This past weekend I was doing the timing belt service on my car and made a couple stupid mistakes. This should have gone smoothly since I just did the same exact service on my buddies evo last weekend.

When I started the install I set the engine to TDC confirmed all the timing marks lined up and all was well. Tore everything apart installed new pulleys water pump tensioner belt etc.

When I went to rotate the crank to confirm that all was well before putting the lower cover back on the first 1/4 turn we noticed the crank trigger plate was making contact with my balance shaft pulley. So I turned the crank back to TDC to try and figure out where I went wrong. I wasnt sure at this point but the contact ruined my new balance shaft tensioner pulley and bent the crank trigger plate.

At this point I needed to get my car back together so I straightened back out the plate and installed my old balance shaft tensioner pulley. It was still hitting. At a loss I called it quits for the night since I knew I would need to order parts.

This morning I realized where I went wrong. When I set the tension of the balance shaft belt it tensioned the belt to the right instead of upward. Since the pulley is offset this put it in the path of the trigger plate thus bending it. Stupid me but now I know and I will never make that mistake again! But it gets worse...

When I pulled the timing belt back off I forgot to put the car back to TDC. So I tried to slowly turn the crank back to TDC while slowly moving the cams back to TDC as well thinking it's gotta be impossible to bend valves by hand. Anyway, I got the crank back to TDC and both cams are also at TDC. However the exhaust cam sat fine but the intake cam doesnt want to stay at TDC on its own for some reason. I have the tool that locks both cam gears in place so I just inserted that and they are both sitting at TDC now.

But I fear that something is amiss right now which is why the intake cam doesnt want to stay at TDC which leaves me with a couple thoughts.

1- If I put back on the timing belt and tension it when I remove the cam gear holder is the belt going to jump?

2- If the head is at TDC all the valves should be closed. Thus technically I should be able to spin the crank freely. If I were to turn the crank a 1/4 rotation pistons 1&4 should drop halfway and 2&3 should move up halfway. If I do this will it give me enough room to then move the cams without risk of the valves contacting the pistons? My thought is that the valve springs are binding a little and I need to just spin the cam around a turn or something to get it to seat properly. Does this sound plausible?

3- Should I just pop off the valve cover and remove the cam rebleed the lifters and reinsert the cam back at TDC? And if I do this is there any reason the cam wouldnt want to sit at TDC?

What would you guys recommend doing? Is there any reason other than spring pressure on the cam that wouldn't want it to sit at TDC? Am I being super paranoid at this point and thus over thinking the whole thing? I obviously don't want to crunch valves so I'd like to confirm if any of this makes sense and the best way to overcome this obstacle. Thanks in advance for your help.

 

The tool to lock the cam gears in place is there to keep them from jumping. That's the reason you use it.

 

As long as it's tensioned correctly and both cams and crank are at TDC your fine

 

Thanks guys for the reassurance. I know how to properly set the tension and I'd think that if that is the case and the marks are all at TDC then there is no chance of it somehow getting messed up.

What I still cant grasp however is why the intake cam doesnt want to sit at TDC without using the cam gear holder tool. I know its the valve springs trying to move it along and find a nice resting place but that should be at TDC...

For sake of discussion when I've installed cams in the past or pulled my head doing a headgasket I'd start by setting the car to TDC and then pop the cam gears off and the cams wouldnt shift. At this point obviously with the cams gears no longer attached there is no tension from the belt to stop movement and the cam gear lock tool is not even needed yet they stay in place.

So what is different in this case? This is why I feel like the cam needs to go through an entire cycle to get everything back to normal as maybe the valve springs are binding right now or something?

Once I get the timing belt back on I will obviously turn the crank a few times to ensure nothing is hitting and all the marks remained lined up and this could make the cam rest easy again but I just wish I could get it to sit there nicely prior to doing that to reduce the chance of f**k'n something up.

So has anyone else experienced this where the cam didnt want to sit at TDC? I've swapped cams a few times done a couple head gaskets and what not so this isnt my first rodeo but this is the first time I've experienced this issue.

