Tibo

iTrader: (15)

I've been suffering from an oil leak at the back of my engine. It seems to drip about one drop every 2 mins. It was dripping off of the oil pan and trans front cover so I replaced all of the normal culprits like the valve cover gaskets rear main oil seal and the oil pan gasket. Still leaking. I thought it was coming from the oil pressure sending unit so I pulled the header and looked up and saw that the mating surface (head gasket) between the cylinder head and engine block's deck had oil there. You could see it and clean it with a paper towel. It is just below and slightly behind the spark plug on cylinder #7. I verified that the heads are torqued down to the correct spec.

It doesn't make sense for the head gasket to be bad and causing the oil leak because the only oil passage is the top back corner for the oil return. The back of the block, back of intake, top oil gallery plug, below the valve cover gaskets and distributor are all clean of any oil residue. Could this be a bad head gasket from the area of the oil return or some bad RTV between the block/head/intake letting a small leak snake around the head gasket?

Any suggestions?

cardo0

The oil returns from the cylinder heads are on the intake side of the heads and are not pressurized meaning any oil on the separation line between the head and block is dripping there from above and flowing downward. Even with a blown head gasket the only leak you could see would be coolant - not oil.

Try cleaning the area dry and spread some white flour in the entire area. Then drive around the block and have a look for drip trails.

Good luck.

OrangeBird

iTrader: (1)

Are you 101% sure it's not coming from the distributor ? I've seen more than one mystery leak in that area turn out to be coming from it .

Tuned Performance

iTrader: (92)

Try a oil dye that you can use a black light to look at the block.

https://www.ebay.com/sch/i.html?_fro...e+oil+dye+leak

Jorlain

iTrader: (4)

China wall leak, maybe?

Tibo

iTrader: (15)

I'd bet money against it being the distributor leaking oil. It has a new gasket, it's bolted on tight and the area is clean of any oil trail. The rear China wall is the only thing to make sense but that seems like long shot. It only leaks when the engine is running also.
Ill probably end up buying some UV dye and cleaning the area as well as I can. The hard part is that you need the header off to get a good look so I'll have to run it, let it cool, remove the header and then look again.

427seven

i'd bet all of china it's the intake manifold, happens all the time..... The point where the intake end gaskets join the intake/head gasket..... Although there was one time.... it was the oil pressure sender behind the intake manifold (87tpi).

NoEmissions84TA

iTrader: (1)

I agree with the china wall. Using synthetic oil, I guess? Some of the additives like to break down regular RTV. Use the Permatex MAX OIL RESISTANCE sealer next time.

Jorlain

iTrader: (4)

I've used The Right Stuff, Ultra Black, and Ultra Grey with good success. Lay a good bead and then let it sit long enough to get a little bit of a skin to it. Drop your manifold on. Boom.

BOOT77

What type of head gaskets did you use? Some have oil leak problems with MLS type. Also the gasket tips to the china wall of some are just a bit to short, recently read bout a guy who had to pull his intake and worked in some RTV to fix it w/o pulling the heads. Also have read about the same tip area being lower/deck or higher/head and not clamping those gasket tip areas well enough, another thing RTV fixed on that engine but heads had to be removed and it applied on the tips.

Recently had a sim issue but before I solved it had to pull the head due to bad machine work anyway. So I suggest as Tuned Performance mentioned dye or it'll be really hard to tell. Only way to maybe rule out head gaskets is jack up the rear and run it to see if the leak is now at the front. GL

Tibo

iTrader: (15)

I had an extra 1205 intake gasket laying around so I replaced them and put in new ultra black permatex rtv. Ill find out next week if it was the rtv at the back of the engine. If it's not I'll pull the head in the future.

