Possible rattle between 2500-3000 rpm???

[JKELLYN13]

I am posting this because I have an 02 ST 2wd with 205k miles on it. It mostly is in fantastic shape with the exception of the common issues with leaking valve cover gaskets and bad ball joints(both to replaced within the next month). However I have noticed that when the engine is cold and not warmed up there is a slight rattle type sound from under the engine bay area that only happens between 2500-3000 RPM. This goes away when the engine warms up and is not at all speeds or RPM's. I have checked the exhaust heat shields and connections and all are good and can not detwrmime where or what the issue is. Anybody have some ideas???

 

[2000StreetRod]

primary chain tensioner?

If you have the SOHC V6, when the primary (crankshaft to jackshaft) chain tensioner fails there is typically a rattle between 2500 and 3000 rpm.

Your 2002 should have the improved tensioner with the wider base and six leaves shown on the left below.

However, even the improved one can fail after 200K miles. You might try listening with a mechanic's stethoscope or a length of flexible hose to see if you can locate the general area the rattle is coming from. Be careful of rotating engine parts.

 

[JKELLYN13]

Ok thank you for the input. That is kind of what I was begining to think it was as well. My next question is how difficult would that be to replace inside the truck? I work 60 hours a week for a Toyota dealer in the parts department and only am off on sundays so you can see I don't have much free time to give the ST the attention she sometimes needs.

 

[Bretton65]

If you have the SOHC V6, when the primary (crankshaft to jackshaft) chain tensioner fails there is typically a rattle between 2500 and 3000 rpm.
View attachment 84899
Your 2002 should have the improved tensioner with the wider base and six leaves shown on the left below.
View attachment 84900
However, even the improved one can fail after 200K miles. You might try listening with a mechanic's stethoscope or a length of flexible hose to see if you can locate the general area the rattle is coming from. Be careful of rotating engine parts.

Thanks for the great picture of the primary chain tensioner. Replacing that is my summer project. I searched through all of the tensioner posts and was wondering if there was one for replacing just this tensioner. Do you know of one? Thanks!

 

[Tech By Trade]

Hope you have deep pockets then. Welcome to the club.

 

[2000StreetRod]

check the oil pan

. . . My next question is how difficult would that be to replace inside the truck? . . .

Probably the only simple and fairly reliable way to confirm the primary tensioner has failed is to remove the lower oil plan and check for broken spring leaf and plastic parts. In my case the tensioner failed (no pressure on the chain) but remained intact.

The sludge is a result of the previous owner installing a low temperature thermostat in a futile attempt to compensate for an inadequate (single row) radiator.

The primary tensioner can be replaced with the engine in the vehicle and retiming the camshafts is not necessary. However, the front timing cover must be removed which involves removing the serpentine belt, viscous cooling fan, the harmonic balancer, alternator and support bracket, setting aside the A/C compressor and power steering pump and support bracket. I can't remember if removing the radiator is required but doing so gives easier access. It could be done in a day but you should have back up transportation available in case problems are encountered. Some members have difficulty removing the harmonic balancer.

 

[2000StreetRod]

Primary tensioner replacement procedure

Thanks for the great picture of the primary chain tensioner. Replacing that is my summer project. I searched through all of the tensioner posts and was wondering if there was one for replacing just this tensioner. Do you know of one? Thanks!

In the next few days I'll post the procedure in My Helpful Threads.

 

[BobRob]

I had the same symptoms with my 02 4.0 SOHC. Here is a link to the thread and to another where I chatted with another guy going through the same thing.. HTH..

http://www.explorerforum.com/forums/showthread.php?t=424021

http://www.explorerforum.com/forums/showthread.php?t=425212

 

[JKELLYN13]

Thanks to all that have assisted and chimed in. Yea due to my work schedule I dont have alot of free time to fix things on the truck this invasive. Pockets are deff not deep I have 2 kids under 3 and a finacee that stays home to take care of them so yea... I get mostly gas money with a little extra here and there. I had planned on doing all the little maintanence items before my honeymoon in october but sofar this is taking center stage for obvious reasons. I called a sister ford dealer to my toyota dealer and he quoted me 3 hours labor to change the timing chain and guides. Also I have a master ford tech that works here at toyota with me so I'm tempted to see if he will do it for 3 hours laber here since our employee labor is only 35$ an hour.

