2.7L Compression Test Numbers

you may have bent a valve with the timing wrong, check compression, if you are lucky and still have good compression then no damage was done to the valves.

there is definitely a mark on the crank gear to line up the chain, they are all made with one so you just need to find it.

what you did was move the timing to make it work with out of aligned cams opening and closing at the wrong point in the pistons stroke so that is the problem. I think you got the cams in alignment but the crank gear is one tooth off and that is going to be your problem but to avoid serious damage later you need to confirm all marks line up correctly, then set your distributor correctly and adjust the timing.

start over, pull it apart and line up the crank marke then line up the cams and then try it

a simple moment of brief slack in the chain is all it takes to slip off the crank gear and move a tooth out of alignment even though you might think it didn't move. I suggest you think about just putting on a new chain since you have to realign it on the gears anyway and this way you have a renewed valve clearance and new timing chain which should get you another 100k miles easy before things start to wear.

 

I can't see for the life of me how I would have gotten the crank gear off by a tooth since I zip tied the intake cam drive gear to the chain and never actually removed the intake cam. I'm inclined to agree with you but I just can't figure out how that could have happened.

How would I go about fixing something like that?

 

I forgot to say that I did a compression test right after replacing the shims and realizing that it wouldn't start. No noticeable changes in the compression numbers compared to the pre-op numbers.

 

its easy because the zip tie ensures the chain doesn't move on the cam gear but the chains position on the crank gear isn't secured and it relies on the chain tensioner to keep it in place and when the cam moves and the chain moves even a little it can have slack. think of it as a fan belt you hold at the top pulley and you see how much it can move around on the bottom pulleys.

I cant say im 100% right on this but at this point you have to start from the beginning and confirm the crank gear is in proper alignment as well as the cam gears.

the chain has a certain amount of built in slack to it and there is always one side to it not under tension so you never have both sides tight.

while I haven't done ours yet most require you pull the crank balancer pulley off and remove the timing cover under it then you have access to the chain tensioners and can see the alignment marks on the crankshaft timing gear.

also, are you 100% sure you have the correct valve clearances now? you didn't get them mixed up or order the wrong sizes?

 

Pull the cams-both- and remove the chain from the cam sprocket- have an extra set of hands to help hold the chain and keep it from falling down into the motor. Set the crank pulley to top dead center (with both cams out all vaves will be closed when your rotating the crank and you wont smack any valves) then re install your cams with the timing marks, put your dist in pointed to cyl #1 on the cap. Easy as pie- wish you were closer id give ya a hand.
Usually 1 or 2 teeth even on an interferance engine isnt enough to make piston to valve contact. I bought an audi with a 2.8 that skipped 3 teeth and ran fine with a new belt,
Ive also had a honda vtec one tooth off before and people say those are the tightest tolerance interferance motors out there...
If you bent a valve it would definantly show up on a compression test.

 

Thank you.

Quick question though. I had a dowel rod in the first cylinder watching it go up and down as I manually rotated the engine. Since the pulley is directly connected to the crank shouldn't the timing notch have hit the zero indicator while the dowel was at the top of its stroke? It didn't which really confuses me.

 

Yeah OP, got my fingers crossed that if you just get timing right, she will fire up again and purr for you. I did a timing belt on a 05 V6 Accord and after I pulled the pin for the tensioner I only rotated the motor once or twice which didnt take the slack out of the belt. When I went to start the engine after I finished, it skipped a tooth and wouldnt start. The next day I re-did everything from step 1 but this time rotate the motor 6-8 times to completely take out slack. To my immense relief, she fired up and ran smooth.

Hope your issue is solved by just re-tracing your steps and doing everything correct from step 1.

 

well here is the kicker, the piston reaches the top twice, once is the compression (firing) stroke and the other is the stroke where it rises to push out the exhaust and sucks in fuel on the down stroke so when it rises on the firing stroke it is filled with the fuel air mixture for detonation. if the valves are opening or closing too soon or too late then its not going to have good combustion because the fuel/air mix is messed up.

just because the piston is all the way up doesn't tell you if that is the compression stroke or not. every other time the #1 piston is at top dead center is the number one firing point. the other is what they call having the engine set at 180 out because timing is set on the wrong stroke.

I don't thing this can be your problem but if the plug fires too soon or two late it runs like crap and the plug fires "just before" it reaches the very top so its a hard thing to guess by looking at it.

 

That's what I was thinking too but I'm almost certain that the cylinder isn't at the top of either the compression or exhaust stroke when the timing mark hits zero. I'm pretty sure it's mid-stroke.

I'll check again tomorrow night and report back.

 

not positive I understand what you're saying
there's no way you can possibly be 180 out on the bottom end unless your timing mark is off on the crank pulley and your pistons are at TDC, if the cams are not rotating and you put the bottom end at top dead then center using the pulley then line the cams up it should all be good.

 

another thing once you get everything buttoned up correctly and rotate the engine by hand realize that your timing marks are not going to line up after you spin the engine a complete revolution, don't panic this is perfectly normal.

 

Did you install the service bolt into the exhaust cam gear before you removed it? There are 2 gears. The front one is spring loaded and will turn relative to the back one without the service bolt installed. I believe it's designed this way to reduce the noise between the intake and exhaust cam gears.

Did you mark the front or rear of the gears when you lined them up? The rear exhaust gear is the most important to keep lined up with the intake gear. That's why the alignment dots are on the rear side of the gears.

The crank pulley is supposed to stay aligned by a key in the crankshaft and a slot in the pulley. If the key broke, or the pulley got worn away (from maybe the bolt being loose and it wobbling slightly), then it wouldn't line up anymore. Also, some cars have a pulley with rubber between the inner and outer part. It's possibly for the outer part to slide out of alignment, but I'm not sure if Tacomas are like this, and I'd think the pulley would be wobbling a lot if it got loose like that.

 

I've been chasing a vibration for a long time. It's very possible that the pulley / harmonic balancer is off. I will look into it more tomorrow before I say something stupid and further display my ignorance.

I didn't use a service bolt at all but I'm pretty sure that on this model the service bolt is on the intake side along with both of the gears that you mention.

I did mark the exhaust cam before removing it and am as certain as I can be that they meshed up just as they were prior.

 

If anything happened it has to be with the connection between the exhaust cam and distributor or a side effect of inducing a very small amount of slack in the drive chain when I tilted the intake cam slightly foreword. One of the few things I'm sure of is that both cams are still aligned with each other and correctly tightened down.

 

3RZ-FE? The service bolt goes on the exhaust camshaft.

Did you mark the front or the rear side?

 

Rear.

 

I was not speaking to his problem at all but instead I was answering his question about the piston being at the top of #1 cylinder "had to be" the timing firing mark alignment point so I explained it gets in that position twice for each firing so there is a time its 180 out and not ready in position to fire.

the fact that he had to reposition the gear position on his distributor just to get it to run (and its still not aligned right) says for sure its out of alignment and since the cam marks are aligned it has to be the crank gear that is in the wrong spot

 

Before you do anything else, change the plugs! Starting it with the timing wrong can (and will) foul the plugs. This happened to me. It started up for a second afterward, but could't maintain it. Future tries it wouldn't start at all.

If you have the #1 piston at TDC, then you have the distributor pushed in with the rotor at 12:00, and it properly rotates to point at the #1 post, then your timing is right (assuming you zip tied the intake cam to the chain, which you did).

The only thing keeping your truck from running is most likely fouled plugs. Once I did all of those steps that you did, I had to put in new plugs before it would run.

 

That's an interesting thought.

 

when you line up the timing mark on the crank pulley how do the cams look? some pics of that would be helpful.