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How to: SOHC V6 Timing Chain Inspection & Repair

rewind1

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The tranny in my 2002 xlt just gave up the ghost so i'll be tossing one in in the next month.
I'm wondering if I should take the time to replace the chains while the tranny is out.

Is it possible to replace the rear cassette with the tranny out of a 3rd gen? I found a thread saying its possible in a 2nd gen but nothing on the 3rd.
 


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2000StreetRod

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I suggest that you review the following thread: http://www.explorerforum.com/forums/index.php?threads/sohc-v6-rear-cassette-replacement.306370/
In order to replace the jackshaft rear sprocket the flexplate must be removed to gain access to the jackshaft rear plug and sprocket retaining bolt. I suspect it is possible to replace just the rear guide assembly without removing the jackshaft rear sprocket and chain but the flexplate must be removed to gain access to the rear guide assembly lower mounting bolt.
 




ICoull

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The tranny in my 2002 xlt just gave up the ghost so i'll be tossing one in in the next month.
I'm wondering if I should take the time to replace the chains while the tranny is out.

Is it possible to replace the rear cassette with the tranny out of a 3rd gen? I found a thread saying its possible in a 2nd gen but nothing on the 3rd.

Ooops. this 'reply' went blank. Can't seem to delete it. Please see reply below.
 




ICoull

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Short answer on the third generation 4.0 l is yes. In addition to getting the tranny out of the way you will also be removing the 'flex plate' that it bolts to, this gives access to the plug and lower tensioner bolt.
 




rewind1

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I suggest that you review the following thread: http://www.explorerforum.com/forums/index.php?threads/sohc-v6-rear-cassette-replacement.306370/
In order to replace the jackshaft rear sprocket the flexplate must be removed to gain access to the jackshaft rear plug and sprocket retaining bolt. I suspect it is possible to replace just the rear guide assembly without removing the jackshaft rear sprocket and chain but the flexplate must be removed to gain access to the rear guide assembly lower mounting bolt.

I checked that out,too. I think I've read all of your threads haha.
Are you suggesting that I replace only the chain guides and not the chains themselves?
The purpose of the tensioner is to pick up the slack from the chain stretching, right? With 200k on this motor, I would think the chain is probably very stretched and might be ready to meet its maker.

I think I am pretty well read on this system (for not having touched it before) but maybe I still misunderstand how it all works. Let me know.

Thanks for the wealth of information you provide on this topic. Its really very good, in depth, and complete.
 




rewind1

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Short answer on the third generation 4.0 l is yes. In addition to getting the tranny out of the way you will also be removing the 'flex plate' that it bolts to, this gives access to the plug and lower tensioner bolt.
So i take it the long answer is, "Yes, but it ain't easy". haha
 




2000StreetRod

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I checked that out,too. I think I've read all of your threads haha.
Are you suggesting that I replace only the chain guides and not the chains themselves?
The purpose of the tensioner is to pick up the slack from the chain stretching, right? With 200k on this motor, I would think the chain is probably very stretched and might be ready to meet its maker.

I think I am pretty well read on this system (for not having touched it before) but maybe I still misunderstand how it all works. Let me know.

Thanks for the wealth of information you provide on this topic. Its really very good, in depth, and complete.
It used to be possible to purchase just the guide assembly but now the entire cassette (guide assembly, sprockets and chains) must be purchased. The chains do elongate a little with age and the tensioner keeps the chain taught enough on the slack side of the cassette to keep the chain from slipping. I agree that with 200K on the odometer it is best to replace the entire cassette.
 




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The tranny in my 2002 xlt just gave up the ghost so i'll be tossing one in in the next month.
I'm wondering if I should take the time to replace the chains while the tranny is out.

Is it possible to replace the rear cassette with the tranny out of a 3rd gen? I found a thread saying its possible in a 2nd gen but nothing on the 3rd.

