Overpressurized Coolant System

[thekingof7]

This is a continuation of http://www.audizine.com/forum/showth...-Bad-Reservoir.

I have since had the head tested (ok), and have completely redone the head gasket job. Just for the hell of it I tried felpro bolts and gaskets, I have not noticed a difference from the Victor.
At this point the car throws no codes and seems to drive nicely, but I have noticed coolant coming from the reservoir from the pressure release valve in the neck of the reservoir. (Cap has been replaced) This only happens when the engine is under load, idling will not produce the symptom.
When draining the tank to check for anything odd, I noticed a decent amount of silt-like material in the coolant. It was sandy and a bit reddish. Could this be indicative of a blocked passage of some type? Could this cause the system to overpressurize? Air in the system?

I am confused, as the head gasket was replaced twice, ran great each time, but has the same issue with the coolant system becoming overpressured.

-Anyone have any experience with this?

[onceover]

Did you have the head pressure tested when you did the head gasket?

Any issues with overheating? I dont see how you can get excessive pressure otherwise, unless the head is cracked.

[thekingof7]

No overheating to speak of. The shop I took it to said they pressure tested it and everything was fine. Could air in the system cause anything like this? Are those particles in the coolant indicative of something?

[FromS60toB61.8t]

in for the results...

had crazy pressure in mine last week, almost exploded my coolant tank.

did the thermostat and coolant temp sensor today and its better but still get slight pressure and my radiator only gets hot on the driver side rail. Passenger side stays cold along with the top of the radiator fins. Heat also isnt working.

my next thing will be to get the radiator cleaned/tested.

Im also getting the brown/reddish silt so i want to know how yours turns out along with me letting you know if i find out whats wrong with mine.

(Backstory of mine)

metal water pump gave out after 25k miles on it @ 104k miles
Head was rebuilt, head gasket replaced, full timing belt svc done, all was well for 3k miles.
Replaced coolant flange last month with the ECS kit and Vaico purple 50/50 mix(non oem coolant temp sensor)
Temp was sometimes reaching normal opperating temps but usually only showed 1/4 temp on the gauge even on 85F days (guessing it was the non oem sensor)
System got pressurized 2 weeks ago, put stretch lines all over my tank, blew out the rear charge pipe elbow, melted the bleeder on the rail, blew out all of my coolant.
thermostat replaced with oem, temp sensor replaced with oem, VW/Audi 50/50 coolant mix, fans are kicking in, heat not working, radiator not getting hot up top or passenger side.

[Waspjr]

Try some snoop detect it is easy and cheap to do its a fluid that will change colour when combustion gasses flow threw it.
It goes on the coolant reservoir

[diagnosticator]

When you had the head off the block, did you check the head for warping? If the head is warped, that will explain the symptom. It is also consistent with a warped head, for the gasket to leak combustion gasses into the cooling system during high load operation, but not at idle or low loads. If the head is warped, it does not take much pressure from the combustion process to lift the head enough to loose the pre load clamping pressure of the head on the gasket/block at the cylinder where the warp distortion is the greatest, typically cylinders 2 and or 3. If the bolt holes where not cleaned and the threads oiled during installation, then the head bolts may not be clamping the gasket with the force needed to maintain the gasket seal.

[Waspjr]

When you had the head off the block, did you check the head for warping? If the head is warped, that will explain the symptom. It is also consistent with a warped head, for the gasket to leak combustion gasses into the cooling system during high load operation, but not at idle or low loads. If the head is warped, it does not take much pressure from the combustion process to lift the head enough to loose the pre load clamping pressure of the head on the gasket/block at the cylinder where the warp distortion is the greatest, typically cylinders 2 and or 3. If the bolt holes where not cleaned and the threads oiled during installation, then the head bolts may not be clamping the gasket with the force needed to maintain the gasket seal.

Every head leak possibility or weird condition i snoop it. Spend the 30.00 and don't guess
Sorry i think its a lil more than that but if you are ever iffy just snoop it then like (up) says and get it checked out.

