I’m having some problems with this engine after some recent work.
Mostly stock 1969 400G with C heads, stock intake and exhaust manifolds in a ’69 442 vert.
Had been rebuilt sometime before I got it. Bored .30 over, heads re-done, I don’t know what else.
The engine ran ok, compression 180 to 168, but valve guides were shot (or installed poorly) as it was burning oil in three cylinders, about 1qt every 750 miles. Plugs would foul at 2000 miles. When I pulled the intake manifold off I could see that crossover exhaust was leaking into two cylinders across the turkey tray.
I pulled the engine and trans last winter, plus took care of a few other things.

• The TH400 was leaking from the front, rear, side, and slipping. I had it rebuilt w/shift kit, new B&M torque converter.
• New spicers on driveshaft and high-speed balanced.
• Steering gear rebuilt w/tighter ratio, it was leaking as well.

I had the heads rebuilt, new valves, guides, seals. New roller timing chain, gears, water pump, roller rockers on studs, fuel pump, coil, aluminum radiator, all hoses, belts, thermostat 180* or 185*, etc. Also re-wired the engine harness.
I used FelPro head gaskets and ARP bolt set, new FelPro gasket set on the timing chain cover, new FelPro turkey tray. New bolts on the intake and exhaust manifolds, water pump, all torqued to spec and in sequential steps (where required).
I reassembled the engine, set timing to 8BTCD, runs better than ever. Plenty of power, no smoke, real joy to drive.
Except for the coolant leak into the engine.

 

After about 100 miles of driving a noticed the coolant was low, about 2qts. I topped it off, drove another 50 miles or so, then changed the oil & filter again.
Coolant was low again. And I discovered this yellow/white waxy substance on the oil filler cap and the top of the dipstick.
Re-torqued the intake manifold, timing chain cover and waterpump bolts. Cleaned it up, drove another 70 miles to 100 miles.
Still losing coolant, though no visible leaks, drips, or puddles. Still find a little of that waxy substance on the top of the dipstick, though none on the oil filler cap.
Now I find this substance on the oil breather cap, passenger side valve cover. This breather cap feeds into the base of the air filter housing. None on the driver side PCV valve.
I also have this large amount of oil on the bottom tray of my air filter. There were also some droplets of coolant there.
No oil in the coolant, though level still drops when driven.

 

More pic's, sorry out of order

 

Pic's of the oil filler cap, breather cap, air filter base.

 

Coolant is clearly leaking into the engine, then evaporating and going thru the oil breather and into the carb. Here’s my list of possibilities:

• Cracked block. Unlikely, never lost a drop of coolant in four years.
• Cracked head. Unlikely, my machinist does fantastic work, and has done quite a bit for my family. He certainly would have discovered and said something.
• Cracked head while torqueing to block. Possible?
• Blown head gasket? New FelPro’s, new ARP bolts. Possible, though nothing in the exhaust.
• Bad seal on new turkey tray? Possible and likely. I used black RTV around all the openings, both sides.
• Cracked or warped intake manifold? How common or likely would this be?
• Poor seal on the timing chain cover? I used black RTV, thought it was sealed up completely.

I’ll start removing the intake manifold as that seems most likely.
I’m thinking of replacing it with a new Edlebrock Performer. Would I get much improvement on a mostly stock engine, besides losing 40lbs? What gaskets are used between the Performer and the heads?

Please let me know your thoughts and ideas.

 

Hi, i have same engine, just installed performer intake and gasket and modifyed turkey tray to avoid Oil splash, i can see if i find the part nr for the intake gaskets, it should be a thread here somewhere too about it.

About the leakage problem, do you know if the heads are complete flat under? Or the block? Do you get water in to the silynders? What color have the exhaust?

I remeber i had this White slime from an old 4cyl engine long time ago, but cant remember why it be like that, maybe water in the Oil.

Here is one thread of my gasket install without turkey tray. As u can see i cut out for the exhaust crossover ports too..

https://classicoldsmobile.com/forums...-question.html

And in this thread i modify the old turkey tray to avoid some extra Oil splash. (i hope)

https://classicoldsmobile.com/forums...crossover.html

 

I replaced the head gaskets, seems to have solved the problem.
I removed the intake and heads with the engine still in the car.




I checked the heads and block surfaces, no visible cracks or scratches. They're all straight and true (to my un-calibrated straight edge).
I then cleaned them several times and used a penetrant dye test. No cracks.
I put on new Fel-Pro head gaskets and sprayed them liberally with Permatex copper. New "turkey tray" intake gasket with black RTV around the coolant, intake, and exhaust openings. Torqued heads and intake to spec.
Let the oil pan drain for a couple of days, replaced filter. I poured about a quart of oil on everything in the valley, let that drain out. Cleaned out the pushrods (had some of this waxy stuff in them), the lifters, and all the oil passages I could get to.




I've put over 200 miles on it since, no coolant loss. I don't have any of that waxy residue in the oil filler cap or the valve cover breather. No oil or residue in the carb or air filter base.
I'll change the oil again tonight, though it looks clear and new.
I'm keeping my fingers crossed that this is done!

 

Sounds like you got er fixed, well done. Now on to the next project and/or perhaps some enjoyment.