'84 300CD - Oil Filter Housing Gasket R&R - Anything I Need to Know?

[nhdoc]

I noticed a dripping of oil from the area around the oil filter housing/block interface that leaves a spot on my garage floor so I ordered a new gasket. The PO had it "fixed" at a tech I know down in Norwood Mass who was too lazy to actually install the proper $2 gasket but instead used sealant to make his own...so $200 and 2 years later it is leaking again...big surprise there. Knowing this tech's work it doesn't surprise me one bit.

Anyway, I ordered the gasket and was looking at the job...looks pretty straightforward...remove the cooling lines, the pressure sensor line and what looks to be 5 6mm allen headed bolts and the housing should come off...anything I am missing here? I figured it will be messy but there looks to be enough room between it and the steering box to get it out and clean up both surfaces for the new gasket. Anything I can expect to run into that isn't obvious??

It's a royal PITA job. It's only 5 bolts, but 4 of them are pretty difficult to get with the steering box in the way.

Try tightening the bolts first. The heating and cooling can work them loose over time.

[MarkM]

Access to the bolts is not easy...I did this when I had the head of for a valve job. I recall that one of bolts sits so close to the chassis that I had to use an allen wrench with the short end ground down to about a half inch. Then to get leverage, I used a quarter inch rachet extension with a socket on the end that just fit the allen wrench...and even at that, I couldnt get the bolt really as tight as it should be.

Another thing, when you pull apart the housing, the gasket will pull apart.....major pita to clean off old gasket....not really that bad, but because of limited access, you need to use a hand held razor blade and just work at it methodically.

Detaching and reattaching the oil cooler lines is no picnic either, due to limited access. Use claw foot open end or flare wrench (little attachments for rachet set).

When I was done, It was one of those jobs that I initially thought would be fairly simple, and in the end I hoped I would never have to do it again.

If I were to do it again, I would combine this with replacement of the oil cooler lines (I have heard catastrophic stories of these lines failing...dump your oil while you are driving 70!), and motor mounts. Since you are going to detach the oil lines, it is a good time to replace, especially if leaking. With the motor mounts off and the engine raised, it is much easier to get the new lines in, and with the motor mounts off, I believe you can jack up the engine and move it a little to the side to provide a few more vital inches of access to the oil filter housing.

A few last things...

After I did the job on my car, I remember hearing that there is either a small port with a replaceable item in the housing, or that should be removed and cleaned out, or something to that effect, an oil return port with a screen or something. I remember being mad that I didn't know about it until after I did the work! Anyone know what this is?

Also, use gasket sealant on both surfaces to ensure no leak. You will never do this again, so why not! After I did the job on my car, the damn thing still leaked!!!

With the oil filter housing off, you might as well put in a new engine shut off valve (mounted on the inj. pump)...otherwise this simple little job is a bit of a pain with the oil filter housing in the way.

Finally, again with the oil filter housing off, I believe you have much better access to the tightening bolts on the injection pump....this might be an opportune time to adjust the start of fuel delivery (engine timing) if its off the mark...to do this you need to loosen and rotate the IP to the proper position.

Good luck,

Mark

[nhdoc]

Maybe the 300CD is a little easier...it doesn't seem all that tight on my 300CD, is it possible the Coupe has a little more room than the sedan in the area between the housing and the steering box?

Thanks for all of the tips...I won't tackle this project for a couple of weeks and will try to tighten up the bolts in the mean time to see if that helps stop the leak.

[Brian Carlton]

Originally Posted by MarkM

Also, use gasket sealant on both surfaces to ensure no leak. You will never do this again, so why not! After I did the job on my car, the damn thing still leaked!!!

I strongly disagree with the suggestion to use any type of gasket sealant on that gasket. The OE gasket is designed for all the sealing power that is necessary. It may have leaked due to the application of the gasket sealant.

Getting every last molecule of the old gasket off the ground face on the block is mandatory.........or you'll be doing the job twice. If you don't spend at least one hour with a single edge razor blade and some gasket remover, you're not doing the proper job.