[diagnosticator]

in for the results...

had crazy pressure in mine last week, almost exploded my coolant tank.

did the thermostat and coolant temp sensor today and its better but still get slight pressure and my radiator only gets hot on the driver side rail. Passenger side stays cold along with the top of the radiator fins. Heat also isnt working.

my next thing will be to get the radiator cleaned/tested.

Im also getting the brown/reddish silt so i want to know how yours turns out along with me letting you know if i find out whats wrong with mine.

(Backstory of mine)

metal water pump gave out after 25k miles on it @ 104k miles
Head was rebuilt, head gasket replaced, full timing belt svc done, all was well for 3k miles.
Replaced coolant flange last month with the ECS kit and Vaico purple 50/50 mix(non oem coolant temp sensor)
Temp was sometimes reaching normal opperating temps but usually only showed 1/4 temp on the gauge even on 85F days (guessing it was the non oem sensor)
System got pressurized 2 weeks ago, put stretch lines all over my tank, blew out the rear charge pipe elbow, melted the bleeder on the rail, blew out all of my coolant.
thermostat replaced with oem, temp sensor replaced with oem, VW/Audi 50/50 coolant mix, fans are kicking in, heat not working, radiator not getting hot up top or passenger side.

All of the symptoms you describe are associated with having air trapped in the cooling system. When refilling the system with coolant, fill the expansion tank, and allow the coolant to slowly drain into the engine. After the tank is nearly empty, refill the tank and wait for the coolant to drain into the engine. Refill the tank again and repeat until coolant flows from the bleeder plug in the coolant pipe. Reinstall the bleed plug and top up the coolant tank, then tighten the tank cap. Next, run the engine at 2000 RPM until the rad fan runs, then either drive the car or turn the engine off and let the system cool down before removing the tank cap to top up the coolant as needed. It could take as much as an hour to refill the cooling system.

[diagnosticator]

Every head leak possibility or weird condition i snoop it. Spend the 30.00 and don't guess
Sorry i think its a lil more than that but if you are ever iffy just snoop it then like (up) says and get it checked out.

I agree with you.

[FromS60toB61.8t]

All of the symptoms you describe are associated with having air trapped in the cooling system. When refilling the system with coolant, fill the expansion tank, and allow the coolant to slowly drain into the engine. After the tank is nearly empty, refill the tank and wait for the coolant to drain into the engine. Refill the tank again and repeat until coolant flows from the bleeder plug in the coolant pipe. Reinstall the bleed plug and top up the coolant tank, then tighten the tank cap. Next, run the engine at 2000 RPM until the rad fan runs, then either drive the car or turn the engine off and let the system cool down before removing the tank cap to top up the coolant as needed. It could take as much as an hour to refill the cooling system.

I filled the tank, waited for it all to drip down, it took in about 1.5 gals. Turned the car on, let it idle for 15-20 mins until it reached temp and after a but with heat turned on low. A while after it idled for a bit there was some gurgling in the tank and it dropped from the max line to just bellow min. Drive it around a bit, light and heavy load. Parked and let it cool down. Coolant read still just under min. Radiator still cool on the top fins and passenger side. Once it cooled down I opened the cap and all of the coolant that bubbled away rushed back into the tank and it read just over the max line now.

[thekingof7]

I filled the tank, waited for it all to drip down, it took in about 1.5 gals. Turned the car on, let it idle for 15-20 mins until it reached temp and after a but with heat turned on low. A while after it idled for a bit there was some gurgling in the tank and it dropped from the max line to just bellow min. Drive it around a bit, light and heavy load. Parked and let it cool down. Coolant read still just under min. Radiator still cool on the top fins and passenger side. Once it cooled down I opened the cap and all of the coolant that bubbled away rushed back into the tank and it read just over the max line now.

You mind starting your own thread man Sounds like you got a whole 'nother set of issues.

[thekingof7]

Attn! Check the thread I linked you to at the top of this thread. It will fill you in on everything done.

The head was milled and pressure tested. When it was milled, the machinist told me how warped it was. The measurement for the warp was actually still within spec but I chose to have it milled down anyway.

I'll check the radiator and see how it feels but it seemed to be heating up normally. Is there any relation to the odd rusty sand I found? Could this cause over pressure?

Has anyone heard of the block warping on these 1.8s? I dont have a nice machinist's straight edge tools for checking.