Tibo

iTrader: (15)

I was able to change the intake manifold and use Permatex Ultra black RTV on the China wall front and back. It still leaks. As a matter of fact it leaked worse now then it did before I changed the intake gasket. Is possible that it could be the valve cover gaskets so I switched to normal RTV Ultra black gasket maker. I'll give that a try once it fully cures to see if that did everything. I also pulled the oil pressure sending unit and cleaned and sealed the threads and put it back in. For the valve cover gasket I had been using one of those Lube Locker design gaskets. It's a nice Fel-Pro piece that uses a steel shim with rubber all around it and the torque limiting bolt holes. The valve covers themselves also have a design so there is a lip around the gasket for the gasket to sit in. I think I'm just grasping at straws with it maybe being the valve cover gasket area. So if it's still leaks I will buy the engine oil dye to find out where it is leaking from. Will have ruled out all of the normal culprits.

NoEmissions84TA

iTrader: (1)

Is the intake side of your valve cover hitting on the intake manifold, keeping it up slightly and preventing a complete seal?

Tibo

iTrader: (15)

These are inexpensive valve covers and I did have a problem with the outer lip on the intake manifold side hitting the cylinder head gasket surface. Basically it wasn't wide enough so I had to take the lip down. I did that a few months back. Never really caused any leaking since it was on the intake side and oil really doesn't get up to that level.

Tibo

iTrader: (15)

Seems like it was the valve cover mating surface that was leaking. Really surprising to me since I was using good gaskets. Fel-Pro VS12869T. I Might have gotten a set of valve covers with a mating surface that's not flat is all. It will sure be bear to remove them now though...

Also, I found out that AutoZone is clearancing out the Permatex Ultra Synthetic RTV for $4 a tube, down from $11. If you drive by an AutoZone stop in a see if they have any left!

NoEmissions84TA

iTrader: (1)

Which one exactly? It might be in your area only, but nothing is on clearance in my area.

Tibo

iTrader: (15)

The Permatex Ultra synthetic RTV. It is not advertised as a clearance or sale item but when you ring it up at the register it comes up at $4.00. When the manager rang it up I actually yelled "What?!" The manager told me that they must be dropping that product and clearancing it out. I then yelled "I'll take all that you have and call all the other stores and have them transfer in what they have!" It's possible for it to be a regional thing. I know some products are offered at some and not others.

LB9GTA

iTrader: (1)

Try using this
https://www.permatex.com/products/ga...-gasket-maker/

Use it on the china wall.

I had the same problem with cheaper valve cover gaskets.

Tibo

iTrader: (15)

I'm going to buy a big tube of that on Amazon. It gets old applying RTV, waiting an hour to torque and then waiting 24 hours to put the seal in use. I've heard that in addition to the near instant use after install that "the right stuff" is also stickier and won't sag or droop before you get the item together.

cuisinartvette

x2 they always seem to leak from that corner. before you put it back together get some rtv in that area where the head meets the china wall youll see it. oil seeps through there and runs down theback/side and drips on the exh

Tibo

iTrader: (15)

I know the area you are talking about. I made sure to apply the RTV liberally to those areas and it still leaked so I knew that wasn't the problem.
It ended up being a leak at the rear outside corner of both valve covers. Admittedly, the valve covers are cheap cast aluminum chinese parts. I had to remove it's outer lip just to allow the cover to sit on the cylinder head mating surface. There also was a slight curve to the mating surface of the valve cover when put against a straight edge. I'd guess it was 1/16" difference from front to back and it was just too much for the FelPro gasket to deal with. I'm not willing to 100% blame the valve cover manufacturer since I had to weld 8 mounting tabs on the top of each valve cover, so it may have warped from the heat. I didn't install these prior to welding so I can't say. At any rate, RTV in place of a normal rubber gasket seems to have solved the issue.

However I'm still dealing with a leak between the front of the oil pan, the FelPro PermDry gasket and the timing cover. It does not appear to be a leak from one of the corners of the front of the oil pan and I did use RTV in those corners. I know It's a recipe for disaster because the parts are all different brands, the timing cover is just some aluminum no name piece (again, probably cheap chinese casting) and the oil pan is the pricey Summit piece that has more capacity and the scraper, trap door and windage tray.