Also getting ready to have tranny rebuild on 07 eddie bauer in the coming week and was wondering the same about timing cassette while trans is out ? did nt see any replies , have you heard anything back ?
 




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Also getting ready to have tranny rebuild on 07 eddie bauer in the coming week and was wondering the same about timing cassette while trans is out ? did nt see any replies , have you heard anything back ?
Might as well! With the trans out, you have access to the rear jackshaft plug and the cassette bolt. If you replace the chain and cassette in the back you will at least feel safe about not having to pull the motor if it grenades down the road. As for the front, they'll go too eventually but you don't have to pull the motor.
 




CSUK

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test before installation?

Cloyes timing chain kits have a pretty good reputation vs the price. Did you test the hydraulic tensioner before installing it? I oil the tensioner and then compress and release the piston with my thumb to make sure it moves smoothly and doesn't stick. Cheap aftermarket tensioners have been known to seize. If they seize in the fully extended position the cassette guides breaks. If they seize in the retracted position the chain can slip.

I'd contact Rock Auto to see if they will replace it at no cost to you.

Hello, I'm new to the forum and will definitely subscribe to Elite Explorers to do my bit to keep this site going! Thanks for all the writeups! I intend to make a few posts with my stories so far with the EX to possibly help other folks out especially those with a RHD truck like mine!

My truck is not required urgently for driving as I have a loaner for as long as is needed. I'm probably going to be working on the entire drive drain from front to rear replacing as many seals, filters, and fluids as possible so long as the engine can be salvaged!

I have a 1998 Explorer XLT 4WD model 4.0L SOHC with a genuine 63K on the clock and an apparent chain rattle at idle even after the engine is warmed up fully. I suspect the front main tensioner is bad and who knows what else I will find when it's apart. I decided to pull the engine apart and do the maximum I am able to do without removing the engine. I don't have the facility to remove the engine so I will remove the transmission if I need to do the rear cassette. Is it possible to replace the rear cassette ONLY i.e. not to have to take the front apart at the same time?

I'm undertaking the front timing chain tensioners and guides fix this weekend and am at the point of prying the timing cover off. I just read the above and got a bit worried. I saw the advice to change the cylinder head and block tensioners as a first attempt to fix the rattle problem and I did the rear one first and it did seemed to make a difference in the rattling noises. I replaced the front tensioner and that seems to have made no difference and after a very short while the rattle seemed to get worse not better! I used the Cloyes branded tensioners which are supposed to be good ones so could one of those be BAD? I'll remove the front one and test it. Should I remove the rear one and test that also?
 




CSUK

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I now have the front timing chain cover off and it's the left cassette guide that is shattered into pieces. I can't remove the jackshaft sprocket because I don't have the TTY bolt to replace the old one. To ship one of those to the UK will cost about $35 and I think the chains are not a problem at just 63K so I don't want to replace the chains. I didn't run it more than about 100 miles after replacing the cylinder head tensioner before I decided enough was enough and started to pull it apart so I'm hoping there is no damage done!

I want to remove what is left of the left cassette and replace it with one I have in a kit. I will also replace the other two front tensioners and guides if possible. I'm not yet sure about replacing the jackshaft tenstioner using the shortcut method of just replacing the spring part, or if I will cut the chain instead! I just put the front differential back in a couple of months ago and it looks like the exhaust needs removing to get the upper oil pan block removed and get to the lower two bolts jackshaft tension bolts and that seems like a lot of work. Having said that will I need to do it anyway now that the left guide has shattered?
 




2000StreetRod

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I have a 1998 Explorer XLT 4WD model 4.0L SOHC with a genuine 63K on the clock and an apparent chain rattle at idle even after the engine is warmed up fully. I suspect the front main tensioner is bad and who knows what else I will find when it's apart.

That is extremely low mileage for a 19 year old vehicle. The original Ford tensioners and cassettes usually last more than 100K miles with normal usage. But in your case age may be a factor. I agree that it is more likely that the primary (crankshaft to jackshaft) tensioner or the balance shaft tensioner has failed than the cassettes or their associated tensioners.

