Oil leaks fixed! - PeachParts Mercedes-Benz Forum

Aaron · #1 01-17-2003, 10:58 PM

Hey guys,

Finished the 300SD's oil cooler lines and O/F housing-to-block gasket tonight. Also put in new motor mounts while I had the engine lifted. Filled her up with 8 qts of fresh Agip 10W-40 and I'm LEAK FREE!! Of course the turbo drain seal is still seeping a bit, but that can wait till springtime.

Now, an INTERESTING observation....

Bought two O/F housing gaskets, one from my parts supplier (Brinson Company) and the other from the local MB dealer. The difference was stunning between the two. The one from Brinson (who happens to be one of the top OEM German aftermarket suppliers) was made of paper and the one from the MB dealership was an actual gasket material, much beefier. I was about to use the one from Brinson until I bought this other one to have as a spare from MB and boy did I change my mind fast!

Of course, each time I do this job, I apply Wurth black RTV to both sides of the gasket just for extra precaution. Also, the other gasket between the pressure sending unit and the housing gets a light coating of Wurth RTV as well. Keeps everything good and leak tight. The last time I did this job on one of my own cars (so I could gauge how long it stayed dry) was on my '80 300SD. I did it at 120K and sold the car to TXBill with 201K on the clock, and it was still perfectly dry around the housing and I did use the same Wurth RTV. Some guys like to apply the gaskets dry, but I'm quite the believer in Wurth products. I wouldn't put my money on Permatex to hold as well.

Well, after this last task, I treated myself to a pint of Guinness at the pub tonight and thought of all the oil I would not be wasting anymore!!

jcd · #2 01-18-2003, 09:57 AM

The OF housing is my only leak and I'm going to tackle it this Spring. I got the gasket from the MB dealer and it is QUITE the gasket.

My oil cooler lines are OK......have you had any issues with leakage after removing and replacing from the oil filter housing. That is my only concern with the job.

Congrats on becoming leak free.

JCD

1977 300D

Aaron · #3 01-18-2003, 01:34 PM

JCD,

Only red flag here is to be VERY VERY careful when removing the 27mm fittings from the oil cooler. Since the cooler's threads are aluminum, they WILL strip out if you're not careful. I've been lucky every time I've had to do this job and haven't ever had to replace a cooler. The trick is to go very slowly, a little at a time, maybe 1/4 turn, go back and forth with the wrench on each turn as well, to kind of "break up" any corrosion on the threads. Haven't ever had any problems with leaks once the job was done.

Also, when reinstalling the O/F housing, make sure to evenly torque the hold down bolts. I'm sure of the exact torque figure, but get them relatively tight, just not overtight.

If there is a local shop with a parts steam cleaner in their garage, ask them if you can put the housing in there for 1/2 hour after you get it off. It will clean it to look like brand new. Of course, try to scrape all the goo off of it before throwing it in the parts washer.

Finally, your car will have a 12mm line connected to the back of the housing, this is the oil pressure gauge feed. Be careful and use a flare-nut wrench to undo this fitting. Sometimes the plastic tube will turn with the fitting, so try to break it loose with a sharp "snap" before proceeding to undo it all the way. Since the part where that 12mm fitting connects to the housing can be unbolted from the rest of it (four 10mm bolts) make sure to get that gasket as well from your dealer. Just have your parts guy pull up the diagram, you'll see what I mean.

Good luck! I was going to post pics for all of you to see here but the thought of bringing my digi completely slipped my mind. Sorry!

Fredmburgess · #4 01-18-2003, 10:25 PM

Hey Aaron,

Have to pull the oil filter housing off the 300D tomorrow...someone who should remain nameless but is, well, me, got a little impatient getting that last glowplug out and sheared the sucker off!..doh! So, have to move the filter housing so I can get to it. P/O obviously didn't believe in anti-sieze on threads...

Saw your post about RTV on gaskets. Spent the past 20 years doing sales engineering for gasket materials and would just suggest that if you're going to put RTV on a fiber ("paper") based gasket you avoid putting any around the bolt holes. RTV reduces friction and softens many fiber gasket materials, encouraging crush/extrusion at the bolts (where loading is highest). Mid span is typically not a problem. This wasn't an issue when most of these cars were built as fiber in the "paper" gaskets was asbestos, and lots of it. Made for great crush resistance. Non-asbestos materials tend to have far less fiber (kevlar and such cost 10 X asbestos price) so typically less crush resistance and tensile strength. There's plenty of load around bolts to seal there anyway.

I know more about gaskets than removing stuck glow plugs. I'm sure tomorrow will be lots of fun...

