coolant leak

[lowthreeohz]

i've been working on this 1.0 g10 engine and it's all back together, but the coolant / thermostat housing that mates up to the head just wont stop leaking.

i've tried mounting it

bare (metal to metal)
bare (with black RTV)
gasket paper
gasket paper with RTV

it weeps out of the base of the housing no matter what. head surface is fresh from the machine shop and i took a wire wheel to the housing to clean it up.

wtf am i doing wrong?

[mstng86]

Pics?

[dee]

Stop putting coolant in it, leak fixed. In all seriousness though do the rtv but let it setup good before pouring anything into the system and see if that helps.

[lowthreeohz]

Stop putting coolant in it, leak fixed. In all seriousness though do the rtv but let it setup good before pouring anything into the system and see if that helps.

I followed the directions on the RTV - allowing 1-2 hours for it to setup - before i finished threading the housing on.

[lowthreeohz]

Pics?

really? of an installed thermo housing?

[mstng86]

I figured maybe you took it all apart and was asking what to do now.. I would think the RTV would have taken care of it.

[lowthreeohz]

it's been apart and back together 3 times in 2 days. i'll try again when i wake up....i should go to bed.

[Superwho]

Try soaking the gasket in water first.

[dee]

I followed the directions on the RTV - allowing 1-2 hours for it to setup - before i finished threading the housing on.

Look it over real close when it's leaking and make sure it's leaking between the two and that the aluminum doesn't have a pinhole in it.

[Mysticcobrakilla]

Try this, we use it at work with great success.

http://m.summitracing.com/parts/lct-37394/media

[DriveWayBuilt]

I had the same problem with my 351. I made a new surface with JB weld then made it flat worked for me (thermostat housing)

[shumpertdavid]

I followed the directions on the RTV - allowing 1-2 hours for it to setup - before i finished threading the housing on.

assuming I understand you correctly (you're putting rtv on, waiting 1-2 hours then bolting the housing on), then you are doing it incorrectly in my opinion. Put a thin coat of rtv on the cylinder head side, a thin coat on the housing side, allow 3-5 minutes for the rtv to skin over, and reassemble with a gaskets. If there is a recess for the thermostat to sit in (like on a 302-351) then you can use a little rtv in the groove to "glue" the thermostat in. You may also want to take a file and work the housing over a little to make sure it doesn't have any high spots. If the bolts have been overtightened then the bolt hole ears could be high causing the housing to not sit flush.

[lowthreeohz]

assuming I understand you correctly (you're putting rtv on, waiting 1-2 hours then bolting the housing on), then you are doing it incorrectly in my opinion. Put a thin coat of rtv on the cylinder head side, a thin coat on the housing side, allow 3-5 minutes for the rtv to skin over, and reassemble with a gaskets. If there is a recess for the thermostat to sit in (like on a 302-351) then you can use a little rtv in the groove to "glue" the thermostat in. You may also want to take a file and work the housing over a little to make sure it doesn't have any high spots. If the bolts have been overtightened then the bolt hole ears could be high causing the housing to not sit flush.

I followed the instructions on the back of the RTV.. it says to thread the objects together and when rtv starts to ooze out of the seam you stop, let it setup, then come back in an hour to finish tightening down.