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| Understanding the oil pan | Rating: 
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| Posted: 11-04-2010 02:04 pm |
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1st Post |
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Dan (Florida) Member
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I just finished three days of pulling a very oily engine from 19444 in order to replace the rope rear main seal. I tried everything I could think of to not pull the engine out but to no avail. To date the back patio / car/ engine / dog / myself have been pressure washed four times ,but everything points toward an eventual repair/reinstall after it quits raining. My question is this. Why is the oil pan divided laterally with passages on both ends. The rear compartment is the larger one, but the front compartment contains the pump pickup. It would seem that the only time you could have maximum supply of oil to the pickup is during straight ahead braking and minimum supply during acceleration. Every action except braking deprives the pickup of oil. Is there a reason for this layout? My thoughts are pointing to the old "brick in the toilet tank" concept in the back compartment to displace more oil toward the front. Any thoughts on this? It would seem that a narrow/deep sump would be a more efficient collector and be easier to work on.
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| Posted: 11-04-2010 08:27 pm |
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2nd Post |
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James Sohl Member
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Dan, The rope seal can only be replaced by removing the crank. Perhaps others can comment on their experiences with rope seal replacement and the results. I've been-there-done-that once with so so results. For my experience, leakage was much reduced, but not entirely stopped. As best I can remember, the issue was that the ropes come in two halves that fit very tight in the grove. When pushed into place, the ends 'stick out' a little above each end of the grove and are supposed to be 'trimmed' to fit. The devil is to decide is how much 'stick out' should be left after trimming. In talking to mechanics who had experience with rope seals (they are very common in older engines) opinions very, but it seems that most agreement seemed to center on leaving about 1/64th (.015 thou) above the surface of the mating parts. I did talk to one JH owner who claimed to not trim the rope halves at all. Hmmm. Anyway, as close as I could get it, I trimmed to about .015 and there was still a very much slower drip. I'm sure others will have different stories with different results. Good luck! Please note, the .015 is measured on a fully seated rope seal. Just getting the things in there for a measurement was quite a pain. As to the sump, Lotus had to fit the 907 over the Vauxhall front suspension, thus the front of the sump is very shallow. At the rear, where you would expect a deeper sump, Lotus again had to meet minimum ground clearance restrictions, and also, not have the sump be the lowest part of the car where every rock could, in principle, jump up and ruin your day. Therefore, the wide, relatively shallow sump. As to the 'box' for the pick up, the concern is what happens on hard, lengthy cornering, as would happen with 'sport' driving or competitive racing? The oil flows left or right, except in the smaller 'box' where the oil can't go left or right (as much) under cornering. Does it work? Not all that well. Oil sumps were changed several times within the first few years of production 907's. 907's essentially the same as the JH5 were the original engine in the Esprit, with obviously superior ability to corner and create even more problems with oil pick up. What should you do? For 'street' use, just keep the oil topped up. For track use, seriously consider that Acc-u-sump, or similar systems are very effective, legal in almost all forms of competition, and really, a lot cheaper than repairing damage caused by a spun rod bearing!
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| Posted: 11-04-2010 10:54 pm |
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3rd Post |
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whitedog1 Member
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In years gone by, I remember replacing a rope seal on a crank in an engine (a series Rover maybe?) that solved the need for crank removal by using a wire leader that is fed through and used to then pull the seal into place. Since I have no experience (yet) on replacing one in situ on the JH, not sure if it's applicable or practical, but it may be worth the effort to try.
