Please help walk me through timing belt project

[Eikon]

Hey gang... I am struggling with this project. I could use some very detailed instructions to help guide me through it.

I have a pretty loud belt noise coming from inside the timing cover on my RB20. I think my timing belt is too tight. Either that, or something is not working properly. I could live with the sound, but I am sure that it would break something sooner or later, so I want to try to fix it.

So, my task is to try retightening the timing belt to make sure it is properly tightened and not too tight.

Here are some instructions that I am working from courtesy of JonPowell in another thread. "Pretty close, except you forgot a couple things....

Engine must start at TDC,

ALL drive belts off, waterpump pulley off, upper timing cover off, insure cams are aligned with marks on rear timing cover and crank is at TDC on lower timing cover, loosen tensioner pulley nut, hold in place with allen wrench, tightern bolt, rotate crank 2 times & make sure that the cam & crank marks STILL line up, reassemble in reverse."

This is a good start, but due to my lack of experience, I need more detail.

Here's what I have done so far.

1.) unplugged CAS2.) removed CAS3.) removed top bolts from black timing cover.

I can see that there are 2 or 4 more bolts holding on the timing cover, but I can't do anything about removing the timing cover until I remove the two belts in front (water pump and power steering I think).

First question... per Jon's instructions, I have to get the engine to TDC first off... How do I do that?

Second... How do I loosen those two belts so that I can move on to the next step?

Thanks a ton everyone! Any help is very appreciated. Any pictures included to help would be especially helpful.

Thank you thank you thank you

[Nameless EJ6]

You'l have to read through stuff untill you get the idea.

Here's a thread I posted some TDC info in.

http://www.240sxforums.com/for...+belt

Here's more timing belt ****.

Tension info.

http://www.240sxforums.com/for...+belt

More info:

http://www.skylinesaustralia.c...+belt

There is seriously a LOT of info on this out there. Look on other forums as well. If oyu have a hard time with the TDC thing, google it and you'll learn how to do it.

Try the australian forums. They have really informative posts.

[PsiloX]

TDC means Top Dead Center. To be in TDC you have to move the no. 1 cylinder to its top most postion of the stroke. Usually this requires the removal of the spark plug in the No. 1 to check is position.

All your marks should be lined up at that point.

Hope this helps. If you really run into problems I only live in Oshkosh and I've done it before.

[Boardman]

you DON'T need to set the engine/cams at TDC.remove the crank pulley and lower cover,get some liquid paper and make marks on the old timing belt where it lines up with the cam sprockets+crank. loosen the tensioner- remember which way the spring goes!!remove belt- don't move any engine parts.liquid paper the new belt in the same spots as old belt- and install it- tighten tensioner- you're done.

[gawdzilla]

you DON'T need to set the engine/cams at TDC.remove the crank pulley and lower cover,get some liquid paper and make marks on the old timing belt where it lines up with the cam sprockets+crank. loosen the tensioner- remember which way the spring goes!!remove belt- don't move any engine parts.liquid paper the new belt in the same spots as old belt- and install it- tighten tensioner- you're done.

very dangerous to do that. if you're at a bad spot on the timing belt (i.e. tension is on the cams from depressing the valve springs), the cams WILL rotate when you loosen the belt and possibly cause piston to valve contact. TDC is a good place to have the motor rest where there is minimum tension on the cams.

[Eikon]

TDC means Top Dead Center. To be in TDC you have to move the no. 1 cylinder to its top most postion of the stroke. Usually this requires the removal of the spark plug in the No. 1 to check is position.

All your marks should be lined up at that point.

Hope this helps. If you really run into problems I only live in Oshkosh and I've done it before.

MY NEW BEST FRIEND!!!! I would love it if we could get together sometime. I am pretty inexperienced with engines and while I'm not afraid to get my hands dirty, I am pretty nervous about timing belts. I just don't want to risk blowing up an expensive engine. If you are willing to help me out I would GREATLY appreciate it.

I am going to pull off the timing cover and put the CAS back on and then run the engine again. I want to see if I can listen and look a little closer to see if I can really tell where the sound is coming from.

I found the full FSM for it, so that will help me walk through everything as well.

If the belt is tensioned properly, what else could cause the noise? Something with the cams? Maybe a bad idler/tensioner?

Thanks for the pics Boardman!

Thanks again for everyone help and imput!!!!

[Boardman]

very dangerous to do that. if you're at a bad spot on the timing belt (i.e. tension is on the cams from depressing the valve springs), the cams WILL rotate when you loosen the belt and possibly cause piston to valve contact. TDC is a good place to have the motor rest where there is minimum tension on the cams.