I decided to pull the engine apart and do the maximum I am able to do without removing the engine. I don't have the facility to remove the engine so I will remove the transmission if I need to do the rear cassette. Is it possible to replace the rear cassette ONLY i.e. not to have to take the front apart at the same time?

It is possible to replace the rear cassette by removing the passenger side valve cover and the transmission. The timing tool kit (OTC 6488) will simplify the process. It includes a tool that fits between the firewall and the camshaft sprocket retaining bolt allowing the use of a standard torque wrench. Personally, I dislike working under a vehicle due to safety and inconvenience.

I'm undertaking the front timing chain tensioners and guides fix this weekend and am at the point of prying the timing cover off. I just read the above and got a bit worried. I saw the advice to change the cylinder head and block tensioners as a first attempt to fix the rattle problem and I did the rear one first and it did seemed to make a difference in the rattling noises. I replaced the front tensioner and that seems to have made no difference and after a very short while the rattle seemed to get worse not better! I used the Cloyes branded tensioners which are supposed to be good ones so could one of those be BAD? I'll remove the front one and test it. Should I remove the rear one and test that also?

Some members have found that the springs in the new hydraulic tensioners are weaker than the springs in their old stock tensioners. That's why there's a start up rattle until the hydraulic pressure builds up in the tensioners. Using synthetic oil should reduce the rattle time since it flows easier when cold. In my opinion the only way to totally prevent start up rattle is to install a pre-oiler. I suspect removing the oil pan and inspecting for failed parts is the easiest method to identify primary tensioner and balance shaft tensioner failures. When either fail the rattle normally occurs at mid-range engine speed rather than cold start because they are not hydraulic.
 




2000StreetRod

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I now have the front timing chain cover off and it's the left cassette guide that is shattered into pieces. I can't remove the jackshaft sprocket because I don't have the TTY bolt to replace the old one. To ship one of those to the UK will cost about $35 and I think the chains are not a problem at just 63K so I don't want to replace the chains. I didn't run it more than about 100 miles after replacing the cylinder head tensioner before I decided enough was enough and started to pull it apart so I'm hoping there is no damage done!

I want to remove what is left of the left cassette and replace it with one I have in a kit. I will also replace the other two front tensioners and guides if possible. I'm not yet sure about replacing the jackshaft tenstioner using the shortcut method of just replacing the spring part, or if I will cut the chain instead! I just put the front differential back in a couple of months ago and it looks like the exhaust needs removing to get the upper oil pan block removed and get to the lower two bolts jackshaft tension bolts and that seems like a lot of work. Having said that will I need to do it anyway now that the left guide has shattered?

It may not be necessary to remove or loosen the jackshaft front sprocket retaining bolt to replace the left cassette. On your 1998 the holes in the sprocket are larger than on the 3rd generation models. You may be able to feed the cassette lower positioning bolt thru the hole in the sprocket as shown in post 10 of this thread. You may have to rotate the crankshaft/jackshaft some to get the bolt out and in. I suggest removing the spark plugs so you can detect any interference between pistons and valves before rotating the crank if the left camshaft sprocket retaining bolt has been loosened. You'll need to remove the cassette pieces from the lower oil pan and pickup tube screen. I doubt it is necessary to remove the upper pan to find the pieces.

I have no experience with 4WD but I've read that the front differential is usually lowered to be able to remove the upper pan. Have you determined if the balance shaft or primary tensioners have failed?
 




CSUK

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Thanks for the quick reply StreetRod I was getting a bit down at the bad luck, but I see that other folks including you have recovered from this exact situation so all is not lost and I will carry on with the job!

