Cooling system problem?

[oldskewel]

Originally Posted by andrewwynn

I think more likely just head pressure vs. air pressure. I'm not aware of any check valve that could actually cause pressure.

I'm thinking more that things were under pressure when it was warm, and then it just held, even as things cooled and contracted. Kind of like how if a garden hose with a trigger nozzle is pressurized and then turned off at the hose bib - the pressure is retained in the hose until the trigger is pulled, and then the pressure releases and the hose contracts slightly.

[oldskewel]

Originally Posted by Effduration

Sorry to hear...Any signs of coolant in any of the cylinders ?

stumble on cold start-up
puff of smoke on cold start up

If either, I suggest you swab each cylinder one morning after a full-temp run the day before.

This happened to me after doing a head gasket on my E53...5k miles and a year later, I found coolant in a cylinder, leading to head gasket #2..

Good tip. No running problems noted at all. As an alternative to the next-day test you suggest (but same effect), when I did HG #1, I actually used my Motive Brake Pressure bleeder to pressurize the cooling system to about 20 psi, I think, and let it sit like that for an hour before finding coolant in the cylinders.

I wish I had not sold my timing kit on Craigslist. Will need to buy a new one on eBay if I do end up doing a second HG.

[andrewwynn]

Originally Posted by oldskewel

I'm thinking more that things were under pressure when it was warm, and then it just held, even as things cooled and contracted. Kind of like how if a garden hose with a trigger nozzle is pressurized and then turned off at the hose bib - the pressure is retained in the hose until the trigger is pulled, and then the pressure releases and the hose contracts slightly.

Not with the reservoir cap off. I'm not aware of any possible way for air pressure to stay. I have had vacuum in the system that collapsed the hoses before but only until letting air in (sadly but breaking my thermostat in half)

[80stech]

I'm curious if you used the timesert/bigserts ?

[oldskewel]

Originally Posted by 80stech

I'm curious if you used the timesert/bigserts ?

I used the special length TimeSerts for the M54, not BigSerts. I did not even know about BigSerts until they were mentioned (I think by Effduration) while helping someone else's HG repair.

[Effduration]

Originally Posted by oldskewel

….
I wish I had not sold my timing kit on Craigslist. Will need to buy a new one on eBay if I do end up doing a second HG.

Happy to loan you my timing kit for the cost of shipping

I rent time-sert and big-serts kits 1090 & 1090BS as well.

When my Head gasket job failed, it was either a problem with the head or maybe I damaged the head gasket on installation.. my regular time-serts did not fail.

I don’t use big-serts unless the hole has been previously repaired with an insert
(Regular time-sert, helicopters, etc.) and subsequently failed..

[80stech]

@Oldskewel-- How are things going with this?

[oldskewel]

Originally Posted by 80stech

@Oldskewel-- How are things going with this?

Nothing going on. I'll surely keep this thread updated with progress, more questions, and hopefully the answer.

My daughter took a different car off to school (down in L.A., and she is immediately missing the feeling of security the X5 gave), and the X5 is in my driveway while I am 1000 miles away in WA indefinitely, taking care of my elderly parents.

[80stech]

The X5 is for sure up there for making a person feel safe driving it. Taking care of parents or being a caregiver in general is a lot tougher than most people realize. You have my best wishes.

[DoubleAIm]

What does the wires going to the thermostat do? Temp sensor? Thermostat open/closed sensor? Also, the temp gauge reads off which temp sensor, lower coolant hose, thermostat or the sensor on the engine block near the back?