FE Oil Purge

[Mongoose930]

Looking for a little help with a big oil leak. After finally winning the intake manifold gasket battle last year, my engine has been running without any oil leaks until today. I took the car out for breakfast this morning and when I came out of the restaurant, there was a sizeable puddle of oil underneath the car at the back of the block on the drivers side. I drove the car home and when I parked it and looked underneath, I could see a steady stream of oil leaking from the bottom of the bellhousing. Again, a puddle the size of pie plate in about 30 seconds and then the stream stopped. I put the car up on the lift and cleaned everyting up. I started the car while up on the lift and there was no leak after letting the car run for a minute or two. Shut the car off and again, a stream of oil came pouring down - probably a 1/4 cup+ of oil. I can't see where it came from but it is not leaking around the valve covers, oil pan or the rear of the manifold. It seems to be coming from the the left rear of the block. Could this be some type of blown head gasket? What else should I be looking for to isolate the problem. It seems strange to have the leak when you shut the enginge down. Any suggestions would be greatly appreciate.

[Mongoose930]

I figured I would rename the post in the hopes of getting some thoughts on where this oil is coming from.

[lovehamr]

JMHO but it sounds like a possible rear main seal or a leaking galley plug. I will say that I've seen rear intake manifold leaks that looked for all in the world like they were coming from under the bellhousing just because that's where it dripped from. Failing that, you may want to get some leak detection dye and give that a shot. Or pull the trans and bellhousing to take a look, might have to do that anyway.

[undy]

Such a quick and massive leak sure sounds like an unseated rear oil gallery plug.

[Mongoose930]

I am 99% sure the leak is not from the intake manifold as I redid that twice last year and I looked in all the usual areas prone to leakage and I don't see anything. The flow seems to be coming down the back of the block but in front of the bellhousing which leads me to believe it is not my rear seal. What is really confusing is why the leak only occurs when I turn the engine off. As soon as I cut the power, a stream of oil pours out and then it stops. The car is not leaking oil while it is running. Very confusing.

[elmariachi]

If its not from the intake and not from the rear seal then all you have left is cam cover and adjacent galley plugs. Easy for me to say because I have a tranny jack and a low tolerance for pain but I'd be pulling the tranny and taking a good look around.

[Gaz64]

Yes, does sound confusing.

It can't be a pressure leak, pull the gearbox out for a look.

The oil is probably all over your clutch now.

[Dinobyte]

I would double check a couple of things...

Valve cover seal...it may not be it, but check...feel the back of the head, closest to the firewall...if you feel any oil, you may have a leak.

Broken rocker arm....crazy, but it will cause overpressure because the valve is not opening, and start forcing the oil out in odd spots of least resistance.

Oil Pan seal...make sure it is good...it may just need to be tightened.

After that, you get into some of the major mechanicals and or rear seal issues.

Sorry about the leak. :-(

[Mongoose930]

Thanks for all the suggestions. I am assuming the worst but hoping for the best. The more I think about it, the more I think it may be an intake or valve cover gasket leak. Any other options are not so good...

I have checked the calibration on my torque wrenches tonight and I plan on tightening everything up in the morning. One way or another, I will figure out where the oil is coming from tomorrow. The thing that has thrown me off is that the leak only occurs when I shut the engine down.

I will let you all know what I find out this weekend.

[elmariachi]

Originally Posted by Mongoose930

The thing that has thrown me off is that the leak only occurs when I shut the engine down.

That would suggest it could be in the rear main or pan rail area. Pan is not nearly as full when the car is running. You shut it off, the pan fills up and oil comes out of the breach.

Most auto stores carry a dye kit that involves a small bottle of florescent dye, a penlight and yellow goggles, usually about $20. Dump the dye in the oil system, fire it up and watch for the pretty (ugly) neon green to appear.

[RICK LAKE]

Mongoose930 Jim been reading my threads. Elmaraichi has it right. Go and buy the leak finder kit with the dyes. Make sure you oil is full and run the car for a couple of minutes. use glasses and light to find leak and repair. This is right out of the manual. I don't understand why you have no leak with motor running and get a flood with motor off. You have good oil pressure with motor running?? If your car does have a PCV in it, there may be enough vacuum inside to keep the oil from leaking out and when motor is turned off, out comes the extra. I am thinking valve cover gasket leaking between intake manifold and head. Returns are slow. Do you have the tins under the rockers?? Get kit and you will fine out. Rick L. Ps Jim you have learned well, grasshopper.

