MG-Rover.org Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter #1
Hey there.

I've been having Problems with my 2001 45 1,6l. The car had the the head gasket changed cause of failure in 2011.
Heater is blowing cold and temperature of the engine rises if the car is driven.
Allready changed Thermostat with housing (twice), did the coolant pump with Timing belt and flushed the System twice. Even vacuum filled it.
Problem still remains. I dont know what to do anymore. Could it be another HGF?

Thanks in advance
 

·
Registered
Joined
·
1,783 Posts
Could be HG failure but the heater should be get hot. Silly question but the cooling system is definitely bled correctly isn't it? I always find removing the top hose from the radiator and filling that up up&go there's coolant in the engine block helps massively
 

·
Registered
Joined
·
6 Posts
Discussion Starter #3
Didnt tried it with directly filling it into the hose yet. Tried to bleed the system like normal serveral days in a row with open reservoir cap until coolant rises, close it and let it warm up till the fans kick in. Also cleaned the jiggle valve. I heard it may help drilling it out. Ill try filling trough the top rad hose. Thanks for your clue :)
 

·
Registered
rover_25
Joined
·
142 Posts
Also try running the car with the cap off and squeeze any coolant hose you can see to burp any air pockets out.
 

·
Registered
'06 MG ZR +120 (HQM) '04 MG ZR 105 (IAB)
Joined
·
9,334 Posts
...Also cleaned the jiggle valve. I heard it may help drilling it out
The jiggle valve is there to allow gases trapped in the top of the head to vent to the expansion tank and relies on the fact that gas will leak through a very small gap easily whereas fluid coolant won't.

If you remove the jiggle valve, it will simply allow a constant flow of coolant to discharge to the expansion tank, and as the jiggle valve is almost straight above where the inlet from the water pump lies, this will be primarily cooled coolant that has just returned from the radiator, and will also reduce the flow through the rest of the head. As there has been much evidence over the years that the flow through the head is barely sufficient at times, reducing the flow further by removing the jiggle valve would be less than beneficial! I would strongly advise leaving it in place.

As to whether you could have a repeat HGF; whilst very possible, the most usual advice is that if you do not have any of the usual symptoms of HGF (any combination of coolant loss, emulsified oil in the expansion tank or in the oil filler cap, or significant residual pressure remaining in the coolant system even when it has cooled completely), then it probably isn't HGF.

Overheating is not in itself a sign of HGF, but may result from coolant loss or exhaust gas leaking into the coolant system and causing air locks. I would think it is possible that you have simply created an air lock during refilling - as well as trying John's idea of filling the system up via the top hose, ensure that the heater is set to hot to allow air to be expunged from the heater matrix during filling. Similarly to filling via the top hose, I usually remove the small coolant pipe from the elbow at the front of the engine and fill steadily via the expansion tank until the coolant runs out at this point. I then refit the hose and continue filling. I then squeeze hoses thoroughly to help move any remaining air pockets and continue doing so whilst warming the engine up - I usually do this with the coolant cap in place (I don't think there is really a great deal of benefit in leaving it off).

However, if you are using a vacuum fill system, you shouldn't be having problems with trapped air anyway?
 

·
Registered
Joined
·
6 Posts
Discussion Starter #6
Thanks for your reply. Good to know, so i will leave the valve in place.
Maybe i should note that the Problem appeared suddenly while driving. Heaters went cold and the engine temperature went up. Only after that i changed all those parts (Stat, WaPu, Cap)
Also there was a smudgy residue in the expansion tank and the coolant was a muddy Brown (but no emulsion). Cleaned that out troughly as well as rinsing all the hoses and engine with a little pressure and clean water.
As far as i can see there are no coolant leaks in the engine bay nor is the carpet wet.
The Problem also only occurs while driving. If the car is standing, i could even rev it without anything happening after i let it heat up.
As you said there shouldnt be any air locks from the start to begin with cause i filled the system with vacuum.
Fiddling around with this .... for three month now and slowly going crazy.
 

·
Registered
Joined
·
11 Posts
hi, whats the coolant pressure like? if you rev engine does the coolant in the header decrease? i had similiar issue on mgf for a year, idled fine and but occasionally driving along heater would go cold and temp gauge starts rising until it overheated, also once cool and left for a day is there still pressure in system? i started to notice that the coolant in the header tank would almost disappear, also is it losing coolant in that it needs topping up? sorry if i ask stupid questions but i have been there like you, drove me nuts for a long time as everyone said its not hgf which i agreed with.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #8
Coolant in the Header tank decreases slightly if i rev it, but comes back if i get of the pedal. Has not needed top ups Till now. I'll See tomorrow when i get Home of there remains pressure in the System when it cools. Also want to do a sniffer Test.
 

·
Registered
Joined
·
11 Posts
Coolant in the Header tank decreases slightly if i rev it, but comes back if i get of the pedal. Has not needed top ups Till now. I'll See tomorrow when i get Home of there remains pressure in the System when it cools. Also want to do a sniffer Test.
are both pipes to the rad hot when it starts to over heat?
 

·
Registered
Joined
·
11 Posts
next then, if you drive the car with heater set to cold then the coolant flow will be head then thermostat open just to rad and back see if that makes any difference, it might sound odd it helped mine when i was trying to work out if my head gasket has gone as it seem to cut down the creation of air locks. there has to be air being generated from somewhere if the heater goes cold so either from the combustion chamber or leaking inlet gasket/water piper etc. the excess pressure will be a good clue if its head gasket has gone.

i aslo tried a sniff test from one of those from ebay didnt show any gases present unless you put the liquid in front of the tail pipe so i continued to think its not the hgf.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #12
Update now the car isnt covered in snow anymore.
Did a sniffer Test twice (with one i know works) and there seems to be no gases in the coolant. Also got a hint it could be a clogged heater Matrix or my Stat could be sitting in the wrong direction. Checked the Stat and seems to be fine. Also bypassed the heater Matrix and did another vacuum fill. Problem changed. Now the temp raises as soon you get of the throttle. Could be trapped Air. Will try to bleed the System once a day in the coming week and check if the Problem reappear.
 
1 - 12 of 12 Posts
Top