...and thats all she wrote ....

[kevfal0]

Hi there, i recently bought a A4 Cabriolet with a noisey engine as a project car. I assembled all the parts required to do the chain tensioner and also a new timing belt/water pump kit. I lined up all the timing marks and replaced the timing belt/water pump. The issue i have is that when rotating the crankshaft by hand the intake camshaft looks to be jumping i.e. loading up and then snapping free while rotating, not continuous rotation. I replaced the tensioner and chain, noticed there were 20 pins between timing marks as opposed to 19 stated in this post. I installed the chain with 19 pins between timing marks as I thought it might have jumped a tooth. I am still seeing this issue with the intake camshaft while rotating the crankshaft. Does anybody have any ideas as to what could be causing this issue?

[Theiceman]

Good Morning ...

okay we need a little more info on your process... did you try to do this all at once ? or did you do them as completely different projects. ?
did you replace the water pump and timing belt and tensioner THEN notice this skipping effect ?
or did you notice it after you did the tensioner in the head ? ... it certainly sound like timing is jumping but hard to tell...

I suggest you do a video showing as much as you can and upload it to youtube so we can have a look.. it should definitely run smoothly.... also remember you only have spring tension holding the tensioners as you have not started it so have no oil pressure. But still i would NOT start this engine until you figure this out.
Did the car have issues when you got it ? ie was it running well ? there may be some other damage you are unaware of if you bought it as a project car.

[kevfal0]

Good morning Iceman,
I bought the car with what I thought was a rattle chain (noisey at idle but quietened when revved slightly). I noticed the skipping after I did the timing belt/water pump with the chain untouched. I think it was like this when lining up the timing marks before the belt change but cannot be sure. I have rotated the engine through a couple of revolutions now and the timing marks still line up. When installing the cam locking tool it does not slide in as it should and needs the intake cam to be rotated ccw slightly. I will see if i can make a video of this camshaft issue tomorrow and post it up. Thanks

[Theiceman]

Well I would think with the valve cover, fro t timing cover and rear timing cover off the issue would be evident.
Sounds like it could have been there before you got it. I would look at the lifters and springs carefully as you rotate. I have never experienced what you are describing.
Hopefully you dont have a bent valve hanging up

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[kevfal0]

Hopefully you can see this

https://youtu.be/vkbleuB_y7M

[audilove3]

cool looking video. i hope u figure out whats going on. dont let iceman bother u too much

Hopefully you can see this

https://youtu.be/vkbleuB_y7M

[Theiceman]

dont worry about hotboy ( audilove) he is a troll so for the most part we all just ignore him.

Okay on to the problem, something is wrong there..
Try to take a longer video and try to film .the timing chain area. You may need a helper. Looks like the intake snaps around but the exhaust doesnt move.
Also are the plugs out ?? You dont need compression when just checking timing..
Glad you didnt start the car.

edit : i have been thinking this over ... the engine turns clockwise facing the front , that means the exhaust cam has to essentially pull from the bottom of the sprocket on the intake cam to turn it. i wonder if it is the chain tensioner compressing under spring pressure because the intake cam is resisting. eventually the chain will compress the tensioner as far as it can go , the intake will move and the tensioner will pop back out taking up the slack of the chain and forcing the intake to snap around.
This is all just a theory of course and there are two things here i am not sure about ....
1. I have done about 3 of these and NEVER seen that but i always do it with lpugs out ( then the cams arent fighting compression.)
2. the engine when primed will have oil pressure holding the tensioner in place not just a spring.

But here is what i would do ...

take the chain back off. take the the engine off TDC . easy enough to check with a dowel as i think 1,4 and 2,3 move together then when pistons are at half way turn just the intake cam with a tool ( there is a slot in the back ... ) it should turn fairly smoothly with only spring resistance and be fairly consistent.. if then you find it binding and snapping you have found your issue .. it is in the valves, valve spring, lifter area.

these are just ideas of course , i welcome other inputs ..

well except for Audilove guy , he is just a troll who actually steals other members parts..



