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Cam hole offset
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=91257		 Page 1 of 1
Author:  turblediesel [ Sat Apr 25, 2020 6:43 pm ]
Post subject:  Cam hole offset
Finally putting my jeep back together and I have a question about cam locating pins and the cam holes they go into.

I made some cam locating pins to the proper specifications which should work but don't.

I've noticed the locating holes in the cams are offset to the rear of the engine in relation to the threaded alignment holes in the manifold. Everything went together well and the two dowel pins between the head and the intake manifold engaged properly. I had the manifold off to install ARP studs. No head gasket leaks, just a preventative measure. The manifold and cams didn't get dropped or hammered on, nor were the cams removed.

Anyone experience this or have any ideas. It's the first timing belt change on the engine at about 70,000 miles and the first one I've done on this type engine. I've done a bunch of timing belt changes on Fiats and VWs, all older models.
Author:  geordi [ Sat Apr 25, 2020 10:07 pm ]
Post subject:  Re: Cam hole offset
The two access holes for the pins should be directly in line with the holes in the cams when they are rotated into position. If the cams are out of position, then at some point they WERE removed and not reinstalled properly.

Without more information I cannot offer any better answers, the cams should be fully seated forward (to the pulley end) and with no axial play at all. Some engines have a washer behind the snap ring. This is hidden by the end seal which will be destroyed by removing it and need to be replaced.
Author:  turblediesel [ Sun Apr 26, 2020 12:44 am ]
Post subject:  Re: Cam hole offset
The cams were never removed from the manifold and I didn't replace the end seals. I rolled clean shop towels and plastic around the cams to protect them while cleaning.
Author:  turblediesel [ Tue Apr 28, 2020 5:50 pm ]
Post subject:  Re: Cam hole offset
Thanks for your input Geordi. I guess I'll read up and start tearing it down again. Spending more time and money again.
Author:  TKB4 [ Mon May 04, 2020 4:25 am ]
Post subject:  Re: Cam hole offset
Did you remove the valvecover without first putting in the Intake and exhaust cam pins in ? I leave mine in while the valvecover is removed. I first made my own then later bought set of CRD tools so I have both and both work. Never have seen or heard of this and dont see how they could accurately time the engine without a whole lot of trouble and guess work without them ? look in pin hole with scope etc . I would like to know what you end up doing.
Author:  turblediesel [ Tue May 05, 2020 3:59 pm ]
Post subject:  Re: Cam hole offset
I didn't pin the cams at all before reassembly because I hadn't made them yet. I use a piece of bamboo skewer to feel for the cam holes before trying the pins. The intake cam seemed to have come forward a bit just from hand turning the crank and lining things up. I'm one tooth off on the intake so maybe more messing around will bring them forward. Spent some time with the book which didn't have much to offer. Going at it cautiously since it's my first belt change on this engine and I don't want to do it wrong.

Mostly been ignoring it since I have a lot of trees to take down so it'll be awhile before I play with the jeep again.
Author:  jws84_02 [ Tue May 05, 2020 6:01 pm ]
Post subject:  Re: Cam hole offset
So just turn the cams until you can get the pins in. The proper way to do on re install is with the cam sprockets loose anyway. So teeth being off doesn’t matter and is evidence of not doing the job correctly
Author:  turblediesel [ Thu May 07, 2020 3:52 pm ]
Post subject:  Re: Cam hole offset
Right. Pins in from the start makes good sense. A lot less hand cranking of the engine too. I think the cams might have just shifted aft past the cam seals. I've only snugged the cam sprockets down once so I'm hoping to tease the cams forward without pulling the manifold. I'll take it back off if necessary. Going at it cautiously.
Author:  TKB4 [ Mon May 11, 2020 10:33 am ]
Post subject:  Re: Cam hole offset
Sounds like you may end up having to remove the valvecover to get the situation corrected. Perhaps with the cam gear on you might be able to pull the cam forward to allow insertion of the cam pins but I wouldn't trust that the cam mounting inside doesn't need attention. I would then put the cam pins in before before reassembly and tighten manifold down with them in place. When you put the timing belt back on it will likely be correctly spaced at the cam gears. It generally gets off a tooth when putting the belt on the crank. Just something you have to try a few times to get it right.
Author:  layback40 [ Mon May 11, 2020 6:31 pm ]
Post subject:  Re: Cam hole offset
It troubles me that the cam is out of place. It should be in the correct location & not able to move in or out. Once you get it where it should be, best take some time & make sure it cant move over time. If it does, it will destroy the belt & you will be back in there again.
Author:  WWDiesel [ Mon May 11, 2020 11:12 pm ]
Post subject:  Re: Cam hole offset
According to the Factory Service Manual and the Mopar Parts Website, there is a thrust washer (Item No. 6) on each cam along with an internal snap ring (Item No. 7) that holes it in place behind the camshaft seal.
It also shows a washer on the back end of the camshafts. Item No. 2 in drawing below.

