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Steve[uk] Member
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Hi folks just changed the front crankcase oil seal on my 1972 MK1. Trouble is the rear is leaking quite bad. ive been told its the rope type two piece seal. Can this be changed with the engine in situ , Soon as i mentioned it was a MK1 a lot of people groaned and said " Oh Dear ". someone suggested that the sump had to come out and the crank partially lifted out. If any of you folks could share some experiences changing the rear seal on a MK1 your help would be greatly appreciated. All the best Steve [ North Wales UK] |
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Judson Manning Member 
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Steve, The post 1973 907 equipped JHs (aka MkII & JH5) have a removable rear housing and lip-type rear oil seal easily changed (realatively speaking). Among other things, the earlier versions of the 907 have the rope-type seal. The bad news is that the rope-seal is in two pieces embedded in the upper & lower halves of the block. The only way to remove/replace each piece is to split the block and remove the crankshaft. Yes, you read that correctly, the entire bottom half of the engine has to be disassembled just to get to that damn seal. This sets off a cascading series of events (i.e. "while you are at it") that concludes with a (nearly) complete engine rebuild. One possibility is that your engine has developed a lot of crankcase pressure due to excessive blow-by from gummed-up piston rings. The rope-seal may not be 'bad' just not able to handle the pressure. If you suspect your piston rings are gummed-up, try flushing the oil several times using 5W20 and a commercially available crankcase cleaning product. No guarantees, but pretty simple compared to pulling the engine. Judson |
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Steve[uk] Member
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Judson, Thanks for the info it is certainly worth a go, On the crankcase pessure thing, the hose from the breather that comes via the oil filler is just loose as it has different air filters. I thought there maybe too much pressure as when I was trying to establish were all the oil was coming from I notice it was even coming out of the dip tube. I thought that this was due to a poor fitting dipstick and replaced it with a better fitting alternative ( obviously marked off to the same high low level). maybe this is also due to too much pressure inside the crankcase ?. Ive only had the car a couple of months and its been standing for a while with little use before I took ownership of it. I'll give it a go and let you know how i get on. If I can at least stop it so it's only an occaisional drip i can live with that. Funny thing is you can rev it in the garage all day and it won't leak which is why I couldnt see the problem straight away, it only when you take it for a spin and come back you can see it dripping. Would putting the original airfilter setup back on and connecting the breather pipe back onto the airbox add any sort of back pressure and help, or would it make it worse. Many thanks for your help Steve |
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Judson Manning Member
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Steve, I can tell you that when I do customer rebuilds the number one thing I see time and time again is filthy, nasty sludge and varnish clogging up every part of the engine. The piston rings suffer the worst as there is no oil feed pressure to force that stuff out and keep them from bonding to the pistons. The exhaust cam housing and the remote cooler trap 1-2qts of old oil that never gets flushed out during a regular oil change. Add 30 years to this equation and you can see how it gets out of hand. It's no surprise you see leakage after running the car. At lower RPS and nearly closed throttle the pressure is manageable. Start filling those cylinders with big gulps of air and you've got 10-100x the pressure. You have the right idea with making sure the engine can breath properly (make sure the sump isn't overfilled either). Unfortunately, you can't 'suck' enough of this pressure out, it has to be stopped at its source. I think your rope-seal may be fine, but worst case your rings could be shot. I think its worth a try to flush out the engine and hope the rings get un-stuck. Judson Jensen: It's not a car, it's a hobby....for some of us it's an unhealthy obsession! |
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Steve[uk] Member
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Thanks Judson, which engine flush would you recommend using ? Steve |
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Judson Manning Member
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Steve, I hate to give a particular product endorsement as I'm sure you can find a variety of products at your local auto parts store. It may indeed take repeated attempts and/or a variety of off-the-shelf remedies to clean all that stuff out. Again, no guarantees as your rings & liners may be beyond help. Judson |
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Ron Earp Member 
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Some guys swear by good old automatic transmission fluid to help get the job done. It is very thin and lubercates. Clearly, not for extended running but as a flush. I'd think a really thin oil would do the job too, like a 0W-10W. There are engine flushes too at the parts stores that can get it done. I've never had any luck with them fixing anything, but I did use some radiator seal once that did the job. Good luck to you! Ron |
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