Fleetwood Oil Filter Adaptor Leak

[Adam]

So while leaving for work this past Friday morning, I noticed a hissing/bubbling sound from the Fleetwood at Dunkin' Donuts. I decided to head back home to investigate when I started seeing the low oil pressure light come on (solid at idle, flickering on and off at part throttle). Looking under the car after I got back home, there was a substantial puddle of engine oil on the ground.

The leak seemed to be coming from the driver's side of the engine and judging from the stream of oil in the street, it was leaking very fast. The location pointed towards an issue with the oil filter adapter gasket. I had used an aftermarket seal kit to replace leaking parts back when I got the Fleetwood and also aftermarket cooler lines since the factory ones were in terrible shape. Several months ago I re-torqued the filter adapter during an oil change and noticed it was looser than expected. At least it was time for an oil change, so I was not loosing a bunch of new oil... One thing is for sure, stopping at DD probably saved my engine. I could not hear the hissing until I rolled the window down at the drive through. Had I not stopped, I would have gotten a low oil pressure light at highway speeds on the way to work. Now that would have been a terrible story.

So my local Chevy dealer stocks the part under GM# 88893990 for less than $6. Not a bad price.

To start the job, drain the oil and remove the filter. I only had about one quart left in the pan after my leaking, so that is something. The cooler hose assembly is attached to the filter adapter with a 15mm nut and to the front of the oil pan with a 13mm nut. Once that is removed, another quart or so of oil will drain out of the cooler.

Now you can remove the adapter. It is held to the block by two bolts with 1/4" hex key heads. Make sure the gasket and the o-ring come off with the adapter. Now you can clean the adapter.

Found the problem. The o-ring had hardened over the last year and developed a small crack. Upon further inspection, it broke entirely.

Reassembly is reverse of removal. Part of the difficulty is lining up the gasket so the bolts can go through correctly. If you hold the bolt up through the adapter, you can use them to hold the gasket in place as you reattach the adapter.

Leak fixed! This part is cheap enough that it could be replaced as preventative maintenance every year or so as part of an oil change. Or when it starts leaking a little, rather than when it is leaking catastrophically.

[kevm14]

Huh, I figured it was the gasket not the O-ring. I think the same gasket and O-ring has been on my Caprice since 2004. In fact I found a GM Parts Direct receipt for 12556204 (the non-KC4 adapter) dated 2/6/04 (so 10 years and roughly 90k ago). Maybe I should check it for leaks. But can I tell? Ha.

You don't need to drain the oil to change the filter adapter. The level in the sump is lower than the adapter.

[Adam]

You don't need to drain the oil to change the filter adapter. The level in the sump is lower than the adapter.

True. For maximum value, rolling gasket change into an oil change (since removing the filter makes this job much easier) makes sense. If I felt really cheap and wanted to do this as fast as possible, I suppose I could have done it without removing the lines or the filter either.

[kevm14]

I definitely have removed my adapter a half-dozen times over the years. Off the top of my head:

1. When I installed the 94-96 cooler adapter (probably had it off and on a couple times looking into that oil pressure issue)
2. When I changed that out for the non-KC4 adapter
3. When I installed the oil temp sensor (in the adapter)

I don't think I drained the oil for any of it.

Ah, the bolts are on the outside. Maybe it was the 91-93 stuff that had the bolts on the inside (bigger filter).

[Adam]

After more closely examining the driveway and street, it looks like the leak started when I left the house. I see an oil stream from where I backed out and drove away, and another where I came back and pulled into the driveway.

I wonder how long the oil stain will remain on my road....

[kevm14]

Ed tells me you are worried about bottom end noise. I'll be the judge of that.

[Adam]

Oh yeah, there's that. It is fine when it is warm, thereby solving the problem forever.

[kevm14]

It is nearly impossible to really judge the health of an engine at startup when it's cold as hell outside. Lots of stuff sounds nasty.

[Fast_Ed]

Lots of stuff sounds nasty in the cold.. especially LT1's, apparently. Good writeup!

From my extensive knowledge, that sure looks like the timing belt for a 1UZFE in the background of your oil filter adapter picture!

[Adam]

Just an update to this thread. I have now driven ~2000 miles since doing this repair. The oil is down slightly less than half a quart. Previously, it was using a quart every ~1000 miles so it goes to show how terrible some non-OEM parts can be.