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Front and Rear main seals, timing gear removal  Rate Topic 
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 Posted: 03-12-2005 10:22 pm
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Gary Martin JH 15371
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Posted this on the old board and did not get much of a responce (only Greg). So lets try the new board.

While my engine is out, I decided to replace my front and rear main seals. Both were very very hard to get in. Fit is way to tight.

Question about rear seal and clearance for oil slinger. Engine #4129. Removed rear cover, installed new seal from inside cover (inside has a bevel to get it started). I fould it very difficult to get seal into cover far enough so seal was flush with inside of cover. One of the service bullitens says you need to have 2.5 mm to clear oil slinger. Where is this slinger? I did not see anything that would interfer with the rear seal. How crytical is this 2.5 mm clearance ?

A few weeks ago I posted a note about my difficulty in getting crank timing gear off. Greg replied, and I see has info on this in this months news letter. I ended up using a slide hammer. The hammer kit had a rod (about 1/4 in) with a 90 deg bend on the end. This just fit in slot in front cover. By carefully using the slide hammer, and rotating crank around I was able to remove the gear without damage.    

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 Posted: 03-13-2005 12:14 am
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Mark Rosenbaum
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I don't think you put the rear seal in correctly.  JH Service Bulletin 74-9 says  the seal is to be inserted from the outer (rear) face of the casting, not the inside.  The gap between the inner and outer lips of the seal is to face toward the inner (front) face of the casting.  If you start the seal manually, then place a length of 2x4 on its flat surface, you should be able to seat it to the proper depth with just a few raps of a hammer on the 2x4.

The oil slinger is shown in the cylinder block drawing, not the crankshaft drawing.  It's item #36 in drawing http://www.web-masters.com/gms/cyl_blk_a.html .  I think I''ve also managed to attach a copy of the drawing to this post.


BTW, my car is #16371.

Attachment: 549 Block late.gif (Downloaded 28 times)

Last edited on 03-13-2005 12:18 am by Mark Rosenbaum

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 Posted: 03-13-2005 06:56 pm
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Jim Ketcham
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Hello Gary,

I had tried to respond to your post on the old board but it would not let me.

I have the same complaint about the front seal.  It is way to tight and impossible to install without the exterior rubber ripping.  I did get it with a liberal amount of Wellseal around the outside.

I do not see how you could install the rear seal from the inside out without destroying the sealing surface.  I fear you may have ruined your rear seal.  If you press it in from the other direction you should be able to easily get the required .1" setback.

Good luck,

Jim

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 Posted: 03-15-2005 01:06 am
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Arvin Appelman
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The inside edge of the rear seal is not pressed in flush with the engine face of the rear cover.  The standard setback is 0.100 ".  You may want to measure from the rear face of the engine to the sealing surface on the crank flange to determine the proper position for the seal. 

If you press the seal all the way it will leak.  Been there done that, no fun!!

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 Posted: 03-15-2005 04:55 pm
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Greg Fletcher
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Jim makes a good point- these current seals will always be problematic. When I was having difficulties installing the front and rear crank seals, I just took it to my local machine shop. They informed me the seals are too tight by any standard and wondered why the seals where designed like this. I mentioned it's British stuff, and they said "oh, that explains it".

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 Posted: 03-16-2005 06:28 pm
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Gary Martin JH 15371
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After reading the responses mentioning I installed the seal incorrectly, I took off rear cover and removed seal. I tried to install seal from rear of cover as recommended. This just resulted in tearing the rubber coating off. I stoped before destroying the seal.

Since the inside of the cover has a bevel, I went back and installed from inside of cover using a little Wellseal. After getting seal in so was flush with inside of cover using a block of wood, I then used a 1/4" punch and carefully pressed seal in to get the 2.5mm clearance from inside of cover. This placed seal just flush with outside of cover. Then used RTV to install cover (since no gasket is available).

Note: It is a little tricky to install cover and seal. Care must be taken to slip the seal over the end of crankshaft.

Last edited on 03-16-2005 06:30 pm by Gary Martin JH 15371

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 Posted: 05-01-2005 07:02 pm
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Esprit2
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For both front and rear seals,  insert them into the housings from the outside inward.   The open gap in the seal (between rim and seal lip) faces into the engine.

Tricks to make it easier:

The seal bores end in a sharp corner/ edge.   Use a sharp Xacto knife or utility knife to cut a slight chamfer/ lead that will help the seal get started.

Heat the housing to around 210° F.   The kitchen oven works,  but you may have to send your wife off to the mall or something first.   I've used the gas barbecue grill on low.   In either case,  don't trust the temp controls...   use a separate oven thermometer.

Remove from the oven and smear the bore with a sealant.   Smear the seal's OD as well.

Press the seal in while the housing is still  hot.   Move too slow and let it cool down and there's no point in going through the exercise.

These steps make it easier,  but not easy.   Sort of the difference between impossible and aggrevatingly difficult.   Especially the rear seal which is complicated by the need to be pressed in to a dimension (2.5mm / 0.100" from the inner face).   I've made a disc  0.100" thick that's a loose drop-in fit in the housing bore.   Lay the housing on a flat surface,   drop in the disk followed by the seal.   Drive the seal in until it bottoms on the disc.

The real solution is a hydraulic press.   Everybody needs one of those.

Where do you get your seals?   I've had trouble with the non-Lotus front seal from JAE.   They're gray and have a ribbed OD instead of smooth.   I destroyed three in a row before buying a Lotus-branded part...  which went in with minimal complaint.   From the markings on the face,  the Lotus part has a 67.71mm OD while the JAE part has a 68mm OD.

I'm not a big fan of using silicone to seal the housings to the block.   You'll get better results with Loctite 518 or 515,  Permatex Anaerobic Gasket Maker 518 (private label of Loctite 518),  Permabond A-136,  Loctite 504 (old technology),  Wellseal  or Permatex Aviation Form-a-Gasket 80017 (17 = package size,  4 oz bottle).   Don't use Permatex Form-a-Gasket No. 1  or  No. 2 in the little white tubes.

Use the gaskets.   If you insist upon not using a gasket,  the seal with 518 or A-136.

The stock screws for the rear seal housing are Allen drive button heads (at least on a Lotus engine).   I've had some trouble stripping the drive,  so I switched to hex-heads.   They work fine with the stock iron flywheel,  but interfered with an aftermarket aluminum flywheel.   Just a word to the wise.   If you switch to hex heads,  double check for adequate flywheel clearance.

Tim Engel

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