930 Cylinder/Head Seapage?

[MikeD930]

I posted the questions over on another posting under C2 Cylinder/Head Seapage but mine is not a C2 which uses a gasket between the head and cylinder whereas a regular 930 does not.

My '87 930 may have a seapage problem between the cylinder and head on #3 or #4 (the middle cylinder on the driver's side).

How can I be sure if there is a leak between the head and cylinder and not from somewhere else as there are minor leaks elsewhere? This question has been answered by WERK-1 which is to check for leak at the rocker arms with covers off.

Do I need to remove the fan and shroud, clean everything up, button back up then drive for awhile until leaks shows up?

Can the fan/shroud be removed easily with engine in car?

If there is a leak between head/cylinder and the studs are not broken then how long can I continue to drive without hurting the engine assuming I keep the boost around .7 bar?

Would I need to install new valve gaskets after removing the valve cover even if the gaskets are new? I'm not sure if I can reuse them.

How much oil would leak out when removing the covers?

Am I to remove both intake and exhaust valve covers to do the oil leak test at the rocker arms? Or just the intake?

Thanks in advance for answering!

[jwasbury]

Mike,

For starters, why not just jack her up and clean the head to cylinder interfaces from the bottom. Then take her for a spirited drive with plenty of boosting for an hour or so, then jack it up and look closely at the interface area. I think you'd bee able to see discoloration if you've got a lot of leaking compression there.

Just to be clear...you wouldn't be leaking oil from between the head and cylinder, you'd be leaking compression and combustion gasses. Oil leaks would be from the rocker arm shafts, valve covers (or both), or from somewhere else.

[WERK I]

Originally Posted by MikeD94

I posted the questions over on another posting under C2 Cylinder/Head Seapage but mine is not a C2 which uses a gasket between the head and cylinder whereas a regular 930 does not.

My '87 930 may have a seapage problem between the cylinder and head on #3 or #4 (the middle cylinder on the driver's side).

How can I be sure if there is a leak between the head and cylinder and not from somewhere else as there are minor leaks elsewhere? This question has been answered by WERK-1 which is to check for leak at the rocker arms with covers off.

Do I need to remove the fan and shroud, clean everything up, button back up then drive for awhile until leaks shows up?

Can the fan/shroud be removed easily with engine in car?

If there is a leak between head/cylinder and the studs are not broken then how long can I continue to drive without hurting the engine assuming I keep the boost around .7 bar?

Would I need to install new valve gaskets after removing the valve cover even if the gaskets are new? I'm not sure if I can reuse them.

How much oil would leak out when removing the covers?

Am I to remove both intake and exhaust valve covers to do the oil leak test at the rocker arms? Or just the intake?

Thanks in advance for answering!

MikeD,
Sorry I couldn't respond sooner to your questions. In my opinion, $0.02, you should remove the valve covers and check for rocker arm leaks first. While you're in there, you will be able to check for broken head studs. Sometimes the part of the stud and nut will be flopping around in the shaft of the cylinder the stud goes into. Other times, just putting a socket on the nut of the stud and trying to turn it by hand will tell you if the stud is broken. I would also recommend removing both intake and exhaust valve covers. The intakes are a PIA to get off with the engine in the car.........maybe you and your friends would like to have an engine drop party in the near future?
I do not recommend driving a turbo engine car any distance with a broken stud, .7 bar or not. The combustion pressures these engines develop can be quite destructive to the head and cylinder sealing surfaces.

[magic930]

The gaskets can be reused if not too old and removed carefully, although I would recommend switching to the silicon kind which are designed to do that.

While you have the valve covers off , re-torque your head studs with a good quality calibrated torque wrench, this might clear up any leak.

[MikeD930]

Thanks guys. I'll try that once I get the car out of the shop. I'm having new front coil over struts installed along with smaller front tires.