Soft Chain Tensioners

[Extremerc12]

HEllo all,

Have a 98 Explorer 6 cylinder 4L SOHC that has soft front and rear timing chain tensioners. I can put the tensioners in oil and manually pump them rock hard again. Is this an indication of one, bad tensioners or two, an oil pump issue not keeping the tensioners pumped with oil. The reasoning we removed the tensioners was due to a timing chain rattle. We removed and replaced the rear tensioner because of the soft feeling and we believed the tensioner was at fault. The issue still persisted. We removed the front tensioner and found it to was soft with no tension.

Any help would be appreciated.

Thanks
Chris

 

[rb142]

They should be pretty stiff even without oil in them, so it sounds like yours are bad. What matters is how well they are pumped up in the engine. They shouldn't really leak down much, at least not very fast. But it also sounds like your real problem is the chain guide. By the time you hear the chain slapping around, it is too late to fix the problem with a tensioner. It needs to get torn down and repaired before it kills the valves.

 

[koda2000]

the tensioner springs weaken over time. they should be replaced around every 75k for optimal tensioner performance.

 

[bluestream1]

Yes that's what I thought. Unfortunately, the tensioners I bought from Ford were weaker than the old tensioners that were in my engine...

 

[koda2000]

have you installed the oil restrictor tube?

 

[2000StreetRod]

weak tensioner springs

Yes that's what I thought. Unfortunately, the tensioners I bought from Ford were weaker than the old tensioners that were in my engine...

Unfortunately, that seems to have been the trend for both Ford and aftermarket tensioners for the past few years. The only time the spring pressure really matters is when oil pressure is very low or zero - as at engine start. I used to recommend replacing the spring/hydraulic tensioners every 75K miles but no longer do so because of the weak springs in the new ones. My solution was to install a pre-oiler so there is oil pressure in the tensioner pistons when the engine is cranked.

 

[Extremerc12]

I suspect I should reinstall these new tensioners now they are pumped up with oil and see what happens? Is there any reason to believe that the oil pump is going or has gone? I guess the question to ask is, why did the tensioners go soft and why was there no oil in them when removed? That fact that they are so soft would be indicative of allowing too much slop in the timing chains causing the chattering/rattle. I am not 100% convinced the guides are bad and/or broken after feeling and seeing these tensioners. Additionally, as soon as the chattering started, the truck was parked and hasn't run. It moved maybe 2-3 miles since it started.

Thougts?

 

[bluestream1]

have you installed the oil restrictor tube?

Yes, that was done by the Ford dealer in Oct 2001 as part on TM0012

 

[2000StreetRod]

oil relief

As I recall there is a small diameter hole in the center of the piston that eventually relieves the oil pressure. If you pump them in oil with your thumb over the hole it blocks the relief flow.

If your 1998 still has the original timing chain components I predict that as a minimum the primary (crankshaft to jackshaft) chain tensioner has failed unless there is less than 100K miles on the engine. The primary chain tensioner was significantly improved for the 2002 and later models. Unfortunately, the only way to tell for sure is to remove the front timing cover and inspect.

Ford's standard procedure for timing chain rattle resolution was to first replace the spring/hydraulic tensioners - less parts and labor costs. Next was to remove the timing cover and inspect/replace as required the primary chain tensioner, the balance shaft chain tensioner and the left cassette. Last was to replace the right cassette.

If you've never replaced the upper and lower intake manifold gaskets, I suggest doing so and while you have the upper intake manifold off remove the valve covers and inspect the cassettes. That way you'll know if the right cassette has failed and won't waste time replacing other components with the engine in the vehicle. The right cassette was never adequately strengthened. Mine failed at 150K miles.

 

[Extremerc12]

When we put the tensioners in the oil, we just pumped them without covering the hole in the center and they became very firm and hard. A completely different feel from how they came out of the truck.

 

[Extremerc12]

ttt