Advice for a high mileage SOHC

[prayforsurf0]

By doing research for another topic, I came across a bunch of info about how the SOHC engines timing chain guides suck. I had no idea about this being such a huge problem with the SOHC engines. I have a 98' at 215,000 miles.

It seems as though I have a very, subtle rattling noise under the hood as many mentioned is an early symptom of timing chain failure. My driving habits are extremely gentle and I change my oil every 3,000 with Mobil One synthetic, but now I'm paranoid about blowing my chain.

Is it advisable to replace the two timing chain tensioners to hopefully stave off sure doom for a while ? Or am I just driving a time bomb no matter what I do ?

Im very good at maintaining my truck and do a lot to keep it running. I'm really hoping there is some precautions I can take to nurse my truck into even older age.

 

[Robman]

As far as I know, you're already doing all you can to ward off the timing chain monster.

 

[Benji-Man]

My personal experience was an 01 SOHC bought with 20k, timing chain rattled upon startup beginning as early as 60k, routine oil changes all its life. This engine just turned 200k, "knock on wood" and was driven hard all its life. Seemed 2me that parking uphill vs downhill lessened the startup rattle slightly, but it has always been there.

If you don't already have a body lift, the body lift would give more clearance during a motor swap. This rig was driven from St. Louis to Moab in 2013 with 170k and wasn't even worried about its dependability.

Its really personal preference if you pull motor and install new parts before destruction or do you wait until the day and put new chain and guides in the donor motor.

 

[2000StreetRod]

replacing tensioners

. . . Is it advisable to replace the two timing chain tensioners to hopefully stave off sure doom for a while ? . . .

I used to advise members to replace the tensioners every 75K miles because the springs weaken with age. However, for the past couple of years members have reported that the new tensioners available seem to have weaker springs than the old ones being replaced. The springs provide tension on the chain when the oil pressure is low (i.e. engine start). The tension provided by the hydraulic piston is significantly greater than the spring pressure. Many members have cross threaded the bore in the cylinder head when installing new tensioners because of the spring pressure. Also, if not being careful the compression O ring slips out of position when tightening the tensioner resulting in a huge oil leak. Eventually, the piston constantly moving in the cylinder will wear and the clearance will increase which may reduce the pressure exerted on the cassette guide and the tension of the chain. However, I think the cassettes will fail long before the piston clearance matters. Also, if the cassette has already failed, removing the tensioner may allow the broken cassette guide pieces to shift to a position causing more damage.

My current advice is to replace the tensioners when the cassettes are replaced and not before. I also advise manually testing a new tensioner by compressing and releasing the piston while checking for smooth action. Some of the aftermarket tensioners are junk and will seize in the extended or retracted position immediately after engine start. If a tensioner seizes in the extended position the cassette guide will break. If the tensioner seizes in the retracted position the chain will not be taught and may slip causing valve/piston interference. The tensioner should be oiled prior to installation.

Squirt engine oil into the port identified with the red arrow and work the piston until it is well lubricated.

 

[chefduane]

Regular oil/filter changes with Mobil-1 is all I do at this point. My 98 SOHC has 201k miles on it and a recent oil & pan drop revealed timing cassette plastic parts in the pan, although I have very subtle, almost imperceptible chain rattle. You wouldn't notice it if you didn't know what to listed for. But repair/replace is a waste of money at this point IMO. The repair would cost more than the whole truck is worth, and I figure at 201k miles I'm ahead of the game and I'll just driver her 'till she's had enough.

 

[prayforsurf0]

I used to advise members to replace the tensioners every 75K miles because the springs weaken with age. However, for the past couple of years members have reported that the new tensioners available seem to have weaker springs than the old ones being replaced. The springs provide tension on the chain when the oil pressure is low (i.e. engine start). The tension provided by the hydraulic piston is significantly greater than the spring pressure. Many members have cross threaded the bore in the cylinder head when installing new tensioners because of the spring pressure. Also, if not being careful the compression O ring slips out of position when tightening the tensioner resulting in a huge oil leak. Eventually, the piston constantly moving in the cylinder will wear and the clearance will increase which may reduce the pressure exerted on the cassette guide and the tension of the chain. However, I think the cassettes will fail long before the piston clearance matters. Also, if the cassette has already failed, removing the tensioner may allow the broken cassette guide pieces to shift to a position causing more damage.

My current advice is to replace the tensioners when the cassettes are replaced and not before. I also advise manually testing a new tensioner by compressing and releasing the piston while checking for smooth action. Some of the aftermarket tensioners are junk and will seize in the extended or retracted position immediately after engine start. If a tensioner seizes in the extended position the cassette guide will break. If the tensioner seizes in the retracted position the chain will not be taught and may slip causing valve/piston interference. The tensioner should be oiled prior to installation.
View attachment 87034
Squirt engine oil into the port identified with the red arrow and work the piston until it is well lubricated.

Thank you for the wise words everyone, and streetrod for that extensive reply. I've already read much of your writing on the timing chain issue.

Appreciate hearing the encouragement about the high mileage engines, I needed to hear some of that ! Once I discovered this common problem with the SOHC, it felt like that's all I started noticing and reading about on the forum. Couldn't sleep that night ! haha, cheers