Intel's Ronler Acres Plant

Silicon Forest

Sunday, August 21, 2011

Chrysler Sebring 2.7 Liter V6 Assembly Notes

Installing the Camshafts and Timing Chains

Installing the timing chains was fraught with terror. I had two friends who did valve jobs on expensive overhead cam engines and both of them had to do the job over. Both of them did the job with the engine in the car, and they figured that if you didn't move the crank while you had the engine apart, it would still be in the right place when they put it back together. If both cases they were wrong. Once they had their engines assembled and turned them over, the mis-timed valves impacted the pistons and they all got bent.

This engine has dual over head cams, that is two camshafts per bank of cylinders. Two banks of cylinders means a total of four camshafts. Each pair of camshafts has a chain connecting them. The intake camshafts have a second sprocket that is driven by a chain from the crankshaft. So we have two separate situations that need to be coordinated.

Before we start putting anything together, we turn the crank so the mark on the crank aligns with the mark on the block. Normally I would expect this to put piston number one at top dead center, but not here! Shoot, none of the pistons are at top dead center. Oh! Clever devils! I see what they have done. With the crank in this position, all of the pistons are at least an inch down in their bores. So no matter what we do with heads and valves, there is no way the valves are going to impact the pistons. So we just need to not move the crank until we get the timing chains all installed.

Timing each pair of camshafts in a single head is not two difficult. Two of the links are marked and the sprockets on the camshafts are marked as well. Simply line up the marks and then mount the camshafts in the heads.

Now we can install the main timing chain and the large camshaft sprockets. This is a bit tricky. As I recall, the chain is draped over the rear sprocket and then dropped through the hole in the head. Then the front sprocket is inserted in the chain and fed upwards through the hole in its' corresponding head. Or maybe it’s the other way around. Whatever. Now the sprockets can be slipped on the camshafts where they are free to rotate. Now we can adjust the timing marks on this chain and these sprockets so they all line up.

Now we have a problem. The two camshafts in each head are in their proper relation to each other, and the main timing chain and all its' sprockets are all coordinated, but we still haven't connected the camshaft sprockets to the camshafts. This is done with a pair of bolts in each one. Unfortunately, with all the timing marks where they are supposed to be, the bolt holes do not line up. How effed up is that? The bolt holes are diametrically opposed, so the sprockets can be bolted to the cams in either of two positions. Either position will work mechanically because the crank makes one complete turn for each half turn of the cams. So icrank cannot tell if the cam is 180 degrees off. However, there is also the ignition timing to consider. Or what if we get one cam right and the other 180 degrees off? We might have a very rumbly engine.

In any case, the bolt holes were not that far off, and they were both off the same amount and in the same direction, so I simply went with the closer position. One problem is that one cam did not want to stay lined up. It was at a point where at least one of the cams was on the tip. As soon as you put it in position, the valve springs would cause it to move. The camshafts have square recesses to accomodate a square drive socket wrench extension, with that and a pry bar, you can rotate the cam into position and hold it there while you put the bolts in. A rachet won't work. As soon as you get to the position, the springs grab the cam and twist it away. Happens in both directions, hence my conclusion that it must right on the tip of the cam.

Installing the Crankshaft Pulley and Seal

Installing the crankshaft pulley and seal was a bit tricky. The pulley mounts on the end of the crank. The seal rides on a surface just behind the pulley, and slightly larger in diameter. The surface of the crank between these two area is beveled, so by turning the seal while pushing it will go right on. Unfortunately, the seal has to be mounted in the timing cover first, and the protrusions on the cover preclude any rotation while mounting it. If you just push the cover and seal into position, the edge of the seal will catch on the beveled lip on the crank and flip inside out. Somehow I imagine it will not seal effectively like that. Chrysler has a special tool for installing the crankshaft seal. I really don't want to buy one. I can't imagine ever having any other use for it. Besides, as specialized as it is, I am not even sure where I could get one.

So I improvised. I cut the ends off of a pop can and then cut about a one inch wide strip out of the side. I took the remaining piece, spread a little oil on it, wrapped it up on a circle and slipped it inside the seal. Spread the end of this rolled up piece of aluminum so it would go over the crank and pushed the timing cover and the seal into position. Then I pulled the aluminum piece out. Easy as pie. Don't know if it will actually seal or not. Seals are kind of funny. Old, ugly seals can work fine. New seals with microscopic defects can leak like a sieve. The seal suffered quite a bit of abuse while we were fooling around trying to figure out how to get it in position, and the edge of that aluminum is pretty sharp. I could have nicked the seal while I was pulling the aluminum shim out.

Installing the crankshaft pulley took a little work. It is a press fit on the perfectly round end of the crank, there is no key. There is bolt that holds it on. If the bolt had been just an inch or so longer, we could have used it to push the pulley on, but no, can't make it easy. I was able to knock it on using a block of wood and a small sledge hammer. Once I got it most of the way on, the bolt was able to grip the threads and push it home. There is a tab on the bottom of the timing cover you use with a screwdriver and one of the pulley's spokes to keep the pulley from turning while you tighten the bolt.