I haven't removed any sprocket bolts yet and I'm being careful with the timing, however I don't have the timing tool as shipping that here costs a lot and as I'm not changing the chains I thought I would follow your instructions "Left guide replacement - no OTC-6488 use". I could stop now and get the tool but the ££ are mounting up with all the other things that need doing like for example the power steering leak [I'll make a post on fixing that for RHD trucks when I'm done with this problem].

The balance shaft tensioner is a bit cruddy but there is little to no play in the chain. When I press on the balance shaft tensioner spring it easily moves up and down and feels strong enough to keep the chain tensioned but I have no idea exactly how much pressure to expect on the chain, it is not loose though.

The primary chain tensioner seems stuck solid / won't move at all, however it is the old design and I have the parts so I will replace it anyway. The slack side of the primary chain seems very loose and can be easily moved on and off the primary chain guide by about 3/8 inch at the center point.

My next move is to get TDC with the lobe in the right position and mark everything up but because the left guide is broken I don't know if the timing is going to be out, although if I make the marks as instructed and they line up afterward that should be enough should't it? I plan on rotating the engine by hand after I'm done replacing the guides to check for interference.
 




CSUK

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Unfortunately one feature of a RHD drive vehicle is that the LH side is the awkward one not the RH side! The dryer blower etc are in my way so I can't use the vice grips method to hold the Cam still without major work removing the aircon and the blower. Also the accessories are on the SAME side as a LHD vehicle further crowding that area.

Also the compressor and power steering won't swing fully out of my way into the battery compartment due to the way the pipes are routed and the differences in the power steering components i.e. the connectors are on the RH side of the rack not the left side.

So I think I'm going to be looking for someone hiring the OTC 6488 toolset to make things a bit easier. I can get one for ~$350 shipped but I'm probably only going to use it once with any luck, although I could then resell it I suppose.

Someone on YouTube claimed that the LH camshaft sprocket does not need to be removed to change the LH guide? If that is correct then I have no worries but I don't see immediately how that can be correct at all. Video is titled "2002 Ford Explorer Timing Chain Guide/Tensioner Replacement. Don't waste money on Ford tool kit!!!"

I have now paused pending some more research into left hand guide replacement without removing the sprocket, or I'll be waiting on the toolset to arrive I guess! If I end up getting the timing tools then perhaps spending money on the jackshaft bolt makes sense and replacing the chains then becomes possible even if it is not necessary!
 




2000StreetRod

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The timing can be checked by making sure that when piston 1 is at TDC on the compression stroke the timing slot on the camshafts are below the axes of the camshafts and parallel to the head surface that mates with the valve cover.
cam1.jpg

AllenL.jpg

That should be accurate enough for normal driving. I timed my engine without the tool kit and it has frequently revved to 6,500+ rpm with about 6 psi of boost with no problems.

As far as replacing the left cassette guide without removing the camshaft sprocket retaining bolt I don't know. I watched the video and he doesn't show how to do it. The newer cassettes can be disassembled by removing the keeper that holds the pivot pin. The pivot pin on your 1998 is probably pressed with no keeper. However, in the video he says it isn't even necessary to disassemble the cassette guide to replace it.
LftGuide.jpg

Around 2004 there was a casting change in the block or head reducing the pivot pin clearance. For those the shop manual states it is necessary to remove the head to replace the guide assembly. I suspect the newer cassette guides can be disassembled to eliminate the need to remove the heads. It's worth trying to avoid the cost and delay of the timing kit. However, be very careful because the "finger" on the cassette guide is easily broken off.
 




CSUK

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Thank you very much for the pointers! The Cam is showing as being in the proper position with cylinder #1 at TDC. However the balance shaft timing markings are out so I'll need to rotate the engine a couple more times just to make things 100% timing wise before loosening anything. I tried improvising a camshaft holding tool and it didn't give me confidence that it was going to do a good job so I've gone ahead and ordered the timing kit and the Jackshaft bolt, ETA ~2 weeks. I'll now have time to do the other jobs like the power steering leak and dealing with some minor rust problems.

