Scuba Steve

I'm still putting my car back together and noticed that the gear on my car was put on by the PO with the lip towards the rear of the car instead of the front. It seems to be a really easy mistake to make. Would something like that trash a timing belt very quickly? This may be why he had such bad luck with it.

Also, I got 3 of the camshaft assembly bolts in (finger tight) before I noticed that somehow the camshaft had turned about 20 degrees. I turned it back and it jumped back to place. This isn't enough to do anything to the valves, right?

Granite 944

I'm surprised no one has replied to any of this yet. I have no experience with the gear on the crank being put on backwards, but, I would think it would contribute to a belt trashing considering that the flange on this crank gear is now being put to the inside and would be set to far inward (entire gear being offset further inward), and not allow full belt face ingagement. The alignment of gears/sprockets/flanges would be off. The waterpump and cam tensioner shoulders pretty much keep it from going fwd/aft otherwise. I also think by having the flange to the forward side instead of backside will also help keep a loose belt from riding forward onto the BS gear.


As far as the cam housing, 20 degrees is probably getting very close to causing damage, but I'm not sure about the degree of offset necessary to create problems. If you only had 3 bolts in finger tight, and assuming with this info that the cam housing was still not pulled down to the top of the head completely (compressing some of the valves), I'd "guess" you didn't do any damage to any valves. If you really think you may have, after the belts are back on properly and set, I'd rotate engine til each cylinder (one at a time) is down away from the valves, and both are closed completely, and spray a fair amount of carb cleaner in both the exhaust and the intake port holes for that cylinder, looking to make sure it doesn't run straight out past the valve. If it does, yeah, you bent that valve. If testing this way, and no problem, blow out the remaining carb cleaner, and I'd squirt a bit of engine oil back on top of each piston (thru plug holes, to replace any intial start lube lost by using the carb cleaner. No expert here.......just some outloud thoughts. Good luck!

Porsche-O-Phile

It is a very easy mistake to make - I've done it but realized it when I had to put the balance shaft gear on in front of it and realized that if the cam belt "walked" forward slightly on the pulley it could easily get "snagged" on the teeth for the larger b.s. gear. Obviously this clued me in right away that it was on backwards so I had to pull it back off and switch it around, but I suspect the potential for really really bad things happening is significant with the gear on backwards and the engine reassembled / started. If that cam belt gets even a little bit caught by the larger gear you'll get a free membership to the bent valve club. If this is the case on your car, DO NOT start it and fix it now.

Scuba Steve

Thanks - I caught it while the engine was still apart from me working on the water pump. The engine hasn't run in ~2 years by my guess. Valves bent when I got the car and I had always wondered what happened when he started it up after the 1st time he blew the timing belt. By his story, when he cranked it for the 1st time the car backfired and the belt blew immediately (he swears up and down that everything was lined up). I've always wondered what made that happen. Yesterday I found out he had that gear on backwards, and that it's easy to mess up the belt tensioning if you aren't careful. I had the wrong side tight when I let the spring tensioner go so the side with the crankshaft -> idler roller -> camshaft was still loose. But I caught it right away when I started to turn the engine and the camshaft wasn't moving, and fixed it.

I could see how someone could miss that and blow their engine if they didn't check things by turning the engine over by hand first. The belt is tensioned right now and when the pin wrench comes in I'll be able to finish up.

And the valves, they're fine. I put my compression tester in and turned the engine by hand. Compression is in the 40-50psi range so it looks like everything is good. If anything happened my guess is that I wouldn't have been able to get it to register. The cam housing was still 'hovering' well above the head at this point.

M758

I did that on my 84 daily driver. I noticed the problem when I could not hand turn the crank. The gear hit the inside plastic cover. I never trired to crank the engine with the starter however.

I flipped it around and it was fine.

Bree

I know this might not be the correct place for this but it is the only mention anywhere on the entire internet I have found reference to this problem. I ha e a 2005 Chrysler grand voyager which I was doing the timing chain on and in my rush to install the crankshaft sprocket while still hot I accidentally slipped it on backwards and it went all the way and not I can’t remove it as there is no grap for the claw of the puller to get in there any ideas? Thanks

931guru

LS1 Swap FTW!

Bree

Does that mean a full engine swap? I was thinking about welding another sprocket or something to the first and using the puller on that do u think that might work?

931guru

To a man with a welder, every job becomes a welding project.

Jfrahm

Sure, or drill and tap a couple holes for bolts you can grab onto with a puller.

I bought this really great old book full of emergency shop techniques, tips included using dynamite to get stuck taps out of holes. I can consult it for suggestions if need be. The suggestions will involve dynamite.

-Joel.

Tiger03447

That must've been a real explosive book when it was published!! sorry couldn't resist...