Blowin Smoke!, What Now? Options

[ericread]

On Friday, November 28, I drove from Irvine to Van Nuys and back (with a few side trips) to pick up a couple of cases of Brad Penn. A total of about 200 miles. No problems, and my car ran like a champ.

On Saturday, November 23, I replaced the front engine mounts, changed out the distributor cap, replaced the coil with a new Bosch Blue coil and changed the oil.

This morning I decided to take a trip from Irvine to Temecula over the Ortega highway (twisty mountain hiway) returning via I-15 and highway 91. About 150 miles. 40 miles into the trip I notice that I am blowing smoke upon taking my foot off the accellerator. Actually, once I hit the acelerator after coasting I get about a 2 to 3 second cloud of blue/grey smoke from the tail pipe. I continue my trip, but the smoke seems to occur any time I slow down/accellerate at hiway speeds, or even shift.

During my drive, my engine is running great! No missing, no vibrations, and the CHT never cracks 370 in fifth gear at 4000-RPM (~80MPH).

The first think I thought was valve guides, but why would this ocurr in such a sudden manner? And if it is, what next? The engine is really running great, and I'm getting about 25 combined mpg.

What are your thoughts, and what's my troubleshooting process?

My thanks in advance

Eric Read

[r_towle]

Timing may be off...check it.
To much oil...check the dip stick.
Vacuum lines fell off..check MPS and Decel valve...along with all the rest.

If you went from 10W30 weight up to 20W50 you just raised the oil pressure quite a bit. So it may smoke as a result.

Rich

[Jake Raby]

Sounds like you may have a valve guide thats become loose in the head.. Smoke on decel is a direct symptom of an issue with the oil control rings or intake valve guides.

Don't drive it until you do a thorough inspection of the intake valve guides....

ANY valvetrain related issue can occur without any prior symptom, hence the reason why we absolutely over build everything related to heads and valve train.

This post has been edited by Jake Raby: Nov 30 2008, 07:11 PM

[ericread]

Timing may be off...check it.
To much oil...check the dip stick.
Vacuum lines fell off..check MPS and Decel valve...along with all the rest.

If you went from 10W30 weight up to 20W50 you just raised the oil pressure quite a bit. So it may smoke as a result.

Rich

Rich;

Thanks for the advice. The brad Penn oil is what I've been using for the past year. The oil level looks good - I put in 3 1/2 quarts. I will take a close look at the vacuum hose and the timing, but wouldn't either of those negatively affect the engine performance?

Again, my thanks,

Eric Read

[ericread]

Sounds like you may have a valve guide thats become loose in the head.. Smok on decel is a direct symptom os an issue with the oil control rings or intake valve guides.

Don't drive it until you do a thorough inspection of the intake valve guides....

ANY valvetrain related issue can occur without any prior symptom, hence the reason why we absolutely over build everything related to heads and valve train.

Jake;

What's the process I should use to inspect the intake valve guides? Can I do this myself? Do you have a tutorial on your BBS? (I logged in and looked, but couldn't find a reference).

My thanks.

Eric

[r_towle]

Without pulling the head and removing the valve the best test is a side play test with a dial gauge.
To do that right, you need to remove the spring , keeper, and retainer
Look in the manual for how to test your guides...its in the factory manual and in the haynes manual...its also in most general auto manuals for any car with pushrods.

Rich

[r_towle]

The engine is really running great, and I'm getting about 25 combined mpg.
Eric Read

Stock motor? Stock FI?
If so, you are running rich or your timing is off.
25mpg is not right.

Rich

[Jake Raby]

Pull the valve covers. Pull the rocker assemblies.

Using two large screwdrivcers pry the spring retainers fore/aft left and right and look for the one that has the most "slop" in it... Thats probably the one.

[r_towle]

Pull the valve covers. Pull the rocker assemblies.

Using two large screwdrivcers pry the spring retainers fore/aft left and right and look for the one that has the most "slop" in it... Thats probably the one.

yup...or you could do that....

Rich

[ericread]

Stock 2.0L engine, stock FI. Once I determine that a specific valve guide is "sloppy", then what. Any DIY process to get back on the road, or does it need to be sent out?

This is my daily driver, so down time equates to a rental car. What can I do to minimize down time?

Thanks!!!

Eric

[r_towle]

tune up again...
25mpg is wrong.
It could be running a bit to rich...thus the smoke.

Rich

[ericread]

Stock 2.0L engine, stock FI. Once I determine that a specific valve guide is "sloppy", then what. Any DIY process to get back on the road, or does it need to be sent out?

This is my daily driver, so down time equates to a rental car. What can I do to minimize down time?

Thanks!!!

Eric

Never mind. I just read the text from the Porsche shop manual. I see that the valve guides are pressed into the heads, and replacement requires specially equipped workshop and tools. As the manual says " Valve guides cannot be replaced with conventional workshop tools. Send cylinder head to factory for reconditioning or replacement."

Hmmmmmm... (IMG:style_emoticons/default/idea.gif)

[ericread]

tune up again...
25mpg is wrong.
It could be running a bit to rich...thus the smoke.

Rich

OK, Rich is a genius! (IMG:style_emoticons/default/smilie_pokal.gif)

I was running way, way, way too rich. It seems it was smoking all the time, with a cloud of smoke upon decel. At idle, I was spitting fuel out the exhaust pipe! I went ahead and adjusted the valves, set up the timing light and re-set the timing (Pertronix points, so no dwell necessary). No more smoke.

The real question in my mind is how my timing went bad so suddenly? But for now, it seems to be running pretty well.

Thanks for your advice Rich!

[r_towle]

What year is it?
What motor...

There is more you can do to get it perfect.

Rich

[ericread]

What year is it?
What motor...

There is more you can do to get it perfect.

Rich

74 2.0L Original FI
Original HEs with a new Bursch muffler.
Replaced the air cleaner with a K&N Cone Filter.
Thermostat bellows was removed by PO, but all tin is in place.

Thanks Rich!

Eric Read