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[kevfal0]

I think my cam adjuster might be damaged. There is no movement in the sprocket even though the exhaust cam is moving. I took it off and the centre can be easily rotated by one tooth of the sprocket - see video below. Is this normal? If I apply prssure to the pin there seems to be a locking point where the centre will no longer rotate. I have seen images of this locating pin sheared on the back side of the adjuster - is it possible that this has sheared internally? If so, can this be take apart? Are there seals that need to be replaced if taken apart? thanks again

https://youtu.be/oxh-0KfpP5w

[kevfal0]

Think I may have found the answer. All the symptoms i am seeing currently. Is it ok to post a link to a different forum?

[kevfal0]

Think I may have found the answer. All the symptoms i am seeing currently. Is it ok to post a link to a different forum?

Update - Opened the cam adjuster and found the problem - not as easy as a sheared locating pin.
https://youtu.be/KjIdiWZgdQU

[Theiceman]

nice work.... bet you are glad you didnt start it .. that is some instant advance.. lol..

[kevfal0]

Sure am glad I didn't start - just ordered a new cam adjuster. Will update when it's installed. Thanks again

[kevfal0]

Sure am glad I didn't start - just ordered a new cam adjuster. Will update when it's installed. Thanks again

I wonder if there could any other damage due to this part failure? Do you think that timing issue would have bent valves?

[Theiceman]

No I think.you are fine. The car is designed to advance that far. Just not in the broken way yours did..
Just be extra carefull in counting your links this time and observe the cam lobes very carefully when done.
I think you are going ton e pleased with the results.
Also since you are replacing the adjuster you may want to consider the rings on the cover that go inside it.
They can be had on ebay reasonably. I think somone on this site sells them also.

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[kevfal0]

Thanks Iceman, already had the new rings ready to put into it, hopefully should have it running by next weekend - I'll let you know how it goes

[Theiceman]

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[soje]

Update - Opened the cam adjuster and found the problem - not as easy as a sheared locating pin.
https://youtu.be/KjIdiWZgdQU

How did you get the adjuster open? It feels like i'd need to lock it in a vice to get the required torque to remove those bolts. I worry I might stripp the head or threads, or even break one of the bolts off, inside the adjuster.
.

[soje]

So I'm stumped again.

When I took all this stuff apart, the only broken part I found was that indexing pin on the adjuster. The belt is new enough, the tensioner seems as strong as the new one, the follower has some life left on it. What could have caused this?

So the chain was still tight (though we can't be sure if it skipped), and everything was linked. Wouldn't both cams be turning, and doing out of sync. Would that create a higher potential for valve damage? The adjuster was obviously out of position, but who knows how far and what caused it. Could a valve collision have broke the adjuster loose? Could a bad adjuster have caused all this? I have pictures of the cams, but don't know if anyone can actually see how far off sync they are.

If I knew then, what I've learned since, I probably would have pulled the heads. I really need to just pull the intake, and try to use an endoscope to look at the valves. I just learned that I actually can get the adjuster apart. Anyone think I should do that? It doesn't having any rattling parts inside, and if I rotate it, I can hear what sounds like seals releasing or some kind of suctioning sound.

This is a lot of rambling, but if anyone see's something that clicks please share it with me/us.

THe cams after I tried to crank it, with no start.

[kevfal0]

Yeah, just stick it in a vice they're not that right actually. I managed to open 2 just holding in my hand.

[kevfal0]

Yeah, just stick it in a vice they're not that right actually. I managed to open 2 just holding in my hand.

Not that tight

[Theiceman]

yeah hard to tell if those are out of time as i always check at TDC..... it is likley you have bent valves... something broke the pin and spun the intake cam out of time ( exhaust cam stays in time by the belt but spinning the adjuster spins the intake cam ) . but what the hell you need how to learn how to time it anyway. keep going and see what compression looks like. then you can make a decision on pulling the head , getting an engine or scrapping the car if it is not good.
if the chain snaps we have had good success with the intake cam free floating and no valve damage. But with the chain still intact it is held there for the piston to hit the valves, well.... guess we will know shortly.

