Coolant from overflow not returning to rad.
 

After a few problems with coolant leaks after putting my 3.5 in ive finally went out and got a pressure tester and found the rad was bad at higher pressure ( wouldnt leak at low rpms).
So new rad, new cap, new thermostat, upper and lower hoses and now the system is sealed up nice. Holds 18psi all day.
My newest problem is after bleeding the system everything is fine except after a hard run ( high rpm driving) the overflow tank gets filled but does not get sucked back in after cooling.
I have removed the plugs and shot 125psi of air into each cylinder at TDC and none are leaking and there are no bubbles coming from rad.
Could the headgaskets leak at higher pressures only? And what kind of pressure occurs at redline?
Going out to do a compression test on all cylinders right now.
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OK, what about after a "nomal" run--does the coolant get sucked back in?

Normal run doesnt overflow. Its not very warm here yet though.

Compression #s

1. 280
2. 280
3. 275
4. 285
5. 270
6. 290

Gonna take the covers off and recheck torque on head bolts maybe a loose one?
Also all my plugs looked good no signs of burning coolant. I dont seem to be loosing coolant. If i pour the overflow back into the rad its back to normal level.

New radiator cap
 

Yours may hold pressure, but it doesn't release when hot-hot to vacuum the overflow coolant back in.
I've bought bad rad caps before.

I retorqued the head bolts some of them turned a bit. Also re did valve adjustment and added a fuel pressure gauge at end of front rail. ( Ive also got a p1399)
ill be going to honda to get an oem rad cap screw thesr cheap motorad things lol.
Hopeully that will be the end of the problems.

Those are some pretty respectable numbers. My recently installed J35A3 compressions are all around 235. Makes me wonder.

What pistons did you use? I used the CLs pistons.

Maybe not Iggy.

It looks like 2ndgentl got similar results on his J35A3, lower even, then your compression numbers. :shrug: He did the same J32A2 cam swap as you, that's it.

Stock A3 internals except for the A2 cam swap. Maybe that's the difference.

Thanks Zeta. Puts my mind to ease, although it runs like a champ so I wasn't too worried:rolling:

I have to ask, do you have a photographic memory? How you pull this info so easily amazes me.:thumbsup:

Glad to help, if I can.:)

LOL, no I :wish: I had a photographic memory, hehe. I just have a knack for 'details/research' or just get lucky with quick searches.

Waiting on some nice weather to see if it was the rad cap i bought OEM one. Everything works great at idle and 2000rpm. Been freezing rain and snow here ..... :canada:

Im really hoping its not headgasket related but if it is ill be putting ARP studs in next time. I guess with that much compression a leak at high rpm makes sense. Im also hoping my p1399 doesnt come back its a real pita ive swapped to 6 known good coils and ruled out valve adjustment or egr passages. Only thing left is fuel and i got a permanent gauge on it now getting 40 with regulator and 50 unplugged regulator JUST within spec. Problem is most the electronics/ sensors i used were from a donor car that idled fine but i never drove it.
Ive yet to tear apart my original j32a2. Ill make my next motor with it :boogie: