Expert's advise asked on symptoms

[lindemans]

Hi all, great forum by the way.

My 1989 3.2 has 140.000 mls. on it.
Engine runs superb, still powerfull, smooth.
Oil comsumption is exactly one Quart per 1.000 mls. carefully measured over 3.000 mls. This includes shorter rides as well as long and faster trips through Germany (Netherlands to Austria for skiing...) doing 125-135 mph for hours.
Oil pressure is 4 bar or slightly above that when running >3.500 rpm with warm engine (10W40 oil).

I can't notice the engine smoking on acceleration of decelleration, apart from the blue puff on cold start.

Yet the thing that puzzles me: this week as well as a couple of months ago I noticed a blue cloud behind me as I pulled away quietly after having been on idle for a few minutes at the traffic light. Funny enough 2 such incidental occasions only.

Any ideas as to how this originates ?
I was hoping to be able to delay a rebuild given the other (if I am correct) positive symptoms....yet !?

[kenikh]

It is probably valve guides; your oil consumption sounds pretty normal, though. I wouldn't worry about it.

[BReyes]

Your ok today, if you baby her for a while.

Monitor performance/oil consumption. And seek advise of your technician regarding planning to rebuild the heads. At that point, I would change the head studs (clutch, rings, rod bolts).

Regards,

[afterburn 549]

2nd the motion -guides

[Wayne 962]

Read this first:

http://www.pelicanparts.com/techarticles/mult_Engine_Rebuild/mult_engine_rebuild-1.htm

-Wayne

[lindemans]

WAYNE, that's exactly what I already did.
In fact, I have read both your books several times and in my sleep I've rebuilt the thing a dozen times....

To quote your books:
"a quart per 1.000 miles" is about the normal amount for a healthy engine; my actual oil comsumption is maybe 5% more than that but pretty much on target there.

Yet you also write: a blue puff when pulling away from the trafficlights is a sign for significant ring wear.
I observed such a large blue cloud on 2 incidents when driving off after a few minutes idle while waiting at the red light (traffic light that is); once with cold engine, once with warm engine.
It is not a structural symptom though, as normally the sky remains clear behind me.
On cold start its best to stay out of the way though, again big blue puff; however gone immediately when running idle.

That's why I was curious about the possible root-cause and impact on my assumption (and hope) "that my engine is still in fairly good shape".
Should I consider a leak down test to judge the rings here ?

[CliffBrown]

Leak down is the first thing to check.

Also if the rings prove to be good and you determine it's the guides you might want to consider the possible long term problems associated with bad guides.

A tight fit between the valve and guide is required to transfer heat, if the valve starts to suffer additional heat it is normal for it to fail. The exhaust valve operates in the hottest part of the motor and desperately needs to shed heat, the close contact with the guide is the best way it can transfer that heat.

We've all seen the destructive mess after a valve fails.

[dick911]

Hi lindemans,

I know you from another Porsche Forum. About 6 months ago we had some email traffic about rebuilding. You had questions about my rebuild and pictures of it, remember?

All the things you noticed about blue smoke is clearly valve guides en rings. I f buget is a problem I know a really good guy (even with garantuee!) who can perform a top end rebuild. Even well known Porsche traders let him do engines and other repairs.

Normally a 3.2 with such a mileage in (high speed) Europe suffers from valve guides and rings. No big deal to rebuild it. There are good ways to check your bearings and other parts of your engine.
Don't get confused by the known specialists; for a lot of engines a top end rebuild is enough.

If interested contact me at his Forum or the other Porsche Forum in The Netherlands.

Regards,

Dick

[lindemans]

Prima Dick, ik zoek je wel even op via www.porscheforum.nl of stuur even een PB-je daar....

Thanks for all the feedback folks !
I would love the idea of redoing the engine myself when necessary, just getting emotionally prepared.
Although the required one time investment in specific tools offsets quite a bit of the laborcost of outsourcing the job.

I found out that in Europe the /20 engines were all delivered with Mahle Nikasil P&C sets, so that's one potential surpirse eliminated.

[Wayne 962]

Originally posted by lindemans
WAYNE, that's exactly what I already did.
In fact, I have read both your books several times and in my sleep I've rebuilt the thing a dozen times....

Okay, cool. Then do the tests detailed in the "When to Rebuild" article, and let us know what you find. Blue smoke out of a tailpipe is very subjective...

-Wayne

[dick911]

Hi Lindemans,

Already did a pb at the Porsche Forum yesterday evening.

Regards,

Dick

[MBEngineering]

HI if you require tools/engine stand i could poss rent you them out?? send PM or email mb.engineering@btconnect.com

regards mike

[lindemans]

Originally posted by Wayne at Pelican Parts
Okay, cool. Then do the tests detailed in the "When to Rebuild" article, and let us know what you find. Blue smoke out of a tailpipe is very subjective...

-Wayne

Wayne, what exactly do you mean by "very subjective" ?

[BReyes]

Experience tells one alot. So it is subject to opinion. An objective measure such as leakdown gives an objective(demonstrable/repeatable) measure of internal components.

It can be a few guides, maybe a few valves, and the machinist will mix and match and add new guides(valves) as needed. But your rings may be fine.

And last but not least, consider the issue of head studs (and other while you're there details).

When is last time had valves adjusted?

[lindemans]

@BReyes:
I'm pretty strict in following the maintenance book.
Last time valves were adjusted is 13.000 kms ago which equals some 8-9.000 mls. Nevertheless that was just over 2 years ago but I asume valve clearance will change over "miles", not "time".
Of course oil and filters are changed annually....
Gee while reading this back: I should drive more !