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MG TD TF 1500 Rear main new lip seal leak BBS discussion at MG-Cars.net
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MG TD TF 1500 - Rear main new lip seal leak
| I have an oil leak from my new brown and gammons rear main seal in my fresh rebuild. It only leaks after the car has been shut off and it only lasts for a short period of time. In looking at the archives, It's been noted that the drain tube on the last main bearing cap can extend down too far and dip into the oil in the sump and act as a siphon pulling it up from there. Has anyone else heard of this? If so have you been able to resolve it by pulling the sump and shortening the drain tube (don't want to pull the engine if I can help it)? Quoted text from the Archives: As a side note, there is a drain tube that is a part of the main rear bearing housing, that protrudes into the sump, for oil to drain back from the bearing to the sump... There is a theory that if that tube is long enough to touch the surface of the sump oil, it can act as a siphon when the engine is stopped, and will suck oil up from the sump causing a leak at the main real seal... I had a main rear seal oil leak prior to rebuilding my EPEG engine, and upon assembly I cut the tube much shorter and took great care in the installation of the two part seal system... I now have NO OIL LEAKS from the main rear seal... Alex |
| Alex Waugh |
| For a siphon to work doesn't the outlet have to be lower than the inlet? |
| JE Carroll |
| Interesting; Never heard of the siphon theory. I shorten them about an inch to facilitate an easier path for drainback to occur. Have never performed only that modification to see if it alone was the remedy for a leak. Be certain that your engine has adequate crankcase vapor ventilation in place to keep blowby pressures low - aftermarket tappet covers and side covers sometimes do not have proper venting. Dan |
| Dan Craig |
I think our friend Guenter from Germany made the best solution to keep the oil from dripping on the ground,,,,
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| STEVE WINCZE |
| I agree with JE Alex, for the tube to act as a syphon the outlet would have to be lower than the inlet which it is not. Sounds like the seal:( |
| Richard Taylor TD3983 |
| the outlet of the syphon needs to stay below the fluid level of the RESERVOIR (source container)not inlet. regards, tom |
| tom peterson |
| alex, did you use a speedi sleeve? on the moss seal..which looks similar?? i needed to use a speedi sleeve because even with the brand new crankshaft set as far forward as i could the lip of the seal did not have enough contact surface. i sealed the crankshaft to speedi sleeve contact area with loctite sleeve retainer and i used thread sealer on the flywheel bolts as the tails are now running in oil with the seal now on the crankshaft flange. i now this does not help you, but by doing those two things i do not have a drop of oil in 4000 miles...(and there is oil in the engine...LOL!) regards, tom |
| tom peterson |
| I was one who believed the siphon theory until the *real* reason for shortening the tube was explained to me. If you look at the drainage tube and see how high the oil in the pan is when the engine is off you will see that the tube stands in the oil. The run off from the rear main fills the tube and then runs out the trough by the crank. If you trim the tube it will let the oil drop off into the pan and not well up in the trough. |
| Gene Gillam |
| Why wouldn't the liquid seek its own level? Just because the pipe is submerged it shouldn't stop it. I speak with no experience, of course. I'm going to install the B&G (Moss) seal. It sounds as if a speedi sleeve is a necessity. I'll see how it fits up when I get all the parts back from the balance shop. |
| JE Carroll |
| Tom Re: the Moss rear seal kit and Speedi-sleeve.... I'm getting ready to do that mod this Winter, and any tips or photos would be greatly appreciated... I have used the Speedi-sleeve on "B's" with great success, but have never ventured into a "T" engine. Email to: edwardwesson@windstream.net Thanks for any help. Edward |
| E.B. Wesson |
| je carroll, you bring up a good point, the only thing i could think of is viscosity..it may flow into the tube faster than the oil's viscosity allows it to flow out..but these oils seem pretty thin at operating temps..so i'm with you..i don't see how it would not seek its own level..hmmm..regards, tom |
| tom peterson |
| Edward, I have some pics of the Moss rear seal with speedi-sleeve in situ should you still be looking for some. Cheers, David |
| David Tinker |
| I've some pics of the installation of the rear main seal. We did the job this summer. However, I do not know what a speedi-sleeve is... All my pics are > 4 Mb so uploading is difficult. By the way, is there a way to downsize pics (on iMac)? And yes, the new seal does a very good job: no leaks anymore. Jasper |
| Jasper L Nederhoed |
