I have a 98 EXP 4x4 5.4 with factory tow package and and auxiliary heavy duty cooling system , 133k miles 1 quart oil between 5k oil changes..

Where should I start to determine the root cause of the oil in cooling system? I have researched this but some threads point to the oil filter adapter gasket while others point to head gasket issues. I don't mind walking away from this EXP if it is head gasket or motor issues but I just as soon keep driving this vehicle as it has been the best one I have owned in 40years of driving when it is running properly.

 

It might be tranny fluid and not oil. If it is tranny fluid then the tranny cooler built into the radiator sprung a leak and is allowing the fluid to seep into the cooling system.

 

how can I tell if it is tranny fluid or oil?

 

1. What is the color of the "oil" in the reservoir, black, brown, red, etc.?

2. Have you checked the tranny fluid or the engine oil to see if you have antifreeze in either one?

 

Quick thinking Alloro, reps sent.

 

Sorry for not getting back sooner but I was out of town for a few days. Anyway I checked the engine oil and transmission, both appear to be clean as can be, free of anti-freeze and no unsual smell. No signs of any blow-by on the oil filler cap The coolant in the reservoir is brown, similar to a paper bag. I made a 200 mile round trip this weekend and towed a trailer for about 25 miles without any issues.

 

Try to verify that it is not ATF. If it is ATF you may be getting close to a transmission melt down if coolant enters the trans. It doesn't seem like that is the case so it is most likely just the adapter gasket on the side of the block and that's not really hard to replace. I suggest that you replace the gasket, change the coolant and watch for any oil or ATF to get into the system.

 

Due to work the last few months I let this oil in coolant problem linger. About a month ago, I partially drained the coolant reservoir and poured it into a plastic bottle and allowed the coolant and oil to separate. It defintiely appears to be motor oil rather than transmission fluid, so I am going change the oil filter adapter gasket.

It looks like I have to drop the front differential to get at the adapter gasket. It is not clear if I can get away with disconnecting the axles and driveshaft at the differential or if they have to be completely removed. I would appreciate repair tips from someone who has done the oil filter adapter gasket replacement on a 4x 4 expedition, as if I have to tie up this vehicle during the work week I need to jump into a rental car. Thanks.

 

According to my manual the front diff has to be removed or somehow a bunch of clearance has to be there to be able to do the replacememt:

<TABLE width="95%"><TBODY><TR><TD>SECTION 303-01: Engine — 4.6L and 5.4L
</TD><TD align=right>1998 Expedition/Navigator Workshop Manual
</TD></TR></TBODY></TABLE>
IN-VEHICLE REPAIR
<HR>Oil Filter Adapter —4x4

****** name=tps_proctitle content="Oil Filter Adapter —4x4">Removal

1. Raise and support the vehicle. For additional information, refer to Section 100-02 .

1. Remove the lower radiator hose (8286). For additional information, refer to Section 303-03 .

1. Remove the front drive axle assembly. For additional information, refer to Section 205-03 .

1. Remove the drain plug and drain the engine oil.

1. If the vehicle does have an oil cooler, remove the oil cooler. For additional information, refer to Oil Cooler in this section.

1. Disconnect the oil pressure sender electrical connector.

1. Remove the four bolts and the oil filter adapter.

Installation

1. Install a new oil filter adapter gasket (6840).

1. Position the oil filter adapter and install the four bolts.
   • Install a new oil filter adapter gasket.
   • Position the oil filter adapter and install the four bolts.

1. Connect the oil pressure sender electrical connector.

1. If the vehicle is equipped with an oil cooler, install the oil cooler. For additional information, refer to Oil Cooler in this section.

1. Install the drain plug.

1. Install the front drive axle assembly. For additional information, refer to Section 205-03 .

1. Install the lower radiator hose. For additional information, refer to Section 303-03 .

1. Lower the vehicle.

1. Fill the engine with Super Premium SAE 5W-30 Motor Oil XO-5W30-QSP or equivalent meeting Ford specification WSS-M2C153-G.

<HR>
It seems that a rental car is in your future or better yet if you have a reliable shop in your area you might want to pay to have the job done. It looks like a lift would be a real asset for this job.

 

MotoMel,

Thanks for providing the instructions.

I ended up tackling the repair yesterday and it was not very difficult just messy with an endless drip of mtor oil. Differential removal was straightforward even though everything is so rusted and has not ever been apart. Had a problem that I could not get anything into the hex on the oil cooler due to the excessive rust so I ended up having to use vise grips on the round edge of the nut for the oil cooler. I also had the oil pressure switch wire which was pinched between the two halves of the motor mount. Must have been pinched during assembly at the factory. I did not disconnect the radiator hose as it is too difficult to access, but I was able to reach in sufficiently to remove, replace gasket and clean both surfaces.
When all was done, I flushed the system several times. Now what to do with all that coolant.

 

Almost any parts store will take it for recycling.
Glad to hear it is all done and hopefully cured.

 

Its been close to two weeks now and all appears to be well. Will check again tomorrow to be certain. In MA, many auto parts stores will not accept antifreeze.

 

Whats the status of your repair? Has replacing the gasket resolve the issue.

I too have the same issue (and parts in hand). Just need time to do it.

Thanks!!

 

allmighty,
Everything still continues to look good. At least once a week, I check the engine oil level and the coolant reservoir for oil contamination and nothing has changed since the repair. It has now been about 6 weeks since the repair however this time of year we do not use our expedition very much. I have only put about 700 miles on it since the repair.

 

Take it out to play in the snow, if and when we get some snow. Or just wait for spring and play in the mud.