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By Cactus - 12 Years Ago
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Has anyone tried the Best Kevlar rope seal? I can't seem to get a regular seal to stay in my engine. I have been in the process of having this engine built for about the last three years, and to be quite honest, I am getting tired of it. It is a 292 bored 80 over with a 312 crank machined to fit. The first time it was put together the head bolts were improperly installed and it filled with water. Got that problem resolved and now I can't keep the rear main seal form leaking. Recently put in the second one and shortly thereafter it started leaking. Any suggestions would be appreciated.
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By carl - 12 Years Ago
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I had three best gaskets seals in my 312 and all of them leaked.I bought a rear main seal from Don Hyde two years ago and so far no leak,probably 5000 miles. Don machines a Chrysler seal to fit a 312,Do a search on Ford Craft for more info.
Carl
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By Larry D - 12 Years Ago
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I've had the most success with the Best Gasket "Graph Tite" rope rear main seal part # 5249A.
It's a graphite impregnated rope seal so it will never dry out. It comes with the side seals and detailed installation instructions.
This fits all Y blocks from 239 to 312
I've also tried the silicone rear main for the 312 and it still weeps a bit when it sits.
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By Cactus - 12 Years Ago
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I will try that best number, I don't know what is happening with my motor, but it seals up and then after a few miles it starts to leave large puddles. How hard is this graphite seal to install with motor in car?
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By PF Arcand - 12 Years Ago
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Jan: Not saying your main seal isn't leaking.. but according to Ted Eaton, sometimes those leaks can be traced to the rear Camshaft Plug not being installed & sealed properly. That allows oil to leak down in the same area. Also, Ted notes that it's important that the plug not be jambed up tight against the back of the cam, removing clearance at the front. It's worth a look.
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By Cactus - 12 Years Ago
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Thanks Paul, I will check that this time.
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By PF Arcand - 12 Years Ago
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Jan; re your question on installing the Graph Tite rope seal. I undertook doing that and decided without loosening the main bearings & possibly having special tools, it looked like a potential mini disaster. So, I installed the lower piece only. It still leaks some, but it's hard to evaluate, because the front seal in the Fordomatic is leaking also. Sorry, I can't be of more help.
By the way both types of seals are available promply by mail from "Gasket City" in Hamilton Ontario Canada.
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By Larry D - 12 Years Ago
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Gasket City in Canada has been my supplier as well. My machine shop tells me if you are using a rope seal you want a roughened area on the crankshaft where the seal rides as the factory had, if it's a rubber or silicone seal you need to have this area polished smooth or it will just wear the seal prematurely. Maybe Ted Eaton or some of the other engine builders on this site, can offer some advise on crank surface finish in the seal area.
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By stuey - 12 Years Ago
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spotted this whilst searching for pump repair kit stuey Then and Now Automotive Specials/Clearance Items
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By Ted - 12 Years Ago
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For the 292 blocks, I use either the ‘black’ Fel-Pro or ‘black’ Best Gasket neoprene rear main seals and have had no leakage issues with either of these in the 292 blocks. For the 312 engines, I use the ‘black’ seal from FordCraft and that particular seal is a re-machined Chrysler seal. The Best Gasket ‘orange’ seal for the 312 engines has had a history of early failure rates so those are to be avoided until the design is changed up. On the 292’s, the hash marks on the rear main seal journal have not been a problem but any pitting or roughness otherwise on the crankshaft will force the seal to fail much earlier. When re-machining the 312 cranks to a 292 rear main seal, the seal journals end up being mirror smooth with no hash marks and I’ve had no troubles with those either when using the appropriate Fel-Pro or Best Gasket neoprene neoprene rear seal. The seal retainer itself can be the source of oil leaks so particular care must be taken to insure it’s sealed to the block well also. And don’t forget that oil pump as any leaks from it are easily blamed on the rear main seal along with rear block galley plugs and the camshaft rear plug. Here’s the link to the rear main seal installation article that was originally published in Y-Block Magazine. Rear Main Seal Installation Tips
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By Hutz 292 - 12 Years Ago
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Are you sure it's leaking or is it just Sweating from All the Horse Power!!!!
