engine turns over... but only part way
 

came to me years ago with a project car.
2.0L '69E claimed.
what is does; from TDC #1 it turns to the right approx. 60 degrees and stops. from the same starting point it turns to the left 180 degrees and stops.

what I've done;
pulled the plugs, detensioned the valves. no change.

???

all help appreciated.
http://forums.pelicanparts.com/uploa...1538706945.jpg
http://forums.pelicanparts.com/uploa...1538706977.jpg
http://forums.pelicanparts.com/uploa...1538706993.jpg

I'm sure it's not particularly helpful but I'll throw it out there just in case...The only time I've seen a lockout (admittedly I'm not a commercial/pro) was when the rods locked against the oil pump housing...in my case the pump needed clearancing for the new rods. It did something similar to your description, rotated Xº one way and Yº the other. But I'm guessing this once was a running unit that's sat, and now doesn't?

Presume the timing chains haven't been loosened and potentially skipped a tooth? Or somebody's removed the locking pin on the sprockets? Everything under the valve covers in-tact, no broken rockers that are impeding anything?

While assembling my engine I had the left side camshaft chain come halfway off the crank gear. So the chain was only on the back half of the gear. The engine would not make a full rotation and would rotate further one direction over the other. You could not see that the chain was only half on and it took me probably 10 min to figure out what was going on. Look back in there with a light and mirror.

Has it ever run in current condition?

Cam timing way off, piston/valve collision?

I'd pull the valve covers, spark plugs SLOWLY turn the engine over by hand and watch piston and valves.

I hope when you say "turns over" you don't mean with the starter motor, because if you're trying to start it you are probably trashing it as you smash things together. :o

thanks for all the feedback!

it came to me in a project car & was claimed "rebuilt" :(:rolleyes: ...so, no, I've never run it. pulled the valve covers suspecting a possible bent valve, but that all looks OK. backed off all adjusters. no change. engine is on a stand & i'm rotating it by hand from the pulley.
pulley @ TDC, distributor pointing to #1 & the punch marks on the cams pointing straight up.

I'll check the chains in relation to the intermediate shaft gears.

I'm also wondering if the PO dropped something (a nut perhaps?) inside when removing the Zeniths.

Piston skirt hitting the case?

I bought a 968 racecar a few years ago that had a fresh motor, but that had sat for a number of years. When I went to put it in the car, I noticed it wouldn't turn over. It would stop with an audible clunk when turning over by hand. Pulled the oil pan, nothing apparently wrong there. I wondered if it was a valve hitting a piston. Turned out to be rust build up in one cylinder preventing the piston from getting to TDC.

The motor came apart, though I wonder if a liberal soaking with WD40 or similar would have done it. Your engine should have iron cylinder liners too. Try giving them a good soak with some penetrant. I've heard you can get the red spray tubes that come with cans of WD40 to spray sideways by sealing up the end of the tube and drilling a hole in the side.

Scott

BTDT, removed them and use a shop vac. Make sure the container is clean.

If you install one of the cams 180 cam degrees from where it should be, this can happen. I screwed that up once, and an engine builder with a whole lot more experience than I have admitted he had that happen to him once - all it takes is to be interrupted when timing the second (usually the right side) cam. Easy fix if so.

Look at the dots on the ends of the cam shafts. If one is up, the other should be also (or do I have that backward? I try to double check myself on things like this, as it is a bit risky to rely only on memory).

I had a VW motor which had this issue as well, but that was because it sat out and water got into one or more cylinders, and rust built up. But initially there was very little movement at all, and only after liberal use of penetrating oil did it start to free up some, and then more, and more, until finally I could get full rotation. Runs, but only with tape over half of the carb's top as a choke at lower RPMs - ring seal has to be ruined.

Your description sounds a lot more like a valve/piston top issue, with timing being the most likely cause, especially on a rebuild with 0 hours running.

If you believe the engine has never been run (even before your ownership), then improper assembly is certainly a possibility. It's easy enough to confirm cam timing events by pulling off the upper valve covers.

Any luck finding out the cause? Inquiring minds want to know...

Too long pressure plate bolts?

+ 1

nope. was behaving this way before mounting the flywheel.

makes (at least) 2 of us. @ the moment I have an acute storage issue. I hope to return to this by the weekend or shortly thereafter.

it was about 12 years ago that the project came into my possession. I don't recall the exact description of the engine.

cam dots are @ the 12 o'clock position. distributor pointing to #1. pulley @ TDC.
I have not confirmed that piston #1 is @ TDC.

does anyone know about renting one of the tiny cameras that could be employed to peak inside the cylinder checking for a fastener or the like ?
Q#2;
with approx. 240 degrees of travel is it likely that, say, a 13mm nut could cause this much blockage ?

Just buy one. The cameras are cheap

appears so... I had a look $ got about 30,000 hits. everything so far is oriented toward security. I've yet to see something that will fit through the spark plug hole.
suggestions ?
TIA

got it... "inspection camera"

I lightened the shadows in your picture so the left side chain case is more visible.
The right side chain tensioner looks like it might be extended a little compared to when a new chain is installed.
Try removing the distributor at TDC or whatever.
If nothing changes it sounds like maybe you should remove the heads have a look and go from there.

http://forums.pelicanparts.com/uploa...1539923077.jpg

Bore scope

Did you use the shop vac yet?

Any finding.

Turn the engine til it locks. Then see which piston on each bank is close to TDC (I am assuming the dropped nut theory). Poke a screw driver down the plug holes if in doubt - there will be one on 1-3 bank and one on 4-6. If there is a dropped nut it can only wedge when you are very close to TDC.
Knowing the cylinders, then back the engine off so the piston retreats at least halfway, or fully. Rotate the engine stand so 1-3 are vertical and poke around on top of the piston with a flexi magnetic pick up tool. You should catch it if in there. If not, repeat for 4-6 side. If you don't grab anything you can prob assume nothing fallen in.
My 2c
Alan

almost home ?
 

guys... thanks for all the feedback, suggestions & encouragement.
it seems that someone, who shall remain nameless, was being a little too lady-like trying to rotate the engine. (I'm a firm believer in the old addage that if it don't fit don't force it ;) )
seems there was a slight ridge of rust in #6 due to poor storage.
current status = the engine turns over (enter sounds of cheering crowd) :cool:

BUT we're not quite home, yet. very little compression in #6 hole.

rings stuck in their grooves ?
if so, will they free up during run in ?
soak that hole w/ something (diesel ?) for a bit before attempting to fire it up ?

I'm almost there ! :D

Do the usual things when you find low compression in one cylinder:
With the engine at TDC firing position for the cylinder (#6 here), attach at least the spark plug hose connection from a leakdown gauge and blow compressed air in. Listen for where it is mostly coming out. Listen to the intake with the throttle wide open. Listen to the exhaust. You ought not to hear much of anything, and certainly not a different sound from intake to exhaust, if the valves are seating. Then listen to the inside of the crank case - disconnect the breather hose and listen there. You always hear some air escaping around the rings, so try this on #6, but compare that when you move to an other cylinder and relocate your air hose. This should tell you where the compressed air is escaping.

The only thing you could do about a valve leak is verify that the rocker clearances are greater than 0 (in case a rocker adjuster won't let the valve close), which is a bit unlikely.

There is also the possibility that a bit of carbon has broken off and sits on the valve seat, preventing full closing. I suspect that running an engine where this is the case ought to remedy the situation pretty quickly - the exhaust is perhaps the only valve where this could happen?

thanks Walt.
I'll give this a shot & report back.