I know it's small but I can't stop playing with it

jbcollier · Post by **jbcollier** » Sun Nov 11, 2012 10:32 am

Pulled the head off the Smart Car today and one intake valve was indeed disappearing into the head (valve seat recession). Puzzled over that one as the usual suspect is the exhaust valve which runs much hotter. Well, in order to reduce NOx emissions, they added an EGR system (exhaust gas recirculation). The recycled exhaust combines with crank case ventilation fumes to create the most amazing deposits I have ever seen in an intake manifold. Some of these deposits must have interfered with the intake valve seal which then led to the valve overheating (poor contact = poor heat transfer) and, ultimately, the seat's demise.

Worse, the EGR isn't really necessary, the engines actually run cleaner, have more power and better fuel economy with it removed! (Google: diesel egr bypass). Oh well, at least I know that it will be properly fixed when I am finished.

The other usual suspects (followers, hydraulic lash adjusters, timing chains, guides and tensioners) all looked good though I will change them as a matter of course.

jbcollier · Post by **jbcollier** » Mon Nov 12, 2012 4:18 pm

Pulled the valves today and the seat is not recessed (Yippee!). It's the valve that died, so no need for a $1400 bare head, thank goodness. Unfortunately the valves are not in stock so there will be a wait. I'll get the head to the machine shop so they can dip it and what not.

redbike · Post by **redbike** » Mon Nov 12, 2012 7:02 pm

I have absolutely nothing to contribute to the subject but did you know that a pregnant dog can absorb one of her unborn puppies? It's true. You can see six on the ultrasound and the next time there's only five. Ya just don't know what ya don't know.

Angelo · Post by **Angelo** » Tue Nov 13, 2012 1:48 pm

It took nearly 5 days for me to work up the courage to open up this thread and this is the best that you have? I guess its ok, at least my image of you hasnt changed....close call!

jbcollier · Post by **jbcollier** » Wed Nov 14, 2012 6:22 am

Dogs get ultrasounds?

redbike · Post by **redbike** » Wed Nov 14, 2012 10:40 am

Our dogs do; we need to know what's going on. Our breeding program is critical to our ongoing success and so once we've bred a female, we follow up with ultrasound to determine how many pups we can expect. Which is why we make note of the fact that occasionally one 'disappears'. See, ya don't know what ya don't know

jbcollier · Post by **jbcollier** » Fri Nov 23, 2012 5:25 am

Our usual machine shop was busy so I got to thinking: 6 mm valves, hmm... same as a motorcycle. So I took the head to Cycle Works. Had the job done within two days and only charged an hour of labour!

Started buttoning it back up yesterday and got it mostly together, at least enough so I could start it: purrs like a kitten. Now that the EGR is blocked, it should stay that way as well.

jbcollier · Post by **jbcollier** » Fri Nov 23, 2012 10:07 pm

Runs like a top.

Whew, one more thing off my list.