Hi guys I’ve been making threads recently about failing to seal up the China walls under my intake.

Recently got the truck back together and snapped a pic

after about 4 hours of driving the rear gasket is leaking and sticking out from between the valley pan and block. This time I stacked everything:
block
sealer
rubber seal
sealer
valley pan
sealer
intake

I let everything set overnight and retorqued the next day. Engine didn’t leak for the first 2.5-3 hours. I’ve tried this factory intake and a Weiand 8010. I’ve tried 4 different sealants including The Right Stuff, and I’ve tried rubber seals and no rubber seals.

I don’t think the engine has excessive blow by. It doesn’t smell or smoke and it runs really well. The rear china gasket just leaks no matter what I do. Maybe I should do a compression or leak down test all the way around to see what results I get.
I have never done this and had a vacuum leak. Or a oil leak in the front. It is always the rear and the whole seal ends up out from under the valley pan.

I’m thinking about trying one more time without the end seals before I take it to a shop in town. I know the owner pretty well. He does commercial trucks, personal cars, and I’ve seen 10-15+ older vehicles like mine in his shop over the years. He’s not a vintage ford mechanic, but he is smart honest and he does good work. I know many commercial and personnel vehicles with work done on them from his shop. I’m to the point now where I DONT want to do it. This gasket set that’s leaking now is the 3rd one this year I’ve done on this truck. I have boxes of parts sitting in the garage waiting on me to get the intake sorted out. And a project car with boxes of parts out back waiting on me. But I go round and round with this stinking china wall gasket. I’ve done every other gasket on this truck without fail except for the head gaskets which I’ve never had to touch.


Just an update for you guys, and a pic cuz I know y’all like pictures. I painted the intake and valve covers with old ford blue. Last winter I rebuilt and cleaned all the grime off my 2150 so its looking good. I repainted my throttle return spring and coil bracket with Eastwood underhood black which I bought for another vehicle but it’s supposed to resemble old school gm underhood black. It’s a really nice matte color that doesn’t get all greasy looking really easy.


Oh and the double air cleaners are because a single one gets dirty really fast around here. 2 last a big longer before they turn dark grey. Don’t make fun of me!

 

If china wall gasket is bulging outward, then there is excessive crankcase pressure. You either have a little too much blowby, or your PCV setup isn't working properly.

 

Stop using sealant. You can't glue a motor together.

 

My 79 bronco with 351m leaking in front and back I’m yet to try. I got the valley pan and the gaskets sounds like a pain in the rear. I got the California smog equipment which is a lot of vacuum switches and lines egr ect. Hate to spend all that time to have it leak again

 

Is your pcv valve connected through your oil filler cap? It could be that if the filler cap does not have a good seal that the pcv system is pulling outside air instead of crankcase vapor.

Try moving it the rear of the passenger side valve cover. (Is that opening also connected to a vacuum source?) The non pcv should allow filtered fresh air in.

On our 300 the filler cap draws fresh air while the port in the rear gets the vacuum for the pcv valve.