3.8l 1984 with big oil leak December 17, 2015, 09:32:50 PM Hello all have 1984 tbird wit 3.8l now with 71k miles. Began dripping more recently and replaced valve cover gaskets as they were leaking. Leak became much worse and so looked more closely and the engine is leaking mostly from right side of block dripping onto starter, cross member and dripping off bell housing and onto y pipe. For certain valve covers arent leaking but i cant get quite a good enough look without a hoist but seems to be head gasket on right side. The leak has massively soaked the cross member, y pipe the entire transmission, and incredibly most of the underbody all the way back to the rear axle.I bought the car fully knowing the 3.8 ends with cracked heads leaking gaskets etc but i had hoped to get 100k out of it...Anything else it could be??ThanksRuss Quote Selected
3.8l 1984 with big oil leak Reply #1 – December 17, 2015, 10:51:10 PM Usually oil leaks are caused by a clogged pcv filter. These clog up and are often overlooked. It vents pressurized gasses from inside the engine back to the intake to get burned up for emissions reasons. Every engine has blowby. Piston rings are actually a fairly loose seal and the pressures naturally escape into the engine.Then there are the front and rear main seals. The rear is especially hard to diagnois because oil gets flung around by the flywheel and can get all over the place. It also requires dropping the transmission to replace.Clean it up the best you can with a pressure washer, car washes work good for this as they have grease traps, but it does piss off the owners as they have to pay alot to have it hauled off. Then get a cheap wire brush and ser set from harbor freight with some assorted engine degreaser from your auto parts store and clean it all off the best you can. Often times valve covers are overtorqued and bend the flimsy sheet metal covers then they don't really seal at all. I've taken a few off and beat on them with hammers over a block of wood and gotten them much straighter that way.Good luck, and let us know what you find. Quote Selected
3.8l 1984 with big oil leak Reply #2 – December 17, 2015, 11:35:07 PM Quote from: Haystack;452982Usually oil leaks are caused by a clogged pcv filter. These clog up and are often overlooked. It vents pressurized gasses from inside the engine back to the intake to get burned up for emissions reasons. Every engine has blowby. Piston rings are actually a fairly loose seal and the pressures naturally escape into the engine.Then there are the front and rear main seals. The rear is especially hard to diagnois because oil gets flung around by the flywheel and can get all over the place. It also requires dropping the transmission to replace.Clean it up the best you can with a pressure washer, car washes work good for this as they have grease traps, but it does piss off the owners as they have to pay alot to have it hauled off. Then get a cheap wire brush and ser set from harbor freight with some assorted engine degreaser from your auto parts store and clean it all off the best you can. Often times valve covers are overtorqued and bend the flimsy sheet metal covers then they don't really seal at all. I've taken a few off and beat on them with hammers over a block of wood and gotten them much straighter that way.Good luck, and let us know what you find.Valve covers are not leaking...i put felpro permadry gaskets on. Pcv is working fine. Front main is dry. Area of rear main seal is soaked with oil but the entire right half of cross member y pipe tranny and underbody is as well. Dripping from above starter as highest point...i think that leaves head gasket or intake gaskets in rear as two options. But this thing is really leaking bad. Quote Selected
3.8l 1984 with big oil leak Reply #3 – December 18, 2015, 09:54:13 PM Rear intake gaskets are a popular leak point on this engine. Clean up the rear of the engine around the heads/intake and see if you can find the leak. Quote Selected
3.8l 1984 with big oil leak Reply #4 – December 21, 2015, 10:11:02 PM I had a chance to look at it again tonight, definitely not intake gasket. I cant get a good look at the engine block on the right to confirm that its the head gasket. The only thing that Im not sure, as far as oil passages in the cylinder head, theres probably only drain holes, correct?? Surprised it would leak so much from head gasket....After 15 min of idling, maybe 20 drips of oil on ground. Quote Selected
3.8l 1984 with big oil leak Reply #5 – December 22, 2015, 11:02:01 AM Quote from: atengnr;453039.After 15 min of idling, maybe 20 drips of oil on ground.That ought to be easy to find... Clean the area with brake cleaner and run it just long enough to form a few drips... Quote Selected
3.8l 1984 with big oil leak Reply #6 – December 22, 2015, 05:09:37 PM Quote from: TurboCoupe50;453047That ought to be easy to find... Clean the area with brake cleaner and run it just long enough to form a few drips...Yes, will do. I need to get up enough to slide under cross member and get a view of the right side of motor. Will report back. Quote Selected
3.8l 1984 with big oil leak Reply #7 – December 24, 2015, 04:56:58 PM Quote from: atengnr;453054Yes, will do. I need to get up enough to slide under cross member and get a view of the right side of motor. Will report back.Well im embarrassed to say that it was the valve cover gasket leaking. I guess these rubber permadry gaskets need a bit more squeeze to not leak.....this is one christmas gift as although this is a secondary car, I was thinking that I had to let her go.Do you guys shoot for 7-9 ft lbs on valve cover bolts? Quote Selected
3.8l 1984 with big oil leak Reply #8 – January 04, 2016, 03:18:12 PM If its leaking with a new gasket, the gasket surface on the valve cover is probably deformed from previous owner's over-tightening the fasteners and distorting the mating surface. You should be able to flatten the stamped steel valve covers. Quote Selected
3.8l 1984 with big oil leak Reply #9 – January 11, 2016, 10:30:19 AM Quote from: JeremyB;453216If its leaking with a new gasket, the gasket surface on the valve cover is probably deformed from previous owner's over-tightening the fasteners and distorting the mating surface. You should be able to flatten the stamped steel valve covers.Or when originally installed they were torqued too much and crushed/tore the gasket. Quote Selected
3.8l 1984 with big oil leak Reply #10 – January 14, 2016, 06:53:32 PM IRRC, the premium gaskets on my '87 3.8 have crush washers on them that would prevent the gasket from being crushed/torn by over-torqueing the fasteners. Quote Selected
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