Finally a Fox Body Owner - 1988 GT acquired!

Double check that trans fluid is not leaking out of where your speed sensor gets installed in the transmission. My 94 and the 89 I am working on now, both had this leak.

86GT351 said:

5.0 Fox Engines are known for upper oil leaks that appear to be The Rear Main Seal. Behind the Intake where the PCV goes remove the PCV valve. Replace the Valve, The screen in the intake and the grommet. If the screen gets clogged it causes oil to push past the rear lower intake seal. Appears every time to be a Rear Main Seal.

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Thanks man. I had never heard about this until recently so will definitely be taking a look at the PCV valve.

Upon further inspection, it looks like I've got an exhaust leak in addition to the oil leak that was not resolved by the RMS being replaced. I tried a quick fix on the exhaust hardware but it didn't do the trick so I'll have to get under the car for a closer look.


A couple of days ago , I did confirm that the car doesn't seem to be leaking significantly more oil than previously. It doesn't seem to be leaking oil at all while parked/not running. I checked the oil before and after taking it for a 20+ minute drive and it didn't seem to be significantly down.

I still didn't drive it too hard but the few times that I did give it a little more gas, the gears felt pretty good. I am hoping we'll get some slightly warmer weather sometime soon so I can spend a little bit of time in the garage getting a closer look at things underneath the car.

We recently had carpet replaced with hardwood floors in part of our house and I managed to keep a decent enough sized piece of carpet to give me some temporary padding/sort of insulation.

So I finally got behind the intake manifold and saw that the PCV valve was super loose. It seemed like it was still in the hose but was disconnected completely from the grommet and the grommet itself came out really easily. I was also able to remove the screen pretty easily with a magnet:


I replaced the screen, grommet, and PCV valve and everything new seemed to fit pretty decently. These are the new pieces:


It was pretty late when I finished it so I didn’t start the car yet but will do that today and see how the oil leak situation is looking. I didn’t take a ton of pics but recorded some of that process for my next video.

On a non Fox Body related note, I took a new GT for a drive a couple of days ago. This was my first time driving a 2018+ S550. There’s a lot to love about these new Mustangs.


More detailed impressions in my most recent Vlog:

You just fixed your oil leak. Unless your rear intake is leaking as well.

86GT351 said:

You just fixed your oil leak. Unless your rear intake is leaking as well.

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I wish this were true. I'll document more in my next video but there's definitely still some oil leaking. I need to get the car elevated and get underneath to clean things up more and see what else it could be.

Hey Dude, take a closer look at your tail shaft seal when you get under the car. Yours does does appear to have the dust boot, with all that oil in the tunnel and on the exhaust, you might need a new one.



As for the oil leak out of the bell housing…..your rear mail seal might be f.u.b.a.r..

golkhl said:

Hey Dude, take a closer look at your tail shaft seal when you get under the car. Yours does does appear to have the dust boot, with all that oil in the tunnel and on the exhaust, you might need a new one.

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As for the oil leak out of the bell housing…..your rear mail seal might be f.u.b.a.r..

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Thanks for mentioning that. I'll do some investigating.

My latest attempt to get the exhaust leak sorted didn't work. I have not been able to get the hardware on the driver side to tighten down correctly so thanks to a recommendation from another Fox owner, I stopped by Tractor Supply and picked up some new hardware that hopefully will do the trick.


I ordered a replacement hardware kit from LMR and the bolts are too narrow and too short. The bolt on the far right is one of the bolts from that kit. The others are what I picked up today. Will try to see if I can get this sorted out tomorrow, since the weather is supposed to be semi-decent.


I finished editing and uploading my latest Vlog on the PCV valve replacement process:

Hey Dude,
This is a pic of the 89 GT I am working on, looks to have an oil leak from the hoses that connect the pcv system to the intake manifold. It looks to have been leaking right into my bell housing, not unlike yours. You might have to remove the upper intake manifold to access them.

Haven't updated my threads in a while but for good reasons, the main one of which is highlighted in a recent vlog:


Since then, I've made a few small updates to the Fox, documented in more recent videos but hoping to have more time in the garage as it gets warmer and as the new addition sleeps for longer periods of time.