oil leak behind alternator ?
08-06-2015, 03:36 AM
#1
Instructor
Thread Starter
oil leak behind alternator ?
Hi guys i was removing the alternator on my 81 US 928 and i noticed a decent amount of old caked up oil and grime all along the oil pump pressure unit area between the back of the alternator and oil filter. Is there a weak gasket or copper washer that is proned to leaking oil in this area? Also noticed the oil all the way up to the head gasket area towards the front of the car. Yikes i hope the head gaskets are ok. Is it possible it can be leaking from the oil resevior up on top of the engine and running down? Any info is greatly appreciated
08-06-2015, 05:00 AM
#2
Rennlist Member
Best thing you can do for starters is clean up the general area with a powerful de-greaser such as a spray type carb cleaner. It is quite feasible some oil gets spread around if the oil filter is not tightened correctly not to mention the possibility of some spillage when the filter is changed.
That location can also be a bit messy from leaking power steering fluid [ATF] that commonly occurs- are you sure it is engine oil and not ATF? There are also various plugs/union in that location that can also leak.
If there is evidence of oil coming down from further above then the obvious suspect location would be the cam cover seal. Difficult to see but you can run your finger along the lower edge to see if you can find any obvious "wet spots".
Rgds
Fred
That location can also be a bit messy from leaking power steering fluid [ATF] that commonly occurs- are you sure it is engine oil and not ATF? There are also various plugs/union in that location that can also leak.
If there is evidence of oil coming down from further above then the obvious suspect location would be the cam cover seal. Difficult to see but you can run your finger along the lower edge to see if you can find any obvious "wet spots".
Rgds
Fred
08-06-2015, 12:26 PM
#4
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
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To make things easier.... I was browsing in Home Depot, looking for some heavy duty oven and grill cleaner in the cleaning products aisle, when I spotted some Zep heavy-duty foaming spray degreaser. Ingredients list has d-limonene as the active ingredient, which is perfect for use on aluminum. Most others fall into the caustic category, like the popular purple degreasers from Castrol and others. Those are specifically NOT for use on aluminum (read the labels...). Common solvent-based degreasers are OK, but share a long-lasting fragrance that I don't care for. This class includes Gunk Foamy Engine Brite, which is usually my go-to product for this duty in spite of the post-op smell. Anyway, I grabbed one can of the Zep product but have yet to actually use it, mostly since the car hasn't been driven much since it was last bottom-scrubbed. Plus it generally doesn't leak...
To your question, and reinforcing Fred's excellent response: Probable causes are power steering leaks from crispy hoses at the pump (sits right above the alternator), and also at the reservoir/filter. The reservoir/filter is a normal replacement along with power steering system fluid flush and replace, at the same 25k interval recommended for the automatic transmission fluid. Same fluid is used, and it's relatively easy to justify one consolidated mess from one consolidated service. The reservoir is a common ZF part used on many other cars, so it's not too pricey to replace. Plan on replacing those crispy hoses, since they won't seal well on the new reservoir. They are relatively easy to access since the alternator is out of the way. Our vendors have the hoses and the seals for the banjo fittings at the pump.
Also behind the alternator, there's a pair of hose connections for the oil cooler if your car has one installed. Those hoses run to an internal exchanger that lives in the driver's side radiaor tank, with two large connections for the hoses pretty obvious at the radiator end. The other ends of those hoses conect to threaded adapters that go into the block, and are secured with some pretty tough threadlocker/sealant. Leave those fittings in the block, counterholding them securely if you need to remove the hoses for replacement. There are more than a few cases where the threadlocker has been stronger than the aluminum that they thread into.
The bottom of the block section where the hoses connect is an oil thermostat and pressure relief. Access from the bottom, the plug has an aluminum seal. Above that is a spring and piston. Workshop manual has assembly details if you find that this is the source of your oil leak. Low probability.
The oil pressure sender screws into a fat adapter. Sender is small threads, adapter has a sealing ring on it IIRC.
Behind that is the oil filter.
The original oil sump gasket is cork, and it gets hard and crispy with time and heat. The sump itself is aluminum, and the sump bolts do not have lockwashers on them. You may find that the sump bolts are a little loose, and it's possible to very gently draw them up snug again. Use great care to just draw them up. It's easily possible to overtighten them, and there's no good torque value (very small) I can recommend for doing this on a used gasket. Maybe contact with the sump plus 1/4 turn? Anyway, access varies around the sump, so in some places you can use a socket with universal, some places a straight socket, and others will need a box or ratcheting-box (gearwrench) to access them all.
Oil also falls from the cam towers. If the heads have been off, and original factory cam tower gaskets used on reassembly, this is a likely spot for leakage. Greg Brown offers a significantly improved set of gaskets for this, highly recommended.
To your question, and reinforcing Fred's excellent response: Probable causes are power steering leaks from crispy hoses at the pump (sits right above the alternator), and also at the reservoir/filter. The reservoir/filter is a normal replacement along with power steering system fluid flush and replace, at the same 25k interval recommended for the automatic transmission fluid. Same fluid is used, and it's relatively easy to justify one consolidated mess from one consolidated service. The reservoir is a common ZF part used on many other cars, so it's not too pricey to replace. Plan on replacing those crispy hoses, since they won't seal well on the new reservoir. They are relatively easy to access since the alternator is out of the way. Our vendors have the hoses and the seals for the banjo fittings at the pump.
Also behind the alternator, there's a pair of hose connections for the oil cooler if your car has one installed. Those hoses run to an internal exchanger that lives in the driver's side radiaor tank, with two large connections for the hoses pretty obvious at the radiator end. The other ends of those hoses conect to threaded adapters that go into the block, and are secured with some pretty tough threadlocker/sealant. Leave those fittings in the block, counterholding them securely if you need to remove the hoses for replacement. There are more than a few cases where the threadlocker has been stronger than the aluminum that they thread into.
The bottom of the block section where the hoses connect is an oil thermostat and pressure relief. Access from the bottom, the plug has an aluminum seal. Above that is a spring and piston. Workshop manual has assembly details if you find that this is the source of your oil leak. Low probability.
The oil pressure sender screws into a fat adapter. Sender is small threads, adapter has a sealing ring on it IIRC.
Behind that is the oil filter.
The original oil sump gasket is cork, and it gets hard and crispy with time and heat. The sump itself is aluminum, and the sump bolts do not have lockwashers on them. You may find that the sump bolts are a little loose, and it's possible to very gently draw them up snug again. Use great care to just draw them up. It's easily possible to overtighten them, and there's no good torque value (very small) I can recommend for doing this on a used gasket. Maybe contact with the sump plus 1/4 turn? Anyway, access varies around the sump, so in some places you can use a socket with universal, some places a straight socket, and others will need a box or ratcheting-box (gearwrench) to access them all.
Oil also falls from the cam towers. If the heads have been off, and original factory cam tower gaskets used on reassembly, this is a likely spot for leakage. Greg Brown offers a significantly improved set of gaskets for this, highly recommended.