chain guide in progress

[nuQ]

just got a call from keith vanmeter from vanmeter auto in mantua nj who is replacing the guides on my 90Q. notified me that he found the driver side guide toast, which seems to go along with an earlier thread about a broken guide not necessarily destroying the engine. he is dropping the pan and cleaning it out along with the sump. said he found some grooves worn into the oil pump and will replace as well. how many others have been able to maintain the engine with blown guides? jeff:eek:

[PalmerWMD]

NuQ:

They could have jumped <anytime> thenSounds like you were Reeeaal Lucky.

Fred..:thumbup

[DAEDALUS]

My guide was gone at 200k or so. Yeah, the chain could go at any time in that condition. My chain was cutting a groove into the block.

[nuQ]

so a chain cutting a groove into the oil pump is possible and making it necessary to replace?

[DAEDALUS]

No, not the pump. The groove was in the solid Al block. It sounds like what he's saying is that the pump is scored on the inside from sucking up and passing bits of nylon. Not sure how to tell without disassembling the pump, but well, I've never done it. Hmmmm....now that I think about it, I have to wonder if the pump is close enough for the chain to hit it....maybe so. Maybe you're right. I sure didn't notice any wear on the outside of the pump on my car. I'm curious. Make sure you get the parts--I'd like to know more.

[Q45tech]

Why you always MEASURE the HOT idle oil pressure Before you start the guide replacement.......that way you know if you need to order a new oil pump.

Even though the factory minimum is 14 psi, I use a minimum of 16-17 psi with used oil as it should be 3 psi higher than brand new oil.........I like 15-16 psi with brand new Mobil 1 as it doesn't change over 3,000 miles [at least in my engine].

Hot oil means that the coolant has gotten to 176F then wait at least 15 minutes..........idle speed should be at 750 rpm.

Very interesting to watch the 30 psi drop progressively as the oil heats up and loses viscosity! inverse of coolant temp rise.

When you see an EXTERNAL groove cut in the oil pump shaft housing/block you need to measure the chain stretch as it might be excessive...........near the limit of even the NEW tensioners to take up the slack?

Lots of simple guide jobs turn into full blown WORK...[50/50] with oil pan cleaning and [10% pump replacement] we have had to change only [2-3% of the chains].......

Probably more chains needed changing but the extra $1,000 makes this a hard sell since the engine will still last a long time without it..........just not idle as smoothly with a stretched chain.

[nuQ]

thanks tech! makes sense now. the chains are being changed anyway, keith had spoke from the beginning that, although the chains would rarely if ever snap, they do have a tendency to stretch. alot of threads spoke about how new chains are unnecessary, but i guess in some cases it's a good idea to make the change.