Hi Guys, The 289 V8 in my 56 Sky Hawk has been getting unhappy over the past few months and I want to see what you think the root problem is. Since I've had it the oil pressure has been low when warm, delivering barely 10PSI per 1000 RPM. More recently I have noted that when you accelerate, the oil pressure drops - as mush as about 8 pounds, and when idling slightly warm, the oil pressure gauge flickers as much as
5 pounds. When cold or fully warmed up, the flicker is barely noticable if not at all. Now I am beginnning to hear the start of some rapping on slight acceleration at high speeds, so before going any further I'm trying to decide if the problem could be: a-main crankshaft bearings, or b- connecting rod bearings, or c- both, or d- something else. Any ideas??????????
Sounds like bearing problem. How many miles? Could be time to freshen up mains, rods and cam brg. Also, you might check the relief valve to see if it might be sticking, or stuck. Check spring tension and make sure it hasn't been installed backwards. Could even be worn gears in the pump? Has any of these items ever been changed out, engine rebuilt, etc...?
Hi Guys, I did just notice a bit of gas leaking through the vent hole in the fuel pump so I do know I have to repalce that, and there is zero coolant in the oil - I check for that every time I pull the dipstick or dump out the old oil. I also change oil every 1000 miles and had de-sludged the engine with Mystery Oil a few months back. However, low pressure has always been an issue with this engine and I had been told by one or two people that "low oil pressure was a common situation with engines back then and if you don't hear anything weird, forget about it". I never really felt very comfortable with that theorum, especially after my 62 GT split a crankshaft after months of marginal oil pressure. The engine had been displaying a raping sound when fully warmed up at speeds approaching 3000 RPM on the highway, AND the oil pressure had been dropping on throttle ups are months now. The other day I finally noticed that the rapping was getting louder and the oil pressure at 2000 RPM was lower than it had been - and is now below the 1000 pound per 10,000 RPM rule. I figure it probably is time for new main bearings, and connecting rod bearings; these I can do by dropping the oil pan and replacing them myself without pulling the engine. I am hoping to be able to avoid the cam bearings because I'm not equipped to pull the engine and at that point I'd probably just arrange to have the engine pulled & rebuilt. Methinks that the oil pressure gauge flutter of several pounds at idle and flutter on acceleration is an indicator that the crankshaft is being torqued by the force of the pistons / rods under firing stroke as a result of excessive bearing clearance, and replacing the crank and connecting rod bearings with perhaps 1 under sould address that. FYI: the engine has 99,000 miles on it, and to my knowledge has never been rebuilt.
See, my thing is this: I want to use the opportunity to do some of the work myself and learn - thru - doing, but I don't want to spend the next year doing this, nor do I want to have the engine totally rebuilt if it doesn't absolutely need it. So I'm looking to get my intellectual ducks in order and glean a little insight from you guys who have been there-done that. I think Stude V8's are the perfect engine to learn by doing on, since they are such friggin great engines and so bulletproof.
If you have a *good* oil pressure gauge, you'll notice a "little" flicker under acceleration, this is normal with a reasonably worn engine. I think on my '62 it would noticeably drop 1-2 PSI under acceleration when warm; the Porsche a little more than that (but the 944 has a known issue with rod bearings - not mine in particular, but apparently the crank is not drilled correctly for high RPM operation.)
a flexible grease gun hose from wal-mart can be adapted to fit with FLAPS fittings, don't ask me how I know, assume anal engineering................ ,grin>
If you had gas in the oil, you'd have wiped all the bearing all ready and we wouldn't be speculating on what to do. I've all ways considered the "don't fix what ain't broke" idea to be ok, except where worn bearings and old oil lines are concerned. If your main and rod bearings are worn to the point that the engine is knocking, and it has developed lower oil pressure then would be normal, then you assurdly will have worn cam bearings. If the bottom of the engine isn't being properly lubricated, how do you suppose the top end will be?
Of course, like my Avanti, your Hawk may be lucky. When I bought it, it had just over 70K miles on it. It had been sitting for some time and everyone thought the engine was stuck. Turned out to be a missing starter drive, but the front main leaked and the upper rear pan gasket leaked. I took the engine/tranny out and checked everything. No appricable wear noted. New seals, gaskets to reseal engine, tranny, and rear axle. No more leaks, but there again, no problem with oil pressure
All I'm saying is don't short cut it and whined up shooting yourself in the foot.
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