| >By the way, is there a way to downsize pics (on iMac)? If you're on OS X Lion, open the photo in Preview. Under the "Tools" menu is an option "Adjust Size" -- this will let you make the image itself larger or smaller. Also, under "File", go to "Export" and there is an option to adjust the quality (lower quality == smaller file size). By using a combination of these two you should be able to find a nice compromise of image size and file size. For earlier versions of OS X, I'm afraid I'm not sure. You might be able to do it in Preview, but before I discovered Preview could do it I used Gimp running in X (i.e. Unix-y, non-Mac like....). |
| Rob Edwards |
| We spoke briefly about your new crank Alex but I didn't think to ask if it has the scroll or not. May have some effect. Don't have any experience with the B and G seal but do have the Moss USA version and have had no issues with it. Now other locations is another story. How big is the leak? I think cutting the drain pipe is a good idea. Even if the oil is thinned it will flow to the path of least resistance. Trying to push up 5 1/2 quarts of pan oil is tougher than some capilary action out a scratch in the crank flange or gasket crack. Best of luck. |
| LaVerne |
| Rob, Thanks for the explanation. I'll give it a try... Jasper  |
| Jasper L Nederhoed |
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| Jasper L Nederhoed |
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| Jasper L Nederhoed |
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| Jasper L Nederhoed |
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| Jasper L Nederhoed |
| #6 Well, learned something today! Thanks again Bob. Jasper  |
| Jasper L Nederhoed |
| I've been following the 'rear seal' posts (and input from club members who have done the changeover) since I bought the TD 8 years ago...seems it is really a hit or miss venture. I think its about 50/50 on whether or not it solves the leak or not? I know Moss are on 'upgrade 3 or 4' at this point....? |
| gblawson(gordon- TD27667) |
| gordon, i believe, as in all things mechanical, it is the skill of the installer. just my opinion. regards, tom |
| tom peterson |
| I had a similar problem. The PO had a workshop fit the seal for him about 8 months before I bought the car. He can't have used the car much after that because I did about 100 miles in the car and then oil poured out of the back of the engine for several minutes after the engine was shut off just as Alex explains. I took it to an mg specialist who thought a core plug had gone at the back of the engine. We eventually found that the Moss seal hadn't been centralised properly and had been worn away. Correct alignment of the seal is critical. AJ |
| A R Jones |
| Jasper, check your email for Speedi-Sleeve info. |
| Jim Merz |
| Jim, Got it. Thanks very much. It's all clear to me now. What a great BBS this is! Jasper |
| Jasper L Nederhoed |
| Thanks to all that have weighed in. The plan is to use a boroscope to look through the wimdows of my b n g lightened flywheel to see if i can see whats going on. Since the cars been down for 1.5 years, im going to play with it for a bit and then pull the engine over turkey day holiday to see whats going on back there. I will opn a new thread when i have new information. Thanks again for all your help. It's very much appreciated. Alex |
| Alex Waugh |
| AJ So, your saying there is more than one position to mount the seal fixture?...Seems like it should be a self centering part...Where does it need adjustment? (Or should I say how?) Is the position of the rear engine plate the key? Finally, did your PO use a Speedi-sleeve on the crank? (as Moss advises). Thanks Edward |
| E.B. Wesson |
| Hello Alex. On a couple of engines I've done with the Moss style seal I put everything together and found that the lip of the seal doesn't sit on the crankshaft flange. Also I have yet to see a crankshaft flange that was polished on the flange where the seal was to ride. What I have seen would tear up the lip seal within two or three rotations of the crank. I have had to put a speedi sleeve on each one and hang the sleeve off the crank flange toward the engine. The sleeve was loctited to the crank flange to prevent seepage of oil between the two. Then the seal is slipped on and the aluminum holder haves were gingerly put on the block with the silicone sealant and the two housing allen head screws are tightened, note the locating dowels were removed to allow the housing to center its self before the three flat head screws were screwed up firm. As I remember the seal did not set flush withe the aluminum housing. It protruded as much as possible and still clear the back of the flywheel. Butch Taras Glendale, Ca. |
| R Taras |
