Twice in the past several days I have seen a reference to the jiggle test. I think I understand it, remove the oil filler cap to see how much pressure is coming out the cam cover. Should it be a lot or a little? I have replaced the flame trap on my engine with a new one and still I have what I think is excessive crankcase pressure. Oil weeps out of the oil cap as well as from around the distributor base, well many more areas too. I have assumed that the engine is worn out, if thats not the case, is there something I am missing? Is there more to the FT below the mesh screen? The mileage is around 177K and that sounds just broke in by board user standards. I really like my '81 245 GLT and I am interested in making it last. Any input will be appreciated.

The "jiggle test"....

Loosen the oil cap and let it sit in position in the valve cover as the engine idles.

If your crankcase has too much pressure, the cap is likely to jiggle 'n bounce, causing it to rattle.

If you have sufficient crankacse vacuum, the cap will be sucked down aganist the rubber gasket and won't jiggle or rattle.

The source of vacuum at idle on your engine is through the small fitting in the manifold and through the small neoprene hose going to the flame trap. That hose VERY often plugs solid -- it's best to simply buy a new hose from the hardware store. To check, unplug the hose from the flame trap (on your car, it's BURIED under the intake manifold) and feel the vacuum at the hose as the engine idles. Should be lots.

Another problem area is the "breather box" (actually called the oil separator) under the flame trap. When it becomes plugged, fumes never reach the flame trap and your engine develops serious internal pressure. Not only does this pressure cause oil leaks everywhere, but it can sometimes pop seals from their housings (happened to my '83 when I first bought it).
--
Don Foster (near Cape Cod, MA)

Wagonboy
Basics of the jiggle test as I understand it: Loosen the cap and just let is sit on the gasket. It should sit there firmly and not jiggle if air is forced out past it. It should actually suck down. When you replaced the flame trap did you clean out the oil separator box under it? I understand these can clog up also it is bolted to the block, if this is clogged up your nice new flame trap will be useless.
Regards
Karl

86 245 189k KMS
Australia

Thanks for the tips. When time permits I will dig into the area where the breather box lives and check it out.

Don't forget the vacuum connectors on the intake manifold also. They also will plug up with crud. Use a small piece of wire (i.e. coat hanger) to clean.
RP
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RP '87 245 (Ol' Blue)273,000 mi, '93 245 (Ruby)150,000 mi, '02 BMW 325, '98 Mustang Cobra, '87 Harley Heritage....