Julian Mullins Posted February 15, 2017 Report Share Posted February 15, 2017 I am struggle to stop oil leaks. CP engine, recent rebuild. Had an oil leak from rear crank seal (despite having replaced it at rebuild), gearbox out, new seal and speedi sleeve fitted + new copper washer on top housing bolt. Reassembled, oil pressure on cold start up at nearly 100psi. Oil now dripping slowly from spin on adapter/block, run engine up to temperature, tick over oil pressure now at 55/60psi and no longer dripping. Turn off engine and get 4 drips. Replaced spin on adapter/block seal, cold start pressure as before but oil now "flowing freely" from spin on adapter/filter. Could this be the oil pressure relief valve not working, hence too much pressure blowing seals ? Any suggestions would be very welcome Quote Link to post Share on other sites
Sapphire72 Posted February 15, 2017 Report Share Posted February 15, 2017 (edited) Replaced spin on adapter/block seal, cold start pressure as before but oil now "flowing freely" from spin on adapter/filter. First thing to do would be to remove spin on filter, then dig around- where the filter makes its seal- with a thin sharp instrument looking for an old stuck seal. You do have at least one seal in there, right? Edited February 15, 2017 by Sapphire72 Quote Link to post Share on other sites
Julian Mullins Posted February 15, 2017 Author Report Share Posted February 15, 2017 Thank Sapphire72 Do you mean remove the filter from the adapter or the adapter from the block ? Either way only 1 seal fitted to both Quote Link to post Share on other sites
Chris59 Posted February 15, 2017 Report Share Posted February 15, 2017 You should find 2 seals on the adaptator. Be aware, some of these adaptators are real crap. About your car leak, check the engine cranckase vent, it may be blocked. Quote Link to post Share on other sites
Sapphire72 Posted February 15, 2017 Report Share Posted February 15, 2017 (edited) Do you mean remove the filter from the adapter or the adapter from the block ? Julian, I meant to check where the filter screws up onto the adapter. Sometime an ancient gasket is left in the adapter, then a new one is inserted on top of the old one, resulting in heavy flowing leakage. All this applies if you have the type of oil filter and adapter in my photo. Cheers, Walt Edited February 15, 2017 by Sapphire72 Quote Link to post Share on other sites
oldtuckunder Posted February 16, 2017 Report Share Posted February 16, 2017 IMHO 100psi cold is high, and if your getting 55/60 at up to temperature tickover that is also high, I assume by up to temperature you mean really up to temperature not just the coolant up to temperature which at idle will occur about 10-20 mins before the oil even starts to get warm/thin enough to be working properly. Yes I would check the pressure relief valve, sometimes the plunger can bind in the spring, and I assume you didn't fit an upgraded spring? If you fitted new spring and plunger on rebuild may be doubly check, some new ones are crap. I assume that the adaptor was fitted before the rebuild, and wasn't leaking before, so your looking at a refitting issue? The adaptor plate should be fitted with a large circular seal in the block, this is the one people are saying check you don't accidentally have two in there, old ones can harden like iron so much so that you really wouldn't know it was in there, and then at times but not always adding a new one when fitting filter or adaptor it will leak. Also between the adaptor and the block there should be a large circular seal, on better adaptors this is sprung loaded so will take up height differences between block and adaptor machining, on non sprung ones its easy to have an outer seal too thick to stop the inner seal working, or vice-versa. Alan Quote Link to post Share on other sites
Julian Mullins Posted February 16, 2017 Author Report Share Posted February 16, 2017 Gentlemen. Thank you for your advise. I have checked the crankcase breather and no blockage there. I have ordered new seal for the adaptor, a pressure relief valve and an oil filter from Moss so will see what happens when fitted. Thanks again - I will update you soon. Julian Quote Link to post Share on other sites
kevine Posted February 17, 2017 Report Share Posted February 17, 2017 Hi Julian I could not fix a leak involving my spin on filter. (used many filters from all sorts of suppliers) I then purchased a new spin adapter from mocal with an improved design, from my old one.. Leaks then became a thing of the past. kevine Quote Link to post Share on other sites
astontr6 Posted February 17, 2017 Report Share Posted February 17, 2017 Julian, There were 2 adaptors types made by the same company Mocal. The first type does not have a sprung loaded seal in the middle facing the block. These often leak!!! from the outside, the only way to cure this is to machine 1mm off the centre O ring seal boss, re-machine O ring grove section so that the outside enters the block another 1mm. This is what I had to do on my car years ago! This type is not made anymore by Mocal. If you do not want to go down this route, speak to Mocal direct and you can usually do a deal with them about your leaking adaptor and get the latest type at a good discount. But as stated by others above take note of a very old O ring stuck in block? An old scriber makes it very easy to remove. Bruce. Quote Link to post Share on other sites
peejay4A Posted February 17, 2017 Report Share Posted February 17, 2017 A word of warning about the old type. Don't be tempted to tighten it up just a bit more to cure a leak. The cast boss in the block can and will break off. Replacement block required. Quote Link to post Share on other sites
Julian Mullins Posted April 5, 2017 Author Report Share Posted April 5, 2017 Sorry for not updating, I've been away, but now that I am back I have replaced the PRV for a standard one, 3 mm shorter sping than the one fitted. The oil pressure is now down from about 98psi on cold start to about 80 and I've replaced my "old style" spin off oil filter adapter. The perfect cure, no more leaks, so thank you for the advice gentlemen, it's been invaluable. Quote Link to post Share on other sites
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