From FSM: wrote:
(3) Install thrust washer, snap ring, and camshaft oil seal (Fig. 51).
CHECKING CAMSHAFT ENDPLAY
(1) After camshafts are properly installed in cylinder head cover check end play of camshafts with a dial indicator. The end play should be between 0.10 mm - 0.55 mm.

NOTE: If the camshaft endplay is not within specification, measure thickness of the camshaft spacer. Camshaft spacer thickness should be 2.8 ± .02mm.


Image
Author:  geordi [ Tue May 12, 2020 1:23 pm ]
Post subject:  Re: Cam hole offset
That washer on the back end is ONLY for the sealing cap, if the valve cover has the threaded caps. Not all of them do, some have a plastic freeze-plug style cap that appears to just be shoved in. The two styles are NOT interchangeable. I do not know a source for the plastic caps, IDparts does not have them. IDparts does sell the threaded plugs, but those are metal and should be easily reusable.

Unless someone has already messed with the cams, the snap ring at the front should be the only thing required to keep the cams in place. They SHOULD NOT move more than a hair forward or backward, unless perhaps that thrust washer was supposed to be there and was not properly replaced when someone was messing with the cams and snap ring. That is the ONLY way that the cams can be out of position.

It may be possible to pull the cams forward without removing the valve cover from the engine, but it WILL be necessary to destroy / replace the lip seal behind the cam pulley to see where the snap ring is and whether or not it has the thrust washer. NOT ALL OF THEM have the thrust washer either.

If your valve cover at the back does not have a large hex socket in the middle of the cam cap, then you have the plastic caps. DO NOT REMOVE THE PLASTIC CAPS as there is currently no replacement option.
Author:  kmagg [ Sat May 16, 2020 6:52 pm ]
Post subject:  Re: Cam hole offset
Geordi, are you talking about the two rubber plugs in the back of the cam cover like these:
https://www.idparts.com/camshaft-plug-p ... -5221.html
Or something else?
Author:  turblediesel [ Sun May 17, 2020 5:48 pm ]
Post subject:  Re: Cam hole offset
I haven't been near my jeep for awhile due to great weather and a lot of treework. still cleaning up the 23 cottonwoods I dropped. then it's a half dozen birch and spruce that blew down this winter.

I think my cams just shifted back in place until the rear of the cams hit the end cap or the snapring limited out against the cam-cover casting. Thrust is set between the snapring and thrust shim, casting, and pulley.

Plan is to pull the belt and pulleys off and make a fixture to draw the cams forward where they belong. I have new cam seals which I didn't install because my cam-cover/inlet cleaning process was pretty fastidious and didn't turn into the sloppy hosedown I expected. I'll try installing the new seals with the inlet in place if everything doesn't line up happily. If necessary I'll pull the cover off and deal with it on the bench.

I took this apart about 7 years ago and I have a vague memory of looking over the cam cover assembly on a floor pad when it first came off. I think the cams shifted to the rear due to the weight of the cam cover rested on the cam ends as I moved it around. The jeep's been down for 7 years because I haven't been 100% for 7 years due to a dislocated rib which clamped off circulation causing a domino effect of medical problems which I'm slowly coming out of well. Erring on the side of caution with the jeep because I like to do good work and hate to redo the same job. Plus I have other projects and 7 years of neglected work around the house and shop.

I appreciate all the good advice here on the forum.
Author:  geordi [ Tue May 19, 2020 12:59 am ]
Post subject:  Re: Cam hole offset
kmagg wrote:
Geordi, are you talking about the two rubber plugs in the back of the cam cover like these:
https://www.idparts.com/camshaft-plug-p ... -5221.html
Or something else?


That's exactly what I'm referring to - it's good that IDparts now has a source for those, they didn't the last time I talked to them about it (which has been a while)

Turblediesel: The pulleys on the front of the cams have NOTHING to do with the cam positioning. Behind the pulley however is the seal around the cam, and under THAT is the snap ring and the washer (if it has one). Total forward / backward movement allowable should be no more than a few thousands, because the space between the casting and the snap ring should be near zero OR filled with that washer. I still maintain that if the cams HAVE shifted to the rear, then someone at some point disassembled the cam seal and removed the snap rings, and when it was reassembled the washers were omitted by mistake. Pulling the cams forward by using the bolt and a pulling tool will only resolve part of the problem while on the engine. If you use a pick and sacrifice those seals, you can then remove the snap rings and install washers, only losing the seals in the repair. This will be the easiest way and there is no need to remove the cover from the engine.
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