Expansion Tank Blowout- Symptom or Cause

[Houston]

Hello fellow Rover Addicts,

The truck started to overheat while looking for a parking spot in a popular drinking area. A/C stopped blowing cold and moments later I looked down to see the temp gauge approaching Full tilt. I coasted into a parking lot with the engine off. Popped the hood and saw the expansion tank jetting out a plume of steam from the side closest to the fuse box. Looked like a crack in the tank.

So would this be a symptom of extreme pressures (wouldn't the cap just have blown out since its only rated for 20psi) or would this be a cause of coolant loss (since it creates a low pressure situation allowing for a steady depletion of coolant until a tipping point is reached- the remaining little coolant becomes critically heated and all boils off in short order)

I just want some input before I go crazy. It's getting tough with my work load and purchase of a remodel-job house to keep dealing with my lovable F*#(K Up of a truck.

Also- talk me out of a EcoBoost F-150... I'm having a moment of weakness here brothers.

I have a 2004 DII with less than 10k since:

7/25/2010 (96,240 mile Engine Overhaul) Completed by yours truly and a friend. No shortcuts were taken.



Replaced Head Gaskets
Replaced Exhaust Manifold Gaskets
Replaced Engine Water Pump
Replaced Water Pump Gasket
Full Valve Job on Heads
Dipped and decked 3/1000th
Replaced Front Cover gasket
Replaced Front Crank Seal
Replaced Timing Chain and Gear Set
Replaced Valley Gasket
Replaced Intake Gasket
Replaced Rocker Cover Gasket
Re-wrapped degraded wire harness cover
New Air Filter
New Thermostat
New Bosh Platinum+4 spark plugs
New Accessory Drive Belt
Pennzoil 5W/30 and Oil Filter
New Fuel Line and Evap. Line
Replaced Throttle Body Heater Plate Gasket and Hardware

 

[Houston]

Thought this would be a slam dunk for someone. Hmmmm.

 

[ptschram]

I've not had a DII tank split. In the event they are ever available again, I'll have them again.

 

[discostew]

ive seen them crack. Ive also seen the nipples break off. If it was a big pressure build up in the system it would have gone out the cap/boiled over.

 

[jhk07]

I saw this thread yesterday. Maybe I will give you some bad TECH and someone will jump on here and correct me.


My first thought ..... Possibly cap was bad. Pressure built up. Tank was weakest point????


I think I'd replace those, cap and the tank. then keep a very close eye on the cooling system for over heating.


Might be time to invest in a Scangauge or similar instrument for real time temp readings.
It is great peace of mind to know it is 98 outside and I have to give it hell to see 204 on the Scangauge.

 

[mbrummal]

I'm thinking the fan had something to do with it. If the AC started to blow warm there wasn't enough airflow over the condenser or radiator. Also, those spark plugs suck.

 

[ptschram]

The cap should vent long before the tank does.

My money's on weak tank.

 

[DarylJ]

I'm thinking the fan had something to do with it. If the AC started to blow warm there wasn't enough airflow over the condenser or radiator.

It's pretty typical of an overheat situation (when sitting still or moving slowly) to have the AC start blowing warm. It doesn't tell you much of anything, as it is a symptom of the condenser not cooling enough to do its job. Even if the electric fan is doing it's job, it's not going to overcome the ridiculously hot radiator that the condenser is bolted against.

I'd suggest that the first thing I'd replace is the cap (and the broken tank). If you want to get more into this before replacing parts that you'll be replacing anyway, rent a coolant combustion leak tester from Autozone or similar if you still have enough coolant in the system to take a sample. If it comes up positive for combustion gasses, you know it wasn't (just) the cap or tank.

 

[KyleT]

i have seen many blow the nipple off the bottom from fatigue.

 

[discostew]

Ya

 

[Springsroverfamily]

Just replaced the nipple on mine with a brass one from Lowes. I did the repair two weeks ago and have not had a problem since. It took me about 30 minuted to drill and tap the tank.

 

[no694terry]

could the DII's ecu kill power to the ac compressor when the engines running warm as a safety type thing, kind of like how the pressure switches kill power when refrigerant/oil is low?

 

[DarylJ]

could the DII's ecu kill power to the ac compressor when the engines running warm as a safety type thing, kind of like how the pressure switches kill power when refrigerant/oil is low?

The DII's compressor clutch wiring does not go through the BCU. Only the climate control computer, which I don't believe has any idea what the coolant temp is.

 

[JohnB]

True but the aux fan does get powered by the BCU and has every idea about your engine temp as well as vehicle speed.

 

[DarylJ]

True but the aux fan does get powered by the BCU and has every idea about your engine temp as well as vehicle speed.

So it would be on.......which is not a problem and wouldn't be a contributing factor to the AC going warm during an overheat.

 

[uglysteve]

Stuck thermostat, Ageing plastic tanks, bad radiatior cap, fan failure. That is what I would check first.

 

[Houston]

Zombie thread to answer the question...

I hate when I find a question on here and no answer because the owner figured it out, and thusly lost interest in filling int he community. You know... what I did here....

The issue was a viscous fan clutch failure. It was in the throws of going completely free-wheel and thusly wasn't cooling the engine as I crept around the busy traffic. The system pressure spiked and the tank broke where it had been tapping on the mount (not snapped in due to the prongs being bent) for a long time.

If you change the fan clutch buy the 36mm fan clutch wrench and a fan clutch holder. It makes the whole process a 1/10 where, when I have changed my water pump and had to do it before without the proper tools it was a 8/10 frustrating pain in my assets. Thats my opinion, im sure someone is a fan clutch ninja and can take on off with a bar-b-que fork and a machete.

 

[DarylJ]

Thats my opinion, im sure someone is a fan clutch ninja and can take on off with a bar-b-que fork and a machete.

Water pump pliers and a square pry bar work at about a 3/10 if you know where to put them.

 

[honda50r]

I had to resort to an air wrench, mine was extremely fucked