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Camshaft seal question - holding cam sprocket


Zed
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First, Wishing everyone on here a Happy Holiday season.

 

95 M/T Pathfinder - Some of you may recall I had to swap my engine due to a catastrophic oil pump failure. Everything has been smooth thus far, but now I’ve developed a troubling oil leak.

 

It’s been difficult to determine exactly where this is coming from, but it is definitely from the LEFT (drivers side) as I can see the oil is dripping on my alternator. Did all the easy stuff - PCV valve, and tightened down the left valve cover bolts - at least those I could access - boy, those bolts were really loose! However, this has not stopped the leak. So, now I’m suspecting the LEFT cam seal.

 

I’ve already changed the timing belt, water pump and tensioner, but neglected to do the cam and crank seals. Hindsight is 20/20. Ordered my cam seals and getting ready to tear her down.

 

My question is simply - how do you hold the camshaft sprocket in place to remove the cam bolt? I’m not interested in buying some expensive cam sprocket clamp for one time use, and I have seen Dr. Bill’s write-up:

http://www.nissanpathfinders.net/forum/topic/23280-replacing-the-timing-belt-adding-an-at-cooler/page-2?hl=%20timing%20%20belt

 

where he uses angled metal bars to wedge the cams sprockets. Seems a bit…uhh…primitive (although it seemed to work for him just fine). I was wondering what other suggestions are out there from the horde about holding the cam sprocket in place to pull the bolt. A little concerned about spinning that sucker around.

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I use a long extention through one of the holes up against the head NOT the timing covers, and use an impact gun to remove the bolt.

 

To install it there's a notch on the cam itself that you place an adjustable wrench on to hold it in place while you torque the bolt back to spec. To get to the notch you have to remove your valve cover and rocker arms.

 

I'd imagine holding the sprocket in place with the old belt if you still have it and torquing the bolt down would work too.

 

Sent from inside my potato

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Thanks RC -

 

Makes sense. I'll probably keep the old belt on to put it back on and torque it to spec. Not sure I want to remove the entire upper intake plenum to get to the cam notch. Just worried I'll spin that sucker and give myself another headache to deal with.

Those oil seals should arrive today. I'll probably jump in there tomorrow and assess your method when I get there. Appreciate the input.

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Don't see how I could rest something on the head. Looks like I have to remove the back timing cover plate! How do you take that off before removing the cam sprockets?

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It's been a while but if I remember correctly I angled it down so it was just sorta in there.. been a while since I was behind a timing cover :/ if its easier on you, you can use the belt method to loosen the bolt too just be careful.

 

All this is assuming you have access to compressed air.

 

If you want you could also reinstall the old belt also let everything do the work of holding the cam still and then just pop the old belt off.

 

The cam is going to move once the belt is removed but as long as you don't rotate anything you'll be ok. Oh and make sure you don't scratch the cam when removing the seal, if the seal is hard you can use a heat gun to soften the rubeer to make removal easier. And what I do when installing new seals is to smear just a little bit of grease on the outside of the seal to help it slip into place. I also put grease on the part of the seal that rides on the cam itself. A dry seal could cause leak issues too.

Edited by RCWD21
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well got the cam oil seals in, but the hardest part was re-torquing the cam bolts. Very hard to do, even with air, to keep the cam from spinning. Each cam sprocket moved off of the timing marks when I set the bolt, but I just moved it back into position. This was the part I was worried about. Took a lot of effort to keep it locked down. Hopefully I won't have to go back in there for a while.

 

I installed the T-belt, and gave her a couple of rotations to make sure they are back on mark. My teeth are 40/43, and the cam marks are pretty close. It's getting dark so I'll button everything up tomorrow and hope for the best.

 

Thanks for the input RC.

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You're welcome Zed, glad to hear you got it all back in there. The cam seals usually last a pretty long time so now that they're done you shouldn't have to worry about them for a pretty long time.

 

The belt method is pretty hard but when it comes down to buying an expensive tool that you're not going to be using everyday it's hard to justify buying it.

 

You should be ok as long as you didn't rotate the cam around further than what it moved on its own +/- a little bit.

 

Did you already replace your crank seal while you had it all apart?

 

Sent from inside my potato

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Yeah, did the crank seal and the thermostat. Giving the RTV sealant a chance to harden before I put the coolant back in. The water pump and tensioner were done when I did the T-belt a few months ago. Buttoning it up today. Hopefully, another small success story.

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Ok, got everything buttoned down, and I'm running with no problems. Had some coolant leaking around the thermostat housing and had to redo the gasket seal, but this was probably due to assembling it incorrectly - the FSM does state that there is a TOP on the outer housing.

 

Looking back, I think if I were to do this job again, I would probably zip tie the old T-belt to the cams to re-torque the cam sprocket bolts. I've read a couple of innovative ideas on how to hold the cam sprockets down, but none of them are ideal.

 

Using air on the cam sprocket bolts with a socket extension through the holes of the cam sprocket is simply an accident waiting to happen for someone. For weekend wrench warriors like me I feel like this job (holding down the cam sprocket) has not been thoroughly addressed - but I will say, after fiddling with it, that turning the cam off mark is not such a big deal, as you can always re-position it on mark. But like RC says - you definitely don't want to spin that sucker!!

 

 

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The extension through the hole isn't ideal but none of the bolts I've ever removed were extremely tight to the point where a snap on impact gun couldn't pop it free. The belt at home method I've found is to loosen them before removing the old belt that way the engine and belt can keep it in place, plus if it rotates everything is lined up so there's no risk.

 

And yea on the stock thermostat housing there's a dot or dash that indicates UP. And you're not the only one that hates that little seal area for the thermostat, they could've made it a little thicker in that area and used an O-ring or a thicker gasket. I don't particularly trust RTV on its own.

 

But I'm glad you're back up and running!

 

Sent from inside my potato

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When I did mine, I welded a couple of pegs to a steel rod like a big metal F. I slotted the pegs into the cam sprocket and had a handle to hold the sprocket still while I removed and then reinstalled the bolt. It also made turning the camshaft to align it with the belt easier.

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If I were to do this job again, I would certainly consider something along those lines Slartibartfast. While I feel pretty sure I have the cam bolts set in there well, I really wasn't able to get the torque wrench to click at ~85 ft-lb without spinning the cam.

 

Since this was the first time I have taken the cam sprockets off, there was naturally a level of anxiety about this repair. It's comforting to know I can bounce this stuff off you guys before tearing into this stuff!

 

 

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While dismantling my engine I just had one guy hold the other sproket in place woth a wrench while i loosened mine. As soon as the bolt broke free we switched, the loosened bolt will toghten again but not very much. Done it twice and ut has worked perfectly both times, the i took TBD off both sprockets and zip tied it to itself at the bottom/wedged some wood so reinstalling the belt would be easier instead of counting teeth and dealing with the lower end of TB

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Thanks for the input C-B.

 

Taking the cam sprocket bolts off was the easy part. Getting them back on and torqued to spec without spinning the cams - was difficult.

 

Seems like either make your own tool - like Startibartfast talked about, or

remove the valve cover and rockers to access the notch to secure the cam sprocket

 

Might be worth having a set of cam sprocket clamps - if only for piece of mind.

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