[Mongoose930]

I torqued everything down this morning and let her warm up for a while. As usual, no leaks while the car was running. As soon as shut it down, I saw the oil leaking from the crack between the intake manifold and the head at the back of the block on the drivers side. I put so much time and care into replacing the intake manifold gasket this past summer that I can't believe it is leaking again!!! I guess the good news is that it isn't anything major. I am going to buy a syringe and try to fill the crack from the outside. It probably won't work but I figure it is worth a try.

[RICK LAKE]

Mongoose930 Any chance of getting a first name?? I know it's not mongoose. Picture would really help. If you are having the same problem again, there is a machine problem with manifold and head and block You need to get an angle meter and find out what the problem is with this corner. There may have been too much machine work done and is causing a bad sealing angle for the gasket. A couple of heat cycles and the gasket lets go.
Are you using any sealer on the corners?? RTV? This is an expandsion problem. You might try a stud and nuts in the back corner. Problem is if the angle is to far off you could snap the manifold corner. In the winter pull the motor and have the intake, block and heads all squared. Pull intake manifold and check is the best for now, add some grey RTV seal and follow instruction and 2-3 minutes for skinning and 24 hours for sealer to cure. Also follow toque pattern on bolts. Start at 20 and go 10 then another 5. This is dry on bolts and threads. Good Luck Rick

[Mongoose930]

Hi Rick - I really appreciate the feedback and my first name is Kevin. This problem is actually a little different. When I purchased the car early last year, part of the deal was that the previous owner was going to swap the dual quad set up for a single 4 barrel. That was fine with me as I wanted the single 4 barrel and ended up with a brand new Holley carb and Blue Thunder manifold. Unfortunately, there were a lot of leaks when I finally picked up the car. I had the intake manifold changed but there remained one leak at the back center of the manifold. Third try. I called KC and asked what they used for RTV. Ordered some of that along with Felpro 1247 gaskets. I wanted the Cometic gaskets but they were out of stock and I didn't want to wait the 2 weeks since I really wanted to drive the car. Everything has been fine since last August with about 1,500 miles put on the car. This time the leak is in a different location - the area where the intake manifold meets the head on the drivers side. I have patched it up with RTV and as soon as the rain stops I will take if for a ride to see if the patch holds. I already ordered the Cometics gasket set but I am hoping that I don't need to actually open it up until winter - hopefully the patch holds for now. When I eventually do tear it down, I will measure the angles but I think I am in pretty good shape. I did use sealer on the back corners - Kimball Midwest Extreme Gasket Black RTV II. I followed the toruqe pattern on the Edelbrock website for my intake manifold as the Blue Thunder website was not very helpful. Max. torque of 25 Ft.-Lbs as I have the Edelbrock Performer aluminum heads.

[elmariachi]

Originally Posted by Mongoose930

I saw the oil leaking from the crack between the intake manifold and the head at the back of the block on the drivers side. I put so much time and care into replacing the intake manifold gasket this past summer that I can't believe it is leaking again!!! I guess the good news is that it isn't anything major. I am going to buy a syringe and try to fill the crack from the outside. It probably won't work but I figure it is worth a try.

A couple of things....just confirming you are NOT using the long flat cork gaskets that are designed to lay across the front and rear block rails? Those are generally discarded in favor of a big fat whopping beat of sealant. I personally prefer the The Right Stuff over any other RTV. Assuming you already know this but when you dry-fit the intake ahead of laying down sealant, you can get a good idea of how much sealant is needed and you should use liberally in those areas.

I have had to repair mine in the same area and have found that an Exacto knife and a couple of dental picks work well for pulling the material out of that slot, followed by q-tips soaked by some brake cleaner to clean out the slot you intend to refill. This DID work for me and has held without any problems. You'll most likely have some small RTV bits fall down into the valley so an oil change afterward might be in order. The filter will catch it but I guess it depends on your FE hygiene and peace of mind.

Good luck with it, glad its not in the rear main or pan gasket areas..

[ted]

I'll add that after laying down your bead of RTV on the block rails, take a thin film and smear on the intake rails before setting the intake down. This will give the RTV something to stick to in the event it has already started to 'skin over' before getting the manifold laid in place.

[GT350Mike]

Just a different avenue to consider; I built a 428SCJ back when I was in college (many moons ago) and during the initial start-up, we had an issue with oil leaking from the head gasket. If my memory hasn’t failed me, I think the problem was attributed to the improper application of the sealer to the steel head gasket. As you already describe, the oil is coming from the junction of the intake and head so the head gasket may not be the issue but it is worth checking to completely rule it out as the problem.