Wiring Harness

When connecting the wiring harness to the three ignition coils on the front bank of cylinders, I noticed that there were four identical connectors. This sucks. There is also a connector on a sensor mounted on the intact plenum that uses this same connector. So which one is the odd one? From this photo, I can see that the connector with the brown wire on top goes to the intake plenum. The ones with the green wire on top go to the ignition coils.


Ole Phat Stu said...

"I've been to church two weeks in a row."

Explanation : Charles is repairing a Chrysler Sebring DOHC engine and needs all the help he can get ;-)

Lorie Graves said...

Hi Charles my name is Grady Graves. I am working on a 2.7 liter engine.I timed the cam shafts with the plated links over the timing marks and the primary chain the way you illustrated. We then rolled the engine several revaluations to make sure the engine was free. When we rolled the engine back to the point where the timing marks on the primary chain were back in position. The timing marks on the cam shafts didn't line back up with the plated links on the cam chains. We set them at the rite position when we installed them. Is this ok or do I need to reset them?

Charles Pergiel said...

Yes, it is confusing. You set up everything just so, it all looks good and then you crank the engine over and nothing lines up anymore. The problem is the chain has a mind of its own. The crank sprocket has, what, 2 dozen teeth? The chain has like 200, and I am pretty sure the number is not an even multiple of the crank teeth. If you set it right and the chain hasn't slipped, it is still right no matter what the marks say.

Anonymous said...

I had the same issue turn up when I turned the engine over but it lined back up after another turn of the crankshaft. It should always end up with the timing marks realigned. it may go two complete revolutions of it may go four. But it has to be an even multiple or the timing would not work.

Valerie Bourque said...

Ok...very important question here...are you saying you turned the crank shaft with the chain off? And as long as it is turned in even multiples it is lined back up appropriately to install the chain using the marks??? So, like for instance the crank was accidentally rotated a partial turn without the chain, if I rotate it the rest of that complete turn and one more (2 total turns with chain off) it will undo the accidental partial turn and my timing will be safe???? Please advise!!!

Chuck Pergiel said...

Valerie - NO, do not turn the crank with the chain off. Once you have the camshafts installed, some of the valves will be open and projecting into the combustion chamber. Turning the crank will cause the pistons to impact the valves and they will get bent, ruining all your hard work.
1. Install the heads.
2. Set crank to mark.
From this point on DO NOT TURN CRANK
3. Install camshafts.
4. Install chains.
5. Make sure ALL marks are lined up.
NOW you can turn the crank.

Valerie Bourque said...

Ok. So by accident my crank got turned (while uninstalling the crank sprocket and wedge kept slipping). So helping me from is where I am. I've changed the water pump, all timing component and my head gaskets just in case while I was in that far. Well, now since we put a small nick in the oil pump with a screwdriver and cranked it, we discovered the nick want all the way through and now we are waiting for yet another oil pump to arrive. I can believe how thin it is and that nick actually went all the way through. Anyway, we set all the timing with everything lined up on cams, then on the main chain, but when setting the main chain we had to unset the cam marks from 90° so that the bolt holes lined up. Will we ever have all 3 main timing marks lined up simultaneously with the 4 secondary cam marks???? This is very confusing. One minute I read not to worry about the secondaries after they are lined up, just set the main chain then. So, anyhow, since it appeared we had everything off due to crank spinning without cams, we just lined the crank and cams up when the secondary marks are at 90° with #1 at about 60° after top dead center then went to set the main chain while this was the case, but then we do, we must move the secondary marks off 90° mark. I hand cranked it all the way around until the main chain was back into time to be sure no valves were impacting and we got everything ready to crank. With a new tensioner that wasn't yet primed, I wedged a screwdriver behind the tensioner arm to keep tension long enough to prime it. So that isn't an issue. Well, we didn't start it, just cranked. But when it turned over it didn't turn over it has a compression wah wah sound. We had spark plugs in but no coils, valve covers or intake which means several sensors are not plugged in. The cam Sensor is plugged in. Now we will have to take much of it back down to rechange the oil pump so we will tweak the timing again if necessary. Now, to have cylinder 1 at 60° atdc, the small part of the egg shaped depress or part of the cam was facing approximately toward the passenger floor, on its way back up. Does this sound right? And where should all the other pistons be when this happens? Do I need to have it at exactly tdc on secondaries when I set the main chain and allow the slight movement to get the bolts in get it to the 60° tdc or set the secondaries with it atdc which makes it more than 60° atdc to set the main chain. We have been very careful to pay mind to spring position and piston position on each one to be sure we aren't hitting. I am almost positive we placed the cams back in exactly the same position they came off. And all the 4 cams are times with each other to all be 90° at the same time. I know there are a lot of questions here. This is the first time I've ever done this kind of work on my engine, although I'm the only one who has ever worked on it. I do have my dad to summon for help, for things like timing for instance who has been working on cars for 40+ years, no not the 2.7 alien per say, but I've been very serious about making sure he is aware of all the moodiness it possesses. Mainly the reason I've needed to summon him is due to the crank spinning without cams after removing everything. So, before this causes me to bend my valves, I am just tediously and carefully looking at everything 3 times, 7 times and 28 times before cranking etc.

