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Front Cam Chain Advice

C420sailor

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Gents (and ladies),

'98 Explorer 4x4 SOHC here with 163k on the clock.

I've been having the dreaded rattle for at least 50k, but I was initially told by a mechanic that it was an exhaust shield. Didn't sound like one to me, but I went with it. The rattle has gotten worse, now rattling intermittently at idle, and even at low rpm at slow speed. My ear is telling me it's coming from the front, but I'm not sure if it's the primary chain or the secondary.

I've done a LOT of research on this site about the issue, but as a former Honda motorcycle tech I'm not really a car/truck guy. I have a few questions.

-If the guides are intact but merely worn, will replacing the tensioner stop the rattle? Or will worn guides provide less spring force against the chain?
-If the left bank guides are broken, does the repair in fact require removal of the front timing cover, crank-to-jackshaft chain and sprockets, etc? Or can it be accomplished with only the valve cover removed?

The fact that I'm getting the noise after start-up and even at higher rpm is making me think it's either the primary chain (which lacks a hydraulic tensioner), or that a jackshaft-to-camshaft guide is excessively worn/broken, since oil pressure still isn't enough to take out the slack in the chain. Rattle only at start-up would be indicative of a tired tensioner spring, correct?

Thoughts? Thanks in advance.
 
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2000StreetRod

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replacing hydraulic tensioners

. . . '98 Explorer 4x4 SOHC here with 163k on the clock.

I've been having the dreaded rattle for at least 50k, . . . The rattle has gotten worse, now rattling intermittently at idle, and even at low rpm at slow speed. My ear is telling me it's coming from the front, but I'm not sure if it's the primary chain or the secondary.

Your 1998 came with the 3 leaf primary tensioner that is prone to fail prior to 150,000 miles. Often a rattle at mid range rpm is from the primary tensioner. It is very difficult to isolate to the source of the rattle. I used a rubber hose and a mechanics's stethoscope and thought my rattle was in the front but turned out to be the right/rear cassette was broken. See: Timing chain rattle resolution process - SOHC V6

. . . If the guides are intact but merely worn, will replacing the tensioner stop the rattle? Or will worn guides provide less spring force against the chain?

When I inspected my guides at 150,000 miles they were only about 1/10 worn. The guides should sustain a million miles of chain wear with proper lubrication. The first priority in the Ford TSB regarding timing chain rattle is to replace the hydraulic tensioners. I suspect because it is the cheapest possible fix although unlikely. I suggest replacing the hydraulic tensioners every 75,000 miles but not to eliminate chain rattle. Very few members have solved their chain rattle with hydraulic tensioner replacement. My reason for replacing the hydraulic tensioners is to reduce the possiblity of timing chain slip. The springs (that are weak when new) in the hydraulic tensioners weaken further with age. The only thing that keeps the camshaft chains from slipping when engine pressure is low (at engine start) is the spring pressure. When I installed new OEM hydraulic tensioners I still had startup chain rattle until the oil pressure built up. That's why I installed a pre-oiler: Accusump installation. The piston stroke in the tensioners is more than enough to compensate for guide wear but not enough for guide breakage. My helpful threads (see signature) lists procedures for replacing the hydraulic tensioners but in your case I doubt it will help your problem.

If the left bank guides are broken, does the repair in fact require removal of the front timing cover, crank-to-jackshaft chain and sprockets, etc? Or can it be accomplished with only the valve cover removed?

The front timing cover must be removed to replace the left cassette. However, I have posted a procedure for replacing the cassette without removing the primary chain and does not require the OTC-6488 timing tool kit: SOHC V6 Timing Chain Inspection & Repair Several members have been successful using the procedure. Before replacing anything I suggest that you determine what has failed. I inspected my right cassette first since if it was broken the engine would have to come out and the other failures would be replaced after engine removal.

The fact that I'm getting the noise after start-up and even at higher rpm is making me think it's either the primary chain (which lacks a hydraulic tensioner), or that a jackshaft-to-camshaft guide is excessively worn/broken, since oil pressure still isn't enough to take out the slack in the chain. Rattle only at start-up would be indicative of a tired tensioner spring, correct? . . .

I suspect that you have a primary chain tensioner failure and/or a balance shaft chain tensioner failure if you have 4WD. You probably have at least one (right or left) broken cassette. For OEM timing chain related parts: SOHC V6 Timing Chain Related PNs. Some members have saved money by purchasing a complete timig chain kit on eBay: SOHC V6 Timing Chain Parts Sources. If you purchase an aftermarket kit please post your comments regarding quality of components.
 