This is how the lobes on cylinder number 4 should look when in time .. they should be perfectly symmetrical...

[soje]

Okay. I'm stuck again. Which piston is supposed to be at TDC, when I put the new chain on? When I set the exhaust cam pulley to the TDC mark, the cylinder 1 piston is not at the top. I'm observing this by putting a thin rod through the plug hole and setting it on top of the piston. Do I just need to be on the mark, and not worry about what piston is where? Do I need cylinder one piston to be TDC? Do I need the first piston in the firing order to be at TDC? If there is a specific piston that needs to be at TDC, does it have to be on the compression stroke? Also, when I was trying to turn the engine via the crank, I came to a point where I couldn't turn it anymore. Or at least I didn't want to force anything. I have the transmission in neutral for all this as well. Is it necessary to have the transmission in neutral when doing this?

If I have valve damage. Does anyone have a recommendation on where to by a set of valves? Should I replace them all, or just the bent ones?

I'm going crazy trying to make progress with this thing.

[Theiceman]

piston one is supposed to be at TDC on the timing mark .. remember it takes two revolutions of the crank to have one revolution of the cam . so you are likely at TDC on the exhaust stroke instead of the compression stroke.

[soje]

piston one is supposed to be at TDC on the timing mark .. remember it takes two revolutions of the crank to have one revolution of the cam . so you are likely at TDC on the exhaust stroke instead of the compression stroke.

Thanks again iceman. I couldn't do this without yours and other peoples help. I ask a lot and I'm grateful for the help. I'll definitely share whatever I finally conclude. Hopefully it will help someone else in the future. That being said, I'm still stuck until I can find answers to a few questions.

This is an automatic. I have the electric parking brake applied, and I put the transmission in neutral when I turn the engine via the crank. Does anyone know why the crank gets to a point where it feels like I can't turn it anymore? Should I try to force the crank through this point where it feels stuck?

[Theiceman]

Likely because your cams are put of time and you are hiting a valve.

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[Brillo]

Thanks again iceman. I couldn't do this without yours and other peoples help. I ask a lot and I'm grateful for the help. I'll definitely share whatever I finally conclude. Hopefully it will help someone else in the future. That being said, I'm still stuck until I can find answers to a few questions.

This is an automatic. I have the electric parking brake applied, and I put the transmission in neutral when I turn the engine via the crank. Does anyone know why the crank gets to a point where it feels like I can't turn it anymore? Should I try to force the crank through this point where it feels stuck?

As Theiceman says your cams are probably out of time relative to the crankshaft. Do not force the crankshaft around or you will bend valves (if you haven't done so already). You must retime the cams. Pull all the spark plugs and put exactly equal length wooden dowels straight down the spark plug holes so they touch the top of each piston with the other end sticking well out of the hole. Carefully rotate the crank back (in the direction opposite from which you felt resistance) so that all the wooden shafts are all at exactly the same height (verify with a straight edge). This amount of rotation must be less than 90 degrees and you should not feel any resistance. If you do, read no further - you'll most likely have to pull the cams.

All the pistons are now in mid-cylinder position, at exactly 90 degrees before or after TDC on all four. In this crank position you can rotate the cams with impunity without fear of impacting the pistons against the valves. Now rotate the crank very slightly in the direction the engine runs carefully noting if the pistons #1 and 4 are moving up or down as you rotate. Then rotate the crank back exactly to the 90 deg. position. Remove the timing belt to disconnect the crankshaft from the cams.

Now you can time the cams. Place the cams in the cyl #1 TDC position shown in Theiceman’s photo in post #141. The cam shaft cut-outs will be exactly parallel and facing each other. If pistons #1 and #4 were moving up then they are 90 deg. before TDC of the compression stroke of cyl #1 or 4, I don’t think is matters which.