 

[JKELLYN13]

So I double checked the labor time from ford cause I have a feeling the first guy I spoke with was high or something and yea the labor time is 10.7 hours!!! Do they atleast plan to take me to dinner before bending me over???

 

[BobRob]

So I double checked the labor time from ford cause I have a feeling the first guy I spoke with was high or something and yea the labor time is 10.7 hours!!! Do they atleast plan to take me to dinner before bending me over???

Are they saying for a FULL timing chain job on a 4.0 V6? That would take a very focused technician with proper facilities, experience and tools about 24 labor hours...MINIMUM.

If they are talking about tensioners only, 10 hours seems plausible.

 

[Bretton65]

Thanks to all that have assisted and chimed in. Yea due to my work schedule I dont have alot of free time to fix things on the truck this invasive. Pockets are deff not deep I have 2 kids under 3 and a finacee that stays home to take care of them so yea... I get mostly gas money with a little extra here and there. I had planned on doing all the little maintanence items before my honeymoon in october but sofar this is taking center stage for obvious reasons. I called a sister ford dealer to my toyota dealer and he quoted me 3 hours labor to change the timing chain and guides. Also I have a master ford tech that works here at toyota with me so I'm tempted to see if he will do it for 3 hours laber here since our employee labor is only 35$ an hour.

I am jealous - I hope that he does it for you! That would be awesome.

 

[Bretton65]

In the next few days I'll post the procedure in My Helpful Threads.

That would be great, thanks! I am particularly worried about how to reseal the front of the oil pan. Since it is only the primary chain tensioner and I don't have to worry about the timing I would like to try replacing it.

 

[JKELLYN13]

Yea well see. I just talked to him to see how much he would charge for me to just replace the to main guides on the primary chain as well as the primary tensioner and waiting for him to let me know. Usually he takes care of anything I ask him to do so well see in an hour or so if he comes back with a reasonable number. If not then I guess I'll have to not spend time with the ole' lady and kids on my day off in a couple weeks. But hey its either that or risk losing the engine...

 

[2000StreetRod]

less than five minutes

. . . I just talked to him to see how much he would charge for me to just replace the to main guides on the primary chain as well as the primary tensioner and waiting for him to let me know. . . But hey its either that or risk losing the engine...

Once the timing cover is removed it takes less than five minutes to replace the primary chain guide:
Remove two bolts
Pop out the old guide
Push in the new guide
Screw in and torque two bolts

My guide with 150K miles was barely worn. I only replaced it because it took so little time and I already had the part which was fairly inexpensive.

Since I have been a member of this forum I can't recall any member whose engine was damaged due to a failed primary chain tensioner except if the broken pieces blocked an oil passage. I doubt there is enough slack in the chain for it to slip even if no tensioner is installed. The chain is very strong and destroys the tensioner before there is significant damage to the chain. I encourage you to determine if the tensioner has actually failed before spending the money to have it replaced by a shop. Just pull the lower oil pan and inspect for parts. If you find any parts remove them and clean the ones in the oil pickup screen and reinstall the pan. I reused my OEM pan gasket and it doesn't leak. This could easily be done on your Sunday off. Post a photo of the parts and we might be able to determine where they came from (primary chain tensioner, balance shaft chain tensioner, left or right cassette guide assembly).

 

[JKELLYN13]

Thanks 2000STREETROD youve been a huge help. Yea I may have to just remove the oil pan this Sunday. Its almost time to change the oil anyway so I'll already be under the truck and the pan is 100% easier to remove than the pan on my old 86 mustang gt. Also with 205k miles I may as well replace that gasket they are pretty cheap.

 

[Bretton65]

Thanks 2000STREETROD youve been a huge help. Yea I may have to just remove the oil pan this Sunday. Its almost time to change the oil anyway so I'll already be under the truck and the pan is 100% easier to remove than the pan on my old 86 mustang gt. Also with 205k miles I may as well replace that gasket they are pretty cheap.

Here is 2000STREETROD's excellent thread on replacing the primary chain tensioner.

http://www.explorerforum.com/forums/showthread.php?p=2509603

 

[JKELLYN13]

Finally dropped the pan and found a small plastic piece. How can I post a picture on this forum of the plastic piece?

 

[JKELLYN13]

 

[2000StreetRod]

posting photos

You have to be an elite (paid) member to upload photos to the forum. The alternative to the very reasonable fee of $20 per year to become elite is to post on a public website and then provide a link to that website.