Valerie Bourque said...

So back to where I currently am. Sorry if I'm jumping all over the place. When turning the engine over...and I think now I'm not at full battery doesn't turn over evenly. I saw spurts of I assume gas air mixture coming out of the top holes that lead to the intake plenum, which isn't on yet. But it only came from 1,2 and 5,6. Also, I had oil spurting from the end back of the right cylinder head from the tiny little hole between the cams, but not from the hole on the left head. It was only gurgling out of that one. I have another issue to explain about an injury to the head we caused later on after I get some input on this timing. I'm very desperate for input and it would be quicker and easier to text or talk to someone as it took me since my last post on here to this post to find my way back to this site! I've added it to favorites but I'm afraid it will take me forever to get back here again. Cont. next post.

What I'm wondering now, is there a chart or guidelines somewhere that gives specific locations of the little egg shaped depressors, the springs and the Pistons to get it all back perfect? Or is it possible I have it in time and the uneven wah wah will straighten out once everything else is connected. We can see down into the intake holes and see that no intake valves are bent. But we cant see the exhaust valves. Isn't it usually the intakes that bend, on the left head? I can't seem to find a guide in literature that tells me how to get the cam and crank in time with each other with specifics on spring positions and piston positions and directions. HEEEEELP! We are sure to keep springs and pistons in positions to keep valves safe.

Valerie Bourque said...

BUT, I also had the timing set in a different place initially, and was able to hand crank the engine freely, but when my dad checked everything, he didn't think it was right and that is when we changed it to what it is now. We never cranked it in the first position. That position had all 3 timing marks lined up while the secondary marks on the sprockets were at 90° but the secondary chain marks were one link ahead of their respective sprocket marks. (I thought well maybe i just installed the new secondary chains one link off). It seemed as though cylinder 1 was 60° atdc at this point. I was able to hand crank the engine freely and I thought I had it right. When my dad looked at it, we had long pow wows and I ended up cranking all the way until the 4 cam's chains and sprockets were lined up 90° together, which had my main chain off by quite a few links. So, I removed the chain and reinstalled it, which required me to turn the crank by itself so it would work. (Remember it was turned independently already during working on it). I thought I had backed the crank up the same amount it had been turned when i set the chains in the first place. So I thought I had it right even though the secondary chain links were one tooth ahead of the sprocket timing mark while the main chain was in line. Are all primary and secondary marks going to ever line up simultaneously? This is what my dad is after and I didn't think it was possible to happen that way...mainly due to the bolt holes messing that up. Why couldn't they just put the damn bolt holes in the right place?!

Oh, also, when I had the chains in the first position I thought was right, we smelled no gas. But when I put it in the position my dad had me change it to and hand cranked it, we smelled gas. So, I assumed this had to do with combustion and indicates whether it is working correctly. So, back to the what appears to be gas air mixture poofing out the 1,2 and 4,5 intake holes??? Shouldn't air be going INTO THE engine through those holes and the poof should be going into the exhaust system? Is this telling me I have the combustion backward on those?

And why are there 2 sets of timing marks on the left secondary sprockets? There are arrows painted on and the holes. Is this to ensure the 90° angle before rocking the cams back to bolt them? Why does it have to be so confusing? AND WHHHYYYYYYY did my crank have to move without the cams??!?!?! Whyyyyy me?! The bs ALWAYS happens to me. If I get this car running without bending valves I am gonna make a shirt that reads, I CHANGED A CHRYSLER 2.7 WATER PUMP!!! in every color! Any help is so so so appreciated. I'd be very grateful! It'll be several days before my second new oil pump gets here, but if I can get the timing right now, I can just take it apart correctly AND NOT LET THE CRANK MOVE ACCIDENTALLY THIS TIME and it will be easy to get the timing reset.

When the chain is removed, when you line it up to remove everything, are ALL primary AND secondary marks lined up together before removing...or again does it ever happen that primary and secondary line up together? Ok, I'll stop there since the are 67 questions, and half have been repeated 4 times! Thanks!!!!
813 585 3184
Sorry, so long winded I had to post in 3 posts.

Valerie Bourque said...

Please excuse all the typos and well poor grammatical errors. They are all thanks to the auto change function on my phone. I don't like to call it auto correct because rarely is it ever correct after it changes! So, I call it auto change. This site won't allow update or edit so I couldn't go back and correct anything. Grrrrr being a Speech therapist, it bugs me. :D