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| Posted: 11-05-2010 05:04 am |
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4th Post |
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pbahr Member 
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The Accusump is a wonderful invention. I have a 3 qt unit on YELODOG, and never had loss of oil pressure on the track. Pete
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| Posted: 11-05-2010 06:19 am |
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5th Post |
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subwoofer Member
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Dan (Florida) wrote:I just finished three days of pulling a very oily engine from 19444 in order to replace the rope rear main seal. I tried everything I could think of to not pull the engine out but to no avail. To date the back patio / car/ engine / dog / myself have been pressure washed four times ,but everything points toward an eventual repair/reinstall after it quits raining. My question is this. Are you running a mk1 engine in a late car? The mk2 and later engines have a proper oil seal. It is not too difficult to replace, but a shop press will come in handy. -- Joachim
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| Posted: 11-05-2010 11:52 am |
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6th Post |
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Dan (Florida) Member
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Yes it's a mk1 , The mk2 oil seal doesn't sound like a picnic to change either. I guess the accusump isn't a good thing for the street. I suppose I will use the oil pan as designed although welding the bottom 1 1/2 " of a chevy aluminum oil pan sump on the bottom and extending the pickup tube could solve the problem if the whole thing would fit on engine install. I've done a lot of reading on the rope seal and have installed on 283 chevys in days gone by. The big tip I have heard is to leave the upper half a little long and put a drop of your favorite non-hardening sealer on each end of the rope just before tighten-up. At this point, I guess dropping the crank down a little wouldn't be a problem. I've been told that a seal puller called a "sneaky Pete" can be purchased at most auto parts houses that will pull a seal through , although it may not be necessary. At any rate Its got to be easier than changing the rope seal on the v-12 Jaguar!! Will post photos later, Thanks Dan
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| Posted: 11-05-2010 02:38 pm |
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7th Post |
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pbahr Member
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Correct, the Accusump is not for the street primarily because the JH oil pressures has so great a difference between cold, hot, hi rpm and idle. For street use, it is very useful for charging the oil pressure when you first start the car and then shutting it off. Well, that's when 90+% of engine wear occurs....... Pete
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| Posted: 11-08-2010 11:35 pm |
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8th Post |
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Greg Fletcher Administrator 
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The sump is just a little lame on the 907 and indeed, as you have noticed, the baffles will tend to hinder oil movement more than is required. The best thing on these is to remove the baffle plates and re-weld them to a slightly revised location so oil can move in a less restricted fashion while still preventing scavenging. I have a modified sump around somewhere. I'll take a photo and post that soon so you can see what that should look like.
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| Posted: 11-09-2010 07:14 pm |
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9th Post |
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Dan (Florida) Member
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Thanks but it's all repaired and installed. The job because of all the mess was done outside and had to be done with minimum delay due to weather, falling leaves etc. I'm sure they had reasons for the design but they were probably for a transverse mounting. I echo the sentiments that the job cannot be done with the engine in and crankshaft completely seated although it didnt need complete removal . I hereby elevate myself to a new plateau in story telling
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| Posted: 11-09-2010 08:02 pm |
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10th Post |
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Brett Gibson JH5 20497 Member
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I'd like to see that picture when you get it Greg. Brett
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| Posted: 12-08-2010 04:17 pm |
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11th Post |
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Dan (Florida) Member
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Well I suppose it's back to the drawing board on this rear seal change. The new seal leaks as bad as the old one and picked up a water pump leak in the bargain. The car runs beautiful but still spots the driveway in excess. The rope seal is not an easy install as it is very hard and has to be forced into a narrow spline groove in the block and bearing cap. It mashes out in both directions to form a wide sealing surface. You can't just set it in place and clamp the crankshaft down on it without cutting it to length first which will probably make it too short when you are done clamping. I tried forming it into the main bearing cap by tapping it down with a large socket and hammer to compress it into the spline groove. If you compress too much it will leak, not enough and the crank will not turn over. I formed each half in the cradle half and installed one in the block half and it ended up short. The other end had to be cut long which frayed. I sealed the ends with gasket sealer but it didn't seem to work. The seal comes wrapped with a white fabric woven around it with blue lines in it. There wasn't any instructions with it on which direction the lines go or if it should be sealed into the groove with a sealer. I also wonder if heating the rope before installing would help it to form better. There must be a British technique to be followed that we are unaware of. Any thoughts. The second teardown should be much easier (and cleaner) Dan
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| Posted: 12-08-2010 08:53 pm |
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12th Post |
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Brett Gibson JH5 20497 Member
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Dan, I havent done a JH rope seal but have experience with rope seals on pumps. The one main trick was to never cut a striaght cut across, always make about a 45 degree cut so as they overlap each other at the joint. You probably already know that but just in case. Brett
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| Posted: 12-09-2010 12:25 am |
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13th Post |
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Dan (Florida) Member
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I've done a few pump seals myself in my younger days, but the engine seals have to be cut off square and butt up to each other as they are two piece. Pump seals are one piece and are cut on a 45 and pressed in by a gland nut from the end. A local Brit mechanic seems to think that the seals have to be relatively soft to form into the area they ride in. I'm thinking of having a seal presser machined to the size of the crank journal to press the (warmed to just soft I'm thinking) seal into the block and bearing cap so that they can be more accurately seated and cut square to size. Also to use sealer in the groove that the seal rides in . It's not like American seals are installed at all.
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| Posted: 12-09-2010 12:33 am |
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14th Post |
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Greg Fletcher Administrator
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Hmm, that just reminded me, I think I remember a mechanic friend telling me you need to soak the rope seal in oil for a day or so before you install.
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| Posted: 01-20-2014 02:22 am |
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15th Post |
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bora450 Member
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Greg, Please post your sump photo if you can. My engine is apart so now is the time to modify it. Thanks, Claus
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