The good news is that my 3.6 project has been up and running, hitting a few car shows and being quite fun to drive. At last months Euro-Sunday in Sacramento.
Click to view attachment
The bad news is the engine has been smoking more than I like so I decided to pull it down for valve guides. A disappointment for sure for a low mileage engine. Once down the guides were severely worn. One bank of oil ring gaps were all facing down as well adding to the smoking I'm sure.

The ugly.....the "while you are in there" escalates the price even worse. New hydraulic lifters, rings, chain ramps etc....sigh it's hard on the wallet. I'm hoping to get the dismantler to pay for the parts.
Click to view attachment
Click to view attachment
Click to view attachment

Ouch. Well, it sure does look good. Once it is all back together it should be good to go though.... I hope.

I feel your pain my brother. There is nothing bad about working on any teener except the cash flow situation and the time to do it. At least, thats my story.

that does suck ...


hopefully, that'll be the last time you have to dig into your engine.
Andy

Andy, I'm surprised you didn't notice the intermittent smoke on that last Napa get together. It took me awhile to figure it out since it didn't smoke all the time. Rob Sime was following behind me on the freeway and when I stood on it he said it didn't smoke. When I asked the guys behind me on the drive they told me it was mostly at stops but inconsistent.

When I pick up my mail it always starts to billow out smoke. It's on a angled steep hill. I finally figured the oil would run to the the last valve in the lower valve cover (exhaust) and be very deep. The valve spring and retainer splashing oil hard at this point would just blow it past the worn exhaust guides (over .012 wear) and the smoke would start. That's the only time I could get it to "consistently" smoke.

I try to look at these things as opportunities. Every nut and bolt on the car was off except the engine. It was supposed to only have 40k on it. I'm finding that some 993's driven in LA with A/C on and in traffic can puck a set of guides in even less time. The catalytic converter just burns it off and you don't see it until much later. Rich at Jerry Woods told me he has NEVER pulled down a 3.6 with good valve guides

Anyway, hopefully once it's finished it will stay reliable for many years. I did not want to yank this engine after paint but oh well....

Here is the guide wear giveaway. A picture of the exhaust port before teardown. Note the oil surrounding the valve stem
Click to view attachment

that's because i was in front of you ...
Andy

So is a different material used for the replacement guides?

What causes the guides to wear so quickly?

John, there are a variety of different guide materials out there. All claiming to be the best or better than the others. It was a tough decision. I chose manganese bronze from Si Valve Co. These guides may not transfer heat quite as well as the stock ones but they are harder. On the other hand, once the soft OEM guides get worn and the stem/guide clearance is sloppy, they won't transfer the heat worth a crap anyway.

The factory uses a lot of copper in the guides. It transfers heat well but its soft and wears too easy. To be light and flow efficient, the factory used a small 8mm stem and the 3.6 is a big engine with lots of heat.

I'm pretty comfortable with my choice of guides. It's not a race engine, the car is light and it is well cooled. I suspect my engine will run a long time now.

The most important part is that the guides MUST be honed. You can buy a reamer but reamers tear the metal. Honing is certainly the preferred method.

The 3.6 engines trash guides....Heat, soft guides, A/C on hot days in city traffic, small stems, high rpm, and worse....the sound plates installed on the bottom to make them quieter but hold even more heat in.

Anyway, that's my take on the situation

Sounds like a good choice Paul.

I really respect how much thought you put into each decision.

Thanks Mark. All that thinking works good sometimes to catch the details but I drive myself crazy at times by thinking things to death, even the stupid stuff. Lucky for me my wife respects it more than it annoys her.....

Oh yeah, I get that too. I totally get that...

That's why I love you guys for doing these these before I do them I don't like to make my brain hurt more than it does.

Do 3.2's have similar issues with valve guides? Who is doing your head rebuilding?

John, 3.2's have a similar issue but my understanding is the 3.6's are the most prone to the wear issue. Larger valves and more heat being the issue.

I do my own head work except cutting the seats. I bead blast them, disassemble remove the old guides, install the new ones and hone them to fit. It only cost $170.00 to get the valve faces machined and the seats cut. I verify the fit and reassemble myself to the factory assembled height specs. I saved about $600.00 doing it myself and a machine shop can't hide any mistakes this way.