overheating DOHC

Guard1an · Post by **Guard1an** » Sat Apr 21, 2012 12:44 am

well recently the water pump shit the bed on my 420A swapped 2000 Neon, over heated and blew the head gasket, and warped the head, $230 later I have the head back from the machine shop, reinstalled on car, torqued to spec. Now before it blew the head gasket it would build up insane pressure in the cooling system, enough to bypass the 16lb rad cap and boil out the over flow, I switched to a 13lb brand new rad cap, and not only is it pushing coolant past the cap into the overflow and out, its leaking from the bottom of the damn cap !!!!! I need any help comments or suggestions where to start,

head flat as flat can be, torqued to spec new head gasket,
new water pump
new radiator
hose's are newer
new 195 t-stat

Thanks,
-Mike

boostalot717 · Post by **boostalot717** » Sat Apr 21, 2012 9:45 am

possibly a restricted heater core? You could just loop the lines to test.

NickKo · Post by **NickKo** » Sat Apr 21, 2012 6:23 pm

If it is building too much pressure in the cooling system, I would have to suspect that there is a crack somewhere.... Either in the cylinder head, or maybe even the block.

If you have a radiator pressure tester, you might want to start out there, and see if you can find a point of leakage.

As far as overheating goes, an often overlooked culprit, would be a warped thermostat housing - But I would think that would cause an overall loss of pressure.

- Nick

Guard1an · Post by **Guard1an** » Sat Apr 21, 2012 11:20 pm

well i switched back to the old 16lb radiator cap, and so far doesn't seem to have any issues. I have a spare filler neck, i measured the inside depth where the rad cap seats, and the one i have is shorter than the spare, yea a radiator leak tester is probably the only tool I don't own lol. I know the head isn't cracked, when the head gasket blew I had the head cleaned, magnafluxed, straightened, and had 1 bent intake valve replaced.

-Mike

boostalot717 · Post by **boostalot717** » Sun Apr 22, 2012 10:54 am

Had it magnafluxed huh? Either you got taken or you have the only iron based head I ever seen for a neon. I'm guessing the first.

stdlystdmufn · Post by **stdlystdmufn** » Sun Apr 22, 2012 12:04 pm

or the machine shop just said magnafluxed because people don't know the difference between ferrous and non ferrous heads. or that is all the counter person knows.

Donkeypuncher · Post by **Donkeypuncher** » Sun Apr 22, 2012 2:53 pm

Or maybe air trapped in the cooling system? I've seen that cause overheating on a few different cars.

Guard1an · Post by **Guard1an** » Sun Apr 22, 2012 3:07 pm

well i am used to working with cast iron mopar's, sorry i didn't use the correct termanology, he said it was pressure tested with a uv dye to see if there were any cracks in the head, there weren't. Its a reputable shop dover cylinder head, i am heard nothing but good stuff thats why i went there.

-Mike

Barry McCockener · Post by **Barry McCockener** » Sun Apr 22, 2012 3:30 pm

Donkeypuncher wrote:Or maybe air trapped in the cooling system? I've seen that cause overheating on a few different cars.

That happens to me every couple months. Just have to open the cap, let the car run til the thermostat opens up, and fill it up while it's running so all the air bubbles get out.