stupid leak

agilchrist · 01-30-2010, 05:05 PM

Early 85 944 NA
It's recently developed an oil leak near the rear of the engine. From what I can see, it looks like it might be coming from the head gasket. But now I'm wondering, are there actually any oil passages thru the gasket between the block and head? I know the cam needs oil pressure, but can't remember where it gets it.

HondaDustR · 01-30-2010, 05:33 PM

In order of most likely to least likely:

1. Check the cork gasket on the rear of the cam housing. The bolts are not torqued very hard at all and often back out. Use lock washers on them and do not tighten them too hard or it will squeeze the gasket out and leak. The cork also likes to just deteriorate over time.

2. Rear balance shaft housing plug o-ring has shrunken/hardened and is leaking. Reach up in there and see if the plug is loose. It's a real PITA to get to, so many people have successfully temporarily fixed it by cleaning it and gooping with high temp grey RTV.

3. Cam housing gasket sometimes will leak. It's possible the bolts have loosened, but in my experience they stay pretty tight. There is an oil pressure feed for the cam and lifters at the rear corner and an oil distribution channel along the top length of the housing mating surface. Heat from the exhaust system can break down the gasket over time.
4 and 5 (kind of a toss up). Oil pan gasket, which isn't easy, but there isn't going to be mess much above it, so that will help determine the case. RMS could be it too, and it will throw oil everywhere if it's leaking at the crankshaft sealing area.

6. The cylinder head has a oil pressure feed that goes to the cam housing, so the gasket could be leaking in that back corner.

7. Leak at the seam between the main bearing girdle and the block, which runs between the RMS and the oil pan gasket. Not likely but it's possible if it was badly re-sealed the first time. Not much you could do short of complete engine disassembly, except maybe gooping it with RTV.

agilchrist · 01-30-2010, 05:56 PM

Thanks Honda!
As best I could tell, the leak starts just below the head, and doesn't make too much of a mess. I'd be tempted to ignore it, but it drips onto the exhaust and smokes.
I did have overheating issues last summer, so I hope it's not a warped head. I'll put it up on jackstands tomorrow and take a better look at the source. Thanks again.