[urq] boiling coolant after shutdown

[Pasqualoni, James E]

Hey Ed,

You may also want to try some Water Wetter to reduce any localized boiling.

HTH,
Jim 

-----Original Message-----
From: urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] On Behalf
Of Louis_Alain_Richard at computerhorizons.com
Sent: Tuesday, July 26, 2005 1:04 PM
To: Ed Kellock
Cc: Urq List; urq-bounces at audifans.com
Subject: Re: [urq] boiling coolant after shutdown






My first culprit would be the reservoir pressure cap (or another small leak
permitting a lower system pressure).

Following a lister suggestion, I made a low pressure cap (by cutting the
spring inside) to give the cooling system a break. Like you, I had many
leaks one after the other. My problem with the low-pressure cap was exactly
like yours; at shut-off, I was clearly hearing boiling in the head, by
burst. I guess the cap must have a good pressure to prevent localized
boiling around the exhausts valves. When I put a new cap, and did sufficient
cycles to completely bleed the system (which is (notoriously ?) hard to
bleed), no more boiling issues.  And no more leaks either...

HTH,

Louis-Alain


urq-bounces at audifans.com wrote on 2005-07-26 12:46:30:

> It's very cool here this morning for a change so I decided to drive 
> the urq to work.  I had the heater valve wide open and the engine 
> temperature never exceeded normal, the cooling fan did not come on, 
> even with a minute of idling after reaching work.
>
> Inside the hose from the neck on the front of the head that goes to 
> the top of the radiator, the coolant was very obviously boiling.  Is 
> this even remotely normal?
>
> History: On June 25th, at 3am, I was on my way to meeting everyone to 
> go up the road to the Pikes Peak Hillclimb.  I had been driving the 
> car regularly prior to that and it was running great.  It was cool, 
> jacket weather still in fact, and I drove very sedately for about 5 
> miles, stopping off at a 7/11 for some coffee.  When I restarted the 
> car to leave, the coolant low level warning was on.  A leak had sprung 
> under the clamp on the lower rad hose at the thermostat housing.  I 
> refilled and drove a few more miles to the meeting place.  I stopped 
> and refilled and then drove a short bit more where I finally ditched 
> the car at the gate of Pikes Peak and rode up with Bruce Bell.  Later 
> that day, I retrieved the car and drove very carefully and 
> uneventfully home where a couple days later, I replaced the offending 
> hose with a spare from Ben Howell (Thanks Ben!) along with a new lower 
> temp thermostat and a new thermo-time switch at the back of the head.
> The next day I drove to work and another leak sprang, in the hose that 
> goes from the bottom of the coolant recovery tank to the bottom of the 
> radiator. I replaced that.  The next day the throttle cable came loose 
> from the pedal in a store parking lot during a hail storm, which being 
> the third strike in less than a week signalled the beginning of the 
> cooling off period between the urq and I.  Since then I have only 
> driven the car home from that store, one quick trip around the 
> neighborhood a week or so ago and then to work today.
>
> The boiling in the hose was present back on June 25th, but I figured 
> it was merely a product of my low/leaking coolant tribulations then.
> Now, the system is leak free, with a new thermostat, which obviously 
> opens earlier and causes the car to run cooler, and the temp on my way 
> to work this morning was sub-70 and my drive was not spirited, except 
> for one light blast short-shifting into 2nd, then 3rd, to keep the 
> boost from falling off.  That wasn't more than a couple hundred yards, 
> followed by at least a half mile of 4th and 5th at 40 mph or so.
>
> If you've read this far, thank you, and I appreciate any thoughtful 
> input you may have.  I'm thinking head gasket, but I tend to be 
> overreactive and paranoid sometimes, so I'm hoping that's the case 
> again this time.
>
> Ed
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