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C420sailor

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Thank you so much for all this information. I read through your other post and it was very well done, thanks for clearing up the additional questions I had. I'm going to try to do this job (the fronts anyway) with the engine still in the trucklet. I'll let y'all know how it goes.
 
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2000StreetRod

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primary tensioner and guide

I want to point out that the primary tensioner and guide can easily be replaced without removing the primary chain so retiming the camshafts is not required. You only have to remove the front timing cover.

You didn't say if you have 4WD. The balance shaft tensioner mounting bolts cannot be removed without removing the block girdle (upper oil pan). That is fairly difficult with the engine in the vehicle. However, some members have slipped the broken part of the tensioner off the pivot shaft and slipped on the new part without removing the mounting bolts.

I'll be glad to help you with your repair if you have any questions. If you PM me your email address I'll send you a copy of the Mustang SOHC V6 assembly instructions which I found very useful.
 
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C420sailor

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Yes it's a 4x4.

There's a balance shaft tensioner too? Four tensioners in the motor? I'm having trouble visualizing where this fourth tensioner is.

I took a peek under the hood today and things look tight in there. I assume I'd have to pull the radiator and some accessories to have enough room to get in there and work.
 
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C420sailor

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Disregard, I found a picture of the balance shaft tensioner.
 
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C420sailor

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I took a good look at the engine, and there's no way I can do the repair with the engine still in the truck. I'm sure it CAN be done, but I know myself and working in tight, awkward spaces frustrates me to no end. It'd be one thing if I had the time and room to pull the front end off the truck, or if I could lift the motor out and do the work on a stand.

I'm going to install the 00M12 kit up front and a new rear tensioner as well and see what it gets me. Hopefully that'll buy me another 50,000 miles before slinging a chain or crunching some valves while I slowly build up a new motor for the old girl. I love rebuilding engines :)

Thanks for the help! I'll report back after I get the tensioners in.
 
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2000StreetRod

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00M12 kit

Starting my 00M12 Installation

While you have the intake manifold off to install the 00M12 kit it's not much more work to pull the valve covers and check for broken camshaft guide assemblies.

The SOHC V6 is not an inexpensive engine to rebuild. Some members have chosen to purchase a Mustang engine from a salvage yard rather than rebuild. There are some minor differences in the two engines but they have been documented in threads on this forum. PM me your email address and I'll email you the Mustang engine assembly instructions.
 
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ralasa41

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re timing

HI C420sailor, I have just fitted new timing kit , and I was not sure about doing it at first, sounded a bit complicated, but I got into it and it was quite easy, ( I had the timing kit to setup the timing of the cams), which now I dont think it was needed, all my for chains guides were broken and one cam was 180 deg out, now its purring like a kitten, no rattles, the hardest thing i found to do was, lining the engine and gearbox back up , that took 2 hours.
So get into it, its not to bad , I read a lot of 2000streetrods posts, they were a great help, cheers Pete.
Bye the way I opted for a cheap timing chain kit from Outlet4 USA (ebay).
Im not sure if to recommend it , seems OK so far, If it shits it self I will post up a update
 
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C420sailor

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It sounds to me like you had the engine removed, which isn't really an option for me right now. My roommate would KILL me if I plucked my engine out in his driveway.
 
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C420sailor

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While I'm waiting for the parts to come in, I decided to pop the oil fill cap and see what things looked like in there. With a bright LED flashlight I was able to make out the top of the tensioner side guide and the tensioner. The tensioner was making good contact and the guide looked like it was intact. I could make out a little bit of the side of the guide as it ran down the slack side of the chain. Obviously it wasn't the best vantage point and I couldn't see much more than the very top, but it doesn't look like anything catastrophic happened in there.

Being a man, and therefore lazy as *&%^, I started to wonder: has anyone tried using a borescope through the oil fill cap or tensioner hole(s) to inspect the internal tensioning assembly? Or should I just sack up and pull the valve covers?
 
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BubbaFL

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Being a man, and therefore lazy as *&%^, I started to wonder: has anyone tried using a borescope through the oil fill cap or tensioner hole(s) to inspect the internal tensioning assembly? Or should I just sack up and pull the valve covers?

Just my opinion, but if you don't plan to pull the engine and fix it, there isn't much reason to pull the valve covers and inspect. Just drive until she blows (or starts making really bad noises).
 
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