Cam chain tensioner plastic

[Mshuel]

I’m not an extended oil change guy. For those of you that are, I have a question. For autos with a cam chain, the tensioner use a plastic bearing surface. Since plastic is softer than metal, do extended oil changes do anything bad to the plastic? A used oil analysis shows many wear metals, but I’ve never observed a plastic measurement.

Thank you, Mark.

 

[Rand]

absolutely ask GM why they reduced the OCI on certain engines.. the 3.6 was one IIRC.

 

[Snagglefoot]

Not a pro at this but from various failures I have heard about, the plastic guides just get brittle and brake, ending up in the oil pan or bottom of the timing cover. Not sure if a shorter OCI can help this or not.

 

[clinebarger]

Many of the worn timing chains I replace still have serviceable guides....The GM 3.6L is a prime example, Other than it losing it's Primary Chain Shoe on the oil pump mounted guide.

Ford Modular engines like to break the Upper Bank 1 Guide, The GM 2.2L/2.4L/2.5L Ecotech likes to break the upper guide shoe.

Changing the oil often is the only defense you have against chain wear which likely causes Guide Shoe breakage.

 

[tig1]

I do 10K OCIs and have put around 1,000,000 miles on OCE with no chain or guide issues. Oil used has been all M1 lubes.

 

[KCJeep]

I've still not seen anything definitive that shorter OCI's do anything to improve chain life given the same lube is used. I'd easily believe that oil choice would make a difference though, like a good Euro 5w40 versus an API SP 0w20.

 

[kschachn]

I’m not an extended oil change guy. For those of you that are, I have a question. For autos with a cam chain, the tensioner use a plastic bearing surface. Since plastic is softer than metal, do extended oil changes do anything bad to the plastic? A used oil analysis shows many wear metals, but I’ve never observed a plastic measurement.

Plastic measurement? The UOA is determined by ICP which decomposes all compounds into elements so you'd be testing for carbon or nitrogen. ICP can't test for either, and besides that the oil itself is composed of carbon and some nitrogen compounds.

 

[BMWTurboDzl]

I’m not an extended oil change guy. For those of you that are, I have a question. For autos with a cam chain, the tensioner use a plastic bearing surface. Since plastic is softer than metal, do extended oil changes do anything bad to the plastic? A used oil analysis shows many wear metals, but I’ve never observed a plastic measurement.

Thank you, Mark.

IMO chain guides fail for two reasons: No 1 - Poor quality. No 2 - Excessive chain wear causes the chain to stretch. Once the tensioner can no longer take up the slack, the chain beats the guide to death until it breaks.

So, how does this relate to OCI? Some long drain oils rely on heavy amounts of certain additives which can cause excessive wear on the chain.

Now some engines have a chain design that makes them more susceptible to stretch.

 

[PaxilPlease]

absolutely ask GM why they reduced the OCI on certain engines.. the 3.6 was one IIRC.

I believe I read that the reason why GM reduced the OCI (3.6 I think) was because of higher rates if oil consumption. Lower volumes of oil lead to higher oil temps, which lead to higher chain/gear temps which caused chain "stretching" which caused CEL in regards to timing issues. So, typical people who wouldn't know to open the hood wouldn't know to check and add oil. So, an engine would probably suffer less having only 2 quarts in the sump at say 5000 OCI, than would an engine having 1 quart in the sump at an 7500 OCI

 

[KCJeep]

IMO chain guides fail for two reasons: No 1 - Poor quality. No 2 - Excessive chain wear causes the chain to stretch. Once the tensioner can no longer take up the slack, the chain beats the guide to death until it breaks.

That seems quite plausible to me.

Now if we only knew if shorter OCI's actually had anything to do with chain stretch.