Yeah. That's what a colleague of mine - who has owned a NA and a Turbo - told me today- basically relieving pressure off the radiator or expansion tank. Really smart guy, knows what he's talking about (former nuke sub captain in the Navy), but I've never heard of this. Is it something any of you do? Said he went too long and nearly blew some gasket once...

"on top of the radiator hose to the engine water neck you will find a bolt....you start with car running cold and open the bolt just a little and once the fluid burps out shut it. crack it open and you will see it sputter then as the car warms the fluid will push the air out then shut....rev a few times and repeat before car gets too hot. normally twice and you are golden for another week."

 

Sounds like he somehow got confused and thinks it's necessary to bleed the cooling system regularly.

If he does then there are other problems to be addressed...

 

I wonder if he had a marginal head gasket and was building up air in the system?

 

yeah you should have to do that once- when you fill the system- then not again.

 

Don't overtightened that little bleeder screw... It's an odd thread size and it sucks stripping it out or breaking the head off late at night before a track event...

 

From experience?

 

Anyone have a picture of this bolt? I feel like an idiot but I cant seem to locate it. (87 944 turbo)

EDIT: Nvm, found a pic here:
http://www.944online.com/images/prod...esale29011.jpg

 

Tim, on my new car. I changed the coolant - or, more specifically, I replaced the water with coolant, and the head of the bleeder snapped off when I gave it a most gentle tightening...

I was able to get the stub out by jamming a pick in the bleeder's hole and unscrewing it. Then I discovered that there was a helicoil in the housing... it had been stripped before.

Upon inspecting the broken bits, it turns out that bolt had broken most of the way through much earlier (there was corrosion on the fracture). It's an M8x1.0 (fine) thread, so you can't use a standard M8.

Luckily, I had the right die (and a lathe), so i was able to cut the threads off of a long M8 (that has a smooth shaft under the head), threaded and drill it. Finished up about 1am saturday... left sunday for watkins glen.

 

Umm, no. If pressure needs to be relieved, it'll do it. When it hits 13psi to be exact. This is what your radiator cap is for! When the pressure reaches 13psi, the little spring in the cap is compressed to the point that the rubber seal no longer, well, seals. They only reason something would burst in the system because of pressure would be because a part was already broken (from thermal stress, thermal break down, or whatever).

The only reason you have to "burp" the system is because it takes a long time for any trapped air to make it's way to the expansion bottle (if it ever does). Burping just speeds up the process. Any air that is burped is replaced with water, which is why you have to keep adding water when you're burping the system.

If/When the water heats up, it expands, which is why the expansion bottle is there.

BTW, the 944 uses a "closed" cooling system. Some cars use an "open" system, which essentials burps itself, but this doesn't apply here.

 

If there's one thing I've learned in the Navy, its that Nukes lack common sense. Don't know what your friend is on about, but like everyone else has said, this only needs to be done when air has the potential to enter the system.