 

When I did the belt on mine and my brothers evo neither the intake or exhaust cam stayed at TDC without me holding them there. I don't have the tool to hold the gears together so I hade to hold the cams in TDC wile timing the motor.

 

Thanks for your feedback. Why is it that it seems this is only the case sometimes and other times they will stay at TDC?

I've had my head off the car twice now and both times it stayed at TDC. Same thing with swapping cams. And just for sake of discussion if you look at any assembled head you will see that all the valves are closed which tells me that they should be able to sit at TDC without needing to be held there...so what gives!? Haha!

 

Just make sure the cams are pulling away from each other!

 

^What do you mean by that? And why is that important? There is no timing belt on the cams right now so they can act independently.

 

I just did my timing belt on my 2.2SLR and neither of my cams wanted to just sit right at TDC patiently wait for me to route the timing belt. But i did it the OEM way without a cam gear holder and used those big binder clips to clamp the timing belt to the cams. That way, even if they do move the belt is held on to them in the right position so when you put tension on the belt they dont skip teeth or anything. Probably the easiest motor i have ever timed.

 

i've never done a timing belt, on any car, where the cams wanted to stay TDC. you are never going to have all valves closed at once. that is why you have to keep rotating the engine while doing leakdown tests.

 

Aftermarket cams with larger lift and overlap duration can cause the issue with them sitting up straight at TDC. Also, TDC is for cylinder one. Two and three, I believe, are at BDC. That means cylinder four is at TDC overlap. That's where there may be some slight lift from both sets of valves for cylinder four. Aftermarket cams will likely lift the valves slightly more than the stock cams, putting more pressure on the valve springs. This will push the cam away from the proper overlap position a few degrees.
My HKS cams were doing this for me when I swapped them in and put a new belt on. It's pretty normal. Just make sure they are aligned properly when placing your belt on, release the tensioner, and rotate the crank twice to make sure they're still in time. I'm sure you know this, since you've done a few. You'll be fine.

 

OK, awesome thanks guys. Well Im glad I have the Jay Racing Timing Belt Kit shown here as its probably a lot easier with it than without http://www.jayracing.com/timing-belt...kit-p-214.html

As the car stands now Im waiting on parts. But everything is set to TDC so I should be good to go. I just thought it was strange that the cam didnt want to stay put as I never remembered that happening in the past.

And when you look at a head for sale in the classifieds section for example you will see what appears to be closed valves. Now most dont have cams in them I know but some do but maybe are still off just a couple degrees? Who knows...

Anyway I think I got my answer and I guess I am just being paranoid and I have nothing to worry about. Just the whole thought of crunching valves makes me nervous. Just waiting on parts now but I should have the car back together on Wednesday and I'll report back to those that care, lol!

Thanks to all who have chimed in I really appreciate it

 

All of the valves are not closed at "tdc". The only valves that will be fully closed are cylinder #1 as it is on the compression/power stroke. All the other cylinders the valves will be open to some extent. The cams typically do not rest in the desired position, which is why the tool that goes into the gears exists. Time it, put the belt on, spin it, and see where you're at. I'm sure its fine..

 

Thanks for that and yeah now that you metnion it my buddies car that we did last weekend is on the stock cams and I have GSC S2 with their springs. But yeah I'll make sure everything is lined up rotate the crank 3 times to make sure the oil pump is in phase and nothing jumped and I should be good to go

Thank you. I'm not an engine builder as you have probably figured out. Sure I've done all the work on my car but I typically learn by what I read on here and by what I physically run into as I'm in the middle of working on the car. But I still have a lot to learn and while I know I have more knowledge than the common folk as well as probably a lot of folks on here I still am nowhere near the level of some of you guys. But I love working on cars and I'd rather ask the question and maybe look stupid to be sure then just say f it and hope for the best

 

Great reply, my thoughts exactly. Looking stupid is nowhere near as bad as being stupid!