quote:

Originally posted by egregore:
A number of V6 engines make you remove the upper intake manifold (aka plenum) to change one, sometimes both, banks of spark plugs. Some, like Ford and Chrysler, aren't terrible - and get easier with practice - but Nissans and older Hyundais and Kias are needlessly difficult.

Spark plugs have been an issue on Ford "Triton" truck engines, either from blowing out of the head because there are only three threads, or (2005-08 5.4) the plug tips remaining in the head when you remove them and having to be extracted with a special tool.

I did the plugs on our Flex recently, once I found all the mounting bolts, it wasn't too bad.
Removing the manifold & checking the plug gaps took the longest.

The worst I have is two coil packs under the intake.

I can swap the wires through the plenum, but it takes a while.

Never heard of the plugs being hidden under there.

I work with engine design engineers all the time and not once has the subject of "making customers go to the dealer for service" ever come up. I represent manufacturing to help them make sure they design something we can actually build. There are representatives from service who do the same thing for their function, and we do talk a lot about serviceability.

But the problem is the increasing complexity needed to meet all the regulations, and getting it all to fit in the available space. And of course we hire a lot of engineers from outside the U.S. who probably have never worked on an engine in their life beforehand.

Water pumps inside blocks is pretty bad though. Subaru puts them behind the timing belt cover, driven but the back side of the timing belt. I thought that was bad...

quote:

Originally posted by P250UA5:

quote:

Originally posted by egregore:
A number of V6 engines make you remove the upper intake manifold (aka plenum) to change one, sometimes both, banks of spark plugs. Some, like Ford and Chrysler, aren't terrible - and get easier with practice - but Nissans and older Hyundais and Kias are needlessly difficult.

Spark plugs have been an issue on Ford "Triton" truck engines, either from blowing out of the head because there are only three threads, or (2005-08 5.4) the plug tips remaining in the head when you remove them and having to be extracted with a special tool.

I did the plugs on our Flex recently, once I found all the mounting bolts, it wasn't too bad.
Removing the manifold & checking the plug gaps took the longest.

I did the plugs on my old 3.7L V6 Mustang several times. It was always annoying but doable. Had it not been for YouTube, though, there's a chance I could have been intimidated enough to take it in. That definitely was the case when I tried to do the plugs on the Taurus, where not only is the plenum covering half the plugs it's also got a transverse mounted engine (it was an 04 SES with the DOHC engine).

(My brother drove that Taurus for many more miles after I bought the Mustang. I asked about a dent in the hood once and he said that a plug had vibrated loose and blew out one day on the road. He screwed another one in, and kept on going. He got lucky,I suppose.)

The Nissan VG engine (V6, usually seen in 3.0 and 3.3L, up to 2001) is a mechanic's nightmare. In truck applications, #6 spark plug is between the intake manifold and firewall and can only be done by feel or by removing the intake. Over the years I've seen a dozen Frontiers and Xterras that have a miss, and I pull out five new (or new-ish) spark plugs and #6 completely eaten away because nobody ever changed it. This engine also has a bad habit of the spark plug cavities filling up with dirt, so you either can't get a socket over the plug, or if you do, the dirt falls down the hole when you pull the plug.