It's not dangerous chicken little- oh noes- the sky is falling!!You can try and make up excuses and scenarios to support getting the engine to TDC.But it's not needed. Do it if you want- but you don't HAVE to.

Sorry, the cams WILL NOT rotate when you loosen the belt "And possibly cause piston to valve contact" <- that was funney, LOL.

[Nameless EJ6]

It's not dangerous chicken little- oh noes- the sky is falling!!You can try and make up excuses and scenarios to support getting the engine to TDC.But it's not needed. Do it if you want- but you don't HAVE to.

Sorry, the cams WILL NOT rotate when you loosen the belt "And possibly cause piston to valve contact" <- that was funney, LOL.

They aren't excuses. That is the number one reason for setting to TDC.

Go ahead though.. there's only 359 other slight chances that the cams may rotate on you.

Don't coimplicate things please. He's trying to learn the right way. He can develop a short cut method later.

[Nameless EJ6]

If the belt is tensioned properly, what else could cause the noise? Something with the cams? Maybe a bad idler/tensioner?

Thanks for the pics Boardman!

Thanks again for everyone help and imput!!!!

Go to harbor freight and get a stethascope. Touch it to components and listen for the noise. You'll isolate it sooner or later.

You can also use a long screw driver with your ear on the end.

That's one of the easiest techniques for finding a noise. I've used that method quite a few times to diagnose noises. Works well when you're on flat rate. =p Hope that helps.

PS: obviously don't touch the end on a rotating part. That may hurt.

[Eikon]

PS: obviously don't touch the end on a rotating part. That may hurt.

LOL... I can see where that might cause some pain.

I suppose I shouldn't touch the screwdriver to both ends of the battery terminal either.

Boardman... while I am sure that you are correct that I could accomplish it without setting to TDC.... Since this is a learning process I think I might as well figure out how to do that at the same time. That way I will definitely get it right and not risk messing something up. I appreciate the advice though.

[Nameless EJ6]

I went back and edited that part in.. after remembering what happened to a guy at my previous job. Oh the horror stories.

If you need any help with anything in particular, send me an email:

[email protected]

I've been recognized as the timing belt guru among people that I've worked with. :P Breaking records everywhere I go.

[Eikon]

hey your no longer "Nameless"

thanks man.. i appreciate it. I will let you know how it goes. Just not sure when I will find enough time to get at it.

[gawdzilla]

It's not dangerous chicken little- oh noes- the sky is falling!!You can try and make up excuses and scenarios to support getting the engine to TDC.But it's not needed. Do it if you want- but you don't HAVE to.

Sorry, the cams WILL NOT rotate when you loosen the belt "And possibly cause piston to valve contact" <- that was funney, LOL.

why be an *** about it? i realize the cams arent gonna go flying when you loosen the belt, but they can definitely turn a few degrees. i have seen it happen on a 4g63. why not do it right and put the motor where its happy? maybe you've changed a bunch of Tbelts this way and saved a whopping 30 seconds each time by not putting it to tdc. yes, chances are its going to be fine, but why take the risk

[Ramius83]

And Boardman, I have done your method plenty of times in the past and it works everytime.

But, Nameless is right for learning good habits first, then creating short cuts later.

And setting TDC is simple as hell. Align the left most mark of the circles on the crankshaft pulley to the mark on the lower timing cover. How hard is that anyways???? Simple, fast, no brainer, what else could an RB swap/maintenance need?

[eh?]

That's not a short cut... that would actually take longer than setting tdc. All you have to do is line up the three marks, one for each cam sprocket on the cam back plate on one for the crank sprocket on the oil pump. done it 10 times..takes 2 seonds.

[Slo_240sx]

Umm... why is there even an arguement about this. You made your own marks, why don't you just use the marks that were put there from the... FACTORY? They were obviously there for a reason and you can LP those once they are lines up properly. Why would you even think about taking a TB belt off without it being at TDC? Cams CAN sometimes rotate if you have them at a bad position to where cam lobes at there turning point and the valve spring WILL make it crank. Why go through the hassle when putting a motor at TDC takes 1 minute. This is what seperates a Backyard Mechanic and a Technician. Lets just say if I was hiring, I wouldn't be hiring you.

[PsiloX]

The RB20DET is a non-interference engine so you don't a have to worry about anything getting wrecked besides your timing

But why screw with that if you don't have to.

It really is easy. It was my first timing belt change on anything and I did it and the water pump in about 4 hours.