| Hi everyone, Over the years the Moss rear seal conversion kit prompted a lot of comment either for or against. If you think about the engineering principals involved it is tried and tested technology which is in use in almost any engine you could mention, and that is a lip seal running in contact with a shaft. In the T Series case it is a Chicago Rawhide lipseal running on the flywheel/crank mounting flange hopefully in contact with a Speedi- Sleeve. So why are there so many problems? As a DIY installer certain engineering principals must be adhered to. The Moss installation instructions must be followed implicitely as oil leaks can occur at a number locations which are not necessarilly associated with the Moss seal. I have yet to be convinced about the syphon theory although I did reduce the length of the drain tube during my rebuild. Oil can also leak from a number of areas associated with this installation ie from the sealant bond between the seal housing and the rear bearing cap, the flywheel mounting bolts if the threads are not sealed, between the rear main bearing cap and the block if it is not sealed. Other possible leak areas are the front gearbox seal, and the rear camshaft plug. All these area can produce an oil leak via the split pin at the bottom of the bell housing. In my installation I have also modified the bolting arrangement of the seal housing to the block. I do not use the dowel pin location of the lower oil thrower housing, as I do no believe this produces an accurate location for the seal housing. Instead I use an assembly ring which locates on the crankshaft flange which locates precisely the seal housing concentrically to the crank flange. Other oil leaks can occur from a poorly fitted sump which can also produce leaks. Just my thoughts on the subject, Cheers, David |
| David Tinker |
| I got the borrowed boroscope and will be trying it out this weekend to see if I can pin point the problem area prior to engine removal. It has the ability to save pictures. If I get anything good, ill upload a shot for you all. |
| Alex Waugh |
Edward, You were inquiring about the method used to center the rear seal and why it needs to be done in some cases. The rear seal is not actually self centering when you bolt it to the block using the three countersunk designed flat set screws that come with the kit , as they will not allow for any concentric adjustment with the crank flange, whatsoever. The remedy is to counterbore the original countersunk mounting holes and ream the bores slightly larger if necessary to allow for the use of cap screws and provide room for adjustment. This modification is required if the bottom end of the block has been previously line bored, causing slight misalignment of the crank with the seal's housing orignal mounting points. You can check for concentricity by taking measurements with a small telescoping guage between the seal's seat in the housing and the circumference of the crank flange to see if there are any variances. You can easily do the counterboring using a drill press and a 7/16" four fluted counterbore bit. Moss used to allow you to return the seal housing to them to have this modification done free of charge, but have since discontinued the service. Hope this helps. Cheers Phil
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| Phil Atrill |
Image of counterboring bit
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| Phil Atrill |
| Phil Thank you... Evidently , you are using an end mill for a counterbore... That is something that I have in my shop...Although, I will see if I can find a self-centering counterbore, before actually doing the deed. It's interesting to me, that Moss doesn't just go ahead and make it adjustable, to avoid these problems... After all, if we're mechanical enough to install it, surely we're smart enough to center it. Do you remember what the thread size of the cap screws is? Edward |
| E.B. Wesson |
| Edward, A self centering counterbore would be ideal. I couldn't find one locally so I just centered the end mill in the chuck by first using a drill bit to find the center and then carefully replaced it with the end mill while everything was clamped firmly. The set screws are 16 x 1mm, same thread size as in the block. Cheers Phil |
| Phil Atrill |
| No luck on the boroscope. The head is too big to fit in through the available spaces. Gonna have to take it out before I can see exactly what caused the leak. Will keep you all posted. Alex |
| Alex Waugh |
| Edward, If you intend to counterbore the 3 housing fixing screws I would recommend using mushroom headed capscrews which requires a much shallower c/bore and as the head is a little larger it will not 'bite' into the housing when tightened.(pic attached) You might also want to open up the through holes to 6.5mm dia to allow for some sideways movement. The counterbore size I used was 11.5mm dia. I think you will find that the screw size is standard M6. Cheers, David  |
| David Tinker |
| David and Phil Thanks for all the good info....Once I get into this thing, I know I will be asking more intelligent questions (HA!).... I'm planning on making a centering fixture, to avoid some of the obvious "landmines" in the modification... Edward |
| E.B. Wesson |
This thread was discussed between 10/10/2011 and 18/10/2011
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