Here is the hard part. 90 degrees of crankshaft rotation equates to 45 degrees of camshaft rotation. Since the crank is 90 degrees before or after TDC, you must correspondingly rotate the cams to be exactly 45 degrees before or after TDC. The timing belt pulley has 52 teeth so 45 degrees equals exactly 6.5 teeth (360deg/45deg=8, 52 teeth/8=6.5 teeth). If pistons #1 and 4 were rising in their cylinders rotate the camshaft pulley exactly 6.5 teeth before TDC. Alternatively, if pistons #1 and 4 were falling in their cylinders rotate the camshaft pulley exactly 6.5 teeth after TDC.

Replace the timing belt so that the tension side (the driven side) of belt is as tight as possible between the crank and cam pulleys.

You should now be timed well enough to rotate the crank without causing valve interference. To verify timing move the crankshaft to TDC on cyl #1 and see if the timing marks on both pulleys are in the correct orientation. If you are off a tooth on the cam pulley, make the correction and re-verify all timing marks.

Now you can do a compression test to see if you’ve managed to bend any of the valves.

[kevfal0]

Thanks Iceman, already had the new rings ready to put into it, hopefully should have it running by next weekend - I'll let you know how it goes

All back together after replacing timing belt, water pump, chain and tensioner, cam adjuster and rings - sounds pretty good after a quick spin. Noticed that it is loosing coolant though so ordered coolant flange for rear of engine as it looks to be leaking on top of the transmission - job for next weekend. This forum is great - thank again especially iceman

[Theiceman]

All back together after replacing timing belt, water pump, chain and tensioner, cam adjuster and rings - sounds pretty good after a quick spin. Noticed that it is loosing coolant though so ordered coolant flange for rear of engine as it looks to be leaking on top of the transmission - job for next weekend. This forum is great - thank again especially iceman

yeah the EXACT same thing happened to me .. right after i was done flange started leaking .. it was from me moving all the crap out of the way to get the timing cover off... should have replaced the damn thing as i took timing cover off again to do it .. lol ...

congrats on the fix .. no go pay your penance and go help the next guy ... :)

[kevfal0]

yeah the EXACT same thing happened to me .. right after i was done flange started leaking .. it was from me moving all the crap out of the way to get the timing cover off... should have replaced the damn thing as i took timing cover off again to do it .. lol ...

congrats on the fix .. no go pay your penance and go help the next guy ... :)

Yeah probably should be done as part of the chain tensioner job seeing as parts are not that bad cost wise.

[soje]

As Theiceman says your cams are probably out of time relative to the crankshaft. Do not force the crankshaft around or you will bend valves (if you haven't done so already). You must retime the cams. Pull all the spark plugs and put exactly equal length wooden dowels straight down the spark plug holes so they touch the top of each piston with the other end sticking well out of the hole. Carefully rotate the crank back (in the direction opposite from which you felt resistance) so that all the wooden shafts are all at exactly the same height (verify with a straight edge). This amount of rotation must be less than 90 degrees and you should not feel any resistance. If you do, read no further - you'll most likely have to pull the cams.

All the pistons are now in mid-cylinder position, at exactly 90 degrees before or after TDC on all four. In this crank position you can rotate the cams with impunity without fear of impacting the pistons against the valves. Now rotate the crank very slightly in the direction the engine runs carefully noting if the pistons #1 and 4 are moving up or down as you rotate. Then rotate the crank back exactly to the 90 deg. position. Remove the timing belt to disconnect the crankshaft from the cams.

Now you can time the cams. Place the cams in the cyl #1 TDC position shown in Theiceman’s photo in post #141. The cam shaft cut-outs will be exactly parallel and facing each other. If pistons #1 and #4 were moving up then they are 90 deg. before TDC of the compression stroke of cyl #1 or 4, I don’t think is matters which.

