engine to do this.
You do need a dial indicator and z block.
You also need cam tools if you are going to adjust it.
If it makes noise now, chances are you will need a bit more surgery. At least a new tensioner and then rechecking the cam timing.

Jumped time, check for broken rockers first.
Bruce

OK So I bought the SIR Tools Z block kit and dial gauge. Set the engine at TDC indicated at Z1 on the crank pulley, then zeroed the dial gauge. Rotatated crank pulley 360 degrees back to Z1, and the dial indicates .038 in which is .965 mm. Spec for my 1984 3.2 is 1.1 to 1.4mm.

I rechecked it several times and came up with the same result...see the video link below of my final check. Am I reading my gauge correctly? The gauge goes in reverse when measuring at this stage...I'm guessing that's what the red numbers are for.

Now I need to buy a P9191 tool and reset the cam timing, correct?

https://youtu.be/D_eRg5aTyJg

1) Did you pull all the valve covers to check for broken rocker arms? Though you have driven the car, so maybe that didn't happen?
2) Did you do a leak down? That is step one (if no broken rockers) in checking for bent valves (which don't fully seat). Though nothing in your descriptions really suggests you had valve to piston hits. You have to push the engine pretty hard with a bad tensioner to have that happen. Typically just all that noise, which discourages goosing the engine.
3) I haven't done the math, but I can't believe that being 0.1mm off spec was caused by the chain jumping a tooth.
4) Did you check the lash on #1 before checking the cam timing?
4) Now that you have the Z block, check #4 (after checking the lash).

Your description of your technique sounds about right, though. Me, I have become a fan of digital dial indicators - not expensive at all now, and it gets rid of the "which numbers am I reading" issue. But you can easily enough teach yourself what is going on.

you need to check the other side, if both are the same then you are good.

good, you did notice the dial moves CCW so you need to use the numbers that count UP. not down.
(I think that is how my 77s got advanced 15 degrees).

just make sure you had some "pressure" on the dial gauge before started turning the crank.

When I was curious about the cam timing on my 87 3.2 I checked the valve lift on each side using a digital vernier caliper. It measured out within factory specs.

I second the suggestion to check the other side.

1. Yes, no broken rocker arms. Also rechecked valve clearances and all were still in spec from my valve adjustment a few months earlier before the tensioner collapse.
2. No. Thought I would do this only if I found the cam timing was out of spec. Can I do an accurate leakdown test on a cold engine? Or is accuracy not important and its just to listen if air is coming out of exhaust or intake?
4. Yes
5. I will check the other side today and report back.

Thanks for the hand holding guys!

A few years ago I did a spirited drive up and down Palomar mountain near San Diego and when I stopped 30 miles from home I heard the chain rattle in my 85 Carrera. I nursed it home and replaced the bad tensioner and chain ramps without checking to see if it skipped a tooth. No issues so far.

Not like the early tensioners, I don’t ever recall a Carrera jumping time, it takes too much to press them down to reinstall.
Bruce

i drove my 77s over 250 miles with a collapsed tensioner. it made a heck of a noise at idle, sounded like a bad exhaust leak, but got quiet when driving.
I think the big issue is when you let off the gas, the slack in chain changes.

was out of town, had no choice plus engine was ready for rebuild. oh, non pressure fed tensioners.

Maybe do a quick compression check? If you tapped a valve when the chain collapsed, compression test should show that.

and just because no one explained it to you ....
when you do your valve adjustment you do it on the " back side" of the cam .. the place where there is no lobe ... so if you skipped a tooth the lobe might be a few degrees off but you would still be on the back side of that cam where there is no lobe so it would measure out fine ..


Also you can do a compression test on a cold engine .. might not be ideal .. but would still tell you if one is way off or not... preferably on a warm engine..