Could it be the water pump gasket leaking and dripping off timing cover? Did you check water pump hardware, was it tight?
On my 393w build I just finished I had a cracked water neck that was leaking but you said you replaced that already.

 

Water pump gasket leak? It looks like there is coolant between the pump and timing cover but I could be wrong. The engine leans back so there shouldn't be any coolant in front of the timing cover.

 

While I won't dismiss any possibility at this point, it really looks like the leak is right at the block, not at the water pump, but it's really hard to see until I remove the accessories. I used all new ARP hardware and torqued to spec.

 

Bump. I'm mainly looking for advice on how to deal with the steel core one-piece oil pan gasket when performing the repair.

 

I just did a cam swap on the race car, same gasket (Fel-Pro one piece steel core). I did not loosen the pan other than the front 4 bolts that hold the pan to the timing cover. It is tricky to get it all back on. I use a dab of silicone on the corners. To get the bottom part of the pan gasket back onto the timing cover, I used a small screwdriver bent on the blade end so "pull" the gasket kind of outward and onto the timing cover. A pick would have been better but I don't have one. It helps to have 3 or 4 hands to do it. I only have 2 hands and yes it was a pain in the butt, but I did it. So far no leaks, and I'm totally surprised. Mine's easy to get the pan off (chassis car) and if the time comes when it does leak, no big deal I'll deal with it. Just wanted to see if it could be done without removing the pan.

Is it just me or does the timing cover appear to have been pushed out (broken) from the inside? My eyes ain't all that great and I may be wrong.

 

Loosen all the pan bolts then you will have to pry the gasket out of the two corners of the timing cover where you out rtv. Pan and gasket will drop enough so you can pull cover straight off.

I always use rtv around the water ports of the block and timing cover on both sides of the gasket.

 

When you torque those bolts let them sit overnight if you can, then retorque again, it seems they relax and loosen up a bit, its happened to me a couple times.

 

Thanks for the replies. I was hoping to hear that others were successfully able to replace the cover without butching the oil pan gasket, and am glad that some of you were. As much as it's a pain, I think I will attempt to lower the pan slightly to give myself more clearance (it's in a Fox Body, meaning I may have to lift the engine). I'm hoping the fact that it's a freshly assembled engine means I'll be able to get it apart without much of a struggle due to caked together parts.

toddturbo, I noticed that "crack" after I took the photo as well. I think it's just extra flashing material, but I haven't had a chance to check again. My plan is to pull all of the front accessories off the timing cover area and inspect everything carefully. Thankfully(?), the leak occurs without any pressure in the system, so hopefully I'll get a clearer picture of the problem.

 

Its not a crack, it is extra casting. There is a channel on both sides of the cover that are there to prevent oil mixing with coolant should the seal fail. This appears to be where the leak is coming from. If coolant drips from the tstat it will find this channel and drip down the block

 

Huh. It really appeared that the leak was originating at the timing cover, but what you say makes sense. I could absolutely see some coolant leaking from the thermostat housing (via a mirror) but it looked like most was coming from the timing cover itself.

If what you say is true, I have to wonder why the thermostat keeps leaking. I'm using Stant gaskets which are self adhesive and hold the t-stat in place and seem to adequately cover the sealing surface of the housing, and now have a brand new t-stat housing. I also have to wonder if the timing cover gasket is compromised due to being soaked by coolant anyway?

I'm not going to jump to any conclusions until I get all the bracketry out of the way and can clearly see all around the timing cover area.

 

I don't know where the leak is coming, all I am saying is if the t stat leaks, the coolant will find its way to this channel. Here is a new cover I just laid on a dart block. Entrance and exit points.

 

That appears to be exactly where it's leaking on the ground. Definitely food for thought, but I just discovered one other thing that may be a factor. Do any of the timing cover bolt holes reach the water jacket, or are they blind? Searching online I'm getting conflicting info, but I don't think I used thread sealant on any of the timing cover bolts (used ARP thread lube instead). Mine's an '80s roller block FWIW.

