Quote:
Originally Posted by srmmmm
Is there a specific reason you're doing your guides? I'm at 346,800 miles on mine. When the valve cover and gasket were replaced at about 322,000 miles, the tech was unable to detect any slack or wear on the timing chain at all.
2002 X5 3.0 346,800 miles
2014 428i 39,000 miles
2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles
1970 Firebird Under restoration - Paint shop next month
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"While I'm in there" is why.
I've got the head off. I think it overheated in the past, warping the head. From service records, the PO had some major cooling system / CCV issues about 30k miles ago that may have caused latent damage. Then more recently it started blowing combustion gases into the coolant. So with everything opened up, I'm doing a few other things like VANOS rebuild and chain guides.
In general, at 186k miles and 17 years, everything looks to be really good (other than the warped head), but some of the plastic pieces are understandably brittle.
The coolant pipes on the intake side were crumbling at the ends. And the chain guides similarly seemed brittle. When lifting the head off (block still in the car), it got hung up on some trim stuff at the back end, and ended up dinging the timing guide that sticks up into the front part of the head. I'm sure a professional would just button it back up like that, but I'm replacing it along with the other guides. So yes, brittle, and if you did not ding it, hopefully OK, but in my case, it's not much of a decision.
And in general, this whole engine seems pretty amazing considering the mileage I've got. I saw that the M54 won some award rated as the best engine in the world in like 2002, and was on the top 10 list forever. Well deserved from what I can see.