Fred

#5 03-18-2003, 04:44 PM

I got my housing pulled out, and I notice that there is a gasket that connects to the oil pressure sending unit. Would it be a good idea for me to replace this while I have it out, or should I just not mess with it? I don't think it is leaking from it.

Aaron · #6 03-19-2003, 03:47 PM

Couple things:

123C: Yes, replace that gasket between the housing and the pressure sender cover. Also replace the aluminum seal where the pressure sender threads into the cover. I would also suggest undoing the actual fittings from the O/F housing (the ones where the oil cooler lines thread onto) and replacing the seals there as well.

Fred: I only use a very small amount of RTV on those gaskets. The stuff I use is made by Wurth and I have used it time and time again without fail. Obviously, some folks can over do it with too much sealant or RTV but a little dab never hurt in all my years of experience. As for removal of RTV, if it is just a dab, it will come off easily with a scraper.

#7 03-19-2003, 06:58 PM

Quote:

Originally posted by Aaron
Also replace the aluminum seal where the pressure sender threads into the cover.

Aaron, do you know the size of this seal? I went to my local parts store to get the other gasket/seals and they told me to bring in the old one, and I seem to have lost it.

samiam4 · #8 03-20-2003, 01:23 PM

I can't imagine an oil pump locking up with a piece of RTV,

But in these engines the oil squirters jets have small orfices. A small piece of RTV can easily clog one and the next time you get a high load the piston siezes in the cylinder wall.

RTV has no place in these engines... it's a quick way to kill one. Use Wurth's "flange sealer" instead. Really, old permetex #2 o#3, indianhead shellac, and RTV are very old school. Lots of superior products that are easy to use and will last.

If you are going to keep using RTV products, put the screws/bolts in place finger tight before hand. I've seen thin gaskets split because the lubrication allowed the gasket to be forced out. Not on a O/F housing, but more like transmission cases.

Michael

#9 03-20-2003, 02:05 PM

I used some Gasgacinch gasket sealer on mine. I wonder if I will face any problems if a small chunk of it splits off, like with RTV. I was careful to put a small amount of it on, but I think I might have still had too much.

#10 03-21-2003, 12:10 AM

I am now going to worry about the gasket sealer I put on. Would it be a good idea to change my oil in lets say a 1000 miles to make sure I get out any gasket sealer that may come lose?

samiam4 · #11 03-21-2003, 12:27 AM

I'd probably leave it....

My car had the oil pan off somewhere before 100K. It's RTV and it wasn't till 275k that one of the camshaft oiling holes had a small piece stuck in it. Reduced flow and wiped a lobe..

Stu Ritter told me the story of the one siezing a piston going up a long hill in Colorado. I believe it was a friends car.

Michael

#12 03-21-2003, 12:37 AM

The guys at the parts store I bought the gaskets from told me to use the gasket seal, and not the RTV because of the fact that it can break off and clog up stuff. I am thinking that since I had no excess come out when I tightened the gasket, then I might be doing ok. I am sure it will be ok, since the parts store told me to use it instead of RTV. I am sure I won't even own the car anymore, when something does happen

Fredmburgess · #13 03-24-2003, 09:53 PM

Hey Aaron,

Hadn't checked the board lately - After my comment the evils of RTV, yadda yadda yadda, I pulled my oil filter housing and found that the gasket is a fiber on perforated steel core deal...not something likely to crush even if it was painted with sealant! You're right, of course, that less is more with sealants of all types.

Anyway, got the broken glow plug out after removing the filter housing, replaced all five with anti-seize on the threads, replaced the filter housing gaskets and both oil cooler hoses and wallah...new gplugs AND no more leaks..so things turned out better than expected.

Cheers!

Fred

Aaron · #14 03-24-2003, 11:00 PM

Most likely anyone who puts RTV on an OIL PAN gasket will have used way too much because I have seen that personally. But on an oil filter housing gasket, you only use a SLIGHT BIT around the edges to keep it leak tight. This has worked well for me every time around and cars that I did this job on years and years ago are still holding tight and have done plenty of troublefree mileage since. I am very careful with using ANY type of sealant so I have zero reservation about using RTV sparingly.

NC240D76 · #15 03-24-2003, 11:13 PM

Be very careful with the anti-seize on moving parts.
I used it on a steering cable on outboard motor once (just once) and finally had to replace the entire steering tube on the front of the motor to install a new cable a few years later. I even put the tube in the vise and used a torch to heat it and the cable did not come out. I don't know if being in salt water caused the reaction and I still love it for anything that does not move but I will never use it on anything that moves in any way.