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By Ted - 12 Years Ago
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And don’t forget those two oil pan bolts that go into the rear main seal retainer. Those were originally studs and if replaced with bolts, make sure the threads are coated with some kind of sealer. If the studs had been removed and resinstalled, some kind of thread sealer will be required again. Leakage past those threads looks just like a rear main seal leak.
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By Cactus - 12 Years Ago
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I can't figure this mess out. I am now going to pull the engine and transmission and try to figure it out over the winter. My T-5 leaks too so I can try to get it sealed at the same time. Thanks for all the help. If I can't figure it out I have two options : rebuild as a 292 or go back to a 272 I have. Again, thanks.
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By idaho211 - 12 Years Ago
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Glad I read this thread. I am rebuilding a 312 and just put in the rear main neoprene seal from Best Gasket. It looks like it fits well, but based on feedback should I go with the Fordcraft one? Now is the time for a quick change due to it being apart.
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By PF Arcand - 12 Years Ago
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Idaho: Don't know from personal experience.. however, I've read that some 312 castings vary somewhat in the seal area. In those cases the Best Neoprene seal may not fit well & the new Graph-Tite rope seal may be the better bet. Or you could go with Ted's method. You need to examine it carefully & decide. Others here may confirm this or not?..
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By Cactus - 12 Years Ago
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Just wished to add an update. Pulled the engine today, when I drained the oil, I found a lot of water in it. I guess I blew a head gasket, and I think that seals probably don't do well with a lot of oil pressure and water. I am glad that this car is a "hobby" and not an investment. Maybe I will have this thing running by spring.
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By Daniel Jessup - 12 Years Ago
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Jan, Hang in there, buddy. Major, don't forget the last part of the Marine Corps code... Commitment! The young man that just graduated from boot camp down at Parris Island let me know all about the Honor, Courage, and Commitment of the Corps. I am taking him to lunch tomorrow (he lost a lot of weight down there!)  I am cleaning up the garage just in case you can come by. I know I am a little ways away from you, but if you need to use my engine run stand, I would have no problem with it. dan
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By DryLakesRacer - 12 Years Ago
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Not familiar with the rope gasket in a Y-block but changed countless ones in Chev 6's and GMC's. I have found that the "hash" marks need to be there and can be felt with your finger nail to work properly. When the GMC's got hard to find I when to the Fords and have had very little trouble with originals and Best's. I love to find the old asbestos ones as they are the best. I always cram in all I can in the groove both top and bottom. I also leave the block side a little short by pounding it up inside then leave the cap a little "high" on each side to fill the gap. This stops leaks also. I've even used set screws in the cap to keep them from turning. I know this may sound s little crazy but the use of a PCV valve keeps the engine at low driving/crusing speeds in a vacuum. I'm reluctant to do this on my 56 but I know it works and does not hurt an engine that's fresh. The vacuum definately helps with minor leaks. Most racing engines today run with as much vacuum as they can and not only use their dry-sumps for this but belt driven vacuum pumps also. I use on on my LSR engine....Just a thought..........
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By PF Arcand - 12 Years Ago
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A note on the Best Gasket Kevlar rope seal. The seal comes with a small pin that is recommended to be installed in the seal holder, to prevent slippage during installation.
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By Cactus - 12 Years Ago
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Another update, I guess that i am getting better, there was only water in number seven cylinder this tme. I hope that further tear down will expose the problem.
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By miker - 12 Years Ago
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This is a real long shot, as I don't know your motor. But on a 292/312 crank combo, I fitted a high volume oil pump, and didn't properly baffle the PCV valve location at the old draft tube in the valley cover. The excess oil off the timing gears (we think), went thru the PCV, into the back of the intake manifold, and I blew the head gasket to the water passage at #7 twice. Detonation from the oil, we figured. Fixed the baffle, and it never happened again. This PCV had worked for 3 years before I did the motor with the new, higher pressure pump, so that was all we could figure.
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