stop leak?

[427]

Has anyone had any luck with stop leaks. I think I have a leaking rear main on my f.e. If so, which is the best one. Thanks,Brian.

[DGrant09]

Brian,
Edit - I should have asked you what engine do you have ? - first!
Are you 100% it is the rear main seal and not the rear of the intake manifold where it meets the head and block?? Ours is a 390 and these are quite popular for leaking there.
As for the stop leak, I've always stayed away from it unless there were no other options. When ours was leaking (a lot!) I just carried extra oil and a oil pan to collect the leaking oil when we parked on nice driveways. I do not have a clue what stop leak could do to the oil passages and pump system. I'm sure someone who knows will chime in soon..

[Dragon]

Stop leak works by softening rubber gaskets and seal, making them swell a little bit from absorbing aromatic solvents ( extremely light weight solvents) It works to some degree but if it makes the seals at the rotating points on the crank they can get too soft and dissolve. Making the lek worse at a later point. Lucas makes some stuff that slowed my leaks and did not cause a problem. It did slow down the leak. But beware there are some real bad ones that almost melt your seals.

Now you ask why is a service tech using that stuff. I need to pay some old bills before I tear my motor apart and replace the seals.

[427]

DGRant09 its a 64 427. I built the engine a few years ago totally went through it. I just redone the intake gaskets because I thought thats where it was coming from but I still have the problem. When you drive it hard you see a smoke trail coming from the passenger side rear. And when you look under the hood the passenger side header is smoking from oil,where the collector meets the header. The rear main is all I can think of? Thanks,Brian.

[Dragon]

Depending on the tranny it could be the front seal of the tranny. If you get a mirror and look down the back of the engine that much of a leak will be obvious if from the top. Remove the clutch or torque converter inspection pan and check there.

[427]

Dragon im running a toploader 4spd. So if its the rear main will I be able to tell from looking through inspection cover opening? thanks,Brian.

[Dragon]

Lucky you with that top loader. The front seal almost never fails. If the back of the flywheel is wet you have a leaking rear main. If it was the tranny the clutch would be wet but not the back of the flywheel.

[427]

Thanks dragon I will check into the back of the block. It only seems to leak bad when you drive it hard never when you just cruise around normally. Thanks,Brian.

[fordman]

for some reason i thought you were talking about a antifreeze leak when you said stopleak. i didn't think a 427 had waterjackets near the rear main. so i guess i was right about that.

[DuckRyder]

...It only seems to leak bad when you drive it hard never when you just cruise around normally. Thanks,Brian.

That almost sounds like a crankcase vent problem. Whats the PCV set up?

[427]

DuckRyder I have solid pent roof vave covers and im running a factory 2x4 Ford intake with the tube vent in the front and I have a snorkle on the back of the intake. I used to run Cobra aluminum valve covers that had breathers in them with the same intake setup and the problem stayed the same. The engine does leak oil when it gets warm. The rearmain is the only thing I can think of? Thanks,Brian..

[FoMoCo]

Double check the pcv vac. Sometimes dirt wears a ring on the crank and balancer causing the leak. If the stop leak doesnt work you may want to try a Felpro Sleave-and-seal.

Nick

[69rangerman]

Any chance it's a valve cover gasket? Over time it would seep down the block, blow back to the bellhousing and down to the bottom of the bell/cover plate area.

[FORDification]

You might also want to check out the rear oil gallery plugs (if it was set up for hydraulic lifters) and the rear cam plug. Chances are it's not them, but anything's possible. Unfortunately, you'll have to pull the transmission to check those.

Here's a picture for the visual. In this shot, the arrows point to where most FE's with hydraulic lifters have the oil passages drilled out and then have a Allen-head cap plug screwed in. This 427 was set up for solid lifters, so the oil galleries weren't drilled out, thus no cap plugs.



Your best bet would be to simply power-wash the heck out of the engine to get it super-clean and then let it run for a while and see where the new oil starts to appear.

[Dragon]

The bottom Allen plug is the for the Cam bearings on a side oiler and has the engine oil pressure relief behind it.