The reason for the following questions is that the Cloyes Video on youtube seems to be in error at 6:28 when the Jackshaft sprocket bolt is removed but the RH Cam has nothing holding it in place? Just want to make sure I don't make a mistake and mess up the factory timing unnecessarily!

If I remove the Jackshaft bolt won't BOTH Cams try to move? There is only ONE Cam holding tool in the kit? I guess if the Cam Holding tool is used along with the Cam sprocket holding tool on the LH Cam, then once the LH Cam sprocket bolt is loose I then need to remove the Cam sprocket holding tool from the LH and then I can use it on the RH Cam to keep it from moving, and after that I can then undo the Jackshaft bolt and not have any timing issues due to the Cam's moving? Also I'll need to fasten the Jackshaft bolt before removing the Cam sprocket holding tool from the RH Cam and moving it back to the LH for tightening the LH Cam bolt?

I figure if I can get another 5 years out of this truck after the investment being put into it right now then the cost is only going to be about 1/3 the depreciation cost compared to what my much newer car is loosing in it's value! Also when you think about it there is actually not a lot that will wreck the truck such that it needs to be scrapped. Age is definitely the real enemy of this particular truck hence the need to replace as many seals, and fluids, and other perishable items as required over the next 5 years. Hopefully the rear timing chain guide will hold out for the next ~15,000 miles! If it needs replacing though I can probably get it done as I'll have the timing parts and timing tools already and the rear is much easier to do once the transmission is out compared to stripping everything out of the front of the vehicle! :D
 




2000StreetRod

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I don't know which video you're referring to but normally the camshaft timing components are assembled with the camshaft followers removed. That way there is no valve spring pressure on the cam lobes and no piston to valve interference issues. You are correct that if the jackshaft front sprocket retaining bolt is loosened then timing of both camshafts will be lost. If you send your email address to dclinbeard@bellsouth.net I'll send you a pdf format copy of the engine assembly instructions which I found to be helpful. You are also correct that there are only enough components in the timing tool kit to time one camshaft at a time. As I recall, timing is not done until all of the timing components are installed and the jackshaft front and rear sprocket retaining bolts are torqued but the camshaft sprocket retaining bolts are loose. Then the right camshaft is timed and its sprocket retaining bolt is tightened. The crankshaft holder prevents (via the jackshaft and chain) the right camshaft from rotating when the timing tools are removed from the right camshaft and installed on the left camshaft.
 




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I just sent you a request for the PDF file, thanks for offering a copy I'm sure it will be interesting reading :D

It's the video titled "1997-2011 Ford 4.0L (Explorer/Mustang/Ranger) timing replacement (Cloyes kit# 9-0398SB)". The camshaft followers are not removed in the video and the Jackshaft bolt and the main chain is removed with the RH Cam then free to spin. Timing the engine is therefore necessary if I had followed the instructions in the video which I'd rather avoid.

What you said makes perfect sense when the timing cover and balancer are refitted already. I'm trying to change all the front chains like in the video but hoping to avoid having to time the engine afterwards. It should be possible so long as both cams are held secure while working on the front chains. The crankshaft probably isn't going to move because the pistons make it difficult to move with the spark plugs in place so I'm not worried about the crankshaft moving.

One more thing I'm confused about is that I thought I read that the Woodruff key needed removing in order to remove the balance shaft sprocket, however in the Cloyes video it seems easy to remove without touching the Woodruff key. With the balance shaft chain off I'm hoping that the balance shaft tensioner can then be depressed and slid off the peg that holds it on!
 


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rewind1

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Also getting ready to have tranny rebuild on 07 eddie bauer in the coming week and was wondering the same about timing cassette while trans is out ? did nt see any replies , have you heard anything back ?

I ended up pulling my engine. With all the other work that needed to be done, The trouble of removing the exhaust nuts and motor mounts was well worth the ease of work offered up by having the motor out of the vehicle for the rest of the repair.
 




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