Hey guys, I think I made a mistake.
I have an '88 turbo with the spring tensioner.
I just tried to retension the belt for the first time after the PO had a shop replace it 2000 miles ago. I loosened the two top bolts and spun the engine one time CWfrom the front.
Say you turn it more than 1 turn and then turn the engine CCW with the tensioner still loose. Who knew that the tensioner arm swings out then springs back into place with a click jumping a few belt teeth while the cam pulley stays stationary. (the crank moves ccw...but the cam stays still with the tensioner loose)
If you spun the engine by hand after that occurrence, which cylinder would be in trouble?
The reason I am asking is because after this event, I realigned the timing belt so that it is on the cam pulley mark, flywheel mark, and the mark I see through the top of the clutch housing are all perfectly centered. I turned it over by hand after I tightened the belt and the engine was super smooth. I put on the covers, intake, ac and ps belts and started it up and it ran.......poorly. It shook when it didn't shake before I realigned the timing belt. It shook at idle, and I brought it up to 3000 rpm slowly before I stopped and turned it off and it shook the whole way.
I just did a compression test to see if I messed anything up. (I didn't torque the tool into the spark plug holes but just put in by hand if it makes a difference) I got a reading of 0 on cylinder 2.
So would the cylinder 2 valves bend before the cylinder 3 valves on this cycle? Should I start planning to pull the head?

 

What made you think to " loosened the two top bolts and spun the engine one time CWfrom the front.
Say you turn it more than 1 turn and then turn the engine CCW with the tensioner still loose" IS OK??. if your going to re tension it all you do is make it tighter not loosen it. and if it has the spring tensionor then you really dont need to tigthen up much unless there is alot of play.

 

How did you turn the engine? Though I have never done it I would assume it takes quite a bit of force with a ratchet/socket on the front pulley to bend a valve.

If you can't get any compression at all in one cylinder, you can spot a bent valve just by pulling the valve cover/cam assembly. With that assembly off all the valves should be closed, and the tops ov the valve stems should be at the same height.

The Cam can be off 1 tooth (can happen when tightening the belt if the slack is on the pull side of the belt when you line everything up). This makes for some very crappy running, though often no damage. If you turn it back to TDC again (Via the hole in the bell housing) does the cam marker also line up?

 

Thanks for the replies. I do have the spring tensioner because it is an '88 and I found my procedure on Rennlist because it is not in my factory service manuals nor is it in Haynes.
I was not sure about the procedure I found, so I decided to email Clark from Clark's garage with the following message:
"Good evening,
I have replaced the timing belts successfully on an ‘83 and an ‘86 with no problems. (Thanks Clarks-Garage!)
I took the front end off of my “new” ’87 turbo and I was surprised by the timing belt self tensioner system I saw. I looked in my Hane’s manual, but they do not have the procedure for adjusting the timing belt on the 87 + models. I went to rennlist and they said something about loosening the 2 bolts on the spring tensioner and then turning the engine 1 revolution, then tightening it and checking again with 920x tool.
Which screws am I supposed to loosen to let the tensioner do it’s thing? The ones circled in red
My tension readings are over 4 right now with over 1500 miles on the belt, so I would assume that it is supposed to be 2.7+- .3 like normal. Is this correct?
Thanks for clarifying the procedure for me,"

and I highlighted the two bolts I thought they were referring to on this image.


and he was able to verify that I had the correct procedure.
Now as an afterthought; I see on Clarks-garage that his procedure is to simply release the tensioner and then re-tighten it immediately. This will work.
Another way that is probably better is to loosen the 2 tensioner bolts with the 920X tool on the belt reading tension, then use the 9200 wrench to spin the tensioner body slightly to the desired tension, then tighten the bolts back down.
I figured that I would get better results if I spun the engine one time with the tensioner loose so that the tensioner would have more opportunity to properly reset itself after possibly being frozen stationary for so long. (a dumb thought in retrospect)
However, spinning the engine CW with the tensioner loose is FINE.
Spinning the engine CCW with the tensioner loose is not so good and that is where the trouble started. I would have been a lot better off solo rather than have a helper spinning the engine as well, but that isn't as important as properly diagnosing it now.

 

Assuming LOTS of air wasn't whizzing past the threads on your compression tester, you've answered your own question.

Let us know how it goes from here.

 

+1

Zero on a compression test pretty much says it all. I can't believe a valve could be bent by hand turning the crank, but I guess anything is possible.

And no, you don't have to torque the compression tester hose into the head using a tool - a firm twist by hand is all that you need to make a seal unless the rubber seal is missing from the tool.

 

It would take quite a bit of force to bend a valve. If you were turning it over by hand, I think the moment you hit the valve, the engine would cease to turn and you would scratch your head!

 

You never know. He could look like this:

 

Perform a leakdown test... see where it is leaking on #2....

If it is leaking at all....

It takes some serious force to bend a valve...

 

2 posts says it all.