I'll be glad to get together and help you out as soon as i'm done thing my classes nextweek. Just e-mail me sometime. It's in my profile.

[iliketocrash]

i've experienced cams rotating quite a bit while the belt is off. like others have said, if the cams are in a "bad position" it is possible to bump them while putting on the new belt and experience them turning a lot more than just a "few" degrees. i to have witnessed this on more than just a handful of 4g63ts while working on them. then again this probably differers from engine to engine but i wouldn't really know cause 4g63ts are all i've known up 'till recently.

[Eikon]

***UPDATE***

So I took off the timing cover and put spacers in to replicate the depth of the cover itself and then put the CAS back on.

I turned on the engine.... As usual there isn't much weird noise at first... but after letting it idle for a bit, the noise shows up and gets worse.

What is the noise?.... It is coming from the exhaust cam in the very front. It sounds like the bearings that make the exhaust cam wheel spin. Is that the pulley? Anyhow, it sounds like a bunch of little metal ballbearings grinding on each other. Plus, it sounds like it's laboring to spin freely.

What is it? I really don't know anything about what makes those spin... Well the timing belt makes it spin.. but I don't know how that wheel is connected, what the noise would be, and most of all... How serious is this issue?

Can anyone help me diagnose the problem?Can anyone tell me how to fix it?Since this noise became more noticable, I have driven the car very little... maybe 50 miles in the last 3-4 weeks. Should I keep it in the garage until I fix it?Thanks a ton everyone... I really would be lost without this forum!

[JonPowell]

Sounds like you might have overtightened the belt and the camshaft is tearing into the head....be very careful moving it at all. I would yank the exhaust cam & check the head before going any further.

[Eikon]

That is not what I wanted to hear.

I was advised that I could check the tightness of the belt by hand... not very precise... but, I was told that it should have a little bit of give in it.

I doesn't feel any tighter than the water pump or the other belt in the front of the engine.

I was really hoping that I woudn't have to yank the other belts and pull out the cams or take the head off. That sucks!!!

Anybody else have any ideas??? Not that I would question Jon, but are there other ideas that I could try before going that in depth?

Hey PsiloX... when you are done with school, would you consider coming up to Green Bay to help me out? I would REALLY appreciate it.

Thanks everyone!

[Slo_240sx]

Check your CAS. I've seen alot of the bearings going out lately. Take if off and seen if it rotates funky or even rotates at all. See if you can grab a known working one and try that as well. If it stops than thats what it is. Good luck Bud-Alex

[Eikon]

Can you or someone explain to me a little better how the CAS works.

It really sounds like the noise comes from the very front of the exhaust cam... Like the wheel area... It seems to me like a bad roller skate wheel.

I guess I don't know enough about how a Cam Angle Sensor works... it makes sense a little bit because the sounds comes from the exhaust cam area which is the side of the engine that the CAS sits. I've taken the CAS off and looked at it.. it has an extension that goes into the valve cover... But what does it do in there?

If I can get a better understanding, I think I might have better luck diagnosing.

I found this thread at SDU... Sounds like it might be a good lead.. http://forums.skylinesdownunde...ensor

This thread talks about a loose tensioner bearing... Where exactly would that be?http://forums.skylinesdownunde...ensor

Thanks


Modified by Eikon at 10:22 AM 4/18/2005

[Boardman]

Mine makes that noise- i changed to a power enterprise belt for insurance. So it's not an over-tightened belt. drive on it- i have been for 9 months now

[Eikon]

I also have a power enterprises belt.

Rob from RIPS in New Zealand taught me that a good test of belt tightness is to rotate the belt by hand between the intake cam and the tensioner. He said you should be able to turn it about 45 degrees. Any less and it's too tight.. more and it's too loose.

It seems to go to almost exactly 45 degrees.. so I am feeling a little better about it.

I just don't feel comfortable enough to write it off as a "normal" sound. Though it is encouraging to hear that Boardman has been driving on it OK.

Still hoping to learn more about how the CAS works...

Thanks guys!!

[Eikon]

Two weeks later.. I finally had a chance to get into my garage again.

I took off the CAS again. It seems to rotate OK. There is a point in the rotation where it seems to get a little friction. But overall it seems like it's ok. I am not sure what to think.

Hey PsiloX... I am going to email you. When you are done with your classes it would be awesome if you could come up to GB for a bit and give me a second opinion on my engine.

Hey Alex... How freely should the CAS spin? I know it's hard to describe just by typing something.. but can you give it a shot for me?

Any other ideas guys?Thanks