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Old 08-24-2020, 03:43 PM   #1
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How do you Inspect chain rails

I want to take my car a 02' 2.7 on a 600 mile RT,.but I want to inspect the chain rails,and install new tensioners before I go,once the cams are locked can I just remove valve covers and take a peek ?? Thanks Frank


Last edited by flmont; 08-24-2020 at 08:04 PM.
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Old 08-24-2020, 07:13 PM   #2
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I can't answer your question but my understanding is that there is an important difference between 3 chain engines and 5 chain engines... so best to mention what year your car is...
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Old 08-24-2020, 08:05 PM   #3
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Thanks elgyqc,..I just updated ! its a 02' 2.7
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Old 08-24-2020, 08:36 PM   #4
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What`s the mileage of the car? The side rails are pretty sturdy, at least in my 5-chain engine I just reused them after 100k miles because they were totally fine. What makes you think they might have to be replaced?

If you pull out the scavanging pumps you can look down on the rails using a mirror or a borescope, at least on my engine, which again, is a 5-chain. And it`s on a stand in my garage so there`s plenty of room, which may be different when the engine is in the car. To see the inner surface of the rails of course you would need to remove the tensioners (locking the camshafts too) so you can pull the chain off the rail using a wire or similar. I`m not 100% sure, but I think this inspection is doable without pulling the valve covers off.
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Old 08-24-2020, 09:52 PM   #5
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I have about 88K on it, and its just the chain noise at start up. I intend to change the tensioner's ,labor day weekend, along with some 20W50 oil, I think the tensioners bleed off real quick in the constant 108 deg's of the summer
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Old 08-24-2020, 09:55 PM   #6
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oh plus my cam deviation #'s are 3.5 and 8.2 so i thought maybe the rails are worn down,
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Old 08-25-2020, 07:55 AM   #7
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Ah, that makes sense. It`s then a good idea to pull the cover off and see what`s going on. I don`t know the 3-chain engines but probably the smallest chain pad is the weakest point which is in the cam cover anyway.
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Old 08-25-2020, 05:40 PM   #8
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Iam a 5 chain..but before I pull cover,..Iam going to change the tensioners and go with a little heavier oil,..if that noise goes away I ll feel good,..if not...then off comes the covers..Or I will pull the engine and rework some stuff...I would love to rebuild a 3.2 and throw it in there ! but not sure I want to spend that much yet ! Thanks Frank
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Old 08-25-2020, 07:56 PM   #9
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Iam a 5 chain..but before I pull cover,..Iam going to change the tensioners and go with a little heavier oil,..if that noise goes away I ll feel good,..if not...then off comes the covers..Or I will pull the engine and rework some stuff...I would love to rebuild a 3.2 and throw it in there ! but not sure I want to spend that much yet ! Thanks Frank
Oh, sorry, I didn`t look at the the year of your car. If it`s a 5-chain, then probably the two small chain pads on the variocam unit are shot. In mine they were totally worn off, one came off from the variocam and the pieces were floating around in the engine. The car was at 100k and jumped timing. If those pads are worn, I don`t think replacing the tensioners will make a difference because those are supporting the long side rails. If you remove the plug over the intake camshaft on the scavanging pump side, you can see the pad (one of the two) and the variocam with a borescope. There`s very little clearance there but it`s visible with a small camera.
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Old 08-26-2020, 05:25 PM   #10
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At 8.2 it’s pretty clear that the chain pads need changing. Just the uppers in a 5 chain. I’ve only done this with my engine on a stand. Apparently it’s doable with the motor in the car but I don’t have the patience to lie on my back craning my neck for hours. Cool if you have a lift!
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Old 08-26-2020, 05:26 PM   #11
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Hmm do you mean the green cam cover plug or a different type of plug.Thanks !!
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Old 08-26-2020, 06:56 PM   #12
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well I am sure its not the cam cover plug, But Iam not very Familiar with these engines ,.But I will look it up Thanks
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Old 08-26-2020, 07:12 PM   #13
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Yes, it is the green plug, on the pump side, now it`s unplugged:



You can`t see both, but you can see the upper one that usually breaks, as Newart says. It`s the orange plastic thing deep inside on the right. If it`s in a really bad shape, it`s enough to tell by taking a peek through the hole. With a borescope you can see more.

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Old 08-27-2020, 10:12 AM   #14
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Ahh.Great thank you very much that really helps out,..! I now have a clu..lol. Frank
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Old 08-27-2020, 10:19 AM   #15
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That only gives you a partial peek at two of the eight chain pads, you cannot even see the four large ones, or the two short ones on the short chain:

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Old 08-27-2020, 10:50 AM   #16
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That only gives you a partial peek at two of the eight chain pads, you cannot even see the four large ones, or the two short ones on the short chain:

True, but the large ones last much longer, I don`t think those should be worn off at this mileage. You can`t see the lower small pad, I agree. This test is good to tell you if the upper is shot, and then you don`t have to hesitate to pull the cover off. I think you can have a vague idea about the condition of the large ones after removing the pump and the tensioners and looking down toward the crankcase with a camera or small mirror. The crank-to-IMS chain pad is partially visible after the RMS is removed, that also can give you a vague idea. In my engine at 100k the four long rails were in perfect condition, the crank-to-IMS pad was shot, and the four little pads were disintegrated and the chain was running on the tensioner, metal on metal.
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Old 08-27-2020, 11:28 AM   #17
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True, but the large ones last much longer, I don`t think those should be worn off at this mileage. You can`t see the lower small pad, I agree. This test is good to tell you if the upper is shot, and then you don`t have to hesitate to pull the cover off. I think you can have a vague idea about the condition of the large ones after removing the pump and the tensioners and looking down toward the crankcase with a camera or small mirror. The crank-to-IMS chain pad is partially visible after the RMS is removed, that also can give you a vague idea. In my engine at 100k the four long rails were in perfect condition, the crank-to-IMS pad was shot, and the four little pads were disintegrated and the chain was running on the tensioner, metal on metal.
We have seen all of the rail pads go south at one time or another; the little ones between the cam fail most often due to their small surface area, but the larger ones are not immune. We have also seen the longer units break near their pivot points, which is why updated parts are now available.
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Old 08-29-2020, 02:30 PM   #18
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Could I pull the spark plug tubes and then use a bore scope to get a good look..??

and would a Bore scope that connects to your phone work,.?? Thanks Frank
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Old 08-29-2020, 10:19 PM   #19
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Could I pull the spark plug tubes and then use a bore scope to get a good look..??

and would a Bore scope that connects to your phone work,.?? Thanks Frank
You would still only be able to see the chain rail pads on the little rails between the cams; you will not be able to see the other units as they are too deep in the engine to realistically get a bore scope down there without getting it stuck.
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Old 08-30-2020, 08:14 AM   #20
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Could I pull the spark plug tubes and then use a bore scope to get a good look..??

and would a Bore scope that connects to your phone work,.?? Thanks Frank
I`m not sure if you could take a better look at anything through the spark plug hole than just using the green plug, but here`s a picture I took recently of the variocam, may give you an idea.



For reference, here is a picture for the size of the camera I used for inspecting the actuators, it`s a cheap Depstech camera from Amazon and it works with a smartphone.



And yes, this is only good for inspecting one of the small chain pads, the upper one, but this is the most likely to fail out of all the pads. For inspecting the long side rails I would lock the camshafts and crankshaft, pull the tensioners (to free up the rails) and the scavanging pumps and look into there with a camera. Wear is not likely on these at this mileage, but if one is broken at the pivots probably you will see it.

My bet is you`ll find the small pads worn down, did you see yellowish or brown plastic debris in the oil filter?

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