On 2005-10-19, TeGGeR® <tegger@tegger.c0m> wrote:
> chuck <chuck@localhost.localdomain> wrote in
> news:slrndlcato.6ma.chuck@localhost.localdomain:
>
>>
>> My 91 Civic presurrizes the cooling system upon startup. The overflow
>> tank is also under pressure and there is a slight leak under the cap.
>> There was also a spare cap under the hood when I bought the thing not
>> long ago. Is this pressure normal or is the head gasket going? There is
>> no oil in coolant, no coolant in the oil, and it doesn't smoke. It runs
>> good and doesn't overheat. But if you start it with the cap off it
>> sprays coolant. Should the overflow tank be vented? I only see one hose.
>> THanks in advance.
>
>
>
> Something is seriously wrong here. Are you saying the expansion tank has a
> pressure cap on it?
>

Well, it has a screw on type cap with the single hose from the radiator
attached to it.

> On your car there should be an 0.9-bar cap (13lb) on the radiator. This cap
> should allow pressure to bleed off into a tube in the rad filler nack that
> goes to a non-pressurized expansion tank.

The cap is a 13 lb. I can't see how the expansion tank can be
non-pressurized though. There's only the single hose going to it, and it
screws onto the expansion tank unlike most snap on type ones that I'm
accustomed to seeing. I see no apparent way for the tank to vent. The
expansion tank is original...it slides right onto the motor mount
bracket. Nevermind about the expansion tank...I found a hole drilled
into a flat spot of the threads.

>
> Is the rad cap aftermarket or OEM?
>

It's an aftermarket. Does this *really* matter? I'm thinking about a
thermostat, but it doesn't overheat and it does warm up as it should.

What I'm thinking of doing is screwing my compression testing onto each
cylinder and attaching to the air compressor and looking for bubbles in
the coolant. I guess that would tell me if it is a head gasket.