Expansion Cap Blew off !!!

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bawnmore11

Member
Posts
12
Location
Galway, Ireland
Car is a 2000 1.8 petrol. Yesterday at the NCT (MOT), the guy locked on the accellerator at high revs to test emmisions and seemed to go away. After 4 minutes, the expansion cap overflowed and we had steam and coolant everywhere. Obviuosly i didn't pass and had to listen to "head gasket gone, bring it to a garage" from the test guys who didn't seem to know a whole lot about cars.

So checked it, filled it up, bleed it and took it home. Into own garage, checked fans by disconnecting the temperature sensor and repeated the test. The temperature guage never got to center or the fans never came on but after 5 minutes, off the cap blew and landed outside the car, coolant everywhere.

I had been loosing water over the last while but replaced it weekly often been overkind with the level been a little high to 'compensate'.

I had replaced the caps recently with ones that I bought from eBay which was likely my second mistake.

So guessing that
a) since i can bleed it, the pump is likely working
b) the extra fill and the eBay expansion caps resulted in crap cap
3) ordering a new cap to try test again.

Does that make sense?
 
bawnmore11 said:
Car is a 2000 1.8 petrol. Yesterday at the NCT (MOT), the guy locked on the accellerator at high revs to test emmisions and seemed to go away. After 4 minutes, the expansion cap overflowed and we had steam and coolant everywhere. Obviuosly i didn't pass and had to listen to "head gasket gone, bring it to a garage" from the test guys who didn't seem to know a whole lot about cars.

So checked it, filled it up, bleed it and took it home. Into own garage, checked fans by disconnecting the temperature sensor and repeated the test. The temperature guage never got to center or the fans never came on but after 5 minutes, off the cap blew and landed outside the car, coolant everywhere.

I had been loosing water over the last while but replaced it weekly often been overkind with the level been a little high to 'compensate'.

I had replaced the caps recently with ones that I bought from eBay which was likely my second mistake.

So guessing that
a) since i can bleed it, the pump is likely working
b) the extra fill and the eBay expansion caps resulted in crap cap
3) ordering a new cap to try test again.

Does that make sense?
Click to expand...

Name and shame the garage, 4min at high revs is a bit excessive!

caps are supposed to vent excess pressure at 1.1bar, once vented some of the spring valves don't re-seat themselves properly, try a different cap?
 
blocked jiggle valve in the inlet manifold

incorrectly bled


these are two other options worth checking before hgf
 
Garages seem to like blowing the cooling system on k series engines. I've been present when 2 have let go. Neither had hgf. I'd be asking questions about the length of time at high revs.
 
I've been thinking about it. The fool did leave it for about 5 minutes at full revs. I was wondering why (at hte time) whereas most of the testers just reved the cars for a short period. I did loose the head (mine) for a while and had my test money returned.

Irrespective, it shouldn't have blown coolent and steam everywhere. Fan should have kicked in and everything should have been fine.

So thinking more about it, maybe the thermostat is stuck closed. The temperature sensor for the fan is beside the one for the temp guage. They are both on the bottom radiator hose. So if the thermostat is stuck closed, the coolant would heat in the engine but not in the radiator so would not indicate on the guage or turn the fan on. If I'm right, seems like dubious positioning of the sensors.

I also had a feeling that the engine was running hot even though the temperature guage never went past the middle.

Thoughts as tomorrow, thermostat comes out and new cap will be fitted.

And, fair play to the helpful comments about the K engine being crap. If you know they are crap, go to a different forum or get a life.
 
Just saw 'fan sensor' faulty thought. Wouldn't the fact that the guage never went above middle before expansion cap 'take off', mean that the coolant tempature at the fan temperature sensor was also low. They are different sensors so unlikely to be both wrong.
 
bawnmore11 said:
I've been thinking about it. The fool did leave it for about 5 minutes at full revs. I was wondering why (at hte time) whereas most of the testers just reved the cars for a short period. I did loose the head (mine) for a while and had my test money returned.

Irrespective, it shouldn't have blown coolent and steam everywhere. Fan should have kicked in and everything should have been fine.

So thinking more about it, maybe the thermostat is stuck closed. The temperature sensor for the fan is beside the one for the temp guage. They are both on the bottom radiator hose. So if the thermostat is stuck closed, the coolant would heat in the engine but not in the radiator so would not indicate on the guage or turn the fan on. If I'm right, seems like dubious positioning of the sensors.

I also had a feeling that the engine was running hot even though the temperature guage never went past the middle.

Thoughts as tomorrow, thermostat comes out and new cap will be fitted.

And, fair play to the helpful comments about the K engine being crap. If you know they are crap, go to a different forum or get a life.
Click to expand...

complain to your local authority and test centre, ask under freedom of information request the number of vehicles tested by that muppet which have failed the emissions test......and the statutory legal requirement.
you need to shout a lot to get anywhere with those idiots.

Your fans should kick in when brown sensor is disconnected, if not, then the sensor is faulty ( as already suggested by others above)

The stat stuck shut will cause temp gauge to rise above halfway at standstill and full revs. if you remove it the engine will take forever to warm up and temp plummets when driving normally.

As freelaner suggested post 5, check jiggle valve by repeatedly squeezing top rad hose (engine switched off) ball bearing should make a rattling sound
 
Last edited:
If you take something into a garage and its working fine, then it ####s up catastrophically while theyre working on it, surely its their fault and they gotta fix it??!!

That being said, I suppose it might be difficult to prove they broke it, if it is HGF it could have been building up a long time I guess.

Ive got a K series too, my MOT is due this month, I hope they dont blow mine up too! :(
 
Been working on it slowly.

1) Pulled out the thermostat and it opened when boiled. No thermometer so couldn't check at what temperature but it opened wide and closed when cooling. It was the type that mounted on the radiator hose as opposed to the cylinder block.

So fully refilled and bled it and carried out a Co2 combustion test at the expansion bottle. Nothing was detected so that's good news (liquid stayed blue).

Took a black expansion cap from another freelander. The fit was brilliant as opposed to the 'yellow' one that was there previously. I'm now totally guessing that it was my own stupidity. Never buy an expansion cap for £2.25 on ebay. I had bought TWO of them here. Suspected the first one of leaking so replaced with the second one. The second was the one that launched into outer space.

Am now waiting for the car to cool down to give it the high revs 5 mins test similar to my friendly NCT testman.

Feeling positive :) ish
 
I think it's OK with a 'slight' worry. Reved it for nearly 10 minutes in the garage at 3500 revs. Nothing blew up, the bottom radiator hose got nice and hot BUT the temperature guage never went over 'just below' half way and the fans never came on.

I read in another thread that the radiator is big but....

The fans do come on if I disconnect the coolant sensor. The coolant sensor for the fan and the one for the guague are different so they both can't be faulty.

Long drive tomorrow so the fresh air will keep the rad cool. Guessing that I'm not finished yet...
 
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