 

They are blind but suspect to water creep rusting them in place over time. The anomaly would be if the factory broke through while drilling and tapping. I highly doubt this is your issue

 

VERIFY AREA OF SUSPECTED LEAK CLEAN AREA AND USE A COOLANT DYE (BLACK LIGHT TO PINPOINT ORIGIN OF LEAK)... USE A COOLANT PRESSURE TESTER/LOW PSI

GOOD LUCK.

 

Strokeme-redux: Are you Woody from Ford Strokers? Guessing you may have had some login issues with the password changes here?

IRUNEM7, once I get the front accessories off I don't think I'll need dye to pinpoint the source. It was leaking in a solid stream, but I agree that a pressure tester is a good idea just so I don't have to keep pouring more water in the radiator.

 

Yes, I am. I requested a new password a week ago, I got one today. The new password was for my NEW username. I mean wtf lol So here I sit for who knows how long until I get a new one for the old username

 

Not to derail the thread but I just got a new password for my New user name as well!
Looks like we had the same idea when we created the new user names. Hopefully I will get a password for my old user name, would like to keep my 50+ positive feedbacks......oh well.
Sorry o.p., back to the topic.

 

I've seen the intake gasket leak on the side with the thermostat and it's kind of like this. You could always pressure test it with a mirror and check it. Just don't exceed cap or rated pressure.

 

They are "supposed" to be blind. That said, on stock blocks-that are now 20-60 years old and could have been built a few times...or had water pumps replaced from time to time, I've seen several where the water pump bolts must have either broken or they were lost. Owner or mechanic runs down to the store and picks up a bolt closest to the right length and runs it in. If it's 1/4" too long, it'll bust through the back side every time. I've done it myself-and there's no way to fix it other than lots of monkey snot on the threads, a little prayer, and the blessing from the engine Gods to keep it from leaking.

I actually did this similar deal on my own tractor recently while replacing a water pump. I am not happy with myself, either.

 

It appears that Woody's theory may be correct.

I first removed the belt tensioner and A/C bracket to see things better, and retorqued the timing cover and water pump bolts. I then pulled the t-stat housing off to try resealing it again. I cleaned both the intake and t-stat housing very thoroughly, then superglued the t-stat into the housing (verified the correct direction and oriented the bleed hole to the top). After the glue cured I installed a new gasket. In my previous attempts I had use Stant gaskets which are self-adhesive on one side. This time I used the non-adhesive gasket that came with the new housing and coated it with a thin but thorough layer of Permatex water pump and thermostat housing RTV sealant on both sides. I then installed it back on the engine, and once it was back together (probably 20 mins after I applied the RTV) I hooked up a coolant pressure tester.

Previously there was a constant stream of coolant leaking from the thermostat housing, and possibly the timing cover, with no pressure applied to the system. This time, there was no leaking at all until I added about 10 psi of pressure to the system, and even then it was only small "bubbling" from the bottom of the t-stat (verified with a mirror), not the timing cover, a dramatic improvement. I long ago threw away the instructions to the RTV, so I looked it up online and found they recommend curing for 24 hours. So I think that my adding pressure to the system within 20 mins of applying the RTV was premature and could have caused it to fail, so for now I'll leave it until tomorrow and try again.

I still don't understand why I'm having so much trouble sealing the t-stat housing. I've replaced t-stats on Windsors probably a dozen times and never had a problem using a dry gasket. I'm using the same intake manifold and housing as my last combo which never leaked, so the only new ingredient is the t-stat itself (new Motorcraft). I do have a new t-stat housing now. But whatever the case, if this solves the problem it's 10X easier than replacing the timing cover gasket. I'll report back what happens tomorrow.

 

I didn't read all the way through, but what t-stat housing are you using? I've bought some from the parts stores....they're usually cast iron or pot metal, a.k.a "chinese" (whether they are chinese or not I don't know). Anyway, out of the 4 or 5 I've bought, not a single one of them would seal up. 2 reasons. One, the bypass hole is larger, and won't seal properly-the hole barely overhangs the gasket. Two, the surface was not flat. I kept exchanging them thinking I might find a good one. One afternoon in August, I was on a service call for work and passed a big junkyard full of Ford cars and trucks, so I stopped. Guy had a 5.0 out of a Lincoln sitting on the floor, t-stat housing easily accessible (OEM), and he said I could have it if I needed it. 1/2" wrench and 2 minutes and I was on my way again. That one (OEM) sealed up perfectly on the first try. Actually that's how I found that the aftermarket ones have a larger bypass hole. BTW, this was a Performer RPM II EFI intake, for what it's worth.

