Interesting 1995 F355 issue

Well guys I have a bit of a window in my schedule for the next 1.5 months. Time for the tear down.

My general diagnosis is as follows:

Smoking out exhaust

Cylinder #2 oil fouled a spark plug.

All other cylinders compression/leak down was even

Cylinder #2 was equal on leak down % but was 25psi low on compression.

I have no Crank Case pressure (rings/liners are good)

Compression of Cylinder #2 is inconsistent (valves are moving around in the guides, causing varying compression numbers)

Pulled the Exhaust manifold oil soot in Cylinder #2 exhaust port, all other cylinders are "clean" of oil soot.


I would say this is evidence enough that the heads are coming off !

I did find this thread along the way good read on this issue http://www.ferrarichat.com/forum/technical-q/395581-how-does-leak-down-test-confirm-good-bad-valve-guides-2.html


I'll update latter this week when the motor is on the ground!

 

Hello All, Here is an update on the car.

It's been a long busy summer, race season has been killer this year!

I finally dropped the motor out about a month ago when I had some free time.

I got the heads off and found the true root of my problems.
One of the cylinder liners had totally wore out, all of the cross hatch was gone and the rings on the piston were shot. The Nikasil had totally failed, I have seen a few failures from other manufacturers but never a single liner. (After speaking with a Ferrari Factory Authorized engine builder, he said the liner started to fail on day one back in 1995. He has seen 2 other failures just like this and my car was the 3rd. No idea why this happened maybe not enough oil on initial start up or just bad Nikasil)

Lukily the piston was fine. The skirt didn't even have a scratch, the piston rings took the full abuse of the liner failure.

About 90% of the smoke was from the oil ring on the piston completely letting go, it just hit it's limit. I pressure and vacuum tested the heads and the guides were worn and in need of replacement.

I rebuilt the heads, new guides, seals and full valve job. The exhaust valves were all slightly bent from banging around in the shot guides so new exhaust valves went in too!

Here are some photos of the process so far. I am hoping to get the car back on the road in the next few weeks.

I don't know why people fuss about taking the engine out, I could have done this at home on the ground. I love these cars!




Engine with the heads off



Good Cylinder liner



The Bad Cylinder Liner !




Good valve guide




Bad valve guide (see the oil coking)



Dirty oil covered valves




New Cylinder Liner and new piston rings




Quick shot of my engine tear down area



I hope to put the belts on the motor and start putting it all back together this week. I'll post a few photos along the way back in

 

Leaking (badly) injector in that cylinder?????

 

I actually flow tested the injectors while the car has been apart. They are all within 2% of each other and that is well within tolerance.

Fuel washed cylinders tend to have a lot of scoring because of lack of lubrication.

 

And your sure the header on that side was Ok?

 

Yea, no cracks ect. You see more damage to the valves than anything else.

 

Guys, just an FYI on compression/leakdown tests and valve guides. You would have to have VERY worn guides for comp or LD numbers to be affected -- so worn that valve stem play is causing poor valve seating. Worn guides cause high oil consumption. They don't cause poor compression unless they're very far gone. The only way to know the health of the guides is to keep track of oil consumption or remove the rockers and retainers and measure valve stem play.

 

Was this a valve guide issue or cylinder lining problem? I'm confused...

 

Was it necessary to pull the motor out to pull the heads out?

 

how many miles does the car have?

 

Do you have the torque specs for assembling the head?

 

Very true. But these motors are usually so close, you can pin point a problem cylinder with leak down and compression.

FYI these are Hydrualic lifter motors.. I would hate to shim valves and followers in one of these bastard motors

The guides were bad. But the major smoking issues was the liner/ oil ring being almost gone. Surprisingly the cylinder still had excellent compression.

There is a long long list of why the motor has to come out. We can start with the fact the timing belts have to come off to get the heads off. You try getting the belts off the motor and re timing the engine correctly in the car..

22,000 miles

The full factory shop manual is all over the internet for free! A quick google will find a copy!