Here is the hard part. 90 degrees of crankshaft rotation equates to 45 degrees of camshaft rotation. Since the crank is 90 degrees before or after TDC, you must correspondingly rotate the cams to be exactly 45 degrees before or after TDC. The timing belt pulley has 52 teeth so 45 degrees equals exactly 6.5 teeth (360deg/45deg=8, 52 teeth/8=6.5 teeth). If pistons #1 and 4 were rising in their cylinders rotate the camshaft pulley exactly 6.5 teeth before TDC. Alternatively, if pistons #1 and 4 were falling in their cylinders rotate the camshaft pulley exactly 6.5 teeth after TDC.

Replace the timing belt so that the tension side (the driven side) of belt is as tight as possible between the crank and cam pulleys.

You should now be timed well enough to rotate the crank without causing valve interference. To verify timing move the crankshaft to TDC on cyl #1 and see if the timing marks on both pulleys are in the correct orientation. If you are off a tooth on the cam pulley, make the correction and re-verify all timing marks.

Now you can do a compression test to see if you’ve managed to bend any of the valves.

Forgive me if I'm missing the obvious, but since I had the cams locked with the AST tool and the cutouts were facing each other, wouldn't all the valves have been closed? (I tool the cam lock tool off before I started turning the crank.)

You instructions are definitely a different approach. I'm studying them and will try it. Should I should just pull the head, considering how much work I've already done and the likelihood of bent valves.

Thank you.

[soje]

Forgive me if I'm missing the obvious, but since I had the cams locked with the AST tool and the cutouts were facing each other, wouldn't all the valves have been closed? (I tool the cam lock tool off before I started turning the crank.)

You instructions are definitely a different approach. I'm studying them and will try it. Should I should just pull the head, considering how much work I've already done and the likelihood of bent valves.

Thank you.

Okay. I think I understand. If the belt slipped, then the TDC notch on the exhaust cam pulley wouldn't match the engine. Could I use the TDC mark on the crank, and then take off the belt to set the cam?

[Brillo]

You cannot indiscriminately rotate the crank when the cams are in the cylinder #1 TDC position. In fact, I believe there is no cam position where you can rotate the crank without valve impingement on one of the cylinders. That's precisely why I went through that long dissertation above. In TDC cyl #1 both valves are closed - it's starting its combustion stroke. The intake valves on cyl #2 are closing as it's starting its compression stroke. Cyl #4 is beginning its intake stroke so the intake valves are opening and exhaust valves closed or closing (depending upon the overlap of this engine), and finally cyl #3 is starting its exhaust stroke so its exhaust valves are opening.

Could I use the TDC mark on the crank, and then take off the belt to set the cam?

No. Do precisely what I wrote above if you want to avoid piston to valve impingement. These engines have a 180 degree crankshaft. The crank must be in the 90 degree position in order to move the cams without risking impingement (all pistons in the mid-cylinder position). Impingement cannot occur with the pistons in this position, so that's where you have to time the cams. Plus or minus 45 degrees from TDC which equals exactly plus or minus 6.5 teeth on the exhaust cam belt pulley depending upon whether piston #1 is combustion stroke or compression stroke (moving down or up when you very slightly rotate the crank in the direction the engine runs). Put the crank back in the exact 90 degree position, position the camshafts, and only then reconnect the timing belt. Then put the crank in TDC using its timing mark on the pulley. If done correctly, the cam pulley will also be on its timing mark. If at anytime you feel resistance on the crank stop rotating because something else is wrong which unfortunately might necessitate pulling the head. Once you get the cams timed and the crank rotates freely, then conduct a compression check on all cylinders.

[StylinS-line]

Brillo, very good posts ! Thanks for sharing that valuable info

[Brillo]

Brillo, very good posts ! Thanks for sharing that valuable info

Thanks, I'm here to serve.

[soje]

You cannot indiscriminately rotate the crank when the cams are in the cylinder #1 TDC position. In fact, I believe there is no cam position where you can rotate the crank without valve impingement on one of the cylinders. That's precisely why I went through that long dissertation above. In TDC cyl #1 both valves are closed - it's starting its combustion stroke. The intake valves on cyl #2 are closing as it's starting its compression stroke. Cyl #4 is beginning its intake stroke so the intake valves are opening and exhaust valves closed or closing (depending upon the overlap of this engine), and finally cyl #3 is starting its exhaust stroke so its exhaust valves are opening.