Yes I fought that one too...leaks. And I agree, on 5.0's , 289's, and 302's, they're a pain. The windsors are too because the stat has to be glued on before installing everything but at least on the windsors, you can get to both bolts easier.

Felt it worth mentioning, for what it's worth.

 

Here is a new thought. Your intake gasket may be leaking instead. I had a leak that I thought was the thermostat housing. My story sounds exactly like yours. I replaced the thermostat gasket a couple times. Still leaked. Bought a new FRPP thermostat housing,still leaked.It wouldn't leak at first only after it was warm. I couldn't figure it out until I did the pressure check thing.Even then at first I thought it was the thermostat housing leaking but it really was the infamous Fel-Pro intake gasket leak. It was leaking from the front water port on the passenger side and running down the front of the block from under the thermostat housing.
I must have replaced the intake gasket 4 times that time trying all different brands to get it to stop leaking and then about once a year I had to do it all over again. Lucky thing for me, it never leaked inside the motor. What the giveaway was you would start seeing a little antifreeze on top of the water pump before it really started leaking heavily.

 

I'm using a regular replacement t-stat housing from O'Reilly's. Not sure what material it's made of, but it's likely Chinese. It's identical to the housing I was using previously (which had not leaked for probably 5 years on my old engine). If I had access to a good OE housing I'd use it, but unfortunately I don't. I didn't specifically check the gasket face on the housing for flatness, but in retrospect I should have. I did notice that the bypass hole was bigger than the hole in the gasket. I had three different gaskets available to use (Stant, Felpro, and the one that came with the new housing) and the gasket partially blocked the bypass port on all three. There's nothing I could do about it so I just ran it as is, but I never thought that the OE housing may have a smaller hole.

I was concerned that the leak was coming from the intake manifold, but with a mirror I could CLEARLY see the coolant bubbling where the t-stat housing meets the intake (I took photos but can't post at the moment). I'm also using the 1250S3 intake gasket which has a metal core and won't shift like the standard one. I ran into problems with intake gasket sealing previously and won't use anything but the metal core version anymore. So at this point I'm relatively confident that the intake is okay.

 

I think I've solved it. After the RTV cured for 24 hours I pressure tested it again and no leaks! Well, almost. At 15 psi there was no leak seen however the pressure slowly decreased and I could hear a slight bubbling sound. Poking around with a mirror I confirmed there was a slow drip out of the bottom of the bypass nipple. The t-stat housing appeared to have some sort of epoxy where the nipple meets the housing and maybe that's it. I think I'm going to pony up and buy a new Ford housing and get this done once and for all.

 

Scott - are you disconnecting the hoses before trying to seal the t'stat housing?

 

Yes indeed. I learned long ago that trying to get it in place with the hoses connected is an exercise in futility.

I just bought a new Ford t-stat housing which should be here in a couple of days.

 

I got the new Ford t-stat housing all bolted up and need to let the RTV cure for 24 hours. Before I did that, I decided to compare the gasket alignment on the aftermarket housing vs. the Ford using the bolt holes as the reference points.

Aftermarket + Fel Pro gasket:

Ford + Fel Pro gasket:

You can see that both the holes for the thermostat and bypass are partially obscured by the gasket on the aftermarket housing.

Next, the aftermarket (top) vs Ford, both with Stant gaskets (I had two of these but only one Fel Pro):

Same story, the gasket partially obscures the holes on the aftermarket. Finally, this is what I pulled off the car from yesterday. Note the gasket partially obscuring the bypass hole:

It's clear that the gaskets were designed around the OE Ford housing. I'm hopeful that the better alignment of the Ford housing plus RTV will solve this once and for all, so I'll have to wait and see tomorrow.

 

I'm happy to report no more leaks today, and I was able to take my car for it's first drive since April of last year! MAJOR thanks for Woody for pointing me in the right direction.

 

I like a happy ending. Thanks for posting the followup.