View Full Version : Those Figure 8 Gaskets

07-22-2006, 11:35 AM
You know, I always worry about my Figure 8 gaskets because when I took the head off a year ago, I moved the crankshaft "up and down," maybe just one half of a full revolution, before I remembered to bolt some temporary liner stops on while I cleaned the water jackets.

What sort of damage/symptoms would I look for if I screwed something up? Compression? Overheating? Water in the oil? Oil in the water?

The car has been running fantastic ever since, so is this just the "forget it" category?

07-22-2006, 01:38 PM

You would most likely see coolant in the crankcase oil, if there is a problem. (Oil in the cooling system is possible, but pretty unlikely since the cooling system is pressurized more than the crankcase under normal operating conditions.)

Look for milkiness in the oil, next time it's changed, or any foaming on the dipstick (sorta looks like a dirtier version of the foamy milk on top of a cappuccino).

The most conclusive check would be to drop the sump pan and look inside it, to see if there is any sign that coolant is getting in there. There is usually a layer of scum formed on the walls and/or bottom of the pan, if coolant is getting into the sump.

Any of these symptoms would indicate a leak from the cooling jacket. That would need to be fixed or the bearings, in particular, and possibly the cylinder bores will be damaged pretty quickly because the oil's lubricating properties are greatly reduced.

If you don't see any sign of coolant in the oil, the seal is still good.

There are services were you can send a sample of your used motor oil for lab testing, analyzing it for trace amounts of various things. That might detect really small trace amounts of coolant getting into the crankcase, but is also useful looking for rapid bearing wear, ring wear, etc., based upon the presence of metal traces in the oil (some is normal, this is looking for more excessive wear and higher concentrations of metal).

There is a cost to this service, of course. But your peace of mind might make it worthwhile. I don't have a name to recommend, but you could probably google for one of these services, or look at websites vendors who specialize in racing parts and whatnot (Pegasus, Racer Parts Wholesale, etc.). Or, maybe someone else here can suggest a lab that does this sort of work.