No. Do precisely what I wrote above if you want to avoid piston to valve impingement. These engines have a 180 degree crankshaft. The crank must be in the 90 degree position in order to move the cams without risking impingement (all pistons in the mid-cylinder position). Impingement cannot occur with the pistons in this position, so that's where you have to time the cams. Plus or minus 45 degrees from TDC which equals exactly plus or minus 6.5 teeth on the exhaust cam belt pulley depending upon whether piston #1 is combustion stroke or compression stroke (moving down or up when you very slightly rotate the crank in the direction the engine runs). Put the crank back in the exact 90 degree position, position the camshafts, and only then reconnect the timing belt. Then put the crank in TDC using its timing mark on the pulley. If done correctly, the cam pulley will also be on its timing mark. If at anytime you feel resistance on the crank stop rotating because something else is wrong which unfortunately might necessitate pulling the head. Once you get the cams timed and the crank rotates freely, then conduct a compression check on all cylinders.

Thank you. This is awesome detail.

[soje]

Can I get the belt off via the tensioner? I can only find timing belt replacement instructions, which require a bunch of steps I don't think I'll need to do. I'm just pulling it off and putting it back on.

[Brillo]

I don't know as I've never done that.

[soje]

Hello again.

Thank you all for your help so far. I'm just getting time to work on the car again. I could use help with yet more questions. I appreciate any help you all can offer.

In regards to your instructions Brillo. I took the chain off a long time ago. Your instructions to manually turn both cams until they're 45 degrees from TDC? The exhaust cam is gon6a be easy, because I can count the teeth. I'm wondering if I can then visually set the intake cam to mirror the exhaust. I've seen some people use a straight edge to compare the cam positions. Or I could go through the chain install procedure to ensure that the intake cam follows the exhaust precisely.

Do you know if it's possible or safe to use a straight edge to set the intake cam. or if I need to have the chain installed?

I've got some rough borescope pics, but I don't know how to tell if it looks bad or not. Does anyone know what to look for in these? Some of the pistons are clean and some are all gummed up. That blob is paper towel I dropped in the cylinder. I'm gonna try to use a mirror attachment on the borescope to look backwards in hopes of seeing the valves.

Would it be safe to use some cleaner to try and clean up the gummed up pistons?













Now this looks like a bunch of metal sitting on the piston, but from a different view where it's focused I can't see any metal. If it is metal, it's aluminum, because I stuck a strong magnet down into all the cylinders to see if I could find metal.

[Brillo]

Theoretically, you could do what you say but practically, you'd be introducing another level of error into the process and therefore, I wouldn't recommend it. You are going to have to put the timing chain back on at some point before you start moving the crankshaft so I don't see the point of dicking around with straight edges. I would put the timing chain back on while the cams are at TDC. There are a number of DIYs for synchronizing the cams to each other so do a search for that. Theiceman may have done one of them recently with detailed photos and procedure. Then move the cams to + or - 45 degrees and replace the timing belt. Then move the crank to TDC on #1 and check the timing marks on both cams to make certain the cams and crank are all in synch.

By the way, make sure there are 52 teeth on the belt pulley cos I'm not 100% certain about that. You can always get a cheap timing disc on Amazon (or even a plastic protractor at Wal-Mart) and attach it to the pulley to precisely dial in 45 degrees.

Sorry, can't help you with the horoscope photos but I wouldn't waste my time trying to de-gum anything based on horoscope photos.

[Brillo]

Remember, going 45 degrees before or after TDC on the cams is based on the the direction of the #1 piston as described in my previous post. It's not an optional decision. If the #1 piston is rising in the cylinder at the 90 degree crank position it is before TDC so the cams must be moved to 45 degrees before TDC before reconnecting the timing belt.