A couple of more tidbits:

Get yourself a 1/4" gearwrench (because I've never seen or heard of a 6mm).

Then get a 6mm allen key and cut it twice at the bend. You should have one piece that's 3/4" long and one piece that's about 4" long. For the top three screws, use the 4" piece with the gear wrench. For the lower two screws, use the 3/4" piece with the gear wrench. Don't get any ideas about using a socket wrench with a 6mm hex bit. That's not happening. This one tip will shorten the job by about 1 hour.

BTW, the top three screws must be accessed from the top and the two lower screws are accessed from underneath the vehicle.

One other problem:

When you reattach the oil line to the turbo, it may not thread by hand. Don't force it with a wrench. Since the line has a multitude of bends on it's way to the turbo, it may not be a perfect fit. You're forced to undue the clips all the way down to the turbo, and, may need to unbolt the line at the turbo to get the fitting started at the cooler. Be best to have a turbo gasket available. Don't skip this step and force the threads on the oil filter housing.

It would be beneficial to have a new aluminum sealing ring for the turbo oil line fitting. The old one will probably be mangled pretty good.

[tangofox007]

Originally Posted by Brian Carlton

Don't get any ideas about using a socket wrench with a 6mm hex bit. That's not happening.

Some hex bit sockets have replaceable (and therefore, removeable) bits. They are typically 5/16" on the socket end. They work if you pull them out of the socket. Or you might find replacement bits at a hardware store.

[tangofox007]

Originally Posted by Brian Carlton

Getting every last molecule of the old gasket off the ground face on the block is mandatory.........

The engine service manual cautions (in strong terms) against allowing any remnant of the old gasket to get into the oil intake port in the block. Lest you clog an oil nozzle.

[Brian Carlton]

Originally Posted by tangofox007

The engine service manual cautions (in strong terms) against allowing any remnant of the old gasket to get into the oil intake port in the block. Lest you clog an oil nozzle.

That's a pretty good trick in and of itself. I'll bet that it's technically impossible unless you've got a powerful vacuum nozzle following your every move with the scraper.

[Brian Carlton]

Originally Posted by tangofox007

Some hex bit sockets have replaceable (and therefore, removeable) bits. They are typically 5/16" on the socket end. They work if you pull them out of the socket. Or you might find replacement bits at a hardware store.

That would be perfect for the 3/4" section. But, you still need the 4" section. Using the standard wrench is difficult because the 1" section gets in the way of the power steering gear.

[tangofox007]

The "clean oil duct" is the dime-sized hole on the front, upper side of the mounting pad on the block. The service manual suggests covering or closing the bore. When I did mine, I found a cork that fit nicely. Then ensured the bore was clean after the scraping was complete.

[tangofox007]

Originally Posted by Brian Carlton

That would be perfect for the 3/4" section. But, you still need the 4" section. Using the standard wrench is difficult because the 1" section gets in the way of the power steering gear.

I used bit sockets on an extension bar for the bolts that were not obstructed by the steeering gear box.

[Brian Carlton]

Originally Posted by tangofox007

The "clean oil duct" is the dime-sized hole on the front, upper side of the mounting pad on the block. The service manual suggests covering or closing the bore. When I did mine, I found a cork that fit nicely. Then ensured the bore was clean after the scraping was complete.

That sounds like a perfect solution. Did you trust the cork to press it below the block face........to allow easy use of the scraper?

[Brian Carlton]

Originally Posted by tangofox007

I used bit sockets on an extension bar for the bolts that were not obstructed by the steeering gear box.

I couldn't get a ratchet on the end of the bar due to the gear.........didn't want to risk the universal with the small hex bits.

[tangofox007]

Originally Posted by Brian Carlton

That sounds like a perfect solution. Did you trust the cork to press it below the block face........to allow easy use of the scraper?

I just left the cork protruding and worked around it with the gasket scraper. The port is located such that it is no more than a slight inconvenience. Much less inconvenient than a blocked oil spray nozzle, I'm sure.

[mjpay]

The engine compartments are the exact same in the 300d and the 300cd